Showing papers on "Infestation published in 2021"

Could fall armyworm, Spodoptera frugiperda (J. E. Smith) invasion in Africa contribute to the displacement of cereal stemborers in maize and sorghum cropping systems

Abstract: The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), which has recently invaded the African continent, has become a new threat to cereal production. Being an invasive pest with certain competitive advantages, the impact of FAW on other lepidopteran pests is unclear. This study assessed the infestation of FAW and cereal stemborers on maize and sorghum under mono-cropped systems that are adjacently placed in five districts in Uganda. Data on maize and sorghum infestation cereal stemborers and FAW was collected at 6, 9 and 16 weeks after planting (WAP), to determine intensity and severity. Cereal stemborer infestations on maize at 6, 9 and 16 WAP were only 36.7%, 48.2% and 24.0%, respectively, which was significantly lower than the infestations on sorghum, at 55.5%, 53.2%, 64.0%, respectively. On the contrary, the infestations of FAW on maize at 6, 9 and 16 WAP were 89.5%, 84.7% and 86.0%, respectively, while on sorghum they were 51.0%, 56.5% and 47.0, respectively. The severity of stemborers on sorghum was statistically higher than on maize, whereas the damage severity of FAW was generally higher on maize than on sorghum. Intensity of damage and cavity length due to stemborer on sorghum was higher than on maize. Historical records showed that in maize stemborer infestation could reach 60%. This infestation started significantly declining in 2016, suggesting an early arrival of FAW in Uganda. The present study indicates a possible displacement of stemborer from maize onto sorghum. Any Integrated Pest Management (IPM) package should consider managing FAW and stemborer together in both maize and other cereal hosts.

Tree diversity reduces the risk of bark beetle infestation for preferred conifer species, but increases the risk for less preferred hosts

Abstract: This is an open access article under the terms of the Creative Commons AttributionNonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2021 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society 1AlbertLudwigsUniversität Freiburg, Biometry and Environmental System Analysis, Freiburg, Germany 2Forstliche Versuchsund Forschungsanstalt BadenWürttemberg, Freiburg, Germany 3Geobotany, AlbertLudwigsUniversiät Freiburg, Freiburg, Germany 4Department of Renewable Resources, Earth and Atmospheric Sciences Building, University of Alberta, Edmonton, AB, Canada 5Chair of Silviculture, AlbertLudwigsUniversität Freiburg, Freiburg, Germany

Classification of Plant Electrophysiology Signals for Detection of Spider Mites Infestation in Tomatoes

Abstract: Herbivorous arthropods, such as spider mites, are one of the major causes of annual crop losses. They are usually hard to spot before a severe infestation takes place. When feeding, these insects cause external perturbation that triggers changes in the underlying physiological process of a plant, which are expressed by a generation of distinct variations of electrical potential. Therefore, plant electrophysiology data portray information of the plant state. Analyses involving machine learning techniques applied to plant electrical response triggered by spider mite infestation have not been previously reported. This study investigates plant electrophysiological signals recorded from 12 commercial tomatoes plants contaminated with spider mites and proposes a workflow based on Gradient Boosted Tree algorithm for an automated differentiation of the plant’s normal state from the stressed state caused by infestation. The classification model built using the signal samples recorded during daylight and employing a reduced feature subset performs with an accuracy of 80% in identifying the plant’s stressed state. Furthermore, the Hjorth complexity encloses the most relevant information for discrimination of the plant status. The obtained findings open novel access towards automated detection of insect infestation in greenhouse crops and, consequently, more optimal prevention and treatment approaches.

Cooperative herbivory between two important pests of rice.

Abstract: Normally, when different species of herbivorous arthropods feed on the same plant this leads to fitness-reducing competition. We found this to be different for two of Asia’s most destructive rice pests, the brown planthopper and the rice striped stem borer. Both insects directly and indirectly benefit from jointly attacking the same host plant. Double infestation improved host plant quality, particularly for the stemborer because the planthopper fully suppresses caterpillar-induced production of proteinase inhibitors. It also reduced the risk of egg parasitism, due to diminished parasitoid attraction. Females of both pests have adapted their oviposition behaviour accordingly. Their strong preference for plants infested by the other species even overrides their avoidance of plants already attacked by conspecifics. This cooperation between herbivores is telling of adaptations resulting from the evolution of plant-insect interactions, and points out mechanistic vulnerabilities that can be targeted to control these major pests. Herbivore cooperation between insect pests can result in substantially greater damage to crops but also constitutes a good target for improved pest control. Liu et al. reveal how the brown plant-hopper and the rice striped stem-borer obtain mutual benefits when feeding on the same rice plant.

