Showing papers in "Phytoparasitica in 2017"
TL;DR: Considering that high mortality was observed in aphids within 24 h of exposure to a very low concentration of the butanol fraction from I. rugosus, it is believed this could be exploited and further developed as a potential plant-based insecticide against sucking insect pests, such as aphids.
Abstract: With the aim of selecting potential botanical insecticides, seven plant extracts (Daphne mucronata (Family: Thymelaeaceae), Tagetes minuta (Asteraceae), Calotropis procera (Apocynaceae), Boenninghausenia albiflora (Rutaceae), Eucalyptus sideroxylon (Myrtaceae), Cinnamomum camphora (Lauraceae) and Isodon rugosus (Lamiaceae)) were screened for their toxic effects against four important agricultural pest insects, each representing a separate insect order; pea aphids of Acyrthosiphon pisum (Hemiptera), fruit flies of Drosophila melanogaster (Diptera), red flour beetles of Tribolium castaneum (Coleoptera), and armyworms of Spodoptera exigua (Lepidoptera). Aphids were the most susceptible insect with 100% mortality observed after 24 h for all the plant extracts tested. Further bioassays with lower concentrations of the plant extracts against aphids, revealed the extracts from I. rugosus (LC50 36 ppm and LC90 102 ppm) and D. mucronata (LC50 126 ppm and LC90 198 ppm) to be the most toxic to aphids. These most active plant extracts were further fractionated into different solvent fractions on polarity basis and their insecticidal activity evaluated. While all the fractions showed considerable mortality in aphids, the most active was the butanol fraction from I. rugosus with an LC50 of 18 ppm and LC90 of 48 ppm. Considering that high mortality was observed in aphids within 24 h of exposure to a very low concentration of the butanol fraction from I. rugosus, we believe this could be exploited and further developed as a potential plant-based insecticide against sucking insect pests, such as aphids.
54 citations
TL;DR: The invasion and infestation of the Rugose spiraling whitefly (RSW) on coconut palm (Cocos nucifera L.) in India is reported for the first time from Indian as well as from Oriental region.
Abstract: The invasion and infestation of the Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) on coconut palm (Cocos nucifera L.) (Arecales: Arecaceae) in India is reported for the first time from Indian as well as from Oriental region. The severity of its infestations and impact on coconut cultivation in India is discussed.
51 citations
TL;DR: It is indicated that essential oil from orange peels could be effective in the biocontrol of T. oryzae and this may be associated to its inhibitory effects on acetylcholinesterase and Na+/K+-ATPase activity.
Abstract: This study elucidates the fumigant toxicity and insecticidal mechanism of essential oil from orange peels against T. confusum, C. maculatus and S. oryzae. Essential oil from orange peels was obtained by hydrodistillation. The chemical constituents of the essential oil were identified by gas chromatograph/mass spectrometry (GC-MS). Fumigant toxicity of the essential oil was evaluated against the adults of T. confusum, C. maculatus and S. oryzae. The effect of the essential oil on acetylcholinesterase (AChE) and Na/K-ATPase activities in T. confusum, C. maculatus and S. oryzae homogenates were also determined. The major compounds that were identified in the essential oil include limonene (92.14%), β-myrcene (2.7%), 1,8-cineole (0.33%), α-pinene (0.7%) and γ-Terpinene (0.23%). In the fumigation assay, the essential oil displayed toxic effects against T. confusum, C. maculatus and S. oryzae. Percentage mortality of the insects increased with increase in concentration of the essential oil and exposure time while LC50 reduced with increase in period of exposure. Biochemical studies showed that the essential oil exhibited inhibitory effects on acetylcholinesterase (AChE) and Na+/K+-ATPase activities. This study indicates that essential oil from orange peels could be effective in the biocontrol of T. confusum, C. maculatus and S. oryzae and this may be associated to its inhibitory effects on acetylcholinesterase and Na+/K+-ATPase activity.
41 citations
TL;DR: In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent.
Abstract: Streptomyces griseorubens E44G is a chitinolytic bacterium isolated from cultivated soil in Saudi Arabia (a hot, arid climatic region). In vitro, antifungal potential of S. griseorubens E44G was assessed against the phytopathogenic fungus, Fusarium oxysporum f. sp. lycopersici (the causative agent of the Fusarium wilt disease of tomato). An inhibition zone of 24 mm was recorded. The chitinolytic activity of S. griseorubens E44G was proved when the colloidal chitin agar plate method was used. A thermostable chitinase enzyme of 45 kDa molecular weight was purified using gel filtration chromatography. The optimum activity was obtained at 60 °C and pH 5.5. The purified enzyme has shown a very pronounced activity against the phytopathogenic fungus, F. oxysporum. The molecular characterization of the chitinase gene indicated that it consists of 1218 bp encoding 407 amino acids. The phylogentic analysis based on the nucleotide DNA sequence and the deduced amino acids sequence showed high similarity percentages with other chitinases isolated from different Streptomyces species. In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent.
32 citations
TL;DR: The results suggest a new MED invasion into Brazil and is associated with ornamental plants and the two MED populations are genetically different and suggest that they are separate invasions.
