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Showing papers on "Infestation published in 2019"


Journal ArticleDOI
09 Jul 2019-PLOS ONE
TL;DR: This first surveillance study aimed to describe the health status of Austrian bee colonies and to analyze the reasons for losses for both the summer and winter season in Austria, finding the effect of a high varroa mite infestation level in September had by far the greatest potential to raise the winter losses.
Abstract: Austrian beekeepers frequently suffered severe colony losses during the last decade similar to trends all over Europe. This first surveillance study aimed to describe the health status of Austrian bee colonies and to analyze the reasons for losses for both the summer and winter season in Austria. In this study 189 apiaries all over Austria were selected using a stratified random sampling approach and inspected three times between July 2015 and spring 2016 by trained bee inspectors. The inspectors made interviews with the beekeepers about their beekeeping practice and the history of the involved colonies. They inspected a total of 1596 colonies for symptoms of nine bee pests and diseases (four of them notifiable diseases) and took bee samples for varroa mite infestation analysis. The most frequently detected diseases were three brood diseases: Varroosis, Chalkbrood and Sacbrood. The notifiable bee pests Aethina tumida and Tropilaelaps spp. were not detected. During the study period 10.8% of the 1596 observed colonies died. Winter proved to be the most critical season, in which 75% of the reported colony losses happened. Risks for suffering summer losses increased significantly, when colonies were weak in July, had queen problems or a high varroa mite infestation level on bees in July. Risks for suffering winter losses increased significantly, when the colonies had a high varroa mite infestation level on bees in September, were weak in September, had a queen older than one year or the beekeeper had few years of beekeeping experience. However, the effect of a high varroa mite infestation level in September had by far the greatest potential to raise the winter losses compared to the other significant factors.

51 citations


Journal ArticleDOI
TL;DR: The results indicated that the SENS could successfully detect the presence of early infestation by B. dorsalis in citrus fruits and an optimized sensor array achieved better performance in classification and discrimination than that of the non-optimized.

42 citations


Journal ArticleDOI
TL;DR: In this paper, the authors explored 22 Scots pine populations (Pinus sylvestris L.) in the northeast of the Iberian Peninsula that experienced a tree mortality episode involving bark beetle infestation and drought.

37 citations


Journal ArticleDOI
TL;DR: A mass spectrometry-based untargeted metabolomic approach is suitable to identify candidate compounds involved in the specificity of pea aphid – host plant interactions, which found significant differences among the metabolic fingerprints of the four legume species studied prior to aphid infestation.
Abstract: The pea aphid (Acyrthosiphon pisum), a phloem-sucking insect, has undergone a rapid radiation together with the domestication and anthropogenic range expansion of several of its legume host plants. This insect species is a complex of at least 15 genetically different host races that can all develop on the universal host plant Vicia faba. However, each host race is specialized on a particular plant species, such as Medicago sativa, Trifolium pratense, or Pisum sativum, which makes it an attractive model insect to study ecological speciation. Previous work revealed that pea aphid host plants produce a specific phytohormone profile depending on the host plant - host race combination. Native aphid races induce lower defense hormone levels in their host plant than non-native pea aphid races. Whether these changes in hormone levels also lead to changes in other metabolites is still unknown. We used a mass spectrometry-based untargeted metabolomic approach to identify plant chemical compounds that vary among different host plant-host race combinations and might therefore, be involved in pea aphid host race specialization. We found significant differences among the metabolic fingerprints of the four legume species studied prior to aphid infestation, which correlated with aphid performance. After infestation, the metabolic profiles of M. sativa and T. pratense plants infested with their respective native aphid host race were consistently different from profiles after infestation with non-native host races and from uninfested control plants. The metabolic profiles of P. sativum plants infested with their native aphid host race were also different from plants infested with non-native host races, but not different from uninfested control plants. The compounds responsible for these differences were putatively identified as flavonoids, saponins, non-proteinogenic amino acids and peptides among others. As members of these compound classes are known for their activity against insects and aphids in particular, they may be responsible for the differential performance of host races on native vs. non-native host plants. We conclude that the untargeted metabolomic approach is suitable to identify candidate compounds involved in the specificity of pea aphid - host plant interactions.