Invasion and expansion of exotic whiteflies (Hemiptera: Aleyrodidae) in India and their economic importance

Abstract: Exotic invasive whiteflies (Hemiptera: Aleyrodidae) in India cause direct and indirect yield losses in agriculture, horticulture and forestry crop plants. Around 25 years ago, the spiralling whitefly, Aleurodicus dispersus Russell invaded and established on many host plants including economically important crops in India. Recently, within a span of five years, seven whiteflies invaded India viz., solanum whitefly, Aleurothrixus trachoides (Back) reported to breed on 37 plant species; rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin found breeding on 40 host plants; nesting whiteflies, Paraleyrodes bondari Peracchi on 34 host plants and P. minei Ιaccarino infest about 25 host plants; legume feeding whitefly, Tetraleurodes acaciae (Quaintance) infesting 5 host plants; palm infesting whitefly, Aleurotrachelus atratus Hempel on 4 host plants and woolly whitefly, Aleurothrixus floccosus (Maskell) infesting guava. These invasive species are native to the Neotropical region, mostly from Central America and the Caribbean. Extensive spread along the coastal regions and gardens near the backwater of India is predicted owing to the favorable weather factors and availability of host plants. Species of exotic whiteflies with similar habits co-exist in more or less the same niche and have a similar pattern of growth and development. The intensity of infestation of RSW on coconut, banana and oil palm, the woolly whitefly on guava and the palm infesting whitefly and nesting whiteflies on coconut was severe. The exotic aphelinid parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae), a predator Pseudomallada astur (Banks) (Neuroptera: Chrysopidae) and the entomopathogenic fungus, Isaria fumosorosea Wize (Hypocreales: Clavicipitaceae) play a major role in reducing the population of these invasives. The most insidious spread of these species in India is likely mediated by humans through the movement of infested seedlings and plant materials. Extensive surveys revealed that these species spread rapidly in the large geographical region of India mostly through transportation of infested seedlings. This study reports a major expansion of the geographic and host range and the patterns of co-occurrence, damage and economic impact of these exotic species in India and their natural enemies.

Evidence of the presence of Borrelia burgdorferi in dogs and associated ticks in Egypt.

Abstract: Borrelia burgdorferi is the spirochete that causes Lyme Borreliosis (LB), which is a zoonotic tick-borne disease of humans and domestic animals. Hard ticks are obligate haematophagous ectoparasites that serve as vectors of Borrelia burgdorferi. Studies on the presence of Lyme borreliosis in Egyptian animals and associated ticks are scarce. This study was conducted to detect B. burgdorferi in different tick vectors and animal hosts. Three hundred animals (dogs=100, cattle=100, and camels=100) were inspected for tick infestation. Blood samples from 160 tick-infested animals and their associated ticks (n=1025) were collected and examined for the infection with B. burgdorferi by polymerase chain reaction (PCR) and sequencing of the 16S rRNA gene. The identified tick species were characterized molecularly by PCR and sequencing of the ITS2 region. The overall tick infestation rate among examined animals was 78.33% (235/300). The rate of infestation was significantly higher in camels (90%), followed by cattle (76%) and dogs (69%); (P = 0.001). Rhipicephalus sanguineus, Rhipicephalus (Boophilus) annulatus, and both Hyalomma dromedarii and Amblyomma variegatum, were morphologically identified from infested dogs, cattle, and camels; respectively. Molecular characterization of ticks using the ITS2 region confirmed the morphological identification, as well as displayed high similarities of R. sanguineus, H. dromedarii, and A. Variegatu with ticks identified in Egypt and various continents worldwide. Just one dog (1.67%) and its associated tick pool of R. sanguineus were positive for B. burgdorferi infection. The 16S rRNA gene sequence for B. burgdorferi in dog and R. sanguineus tick pool showed a 100% homology. Analyzed data revealed a relatively low rate of B. burgdorferi infection, but a significantly high prevalence of tick infestation among domesticated animals in Egypt, which possesses a potential animal and public health risk. Additionally, molecular characterization of ticks using the ITS2 region was a reliable tool to discriminate species of ticks and confirmed the morphological identification.