Abstract: In Brazil, the first major invasion event of Bemisia tabaci was that of Middle East–Asia Minor 1 (MEAM1) species, formerly termed as B biotype, which commenced in the 1990s mainly by ornamental plants in Sao Paulo State. More than two decades after this invasion, the presence of the Mediterranean (MED) species of B. tabaci, formerly Q biotype, was reported in Rio Grande do Sul, the southernmost State of Brazil, and now in Sao Paulo and Parana States, in southeastern Brazil. Specimens of whiteflies collected from commercial begonia, hydrangea, petunia and poinsettia greenhouses in Sao Paulo, and also from begonias and poinsettias collected in flower shops in Parana, were all identified as belonging to MED species. Furthermore, the secondary endosymbionts Arsenophonus, Hamiltonella and Rickettsia of MED from Sao Paulo and Parana were detected by PCR and their presence confirmed by sequencing and FISH analysis, and those results differed from MED detected in Rio Grande do Sul that harbored only Hamiltonella and Cardinium. Our results suggest a new MED invasion into Brazil and is associated with ornamental plants. The two MED populations are genetically different and suggest that they are separate invasions.
30 citations
TL;DR: The topical application bioassays showed that deltamethrin and bifenthrin were highly toxic to all larval instars, whereas imidacloprid and acetamiprid were less toxic to fourth instar larvae, showing the importance of assessing potential effect of insecticides on C. septempunctata by topical application.
Abstract: Coccinella septempunctata L. is one of the most abundant ladybird species in Greece, preying on several aphid species and other arthropods, of which many are pests of cultivated plants. These pests are usually controlled with chemical insecticides. During this process, however, beneficials are also exposed to pesticides. The development of Integrated Pest Management (IPM) programs against aphids requires the evaluation of the effects of insecticides on beneficial insects. We evaluated the LD50 of imidacloprid, acetamiprid, bifenthrin and deltamethrin on first, second, third and fourth instar larvae of C. septempunctata by topical application. Moreover, we studied their sublethal effects (LD10) on the development, weight and prey consumption of fourth instar larvae. The topical application bioassays showed that deltamethrin and bifenthrin were highly toxic to all larval instars, whereas imidacloprid and acetamiprid were less toxic to fourth instar larvae. The LD10 dose significantly affected, developmental time, adult weight and daily predation. These results show the importance of assessing potential effect of insecticides on C. septempunctata for developing effective IPM programs of aphids in Greece.
24 citations
TL;DR: Light is thrown on a distinct pattern of gender specific gut bacterial colonization in fruit flies, which have to be factored in for the formulation of fruit fly management strategies.
Abstract: Gut microbes play an important role in insect morphogenesis, nutrition, development of resistance against parasitoids and detoxification of toxic compounds. A culture-based approach is therefore an useful tool for the characterization of cultivable microbial communities associated with the insect gut. In the present study an attempt was made to decipher the gender specificity of gut bacterial communities of two major fruit fly species of India viz., Bactrocera dorsalis (Hendel) and Bactrocera cucurbitae (Conquillett) (Diptera: Tephritidae). Based on molecular identification, B. dorsalis females were found to predominantly harbor the bacterial species Enterobacter cloacae, Enterobacter asburiae and Citrobacter freundii, while B. dorsalis males were found to harbor Providencia rettgerii, Klebsiella oxytoca, Enterococcus faecalis and Pseudomonas aeruginosa The cultivable diversity from females of B. cucurbitae comprised mainly of Morganella morganii and Bacillus pumilis while B.cucurbitae males were predominantly colonized by aerobic endospore formers viz., Bacillus cereus, B. licheniformis and B. subtilis. The above findings have thrown light on a distinct pattern of gender specific gut bacterial colonization in fruit flies, which have to be factored in for the formulation of fruit fly management strategies.
23 citations
TL;DR: Erysiphe corylacearum was identified as the causal agent of this new and highly destructive powdery mildew based on its morphological characteristics and analyses of DNA sequences of the internal transcribed spacer (ITS) and 28S regions of the ribosomal DNA.
Abstract: Hazelnut (Corylus avellana) is Turkey’s most valuable agricultural export, and an essential source of income for many families in the Black Sea Region. In spring 2013, hazelnut leaves, fruit clusters and shoots showing powdery mildew infection symptoms different from those observed previously were discovered in Giresun, Ordu and Trabzon provinces of Turkey. The disease has become epidemic throughout all hazelnut production areas spreading from east to west of the Black Sea Region over the subsequent years. Erysiphe corylacearum was identified as the causal agent of this new and highly destructive powdery mildew based on its morphological characteristics and analyses of DNA sequences of the internal transcribed spacer (ITS) and 28S regions of the ribosomal DNA. Pathogenicity of this species was examined in an infection test and proven for the first time. To our knowledge, this is the first report of E. corylacearum on Corylus avellana worldwide.
22 citations
TL;DR: Topology and soil type appeared to be major abiotic factors affecting incidence of GTD symptom, and it was in fact found to be the definitive biotic factor regarding incidence.
Abstract: Grapevine Trunk Diseases (GTD) are of great importance worldwide, including Hungary, a Center European country with long wine producing history. Several GTD pathogens have been described till now in Europe, but only a few from Hungary. The presence of a GTD pathogen in the vine does not necessarily result in the immediate appearance of disease symptoms, and information on the importance of environmental factors related to disease incidence are still limited. The aim of this research was to assess the occurrence of GTD in the Tokaj Wine Region, and to determine the biotic and abiotic factors influencing disease incidence. Five vineyards within 15 km radius – each with different topology, soil types, varieties and age – were studied for three consecutive years (2013 – 2015). The incidence of GTD-infection was determined every year for each vineyard. Diplodia seriata was isolated with incidence ranging from 50 to 100%, while Diaporthe spp. were the only other – minor – GTD pathogen found. Topology and soil type appeared to be major abiotic factors affecting incidence of GTD symptom. Disease incidence was also positively correlating with the age of the vineyards, and it was in fact found to be the definitive biotic factor regarding incidence. In contrast, D. seriata infection rate appeared unrelated to disease incidence or to any of the biotic or abiotic factors investigated.