36 citations


Journal ArticleDOI
28 Jan 2019-Toxins
TL;DR: Overall, treatment with fungus did not inhibit the infestation by P. ficus, and findings shed light on some of the mechanisms involved in endophytic fungus-plant-insect interactions.
Abstract: Endophytic entomopathogenic fungi are being explored for the management of phytophagous insect pests. The effects of Beauveria bassiana (Hypocreales) inoculation of grape plants on the infestation level of P. ficus, tissue nutrient contents, and growth and volatile constituents of potted grape plants were assessed. Grapevine plants were individually inoculated with a suspension of 1 × 10⁸ conidia mL-1 of B. bassiana by drenching before experimentally infesting each of them with thirty adult females of P. ficus. At four weeks post-treatment, the fungus was re-isolated from leaves of 50% of the fungus-exposed plants. However, no significant difference (p > 0.05) was observed in all the plant growth parameters measured in the fungus-treated and control plants. Plant tissue analysis revealed markedly higher contents of calcium (Ca) and magnesium (Mg) in the leaf tissue of plants exposed to the B. bassiana relative to the control. Gas chromatography mass spectrometry (GC-MS) analyses showed that a significantly (X² = 5.1; p < 0.02) higher number of known anti-insect volatile compounds (nine) were present among fungus treated plants compared to the control plants (five). Naphthalene, which is toxic to insects and humans, was detected only in the volatiles of the fungus-exposed plants. B. bassiana did not have any significant effect on total polyphenol, alkaloid, and flavonoids. Overall, treatment with fungus did not inhibit the infestation by P. ficus. In conclusion, these findings shed light on some of the mechanisms involved in endophytic fungus-plant-insect interactions.

34 citations


Journal ArticleDOI
TL;DR: Overall, T. sinensis proved to be an outstanding biocontrol agent, and its success highlights how the classical biological control approach may represent a cost-effective tool for managing an exotic invasive pest.
Abstract: The biocontrol agent Torymus sinensis has been released into Japan, the USA, and Europe to suppress the Asian chestnut gall wasp, Dryocosmus kuriphilus. In this study, we provide a quantitative assessment of T. sinensis effectiveness for suppressing gall wasp infestations in Northwest Italy by annually evaluating the percentage of chestnuts infested by D. kuriphilus (infestation rate) and the number of T. sinensis adults that emerged per 100 galls (emergence index) over a 9-year period. We recorded the number of T. sinensis adults emerging from a total of 64,000 galls collected from 23 sampling sites. We found that T. sinensis strongly reduced the D. kuriphilus population, as demonstrated by reduced galls and an increased T. sinensis emergence index. Specifically, in Northwest Italy, the infestation rate was nearly zero 9 years after release of the parasitoid with no evidence of resurgence in infestation levels. In 2012, the number of T. sinensis females emerging per 100 galls was approximately 20 times higher than in 2009. Overall, T. sinensis proved to be an outstanding biocontrol agent, and its success highlights how the classical biological control approach may represent a cost-effective tool for managing an exotic invasive pest.

32 citations


Journal ArticleDOI
13 Jul 2019-Insects
TL;DR: A long-term investigation of D. suzukii dynamics in wild blueberry fields from 2012–2018 demonstrates relative abundance is either still increasing or exhibiting periodicity seven years after the initial invasion.
Abstract: A long-term investigation of D. suzukii dynamics in wild blueberry fields from 2012–2018 demonstrates relative abundance is either still increasing or exhibiting periodicity seven years after the initial invasion. Relative abundance is determined by physiological date of first detection and air temperatures the previous winter. Date of first detection of flies does not determine date of fruit infestation. The level of fruit infestation is determined by year, fly pressure, and insecticide application frequency. Frequency of insecticide application is determined by production system. Non-crop wild fruit and predation influences fly pressure; increased wild fruit abundance results in increased fly pressure. Increased predation rate reduces fly pressure, but only at high abundance of flies, or when high levels of wild fruit are present along field edges. Male sex ratio might be declining over the seven years. Action thresholds were developed from samples of 92 fields from 2012–2017 that related cumulative adult male trap capture to the following week likelihood of fruit infestation. A two-parameter gamma density function describing this probability was used to develop a risk-based gradient action threshold system. The action thresholds were validated from 2016–2018 in 35 fields and were shown to work well in two of three years (2016 and 2017).