Economic injury level for Tetranychus urticae Koch on parthenocarpic cucumber under protected environment in north-western Indian Himalayas

Abstract: Damage potential of two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae), on parthenocarpic cucumber, Cucumis sativus Linnaeus, under naturally ventilated polyhouse was assessed by artificially releasing of different mite densities (2, 4, 8 and 16 mites/leaf) at 4, 6 and 8-weeks after transplanting (WAT) coinciding with early, mid and late crop stage. Mites were restricted to feed for 4-weeks (limited feeding duration) as well as throughout crop growth (unlimited feeding duration). Injury inflicted to leaves by mite feeding increased significantly with the advancement in duration of infestation. Tetranychus urticae infestation exhibited varying levels of stunting effects on plant growth. Crop yield under limited feeding duration increased over unlimited feeding duration from 10.7 to 22.4, 6.4 to 15.4 and 0.6 to 2.2% for the infestation initiated in early, mid and late crop stages, respectively, with the loss in marketable yield to vary from 7.4 to 53.3%. Relationship deduced between reduction in yield and cumulative mite days (CMDs) revealed one mite day feeding reduced the yield up to 0.112 g/plant. Whereas, on initial mite density basis, reduction in yield varied from 12.87 to 51.95 g/plant/mite at different plant growth stages. The economic injury level (EIL) determined was very low (0.83 mites/leaf) for the infestation initiated in early stage, whereas, for the infestation initiated in later part of plant growth (6 and 8-WAT), EIL of 1.25 and 3.33 mites/leaf were established.

Evaluation of Two Commonly Used Field Tests to Assess Varroa destructor Infestation on Honey Bee (Apis mellifera) Colonies

Abstract: Assessment of colony infestation by Varroa destructor is a crucial part of the Integrated Pest Management (IPM) applied to beekeeping. Natural mite fall, quantified by counting the mites on sticky sheets, is considered a reference method to estimate varroa infestation level in honey bee colonies. However, in recent years, alternative methods that can be used in field conditions have been investigated. In this paper, we report the results of the evaluation of two different methods to estimate the levels of varroa infestation. The experiment involved 151 honey bee colonies in nine apiaries of four countries (Algeria, Croatia, Italy, Poland). After the main honey flow, we compared the 10-day natural mite fall and the powdered sugar roll methods with the varroa population in each colony. According to our results, the powdered sugar roll method could be suggested to beekeepers as a suitable IPM tool for varroa control, while natural mite fall represents a more accurate method that could be adopted for selection/research purposes.

First Recorded Asian Longhorned Beetle (Coleoptera: Cerambycidae) Infestation in the Southern United States

Abstract: The Asian longhorned beetle [Anoplophora glabripennis (Motschulsky), ALB] was found in Hollywood, SC, in May 2020. This infestation is at least 7-yr old and represents the southernmost infestation in North America. A federally regulated invasive forest and tree pest, ALB primarily attacks maples but is known to attack and reproduce in trees in at least 12 different genera. Damage observed in South Carolina is typical of that seen in other ALB infestations, including oviposition sites, splitting bark around larval feeding sites, and round holes made by emerging adults. Copious weeping from oviposition sites was commonly observed in the summer of 2020, and characteristic frass and wood shavings were commonly exuded from attacked trees. Federal and state regulatory officials established a 152 km2 (58.6 mi2) regulated area in October—which the state increased to 188.0 km2 (72.6 mi2) in January—and to date >4,000 trees (98% Acer spp.) infested with ALB have been identified. Several uncertainties regarding ALB's biology and ecology exist due to this area’s subtropical climate, including impacts to the beetle's life cycle. Questions also surround potential biological control agents in this area and whether new host trees would be utilized. While the standard eradication strategy of tree removal and chipping is being performed, there are several forested wetlands and areas otherwise inaccessible to typical removal equipment where alternate eradication strategies may need to be developed and deployed. Because this ALB infestation is located within a novel environment, it provides an opportunity to research new strategies that will help improve future detection and eradication efforts.