22 citations
TL;DR: Avocado branches at the early stages of beetle colonization may be identified by sugar exudation at the base of the thin branches, and the main approach for reducing damage caused by the PSHB is sanitation, achieved by the removal of colonized branches and intact infested pruned slash.
Abstract: The polyphagous shot hole borer (PSHB), Euwallacea nr. fornicatus (Coleoptera; Scolytinae) has become a serious threat to the avocado industry and several shade tree species in Israel. Branch wilting and tree mortality is the outcome of PSHB galleries. Understanding the relationship between avocado trees and the PSHB is required for considering management strategies. In Israel, 52 tree species from 26 botanical families were attacked by the PSHB, but only 12 species were suitable for beetle reproduction. All examined avocado cultivars were attacked, but ‘Hass’ most severely. Large and medium diameter avocado branches were more resistant to PSHB, compared to thin branches. Effectively, gallery density increased as branch diameter decreased. Concomitantly, in large and medium diameter branches, extensive sugar exudation occurred and beetle attack rarely progressed to the formation of natal galleries, whereas minimal sugar exudation was observed in thin branches. This was more evident in those that were weakened by repeated attacks followed by successful beetle colonization. PSHB prefers and successfully colonized branches that had been previously attacked by its conspecifics, and reproduction was much higher in these branches, as opposed to initial attacks. Lesion frequencies increased from late spring (April) until late summer (September). Avocado branches at the early stages of beetle colonization may be identified by sugar exudation at the base of the thin branches. The main approach for reducing damage caused by the PSHB is sanitation, achieved by the removal of colonized branches and intact infested pruned slash.
22 citations
TL;DR: Analysis of cp gene, DNA A, iterons and recombination events clearly indicate that two groups of ToLCNDV-[potato] infects potato in India.
Abstract: The complete coat protein (cp) gene sequence of eighty Tomato leaf curl New Delhi virus-[potato] (ToLCNDV-[potato]) isolates collected from eleven states were determined. Phylogenetic analysis based on cp gene grouped the isolates into two major clades (I & II) and they shared 95.9–100.0% identity. The DNA A and DNA B of eight representative isolates (six from clade I and two from clade II) were 2739–2740 and 2692–2694 nts long and shared 94.6–99.4% and 97.2–99.5% homology within the isolates, respectively. Among the eight isolates, the DNA A of two isolates (Clade II), GWA-5 and FAI-19 had 94.6–95.3% sequence identity to other six isolates and formed a sub-clade within the ToLCNDV-[potato] isolates. Similar grouping was also revealed with AC1 and AC4 genes of these eight isolates. The DNA A components shared more than 90.0% identity with the DNA A of ToLCNDV isolates from cucurbitaceous crops, tomato, bhendi, 89.0–90.0% with ToLCNDV-papaya isolates and 70.4–74.0% with other tomato leaf curl viruses. Hence, the begomovirus infecting potatoes are the ToLCNDV isolates, designated as ToLCNDV-[potato]. Whereas, the DNA B components shared 86.6–91.7% identity with ToLCNDV isolates from cucurbits, tomato and bhendi. Evidence for intra-species recombination was detected only in DNA A with a maximum of three events in GWA-5 and FAI-19 isolates. Analysis of cp gene, DNA A, iterons and recombination events clearly indicate that two groups of ToLCNDV-[potato] infects potato in India.
TL;DR: Aloe vera pulp at 25% allowed normal buds’ opening and no damage was observed, indicating that Aloe Vera could be an ideal coating base for rose postharvest treatments, and natural antifungal agents efficiently inhibited Botrytis cinerea growth in the concentrations tested.
Abstract: Botrytis cinerea is a fungal pathogen that limits rose production and commercialization worldwide. Therefore, we evaluated a novel postharvest treatment against Botrytis cinerea in roses (Rosa sp. cv Vendela) using coating bases and antifungal agents of natural origin. Aloe vera pulp, cassava starch and gelatin were used as coating bases. Oregano essential oil (Origanum vulgare), thyme essential oil (Thymus vulgaris) and chitosan were used as natural antifungal agents. The coating bases were evaluated in different concentrations to observe effects of toxicity and opening diameter in rose buds. Gelatin and cassava starch coatings inhibited rose opening and showed petal damage in all concentrations tested. However, Aloe vera pulp at 25% allowed normal buds’ opening and no damage was observed, indicating that Aloe vera could be an ideal coating base for rose postharvest treatments. During in vitro assays, natural antifungal agents efficiently inhibited Botrytis cinerea growth in the concentrations tested. Further, mixture treatments of Aloe vera pulp (25%) with oregano essential oil (1%), thyme essential oil (0.1%) and chitosan (0.1%) showed independently neither damage nor opening inhibition in rose buds. Selected combinations of Aloe vera pulp and natural antifungal agents were applied in roses infected with Botrytis cinerea to evaluate their control of this pathogen. Unfortunately, the selected combinations did not reduce pathogen growth during postharvest treatments since they were similar to untreated controls. Further research has to be performed to find ideal combinations with Aloe vera that could inhibit B. cinerea during postharvest treatments in roses.