31 citations


Journal ArticleDOI
TL;DR: It is concluded that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry.
Abstract: Parasites may actively seek for hosts and may use a number of adaptive strategies to promote their reproductive success and host colonization. These strategies will necessarily influence their host specificity and seasonality. Ticks are important ectoparasites of vertebrates, which (in addition to directly affecting their hosts) may transmit a number of pathogens. In Europe, three hard tick species (Ixodidae: Ixodes ariadnae, I. simplex and I. vespertilionis) and at least two soft tick species (Argasidae: Argas transgariepinus and A. vespertilionis) are specialized for bats. Here we report data on the host range of these ticks and the seasonality of tick infestation on wild caught bats in south-east Europe. We collected 1803 ticks from 30 species of bats living in underground shelters (caves and mines) from Romania and Bulgaria. On the basis of tick–host associations, we tested several hypotheses on host–parasite evolutionary adaptations regulating host specificity, seasonality and sympatric speciation. We observed significant differences in host specificity and seasonality of abundance between the morphologically different bat specialist ticks (I. simplex and I. vespertilionis) likely caused by their host choice and their respective host-seeking behavior. The two highly generalist, but morphologically similar tick species (I. ariadnae and I. vespertilionis) showed temporal differences in occurrence and activity, thus exploiting significantly different host communities while occurring in geographical sympatry. We conclude that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry.

31 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the feasibility of dual-wavelength terrestrial lidar in the estimation and detection of I. typographus infestation symptoms and examined the relationship between leaf water content (measured as gravimetric water content and equivalent water thickness) and infestation severity.

27 citations


Journal ArticleDOI
TL;DR: In this article, the authors quantify the dynamics of standing tree infestation patterns from two infestation sources: windthrow and previous-year beetle infestations, and find that the forest within 100m from the active infestation compared to more distant buffers had the highest risk of infestation.

26 citations


Journal ArticleDOI
23 Jul 2019-Forests
TL;DR: It is concluded that solar radiation, easily determined from the DEM, better identified beetle infestations than commonly used meteorological variables and is recommend including potential solar radiation in beetle infestation prediction models.
Abstract: In recent decades, Norway spruce (Picea abies L. Karst.) forests of the High Tatra Mountains have suffered unprecedented tree mortality caused by European spruce bark beetle (Ips typographus L.). Analysis of the spatiotemporal pattern of bark beetle outbreaks across the landscape in consecutive years can provide new insights into the population dynamics of tree-killing insects. A bark beetle outbreak occurred in the High Tatra Mountains after a storm damaged more than 10,000 ha of forests in 2004. We combined yearly Landsat-derived bark beetle infestation spots from 2006 to 2014 and meteorological data to identify the susceptibility of forest stands to beetle infestation. We found that digital elevation model (DEM)-derived potential radiation loads predicted beetle infestation, especially in the peak phase of beetle epidemic. Moreover, spots attacked at the beginning of our study period had higher values of received solar radiation than spots at the end of the study period, indicating that bark beetles prefer sites with higher insolation during outbreak. We conclude that solar radiation, easily determined from the DEM, better identified beetle infestations than commonly used meteorological variables. We recommend including potential solar radiation in beetle infestation prediction models.

Journal ArticleDOI
TL;DR: The results obtained indicate the potential of the measurement method based on gas sensors as a candidate solution for the detection of disease in honey bee colonies, and the development of the method requires further studies.

