Specialist Pest Research Articles

Western corn rootworm resistance in maize persists in the absence of jasmonic acid.

Larva growth, survival, and development speed were not affected by the absence of jasmonic acid (JA) indicating that JA does not have a direct role in maize resistance to western corn rootworm. Jasmonic acid (JA) is a plant hormone that regulates multiple physiological processes including defense against herbivory by chewing insects. Previous research showed its importance for resistance to aboveground herbivory. While few studies have investigated the role of JA in resistance to belowground root-feeding herbivores, none has directly tested the role of JA in such resistance. In this study, we used an opr7opr8 double mutant to directly test the role of JA in resistance to western corn rootworm (Diabrotica virgifera virgifera, WCR), a devastating and specialist pest of maize. The opr7opr8 double mutant is deficient in JA accumulation as we found that it does not accumulate JA nor JA-Ile independently of exposure to WCR. We found no significant difference in growth (body mass), survival, and development of WCR larvae in response to JA deficiency, suggesting that disruption of JA biosynthesis does not impact resistance in maize roots to WCR. Additionally, we observed no significant effect on loss of root tissue caused by WCR associated with JA deficiency, while we found a reduction in shoot growth (mass) associated with WCR herbivory in the opr7opr8 mutant that was not observed in the wildtype. This suggested a role for JA in aboveground growth response to WCR herbivory rather than resistance to WCR.

Functional characterization of Helicoverpa assulta CYP6B6 in insecticide metabolism

The oriental tobacco budworm Helicoverpa assulta (Lepidoptera: Noctuidae) is a specialist pest that may cause serious damages to important crops such as chili pepper and tobacco. Various man-made insecticides have been applied to control the infestation of this pest. To understand how this pest copes with insecticides, it is required to identify key players involved in insecticide transformation. In this study, a P450 gene of CYP6B subfamily was identified in the oriental tobacco budworm, and its expression pattern was revealed. Moreover, the activities of HassCYP6B6 against 12 insecticides were explored using recombinant enzymes produced in the facile Escherichia coli. Data from metabolic experiments showed that HassCYP6B6 was able to metabolize conventional insecticides including organophosporates (diazinon, malathion, phoxim), carbamate propoxur, and pyrethroid esfenvalerate, while no significant metabolism was observed towards new-type pesticides such as neonicotinoids (acetamiprid, imidacloprid), diamides (chlorantraniliprole, cyantraniliprole), macrocyclic lactone (emamectin benzoate, ivermectin), and metaflumizone. Structures of metabolites were proposed based on mass spectrometry analyses. The results demonstrate that HassCYP6B6 plays important roles in the transformation of multiple insecticides via substrate-dependent catalytic mechanisms including dehydrogenation, hydroxylation and oxidative desulfurization. The findings have important applied implications for the usage of insecticides.

Ecology and management of the crapemyrtle aphid (Hemiptera: Aphididae) on crapemyrtle (Myrtales: Lythraceae) in the southern United States

AbstractCrapemyrtle aphid [Sarucallis kahawaluokalani (Kirkaldy 1907)] (CMA) is an introduced pest of crapemyrtle (Lagerstroemia spp. L.), which is among the most common ornamental tree genera in the southern United States. Native to Southeast Asia, CMA has become established on 5 other continents. CMAs produce honeydew as they feed which supports sooty mold growth and can result in leaf defoliation on infested trees. CMAs tend to be most abundant in crapemyrtles planted in locations with extensive surrounding impervious surface cover. A large community of generalist natural enemies are found in close association with CMA, which suggests that CMAs may help conserve natural enemy communities in urban areas. Due to the long-lasting blooms produced by crapemyrtle, and the attractiveness of these blooms to pollinators, insecticides should be used as a last resort to manage CMA infestations. While CMA is considered a specialist pest of crapemyrtle, it has been recorded on 3 species outside of the genus Lagerstroemia. The wide distribution of CMA, closely overlapping that of crapemyrtle, suggests that CMA can likely be found wherever crapemyrtles are commonly planted.

Assessing effective mechanical and chemical strategies for managing Eucosma giganteana (Lepidoptera: Tortricidae) in the perennial oilseed crop, Silphium integrifolium (Asteraceae: Heliantheae).