Host Suitability Index for Polyphagous Tephritid Fruit Flies.

Abstract: Tephritid fruit flies are major economic pests for fruit production and are an impediment to international trade. Different host fruits are known to vary in their suitability for fruit flies to complete their life cycle. Currently, international regulatory standards that define the likely legal host status for tephritid fruit flies categorize fruits as a natural host, a conditional host, or a nonhost. For those fruits that are natural or conditional hosts, infestation rate can vary as a spectrum ranging from highly attractive fruits supporting large numbers of fruit flies to very poor hosts supporting low numbers. Here, we propose a Host Suitability Index (HSI), which divides the host status of natural and conditional hosts into five categories based on the log infestation rate (number of flies per kilogram of fruit) ranging from very poor ( 100). Infestation rates may be determined by field sampling or cage infestation studies. We illustrate the concept of this index using 21 papers that examine the host status of fruits in five species of polyphagous fruit flies in the Pacific region: Bactrocera tryoni Froggatt, Bactrocera dorsalis (Hendel), Bactrocera latifrons (Hendel), Zeugodacus cucurbitae (Coquillett), and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). This general-purpose index may be useful in developing systems approaches that rely on poor host status, for determining surveillance and detection protocols for potential incursions, and to guide the appropriate regulatory response during fruit fly outbreaks.

Disturbance by invasive pathogenic fungus alters arthropod predator-prey food-webs in ash plantations.

Abstract: According to the disturbance-succession theory, natural disturbances support biodiversity and are expected to increase the complexity of food-webs in forest ecosystems by opening canopies and creating a heterogeneous environment. However, a limited number of studies have investigated the impact of disturbance by invasive pathogenic species and succession on arthropod predator-prey food-webs in forest ecosystems. Hymenoscyphus fraxineus is a pathogenic fungus of ash trees that is invasive in Europe and causes massive dieback, mainly of the common ash Fraxinus excelsior across its native range. Here we investigated how this pathogenic fungus affects food-webs of web-building spiders and their prey in understorey vegetation of ash plantations. In 23 young and middle-aged ash plantations that were distributed along a gradient of infestation by H. fraxineus (29%-86% infestation), we measured the vegetation structure (canopy openness, shrub coverage, herb/grass coverage), the trait composition of local spider communities (web type, body size), the prey availability and the prey intercepted by spider webs. We then evaluated the multivariate prey composition (prey type, body size) and network properties. Hymenoscyphus fraxineus opened the ash tree canopy, which resulted in denser shrub coverage. The dense shrub vegetation changed the composition of web types in local spider communities and increasing fungus infestation resulted in reduced mean body size of spiders. Infestation by H. fraxineus reduced the availability of predaceous Coleoptera and increased the availability of herbivorous Coleoptera as potential prey. The mean body size of captured prey and the per capita capture rates of most prey groups decreased with increasing fungus infestation. Hymenoscyphus fraxineus infestation indirectly reduced the complexity in bipartite networks and the trophic functional complementarity in local web-building spider communities. The plantation age affected the vegetation structure but did not affect the studied food-webs. Forest disturbance by the invasive pathogen affected four trophic levels (plant-herbivore-coleopteran intermediate predator-top predator web-building spiders) and, contrary to the disturbance-succession theory, disturbance by the fungus simplified the web-building spider-prey food-webs. The results support the view that H. fraxineus represents a threat to the biodiversity and ecosystem functioning in the simplified ecosystems of ash plantations.

Africanized honey bees in Colombia exhibit high prevalence but low level of infestation of Varroa mites and low prevalence of pathogenic viruses.

Abstract: The global spread of the ectoparasitic mite Varroa destructor has promoted the spread and virulence of highly infectious honey bee viruses. This phenomenon is considered the leading cause for the increased number of colony losses experienced by the mite-susceptible European honey bee populations in the Northern hemisphere. Most of the honey bee populations in Central and South America are Africanized honey bees (AHBs), which are considered more resistant to Varroa compared to European honey bees. However, the relationship between Varroa levels and the spread of honey bee viruses in AHBs remains unknown. In this study, we determined Varroa prevalence and infestation levels as well as the prevalence of seven major honey bee viruses in AHBs from three regions of Colombia. We found that although Varroa exhibited high prevalence (92%), its infestation levels were low (4.5%) considering that these populations never received acaricide treatments. We also detected four viruses in the three regions analyzed, but all colonies were asymptomatic, and virus prevalence was considerably lower than those found in other countries with higher rates of mite-associated colony loss (DWV 19.88%, BQCV 17.39%, SBV 23.4%, ABPV 10.56%). Our findings indicate that AHBs possess a natural resistance to Varroa that does not prevent the spread of this parasite among their population, but restrains mite population growth and suppresses the prevalence and pathogenicity of mite-associated viruses.