Journal ArticleDOI
TL;DR: This study indicates that migrating birds can transport ticks and their pathogens from neighboring countries to Denmark including sites in Denmark without a sustainable tick population, indicating the risk for rapid spread and long distance exchange of tick-borne pathogens in Europe.

Journal ArticleDOI
TL;DR: Sublethal concentrations of acetylcarvacrol demonstrated to impact the reproductive system of R. microplus by causing several damages in the female germ cells, probably contributing for a long-term control of tick infestation.

Journal ArticleDOI
TL;DR: Overall, kiwifruit is a poor host for B. dorsalis, Z. cucurbitae and C. capitata under natural conditions, and this information will help inform decisions about quarantine restrictions and potential crop loss in the event of incursions of these fruit flies into New Zealand or other k Kiwifruit producing countries.

Journal ArticleDOI
TL;DR: The results from a structural equation model revealed that mites and ticks indirectly and negatively affected each other’s infestation probability through an interaction involving the environmental context, indicating the environment of hosts has a strong effect on infestation probabilities and parasite loads of mite and ticks.
Abstract: Hosts and their parasites are under reciprocal selection, leading to coevolution. However, parasites depend not only on a host, but also on the host’s environment. In addition, a single host species is rarely infested by a single species of parasite and often supports multiple species (i.e., multi-infestation). Although the arms race between a parasite and its host has been well studied, few data are available on how environmental conditions may influence the process leading to multiple infestations. In this study, we examine whether: (1) environmental factors including altitude, temperature, vegetation cover, human disturbance, and grazing by livestock affect the prevalence of two types of ectoparasites, mites and ticks, on their host (the common lizard, Zootoca vivipara) and (2) competition is evident between mites and ticks. We found the probability of mite infestation increased with altitude and vegetation cover, but decreased with human disturbance and presence of livestock. In contrast, the probability of tick infestation was inversely associated with the same factors. Individuals with low body condition and males had higher mite loads. However, this pattern was not evident for tick loads. The results from a structural equation model revealed that mites and ticks indirectly and negatively affected each other’s infestation probability through an interaction involving the environmental context. We detected a direct negative association between mites and ticks only when considering estimates of parasite load. This suggests that both mites and ticks could attach to the same host, but once they start to accumulate, only one of them takes advantage. The environment of hosts has a strong effect on infestation probabilities and parasite loads of mites and ticks. Autecological differences between mites and ticks, as indicated by their opposing patterns along environmental gradients, may explain the pattern of weak contemporary interspecific competition. Our findings emphasize the importance of including environmental factors and the natural history of each parasite species in studies of host–parasite coevolution.

Journal ArticleDOI
TL;DR: Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances, which provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales.
Abstract: BACKGROUND This study investigated how infestation rates of an important oilseed rape pest, the cabbage seed weevil (Ceutorhynchus obstrictus) and rates of parasitization by its parasitoids are affected by land use, up to 1000 m from 18 focal fields. RESULTS The mean proportion of C. obstrictus-infested pods per plant was 8% (2-19.5%). Infestation rates were higher if the adjacent habitat was a herbaceous semi-natural habitat than if it was either another crop or a woody habitat. Infestation rates were positively related to the area of herbaceous semi-natural vegetation, permanent grassland and wheat (which followed oilseed rape in the crop rotation) at a spatial scale of at least 1 km. The mean parasitism rate of C. obstrictus larvae was 55% (8.3-87%), sufficient to provide efficient biocontrol. Parasitism rates were unrelated to adjacent habitats, however, they were positively related to the presence of herbaceous linear elements in the landscape and negatively related to permanent grasslands at a spatial scale of 200 m. CONCLUSION Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances. The findings provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales. © 2018 Society of Chemical Industry.