TL;DR: It is revealed that a large variation exists among rice-infecting isolates of R. solani AG1IA in North India and fingerprinting of the isolates using ISSRs along with phenotypic characterization and virulence analysis will help epidemiological studies that can provide new insights into pathogen biology and disease spread.
Abstract: Rhizoctonia solani AG1IA is an important fungal pathogen causing significant yield and quality losses in rice production. However, little is known about the levels of genetic diversity and structure of this pathogen in North India. Out of 240 samples collected from different rice-growing regions of North India, 112 isolates were identified as R. solani AG1IA subgroups using species-specific primers. All 112 isolates were organized into four groups on the basis of percent disease index (PDI). The majority of the isolates were weakly virulent. Population genetic analysis was performed within and between populations using inter simple sequence repeat (ISSR) markers. A total of 8249 alleles were identified from the 112 isolates of R. solani AG1IA through analysis of the ten inter simple sequence repeat markers. All the ten ISSR markers were polymorphic. The average number of bands per primer was 7.3 which ranged in size from 250 to 1500 bp. Genetic structure of the isolates using inter simple sequence repeat primers showed high degree of polymorphism (PIC ≥0.81). The analysis of molecular variance (AMOVA) indicated that most of the genetic diversity occurred within populations (60%), while the variability among populations and among regions contributed 25 and 15%, respectively. Overall, the present study reveals that a large variation exists among rice-infecting isolates of R. solani AG1IA in North India. Fingerprinting of the isolates using ISSRs along with phenotypic characterization and virulence analysis will help epidemiological studies that can provide new insights into pathogen biology and disease spread.
TL;DR: Although F. circinatum became known to science because it induced visible symptoms on pines, it has the capacity for a much broader range of ecological activities than is captured by its designation as a necrotrophic pathogen.
Abstract: What we know about the life history of fungi that cause disease in plants is commonly based on studies of the pathogen’s interaction with a susceptible host: how and when infection occurs, growth and reproduction within the host, and survival during the interval when a growing host is not available. This focus is appropriate, given the need for information that will facilitate management of disease affecting an economically important crop, but it can limit recognition of the full range of resources that may be utilized by fungi that we classify as plant pathogens. This was certainly the case for Fusarium circinatum, which causes a destructive disease of pines known as pitch canker. Although F. circinatum was initially known only as a necrotrophic, wound-infecting pathogen of coniferous trees, recent research has revealed that an isolate of this fungus that will kill shoot tissue when inoculated into a wound can also have a biotrophic relationship with roots of pine seedlings, infect and grow within grasses without causing symptoms, and cause ear rot of corn. Thus, although F. circinatum became known to science because it induced visible symptoms on pines, it has the capacity for a much broader range of ecological activities than is captured by its designation as a necrotrophic pathogen. The physiological plasticity manifested by F. circinatum illustrates the challenge of obtaining a comprehensive understanding of the life history of a plant pathogenic fungus.
TL;DR: Cassava plants treated with Trichoderma harzianum and aureoviride URM 5158 were effective in reducing the severity of cassava black root rot caused by S. lignicola and the production of enzymes was evaluated in cassava plants.
Abstract: Trichoderma spp. are used as antagonists against different pathogens. Despite many possibilities of using Trichoderma as an antagonist, there are gaps in the knowledge of the interaction between Trichoderma, cassava and Scytalidium lignicola. This fungus causes cassava black root rot and is an inhabitant of the soil, so it is difficult to control. Antagonists may contribute to the possible induction of resistance of plants because, when exposed to such pathosystems, plants respond by producing antioxidative enzymes. The test for potential inhibition of growth of S. lignicola CMM 1098 in vitro was performed in potato-dextrose-agar with two Trichoderma strains T. harzianum URM3086 and T. aureoviride URM 5158. We evaluated the effect of the two selected Trichoderma to reduce the severity of cassava black root rot and shoots. Subsequently, the production of enzymes (ascorbate peroxidase, catalase, peroxidase and polyphenol oxidase) was evaluated in cassava plants. All two Trichoderma strains show an inhibition of the growth of S. lignicola CMM 1098. The most efficient was T. harzianum URM 3086, with 80.78% of mycelial growth inhibition. T. aureoviride URM 5158 was considered the best chitinase producer. All treatments were effective in reducing severity, especially treatments using Trichoderma. Cassava plants treated with T. aureoviride URM 5158 had the highest enzyme activity, especially peroxidase and ascorbate peroxidase. Trichoderma harzianum URM3086 and Trichoderma aureoviride URM 5158 were effective in reducing the severity of cassava black root rot caused by S. lignicola CMM 1098.
TL;DR: Bioassay and molecular characterization revealed the conserved nature of the coat protein gene, among the TSV isolates infecting cotton in four different states (Tamil Nadu, Andhra Pradesh, Telangana, and Maharashtra), and Chenopodium amaranticolor and Chenobodium quinoa are excellent indicator host plants with high virus titres.