Distribution, abundance and natural enemies of the invasive tomato leafminer, Tuta absoluta (Meyrick) in Kenya.

Abstract: Tuta absoluta (Meyrick) has become a serious menace to sustainable production of tomato in Kenya. A survey was conducted between April 2015 and June 2016 to determine its distribution, abundance, infestation, and damage levels on tomato, and associated natural enemies. Trap counts of T. absoluta moths were recorded in all surveyed 29 counties, which indicated its nationwide distribution irrespective of altitude. Tuta absoluta was present in both open fields and greenhouses. The highest moth/trap/day was 115.38 ± 15.90. Highest leaf infestation was 92.22% and the highest number of mines and larvae per leaf were 3.71 ± 0.28 and 2.16 ± 0.45, respectively. Trap captures in terms of moth/trap/day were linearly and positively related to leaf infestations in open fields (R2 = 0.81) and greenhouses (R2 = 0.61). Highest fruits' infestation and damage were 60.00 and 59.61%, respectively, while the highest number of mines per fruit was 7.50 ± 0.50. Nesidiocoris tenuis (Reuter) and Macrolophus pygmaeus (Rambur) were identified as predators of T. absoluta larvae. Nine species of larval parasitoids were recovered from infested foliage, with a combined parasitism of 7.26 ± 0.65%. Hockeria species was the most dominant (31.25%) and accounted for 12.88 ± 1.47% parasitism. Two species of larval parasitoids, Hockeria and Necremnus were obtained from sentinel plants with an average parasitism of 1.13 ± 0.25. The overall abundance and parasitism rates of recovered natural enemies were low to effectively control the field populations of T. absoluta. These findings form the basis of researching and developing effective and sustainable management strategies for the pest.

Assessment of Tropical Bed Bug (Hemiptera: Cimicidae), Infestations in Cape Coast, Ghana: Household Control Practices and Efficacy of Commercial Insecticides and Long-Lasting Insecticidal Nets Against Field Bed Bugs.

Abstract: This study reports the first baseline information on tropical bed bug, Cimex hemipterus (F.) (Hemiptera: Cimicidae), infestations in Ghana. The purpose of this study was to assess bed bug infestation levels, and the efficacy of locally available insecticides and long-lasting insecticidal nets (LLINs) in controlling field bed bugs populations in the Cape Coast region. A survey was undertaken to assess bed bug infestation levels and current control practices by residents. In total, 205 bed bug affected households were identified in 20 communities and live bed bug infestations were associated with most of these premises. Many homeowners knew of other households (from 1 to 3) with a bed bug infestation. Residents reported itching and swelling of the skin from the bed bug bites and the bites were considered severe. The most common household bed bug control strategy was the application of insecticides. However, LLINs and commercially formulated insecticides commonly used by households (notably chloropyrifos and pyrethroid-based formulations) did not efficaciously suppress field collected strains of C. hemipterus. Using a dipping bioassay, mean mortality ranged from 0 to 60% for eggs, nymphs, and adults, and less than 40% mortality was observed in bed bugs placed on insecticide-treated filter paper. Each LLINs (all are pyrethroid based) produced a mean mortality of less than 20% in adult bed bugs. For a more effective response to the global bed bug resurgence in developing countries, government and supporting agencies need to render assistance to bed bug affected residents through the provision of improved pest management strategies.

Identification, Distribution, and Habitat Suitability Models of Ixodid Tick Species in Cattle in Eastern Bhutan.