Journal ArticleDOI
26 Sep 2019-PLOS ONE
TL;DR: This study demonstrates that the honey bees from Ethiopia are suitable targets to further decipher the genetic predisposition of resistance against V. destructor and suggests a few adaptations to the test protocols allowing to estimate the protective traits of honey bee colonies under very low Varroa pressure.
Abstract: Worldwide, the ecto-parasitic mite Varroa destructor has been assigned as an important driver of honey bee (Apis mellifera) colony losses. Unlike the subspecies of European origin, the honey bees in some African countries such as Uganda and Ethiopia may not be as threatened or suffer less from mite-infestations. However, only little is known about the factors or traits that enable them to co-exist with the mite without beekeepers' intervention. Hence, this study was designed to investigate these factors or traits that limit the Varroa mite population in Ethiopian honey bees (Apis mellifera simensis). The study was conducted in the primary honey producing region of Ethiopia, i.e. Tigray. Mite infestation levels were shown to be lower in traditional hives (when compared to framed hives) and when colonies were started up from swarm catching (when compared to colony splitting). However, the influence of the comb cell size on mite infestation was not observed. With respect to the bee biology, the hygienic behavior was shown to be high (pin-test: 92.2% removal in 24 hours) and was negatively correlated with phoretic mite counts (Pearson; r = -0.79; P < 0.01) and mite infestation levels in brood (Pearson; r = -0.46; P < 0.001). Efforts to estimate the Varroa mite reproductive capacity were seriously hampered by an extremely low brood infestation level. From the 133 founder mites found (in 6727 capped brood cells) only 18.80% were capable of producing a reproductive progeny. Failure to produce adult male progeny was unexpectedly high (79.70%). We have suggested a few adaptations to the test protocols allowing to estimate the protective traits of honey bee colonies under very low Varroa pressure. Apart from that, this study demonstrates that the honey bees from Ethiopia are suitable targets to further decipher the genetic predisposition of resistance against V. destructor. It is still unclear to what extent simensis differs from the more common scutellata subspecies.

Journal ArticleDOI
TL;DR: Ivermectin may be an alternative choice for head-lice treatment, especially in remote areas, and was considered a preferable treatment option, and safe and effective for field-based practice.
Abstract: Head-lice infestation, pediculosis capitis, remains a public-health burden in many countries. The widely used first-line pediculicides and alternative treatments are often too costly for use in poor socio-economic settings. Ivermectin has been considered an alternate treatment for field practice. This study was composed of 2 parts, a cross-sectional survey and an intervention study. The main objectives were to determine the prevalence and potential factors associated with head-lice infestation, and to evaluate the effectiveness and safety of oral ivermectin administration. A community-based cross-sectional survey was conducted among 890 villagers in rural areas along Thai-Myanmar border. Females with infestations were eligible for the intervention study, and 181 participated in the intervention study. A post-treatment survey was conducted to assess acceptance of ivermectin as a treatment choice. Data analysis used descriptive statistics and a generalized-estimation-equation model adjusted for cluster effect. The study revealed the prevalence of head-lice infestation was 50% among females and only 3% among males. Age stratification showed a high prevalence among females aged <20 years, and among 50% of female school-children. The prevalence was persistent among those with a history of infestation. The major risk factors were residing in a setting with other infected cases, and sharing a hair comb. The study also confirmed that ivermectin was safe and effective for field-based practice. It was considered a preferable treatment option. In conclusion, behavior-change communication should be implemented to reduce the observed high prevalence of head-lice infestation. Ivermectin may be an alternative choice for head-lice treatment, especially in remote areas.