Abstract: Tobacco streak virus (TSV), inciting cotton necrosis, exhibits multifarious symptoms. Common types of symptoms include, purplish brown, necrotic lesions in the leaves, squares, and petioles. Telangana (India) had the highest incidence of TSV (51.11 PDI - hybrid RCH659), among the surveyed locations including, Tamil Nadu, Andhra Pradesh, Telangana and Maharashtra states of India. Environmental factors greatly influenced the establishment of TSV in cotton. Minimum temperature (22.81 °C), relative humidity (81.42%), and leaf wetness (23.94 h) favoured maximum TSV incidence with a mean PDI of 30.68 at Annur, (Tamil Nadu, India). Serological assay through DAC-ELISA confirmed the presence of TSV in cotton samples expressing necrosis symptoms. Bioassay revealed that Chenopodium amaranticolor and Chenopodium quinoa are excellent indicator host plants with high virus titres. Further, molecular characterization revealed the conserved nature of the coat protein gene, among the TSV isolates infecting cotton in four different states (Tamil Nadu, Andhra Pradesh, Telangana, and Maharashtra).
TL;DR: Functional response parameters indicate that the adult beetles and the fourth-instar were the most voracious stages and could be important for the biological control of the aphid.
Abstract: Functional response of Harmonia dimidiata (Fab.) to melon aphid, Aphis gossypii Glover was studied in the laboratory at 25 ± 0.5 °C, 70 ± 5% RH and 12L:12D photoperiod. All the predator stages exhibited Type II functional response to the aphid. Based on Rogers’s random predator equation the predator’s attack rate was lowest (0.128) in the first-instar and highest (0.21) in the adult stage. Handling times of the adult beetle and the fourth-instar (0.148 and 0.164 h, respectively) were much shorter than other stages. The maximum number of aphids that could be consumed over a period of 24 h by first, second, third and fourth instar; and adult of H. dimidiata was estimated to be 47.2, 80.2, 79.7, 146.2 and 161.7 aphids/ predator. Functional response parameters indicate that the adult beetles and the fourth-instar were the most voracious stages and could be important for the biological control of the aphid.
TL;DR: Elimination of external sources of inoculum before starting new plantings and rational use of insecticides to reduce secondary infection may contribute to better disease management of tomato crops.
Abstract: Tomato severe rugose virus (ToSRV) is a serious and prevalent begomovirus that causes severe mosaic and yield loss of tomato plants in Brazil. The virus is transmitted by Bemisia tabaci bitotype B (MEAM1) in a persistent circulative manner. This study evaluated the efficacy of cyantraniliprole foliar spray, cyantraniliprole root drenching, spiromesifen, thiamethoxam, and cartap on the mortality of Bemisia tabaci byotipe B and simulated primary and secondary transmission of ToSRV. None of the insecticides were effective in controlling primary transmission of ToSRV by B. tabaci. Cyantraniliprole root drenching, cartap, and cyantraniliprole foliar spray were effective in controlling secondary transmission of the virus, and infections were reduced by 94.5, 89.6, and 81%, respectively, compared to each of their controls. Thiamethoxam and spiromesifen did not provide effective control of secondary infection. Elimination of external sources of inoculum before starting new plantings and rational use of insecticides to reduce secondary infection may contribute to better disease management of tomato crops.
TL;DR: The results of the seedBioassay resembled those obtained from the whole-plant experiment suggesting seed bioassay as an inexpensive, rapid method for screening-resistant genotypes.
Abstract: The level of resistance and patterns of cross-resistance to clodinafop, sethoxydim, and pinoxaden were examined in 12 putative resistant and one susceptible populations of winter wild oat (Avena ludoviciana) collected from Fars Province, in the southwest of Iran The responses of biomass and length of coleoptiles to the increasing dosages of the three herbicides were determined in both whole-plant and seed bioassays In the whole-plant bioassay, all 12 putative resistant populations were found to be resistant to clodinafop with resistance ratios (R/S) ranging from 176 to >4704 Most clodinafop-resistant populations exhibited low levels of cross-resistance to sethoxydim Three highly sethoxydim-resistant populations, F2, S2, and ES4, were slightly resistant to clodinafop Six populations (M1, M2, F2, S2, S4, and ES4) showed high cross-resistance to pinoxaden with R/S values as large as 1073 to 4029 A highly clodinafop-resistant population, M2, was more sensitive to pinoxaden than the susceptible population The results of the seed bioassay resembled those obtained from the whole-plant experiment suggesting seed bioassay as an inexpensive, rapid method for screening-resistant genotypes
TL;DR: Out of nineteen wild host plants encountered, Pennisetum purpureum and Vossia cuspidata were the most speciose grasses in terms of both parasitoids and stemborers and the implications of such diversity and network structure are discussed.
Abstract: Lepidopteran stemborers are considered as the most important insect pests of cereal crops in Sub-Saharan Africa. However, limited information exists on stemborers and their parasitoids in the rain forest of the DR Congo. In order to enhance the understanding of the pest ecology, sampling in both cultivated and wild habitats has been recommended as a bottom line to any action aiming at the design of pest management measures. Following this recommendation, a survey was carried out in the rain forest of the DR Congo on maize and wild host plants. We collected eighteen stemborer and one earborer species belonging to 5 families. Five species were found feeding on maize while 18 species fed on wild host plants. Busseola fusca was the commonest species feeding on maize which accounted for 50.1%. At least 20 parasitoids species distributed as 15 species on maize and 16 species in the wild habitats were recovered during this study. Cotesia sesamiae, Enicospilus ruscus and Sturmiopsis parasitica accounted for 99.8% of interactions within parasitoid community. Out of nineteen wild host plants encountered, Pennisetum purpureum and Vossia cuspidata were the most speciose grasses in terms of both parasitoids and stemborers. The implications of such diversity and network structure are discussed.
TL;DR: The mode of inheritance of Indoxacarb resistance appeared to be autosomal and inherited as a semi-dominant trait in P. xylostella, and the sub lethal doses and frequent use of ind oxacarb should be avoided for the management of P.xylostlla.