Abstract: Tick infestation is the most reported parasitological problem in cattle in Bhutan. In May and June 2019, we collected ticks from 240 cattle in two districts of Eastern Bhutan. Tick presence, diversity, and infestation prevalence were examined by morphological identification of 3600 live adult ticks. The relationships between cattle, geographic factors, and infestation prevalence were assessed using logistic regression analyses. Habitat suitability for the tick species identified was determined using MaxEnt. Four genera and six species of ticks were found. These were Rhipicephalus microplus (Canestrini) (70.2% (95% confidence interval (CI): 68.7-71.7)), Rhipicephalus haemaphysaloides Supino (18.8% (95% CI: 17.5-20.1)), Haemaphysalis bispinosa Neumann (8.2% (95% CI: 7.3-9.1)), Haemaphysalis spinigera Neumann (2.5% (95% CI: 2-3)), Amblyomma testudinarium Koch (0.19% (95% CI: 0.07-0.4)), and a single unidentified Ixodes sp. Logistic regression indicated that the variables associated with infestation were: longitude and cattle age for R. microplus; latitude for R. haemaphysaloides; and altitude and cattle breed for H. bispinosa and H. spinigera. MaxEnt models showed land cover to be an important predictor for the occurrence of all tick species examined. These findings provide information that can be used to initiate and plan enhanced tick surveillance and subsequent prevention and control programs for ticks and tick-borne diseases in cattle in Bhutan.

Frequency of processed kaolin application to prevent Diaphorina citri infestation and dispersal in flushing citrus orchards

Abstract: BACKGROUND Processed kaolin is a promising tactic that can be utilized for managing Diaphorina citri Kuwayama infestation. However, the frequency of kaolin application to protect citrus trees during flushing remains undetermined. The objective of this study was to ascertain the frequency of kaolin application (2%) required to reduce D. citri infestation and dispersal in flushing citrus orchards and to measure the spectral reflectance of kaolin-sprayed leaves. RESULTS Trees sprayed with kaolin at 7- and 14-day intervals showed an 80% psyllid reduction compared to untreated trees. In addition, there was lower psyllid dispersal in the kaolin-sprayed plots. Spectral measurements (wavelengths between 320 and 700 nm) showed an increased reflectance of 35.4% (adaxial leaf side) and 21.9% (abaxial leaf side) in mature leaves, and 9% (adaxial leaf side) and 2.2% (abaxial leaf side) in kaolin-sprayed immature leaves compared to untreated trees. CONCLUSION Application of kaolin (2%) at 7- and 14-day intervals can be an important and sustainable tool for reducing D. citri infestation and dispersal in flushing citrus orchards. The reduced D. citri population in plots with both kaolin application intervals may be related to the visual effect (whitish aspect) and increased light reflectance in citrus trees, which are probably the main mechanisms by which kaolin interferes on D. citri host finding behavior. © 2021 Society of Chemical Industry.

Leaf antioxidant machinery stimulation by Meloidogyne javanica infestation: A case study on Cucumis melo seedlings

Abstract: Following nematode infestation, leaf-localized responses are vital not only as early infection signs but also as an indication of actions required to preserve crop productivity. In this context, the leaf-level physiological responses of cantaloupe seedlings were evaluated after 40 consecutive days of cultivation under different Meloidogyne javanica juveniles (J2s) inoculation regimes (0, 100, and 850 J2s plant−1). Leaf growth parameters and photosynthetic pigments (chlorophyll, carotenoids) content were not affected by J2s infestation, while foliar Potassium concentration significantly declined. The RuBIsCo activase gene expression was negatively associated with the J2s inoculation level. Total flavonoids, total phenolics, lipid peroxidation indexes, phenylalanine ammonia-lyase activity, as well as, ascorbate peroxidase gene transcription, were higher in the inoculated plants (regardless of the J2s inoculant level). Taken together, present data indicate that J2s infestation impacts primarily the Potassium levels in leaves. Additionally, a substantial stimulation of the plant antioxidant machinery (independent of the nematode infestation intensity) is triggered. Finally, it was established that the transcriptional regulation of the RuBIsCo activase 1 gene under biotic stress has the capacity to be employed as a potential stress indicator marker.