Journal ArticleDOI
TL;DR: Blackberries strongly enhanced D. suzukii abundance within field margin vegetation all year long, whereas fly abundance in vineyards adjacent to BB margins was just enhanced in some seasonal periods, and high fly numbers in BB field margins did result in zero egg infestation of “Pinot Noir” berries.
Abstract: Understanding the dynamics of pest insect populations in relation to the presence of non‐crop habitats and infestation levels of adjacent crops is essential to develop sustainable pest management strategies. The invasive pest species Drosophila suzukii (Diptera: Drosophilidae) is able to utilize a broad range of host plants. In viticulture, scientific risk assessment for D. suzukii has only recently started and studies assessing the effects of field margins containing wild host plants on D. suzukii population dynamics and on infestation risks in adjacent vineyards are lacking. Thus, in a one‐year field study, the role of different field margins on fly abundance and crop infestation in adjacent vineyards of Vitis vinifera, variety “Pinot Noir,” were investigated. Different monitoring methods were conducted to assess fly distribution, sex ratio and grape infestation in 14 vineyards adjacent to field margins containing either blackberry (BB) Rubus spp. or non‐host (NH) plants. Our results show that blackberries strongly enhanced D. suzukii abundance within field margin vegetation all year long, whereas fly abundance in vineyards adjacent to BB margins was just enhanced in some seasonal periods. Moreover, the influence of BB margins was limited by distance. However, high fly numbers in BB field margins did result in zero egg infestation of “Pinot Noir” berries. These results may have important implications for winegrowers to make efficient management decisions: regardless of high abundance of adult D. suzukii, only grape berry monitoring can assess the actual infestation risk and the potential need to take management action.

Journal ArticleDOI
TL;DR: In the Okanagan Basin, British Columbia, Canada, Drosophila suzukii (Matsumura) was first detected in 2009 in a controlled environment as discussed by the authors.
Abstract: Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was first detected in 2009 in the Okanagan Basin, British Columbia, Canada. During 2010–2016, 94 570 fruits of 35 non-crop species, from 12 plant families, were collected from 101 sites where adult D. suzukii flies were trapped, and incubated in a controlled environment. In total, 450 adult D. suzukii emerged from 62 of 929 fruit collections, and from 10 host plant species in five families, of which six species are native to the region. Five plant species are reported for the first time as hosts of D. suzukii, and 11 species for the first time as non-hosts. Measures of fly occurrence and infestation reveal it to be relatively abundant in five hosts and low in others. The fly reproduced in a succession of host plants, with first infestation of each from mid-July through mid-September, and was present until mid-October, but overwintering stages were not found. Degree-day accumulations for the infested period suggest that three to five generations of D. suzukii developed on non-crop plants and formed a large contribution to the annual increases observed in trap counts in a semi-arid cold winter climate, with implications for many strategies of pest management.

01 Jan 2019
TL;DR: The maximum tick infestation was in summer months (June-July) because these months are favorable for Tick development and reproduction.
Abstract: The current study was carried out to check the prevalence of tick infestation in sheep and goats in district Multan, Punjab, Pakistan. For this purpose, a total of 45 animals (25 sheep and 20 goats) were screened out. The various body parts like ears, udder and tails of animals were checked for tick collection. Out of total, 17(68.00%) sheep and 08(40.00%) goats were found infested with tick species. Three tick species such as Rhipicephalus sanguineus, Hyalomma anatolicum and Hyalomma marginatum were identified during the present study. The maximum infestation rate was in sheep as compared to goats. Mostly tick was collected from ears that are suitable site for tick infestation. The maximum tick infestation was in summer months (June-July) because these months are favorable for Tick development and reproduction

Journal ArticleDOI
TL;DR: Root phylloxera infestation imposes a considerable stress to the plants which might exacerbate the negative effects of drought, and events of water shortage favour insects’ feeding damage and increase the abundance of root nodosities.
Abstract: Intensity of drought stress and pest attacks is forecasted to increase in the near future posing a serious threat to natural and agricultural ecosystems. Knowledge on potential effects of a combined abiotic-biotic stress on whole-plant physiology is lacking. We monitored the water status and carbon metabolism of a vine rootstock with or without scion subjected to water shortening and/or infestation with the sucking insect phylloxera (Daktulosphaira vitifoliae Fitch). We measured non-structural carbohydrates and biomass of different plant organs to assess the stress-induced responses at the root, stem, and leaf level. Effects of watering on root infestation were also addressed. Higher root infestation was observed in drought-stressed plants compared to well-watered. The drought had a significant impact on most of the measured functional traits. Phylloxera further influenced vines water and carbon metabolism and enforced the sink strength of the roots by stimulating photosynthates translocation. The insect induced carbon depletion, reprogramed vine development, while preventing biomass compensation. A synergic effect of biotic-abiotic stress could be detected in several physiological and morphological traits. Our results indicate that events of water shortage favour insects’ feeding damage and increase the abundance of root nodosities. Root phylloxera infestation imposes a considerable stress to the plants which might exacerbate the negative effects of drought.