Abstract: The development of insecticidal resistance in diamondback moth (DBM) Plutella xylostella has immediate implications for its management In this study, we examined the mode of inheritance of Indoxacarb resistance in P xylostella The indoxacarb-resistant strain (Px-R) was obtained through continuous laboratory selection with increasing doses of indoxacarb in each generation At the 14th generation of selection, the resistance ratio of Px-R strains was 238 over the susceptible strain (Px-S) The mode of inheritance to Indoxacarb in P xylostella was examined performing standard reciprocal crosses between Px-R and Px-S and response of Px-R, Px-S and F1 hybrid progenies to Indoxacarb through leaf dip bioassay The degree of dominance (D) and heritability (h) of F1 hybrid progeny ranged from −0001 to 00012 and 0499 to 0506, respectively The Indoxacarb resistance was appeared to be autosomal and inherited as a semi-dominant trait The Px-R strain of P xylostella showed little cross resistance to cypermethrin and there was no cross resistance to other pesticides viz, chlorpyrifos, spinosad, karanjin, xentari (Bta-Cry1C) and MVP-II (Cry1Ac) Since the Indoxacarb resistance inherited as a semi-dominant trait in P xylostella, the sub lethal doses and frequent use of indoxacarb should be avoided for the management of P xylostella Moreover, Px-R of P xylostella showed positive cross resistance to synthetic pyrethroids (cypemethrin), therefore indoxacarb and synthetic pyrethroids should not be recommended together for management of P xylostella
TL;DR: The results show that short-term storage at low temperatures does not affect certain properties of the predator when compared to 12 °C and storage periods.
Abstract: Storage of natural enemies at low temperatures has an important role in biological control programs. It is an very critical factor that the stored individuals is used without losing their characters such as longevity, survival, fecundity, etc. In this study, the storage possibilities of Rhyzobius lophantae Blaisdell (Coleoptera: Coccinellidae) adults under low temperatures (4 °C and 12 °C) for four different periods (10, 20, 30 and 40 days) were investigated. The survival rates and life span of adults (male and female), daily and total egg numbers laid by females stored at 4 °C and 12 °C for 10, 20, 30 and 40 days were determined. The survival rates of adults stored at 4 °C for 10 and 20 days were found to be 94.54% and 58.02% respectively. However, no adults stored at 4 °C for 30 and 40 days were observed to survive. The highest survival rate was 88% for the adults stored at 12 °C for 10 days. The average daily laid egg numbers were 12.51 and 9.37, and total egg numbers were 850.30 and 738.30 of adults stored at 4 °C for 10 and 20 days, respectively. The decrease in daily and total egg numbers of females stored at 12 °C was observed with increasing storage period. There was no significant difference in longevities of male and female stored at 4 °C and 12 °C. These results show that short-term storage at low temperatures does not affect certain properties of the predator when compared to 12 °C and storage periods.
TL;DR: The LFIA test strips offered a cost-effective tool to detect CTV in the field or nursery by non-skilled personnel without laboratory equipment and readily detected CTV after six months in storage in a sealed bag with silica gel at room temperature indicating good stability.
Abstract: Maintenance of virus-free citrus in nurseries and orchards is essential to control the spread of aphid-transmitted Citrus tristeza virus (CTV) To this end, a lateral flow immunoassay (LFIA) was developed to detect CTV that was user-friendly and field-deployable Polyclonal antisera was generated in rabbit against purified virions from Nicotiana benthamiana inoculated with an infectious recombinant cDNA clone of CTV (rCTV) Affinity purified rCTV IgG (1 mg/ml) and Mouse IgG (05 mg/ml) were conjugated with gold nanoparticles and coated onto a glass fiber membrane conjugate pad Affinity purified rCTV IgG and anti-mouse IgG were used as test line and control line, respectively on the test strip The LFIA detected CTV within 10 min and was sensitive up to a 1:80 dilution of crude plant sap extract The LFIA was validated using CTV strains T30, T36, VT and RB from greenhouse and field sources and results were 100% in agreement with Enzyme-Linked Immunosorbent Assay and Reverse Transcription quantitative PCR The immunostrip readily detected CTV after six months in storage in a sealed bag with silica gel at room temperature indicating good stability The LFIA test strips offered a cost-effective tool to detect CTV in the field or nursery by non-skilled personnel without laboratory equipment
TL;DR: The results showed that the autumn flight of P. aubei is linked to making hibernation tunnels, while the spring flight to producing nuptial chambers corresponds to a single reproductive period per year.
Abstract: The invasive small cypress bark beetle, Phloeosinus aubei (Coleoptera, Curculionidae, Scolytinae) has two flights in Central-Europe, however, it was unclear, whether this corresponds to two reproductive periods, when nuptial chambers are formed and galleries initiated. The aim of this study was to clarify the life-cycle of P. aubei in Hungary, representing populations in the range of invasion, and to compare preferences towards some popular cultivars of Thuja and Juniper ornamental trees. In order to reveal which is the pioneering gender, and to confirm females’ preferences between healthy and broken trunks behavioral tests were conducted. Results showed that adults prepare hibernation tunnels from August until October. Sex ratio of overwintering adults was nearly equal. The significantly highest number of hibernation tunnels was found on Thuja plicata Atrovirens (mean±S.E.: 6.0±0.7/tree), followed by T. occidentalis Smaragd (2.2±0.8), Juniperus chinensis Spartan (1.6±0.6), and J. scopulorum Blue Arrow (0.2±0.2). Nuptial chambers were made from April until June, by singly females, never by males. Females chose broken, drying trunks over healthy ones. Adults of the next generation emerged from the galleries from August until October. By October adults emerged from 94% of the galleries, and larvae were found only in 6% of the galleries. These results showed that the autumn flight of P. aubei is linked to making hibernation tunnels, while the spring flight to producing nuptial chambers. The latter corresponds to a single reproductive period per year. Control measures against adults should be timed to these two specific periods of the season.