Repeatable differences in exploratory behaviour predict tick infestation probability in wild great tits

Abstract: Ecological factors and individual-specific traits affect parasite infestation in wild animals. Ixodid ticks are important ectoparasites of various vertebrate hosts, which include passerine bird species such as the great tit (Parus major). We studied various key ecological variables (breeding density, human disturbance) and phenotypic traits (exploratory behaviour, body condition) proposed to predict tick infestation probability and burden in great tits. Our study spanned 3 years and 12 nest box plots located in southern Germany. Breeding, adult great tits were assessed for exploration behaviour, body condition, and tick burden. Plots were open to human recreation; human disturbance was quantified in each plot as a recreation pressure index from biweekly nest box inspections. Infested individuals were repeatable in tick burden across years. These repeatable among-individual differences in tick burden were not attributable to exploration behaviour. However, faster explorers did have a higher infestation probability. Furthermore, body condition was negatively correlated to tick burden. Recreation pressure was correlated to increased infestation probability, although this relationship was just above the threshold of statistical significance. Our study implies that avian infestation probability and tick burden are each determined by distinct phenotypic traits and ecological factors. Our findings highlight the importance of animal behaviour and human disturbance in understanding variation in tick burden among avian hosts. Various abiotic and biotic factors, including personality type, influence tick parasitism in birds, but exactly how all these factors interplay remains unclear. We studied a wild population of great tits over a 3-year period and assessed birds for their exploration behaviour and tick infestation. We found that more explorative great tits were more likely to be infested with ticks. By contrast, faster explorers did not have higher tick burdens. Tick burden was nevertheless moderately repeatable among individuals. Our results imply that animal personality influences the probability of parasite infestation, and that infestation likelihood versus intensity are determined by distinct mechanisms. Our work highlights the importance of animal behaviour to understand parasite infestation in wild populations.

High prevalence and low diversity of chigger infestation in small mammals found in Bangkok Metropolitan parks.

Abstract: Chiggers are recognized as vectors of scrub typhus disease caused by the bacteria, Orientia tsutsugamushi. The risk of disease exposure is mainly related to chigger bites when humans or animals roam into vector-infested habitats. In big cities, urban public parks could provide areas for the animal-human interface and zoonotic pathogen transmission. The ecology and epidemiology of urban scrub typhus are still poorly understood in Thailand. Small mammals were trapped and examined for chigger infestation in urban public parks across metropolitan Bangkok, Thailand. We found a high prevalence of infestation (76.8%) with surprisingly low diversity. Two chigger species, Leptotrombidium deliense and Ascoschoengastia indica, were identified using morphological characteristics and molecular confirmation. The generalized linear model identified host intrinsic variables (i.e. body mass index) with host density, habitat composition and open field as the extrinsic factors explaining the abundance of chigger infestation. The bacteria O. tsutsugamushi was not detected in chiggers (90 chigger-pooled samples) and animal host tissues (164 spleen samples). However, the existence of chigger vectors calls for the Bangkok Metropolitan Administration and public health authorities to develop a comprehensive scrub typhus monitoring and prevention strategy in the parks and nearby communities.

Modulatory effects of moringa (Moringa oleifera L.) leaves infested with African mistletoe (Tapinanthus bangwensis L.) on the antioxidant, antidiabetic, and neurochemical indices in high sucrose diet-induced diabetic-like phenotype in fruit flies (Drosophila melanogaster M.).

Abstract: Moringa is a common medicinal plant tree with mistletoe infestation and its leaf is widely used as food and traditional medication in alleviating several metabolic and neurodegenerative diseases. Hence, this study investigated the influence of African mistletoe on the antioxidant, antidiabetic, and neuroprotective activities of infested moringa leaf in sucrose induced diabetes in Drosophila melanogaster model. Glucose and triglycerides were evaluated in the flies' hemolymph and all other parameters were evaluated in the tissues. A significant (p < .05) decrease in survival rate and increase in the level of glucose and triglycerides in flies fed with 30% of sucrose when compared with control was obtained. Treated flies had significant (p < .05) positive alteration in the level of glucose, triglycerides, antioxidants (both enzymatic and nonenzymatic), and enzyme activities when compared with normal and sucrose control flies. This study suggests that mistletoe infestation did not alter the antioxidant, antidiabetic, and neuroprotective effects of the moringa leaf. PRACTICAL APPLICATIONS: This present study has shown that mistletoe infestation did not alter the protective activities of moringa leaf, hence, moringa with or without mistletoe infestation could be taken as functional food to mitigate several metabolic diseases.