Journal ArticleDOI
TL;DR: The results indicate that remote sensing data can be used to assess the areas of poor growth and health of wheat plants due to Hessian fly infestation and suggests that remotely sensed data, including those from satellites orbiting >700 km from the surface of Earth, can offer valuable information on the occurrence and severity of pest infested areas.
Abstract: Remote sensing data that are efficiently used in ecological research and management are seldom used to study insect pest infestations in agricultural ecosystems. Here, we used multispectral satellite and aircraft data to evaluate the relationship between normalized difference vegetation index (NDVI) and Hessian fly (Mayetiola destructor) infestation in commercial winter wheat (Triticum aestivum) fields in Kansas, USA. We used visible and near-infrared data from each aerial platform to develop a series of NDVI maps for multiple fields for most of the winter wheat growing season. Hessian fly infestation in each field was surveyed in a uniform grid of multiple sampling points. For both satellite and aircraft data, NDVI decreased with increasing pest infestation. Despite the coarse resolution, NDVI from satellite data performed substantially better in explaining pest infestation in the fields than NDVI from high-resolution aircraft data. These results indicate that remote sensing data can be used to assess the areas of poor growth and health of wheat plants due to Hessian fly infestation. Our study suggests that remotely sensed data, including those from satellites orbiting >700 km from the surface of Earth, can offer valuable information on the occurrence and severity of pest infestations in agricultural areas.

Journal ArticleDOI
04 Dec 2019-Insects
TL;DR: It is demonstrated that the biochemical and morphological traits that confer drought tolerance in potato do not necessarily confer aphid tolerance.
Abstract: Drought stress on plants can cause cellular water deficits and influence the physiology of host plants, which alter the performance of insect pests. This study was conducted to determine the effect of drought and aphid (Myzus persicae Sulzer) infestation on three potato (Solanum tuberosum L) genotypes under greenhouse conditions. A factorial experiment involving three potato genotypes, two levels of drought, and two levels of aphid infestation was conducted. The potato genotypes possessed different levels of tolerance to drought and are described as tolerant (Qingshu 9), moderately tolerant (Longshu 3), and sensitive (Atlantic). Sixty-day-old potato plants were infested with aphid nymphs and monitored for 20 d. There was a significant variety × drought × aphid interaction effect on the parameters measured. The genotype Atlantic, which is sensitive to drought, exhibited greater tolerance to aphid infestation under drought or no drought conditions than the other genotypes. This genotype also exhibited poor host acceptance and the aphid survival rate, colonization success, and average daily reproduction were low. Qingshu 9, which is tolerant to drought, was highly susceptible to aphid infestation and exhibited high host acceptance and greater aphid survival rate, colonization success, and average daily reproduction compared to the other genotypes. This study demonstrates that the biochemical and morphological traits that confer drought tolerance in potato do not necessarily confer aphid tolerance.

Journal ArticleDOI
TL;DR: This study is the first to quantify associational resistance to a plant parasite in mixed vs .

Journal ArticleDOI
TL;DR: The findings of this 3-year study highlight the need to consider a landscape approach for stemborer pest management, but also indicate that maize is tolerant to low and medium infestation levels of stemborers.