TL;DR: The resistance of rest eight chickpea genotypes to insect infestation was due to the integrative effect of up regulated defensive components in leaves, podwall and seeds, which might be responsible for causing significant shift in oxidative status of these genotypes due to scavenging of free radicals, maintenance of membrane integrity and deterrent to insect feeding.
Abstract: Helicoverpa armigera is the most serious insect pest in chickpea that causes significant yield losses due to its feeding on vegetative (leaves) and reproductive (developing pods and seeds) parts of plants. The present aim of study was to explore response dynamics of induced defence mechanism in leaves, podwall and seeds of ten chickpea genotypes (ICC 506, ICCV 10, ICC 10393, 5283, RSG 963, GL 25016, GL 26054, ICCL 86111, ICC 3137, L 550) after insect infestation. Two chickpea genotypes namely ICC 3137 and L 550 were found to be highly susceptible to Helicoverpa armigera infestation due to higher leaf and pod damage in them as compared to rest of eight genotypes which are found to be considerably resistant due to lower damage. Insect infestation induced decreased activities of defensive enzymes such as peroxidase (POD), catalase (CAT), glutatione reductase (GR) and polyphenol oxidase (PPO), decreased free radical scavenging activities in terms of 2,2-diphenyl-1-picryl hydrazyl (DPPH), decreased contents of signaling molecules such as nitric oxide ((NO), hydrogen peroxide (H2O2), reduced content of insect feeding behaviour regulating molecules such as total phenols, trypsin inhibitor and accumulation of membrane damage marker such as malondialdehyde (MDA) in leaves of ICC 3137 and L 550; decreased POD activity, nitric oxide content and H2O2 in podwall of L550; decreased SOD, GR, nitric oxide content and H2O2 in seeds of L550 resulted in aggravation of infestation induced oxidative stress and makes these genotypes more vulnerable to insect damage. The resistance of rest eight chickpea genotypes to insect infestation was due to the integrative effect of up regulated defensive components in leaves, podwall and seeds such as enhanced activities of CAT, POD, GR, PPO and PAL along with accumulation of H2O2` and total phenols in leaves, increased SOD, POD, GR and PPO activities along with increased contents of trypsin inhibitor and total phenols in podwall; increased SOD, GR, PPO activities and accumulated total phenols in seeds of resistant chickpea genotypes might be responsible for causing significant shift in oxidative status of these genotypes due to scavenging of free radicals, maintenance of membrane integrity and deterrent to insect feeding. Induced glycine betaine after herbivory was found to be positively correlated with superoxide dismutase and trypsin inhibitors. H2O2 content was positively correlated with trypsin inhibitor, DPPH, ferric reducing antioxidant power (FRAP) and total phenols in leaves and with FRAP, DPPH and total phenols in pod wall indicating that H2O2 might be stimulating the cascade that will be helping to scavenge free radical species and correlation with phenols and trypsin inhibitor indicated that it act as toxicant to insect feeding.
TL;DR: The equal mating type distribution of the pathogen at both geographic and host species levels suggests a potential for sexual reproduction of Alternaria spp.
Abstract: Alternaria genus includes many plant pathogens on numerous hosts, causing leaf spots, rots and blights. Alternaria blight has been observed as one of the important fungal diseases of pistachio (Pistacia vera L.) as well as its wild relatives (P. terebinthus, P. lentiscus, P. khinjuk, P. atlantica, P. mutica) in Turkey. Alternaria species were sampled from Pistacia spp. hosts from different geographic regions in Turkey during field trips in late spring to early fall of 2013. Alternaria blight symptoms were observed mainly on fruits and rarely on leaves. Four hundred and twenty two of the isolates were morphologically defined as A. alternata, A. tenuissima, A. arborescens and also intermediate morpho-species between A. alternata/A. arborescens. Pathogenicity of the isolates was confirmed with host inoculations on detached fruits. Mating types of 270 isolates of Alternaria spp. from the collection were identified using a PCR-based mating type assay that amplifies either a MAT1-1 or a MAT1-2 fragment from the mating locus. Although a strongly clonal population structure was expected due to the putative asexual reproduction of these fungi, both idiomorphs were detected at equal frequencies at several different spatial scales. The distribution of mating types within each geographic region, within host species as well as in overall collection was not significantly different from 1:1. Amplified fragments of partial idiomorph sequences were obtained for representative isolates. Parsimony trees were depicted based on sequence data of mating type genes for these representative isolates as well as some other Alternaria species obtained by Genebank. Several point mutations presented a few clusters which are supported by high bootsrapped values. The Alternaria blight disease agents both from cultivated and wild hosts were pathogenic on pistachio which may cause difficulties to control the disease because of extensity of pathogen sources. Besides, equal mating type distribution of the pathogen at both geographic and host species levels suggests a potential for sexual reproduction of Alternaria spp. in Turkey.