Journal ArticleDOI
TL;DR: It is indicated that canine tungiasis persisted in the area during all periods of the year, and the seasonal variation described in human studies from other endemic areas was not observed.
Abstract: Tungiasis is a zoonosis neglected by authorities, health professionals, and affected populations. Domestic, synanthropic, and sylvatic animals serve as reservoirs for human infestation, and dogs are usually considered a main reservoir in endemic communities. To describe the seasonal variation and the persistence of tungiasis in dogs, we performed quarterly surveys during a period of 2 years in a tourist village in the municipality of Ilheus, Bahia State, known to be endemic for tungiasis. Prevalence in dogs ranged from 62.1% (43/66) in August 2013 to 82.2% (37/45) in November 2014, with no significant difference (p = 0.06). The prevalence of infestation remained high, regardless of rainfall patterns. Of the 31 dogs inspected at all surveys, period prevalence was 94% (29/31; 95% CI 79.3-98.2%) and persistence of infestation indicator [PII] was high (median PII = 6 surveys, q1 = 5, q3 = 7). Dogs < 1 year of age had a higher mean prevalence of 84.5%, as compared with 69.3% in the older dogs. No significant difference was found between the risk of infestation and age or sex (p = 0.61). Our data indicate that canine tungiasis persisted in the area during all periods of the year. The seasonal variation described in human studies from other endemic areas was not observed, most probably due to different rainfall patterns throughout the year. The study has important implications for the planning of integrated control measures in both humans and animal reservoirs, considering a One Health approach.

Journal ArticleDOI
TL;DR: The results suggest that linking population-level effects to parasite infestation pressure across climatic and environmental gradients may be challenging without correctly accounting for these effects.
Abstract: An individual-based model was parameterized to explore the impact of a crustacean ectoparasite (sea louse, Lepeophtheirus salmonis & Caligus spp.) on migrating Atlantic salmon smolt. The model explores how environmental and intrinsic factors can modulate the effect of sea lice on survival, growth and maturation of Atlantic salmon at sea. Relative to other effects, the parasite infestation pressure from fish farms and the encounter process emerge as the most important parameters. Although small variations in parasite-induced mortality may be masked by variable environmental effects, episodes of high infestation pressure from fish farms should be observable in wild populations of Atlantic salmon if laboratory studies accurately reflect the physiological effects of sea lice. Increases in temperature in the model negatively influenced fish survival by affecting the development time of the parasite at a rate that was not compensated for by the growth of the host. Discharge from rivers was parameterized to increase migration speed and influenced parasite induced mortality by decreasing time spent in areas with increased infestation pressure. Initial size and growth of the host was inversely related to the impact of the parasite because of size-dependent parasite-induced mortality in the early phase of migration. Overall, the model illustrates how environmental factors modulate effects on the host population by impacting either the parasite load or the relative effect of the parasite. The results suggest that linking population-level effects to parasite infestation pressure across climatic and environmental gradients may be challenging without correctly accounting for these effects.

Journal ArticleDOI
TL;DR: This study infested 0+ and 1+ hatchery reared brown trout with glochidia from closely related mothers and kept them under common garden conditions to observe a pure age dependent host response to infestation, and observed a significant age-dependent relationship.
Abstract: The freshwater pearl mussel (Margaritifera margaritifera) is an endangered bivalve with an obligate parasitic stage on salmonids. Host suitability studies have shown that glochidial growth and load vary significantly between host strains as well as among individuals of a suitable strain. Variation in host suitability has been linked to environmental conditions, host age and/or size, genetic composition of the host and parasite, or a combination of these factors. In our study, we wanted to investigate if brown trout (Salmo trutta) displayed an age-dependent response to glochidial infestation. We hypothesised that 1+ naive brown trout hosts tolerate glochidial infestation better than 0+ hosts. In order to test our hypothesis, we infested 0+ and 1+ hatchery reared brown trout with glochidia from closely related mothers and kept them under common garden conditions. This allowed us to observe a pure age dependent host response to infestation, as we eliminated the confounding effect of genotype-specific host interactions. We analysed the interaction between glochidial load and host condition, weight and length, and observed a significant age-dependent relationship. Glochidial load was negatively correlated to host condition in 0+ fish hosts and positively correlated in 1+ hosts. These contradictory findings can be explained by a change in host response strategy, from resistance in young to a higher tolerance in older fish. In addition, we also examined the relationship between glochidial load and haematocrit values in the 1+ hosts and observed that haematocrit values were significantly higher in heavily infested hosts. Our results have important conservation implications for the management of wild pearl mussel populations, as well as for captive breeding programmes.