TL;DR: The optimal host fruit for P. concolor development seems to be Mastoidis variety with great biological parameters and percentage of parasitism, which is similar to other varieties such as Koroneiki and Kalamon.
Abstract: Psytallia concolor (Szepligeti) is a koinobiont endoparasitoid of many Tephritidae larvae, including Bactrocera oleae (Rossi), and has been used in Mediterranean areas for biological control of olive fruit fly by inundative release. The present study evaluates the influence of olive fruit variety (Amfissis, Arbequina, Branquita de Elvas, Carolea, Kalamon, Koroneiki, Leccino, Manzanilla, Mastoidis, Moroccan Picholine and Picholine) on P. concolor parasitism efficiency and performance in the field during two successive years. The results showed that the percentage of parasitism was significantly higher (>30%) in Mastoidis and Koroneiki (light-weight varieties 4.21 mg) as well as the length of the developed adult parasitoids (>3.5 cm) in Mastoidis and Manzanilla were significantly higher than these individuals developed from other varieties such as Koroneiki and Kalamon. Finally, the optimal host fruit for P. concolor development seems to be Mastoidis variety with great biological parameters and percentage of parasitism.
TL;DR: The ficus whitefly Singhiella simplex (Singh) (Hemiptera: Aleyrodidae) is for the first time recorded for the whitefly fauna in Turkey.
Abstract: The ficus whitefly Singhiella simplex is an urban area pest which originated from Asia.Singhiella simplex (Singh) (Hemiptera: Aleyrodidae) is for the first time recorded for the whitefly fauna in Turkey. The pest was found on Ficus microcarpa in Antalya province, Turkey. Its identification, host plants, and distribution across the world are briefly described.
TL;DR: The temperature and CO2 levels were significant factors of influence on disease incidence (DI) and severity (DS) in all the trials, and their combination significantly influenced the DI and DS of F. equiseti leaf spot on both hosts.
Abstract: This study was undertaken by simulating the effects of increasing the temperature and CO2 values on the incidence and severity of F equiseti on wild rocket (Diplotaxis tenuifolia) and radish (Raphanus sativus), under phytotron conditions Two sets of 3 trials were carried out in which eight different temperature and CO2 combinations were tested:1) 400–450 ppm CO2, 18–22 °C; 2) 800–850 ppm CO2, 18–22 °C; 3) 400–450 ppm CO2, 22–26 °C, 4) 800–850 ppm CO2, 22–26 °C, 5) 400–450 ppm CO2, 26–30 °C; 6) 800–850 ppm CO2, 26–30 °C; 7) 400–450 ppm CO2, 14–18 °C; 8) 800–850 ppm CO2, 14–18 °C The temperature and CO2 levels were significant factors of influence on disease incidence (DI) and severity (DS) in all the trials, and their combination significantly influenced the DI and DS of F equiseti leaf spot on both hosts Disease incidence and severity increased on wild rocket at 850 ppm of CO2, in comparison to 450 ppm, in each tested temperature range The highest CO2 value on radish, for all the tested temperature regimes, caused an increase in DI and DS, which resulted statistically significant at the highest tested temperature range The results obtained in this study add more concern to the possible negative effects of the spread of F equiseti on vegetables in Italy as well as in other areas suffering from increased temperatures as a consequence of climate changes
TL;DR: Correlation analysis revealed that bolls per plant, boll weight, germination, ginning out turn, staple length, and staple fineness resulted in negative and significant correlation with density of D. koenigii.
Abstract: The cotton stainer, Dysdercus koenigii Fabricius (Hemiptera: Pyrrhcoridae), has become a major threat to transgenic cotton as it causes warts on the internal carpel wall of cotton boll, severe lint staining, lint locks, and lint lesions. Thus, keeping in view the importance of this pest on cotton, in the present study, screening of 13 transgenic cotton genotypes was performed and the population of D. koenigii was determined on these genotypes during 2012–13. Furthermore, among these genotypes, a high yielding advanced cultivar (FH-114) was selected for further experiments. A number of five different densities of D. koenigii (5, 10, 15, 20, and 25) at adult stage with well-developed proboscis were released in the cages along with a control treatment. Cotton genotypes FH-312, FH-2073, FH-Lalazar, FH-142, and MNH-886 possessed minimum population (1.33 D. koenigii per plant) compared to FH-324 and FH-444 (6.0 D. koenigii per plant). The number of bolls per plant and boll weight decreased as a result of increased densities. The increased density of D. koenigii resulted in fewer bolls per plant (12.1 bolls), reduced boll weight (2.1 g), germination (39.1%), ginning out turn (38.3%), staple length (27.8 mm), and staple fineness (4.0 μg/in.) when compared with un-infested plants (30.6, 3.2 g, 77.3%, 41.5%, 28.8 mm, and 4.4 μg/in.), respectively. Correlation analysis revealed that bolls per plant, boll weight, germination, ginning out turn, and staple fineness resulted in negative and significant correlation with density of D. koenigii with r-values of −0.95, −0.98, −0.98, −0.8, and −0.85, respectively. Coefficient of determination (R2) demonstrated that bolls per plant, boll weight, germination, ginning out turn, staple length, and staple fineness contributed with 91, 96, 96, 79, 43 and 73%, respectively, to the total variability at different densities of D. koenigii. Our findings demonstrated that D. koenigii has become potential major pest and causes quantitative and qualitative losses to transgenic cotton, hence, there is a need to develop appropriate control measures for controlling its population to avoid further losses.