Eucosma giganteana (Riley) is a native specialist pest of silflower, Silphium integrifolium Michx., which is currently being domesticated as a perennial oilseeds crop. The larvae of this moth attack silflower capitula and root crowns, causing both seed damage and long-term degradation of plants. To determine methods to manage E. giganteana in silflower crop fields, we conducted a laboratory bioassay and 3 field experiments to assess the effects of a suite of organic, conventional, and mechanical treatments on E. giganteana mortality and colonization of flower heads. Pyrethroids (permethrin, cyfluthrin), chlorantraniliprole, and methoxyfenozide each had significant insecticidal effects on E. giganteana in at least 2 of the experiments conducted. Nematodes marginally increased larva mortality in the laboratory bioassay and could be further investigated as a soil-applied biological control. In 2 separate field experiments, trimming the top 15% of silflower plants to delay flowering did not alone reduce E. giganteana colonization of flower heads throughout the growing season. However, when trimming was paired with a single chlorantraniliprole application, colonization of capitula was reduced by 83% over untreated control plants. Collectively, these experiments provide evidence for several treatments that could be further tested and incorporated into an integrated pest management strategy for E. giganteana.

Banker Plant Bonuses? The Benefits and Risks of Including Brassicas in Field Margins to Promote Conservation Biocontrol of Specialist Pests in Oilseed Rape.

European agri-environment schemes include the use of flower-rich field margins to promote on-farm biodiversity, but species mixtures rarely include Brassicaceae. As pests of oilseed rape (OSR; Brassica napus) and their parasitoids are mostly brassica specialists, including brassica 'banker plants' in the mixtures would help support these important biocontrol agents and improve pest control throughout the crop rotation. We assessed the potential of six brassicaceous plants (replicated plots grown in the field) to enhance populations of parasitoids of OSR pests whilst minimising proliferation of their pest hosts. Fodder radish (Raphanus sativus) facilitated high production of parasitoids of the pollen beetle pest (Brassicogethes aeneus) but may proliferate Ceutorhynchus weevil pests due to low parasitism. Turnip rape (B. rapa) and the B. rapa hybrid 'Tyfon' showed potential to perform a trap cropping function for pests, but their early flowering phenology resulted in B. aeneus larvae escaping parasitisation, potentially assisting proliferation of this pest. Forage rape B. napus exhibited similarly high B. aeneus parasitoid production characteristics to R. sativus but did not potentiate problems with other pests, indicating that it would be a favourable banker plant option. Careful selection of plants in field margin mixtures is therefore needed to maximise their benefits and ideally the whole crop pest-beneficial complex needs to be studied, as focus on a single major pest risks unintended consequences with other pest problems.

Tolerance to dietary linalool primarily involves co-expression of cytochrome P450s and cuticular proteins in Pagiophloeus tsushimanus (Coleoptera: Curculionidae) larvae using SMRT sequencing and RNA-seq

BackgroundPagiophloeus tsushimanus (Coleoptera: Curculionidae), an emerging forest pest exclusively infesting camphor trees, has recently caused severe ecological and economic damage in localized areas in China. Its population outbreak depends largely on the capacity to overcome the pressure of terpenoid-derived metabolites (e.g. linalool) from camphor trees. At present, the molecular basis of physiological adaptation of P. tsushimanus to dietary linalool is poorly understood, and there is no available reference genome or transcriptome.ResultsHerein, we constructed the transcriptome profiling of P. tsushimanus larvae reared on linalool-infused diets using RNA sequencing and single-molecule real-time sequencing. A total of 20,325 high-quality full-length transcripts were identified as a reference transcriptome, of which 14,492 protein-coding transcripts including 130 transcription factors (TFs), and 5561 long non-coding RNAs (lncRNAs) were detected. Also, 30 alternative splicing events and 8049 simple sequence repeats were captured. Gene ontology enrichment of differential expressed transcripts revealed that overall up-regulation of both cytochrome P450s (CYP450s) and cuticular proteins (CPs), was the primary response characteristic against dietary linalool. Other physiological effects possibly caused by linalool exposure, such as increase in Reactive Oxygen Species (ROS) and hormetic stimulation, were compensated by a handful of induced genes encoding antioxidases, heat shock proteins (HSPs), juvenile hormone (JH) epoxide hydrolases, and digestive enzymes. Additionally, based on co-expression networks analysis, a diverse array of hub lncRNAs and TFs co-expressed with CYP450s and CPs were screened as the potential gene regulators. Temporal expression of candidate transcripts determined by quantitative real-time PCR also indicated a cooperative relationship between the inductions of CYP450s and CPs upon exposure to linalool.ConclusionsOur present study provides an important transcriptome resource of P. tsushimanus, and lays a valuable foundation for understanding how this specialist pest copes with chemical challenges in its specific host environments.

An inducible gene from glycoside hydrolase one family of Plutella xylostella decreases larval survival when feeding on host plant.

Glycoside hydrolase family 1 (GH1) members exhibit a broad substrate spectrum and play important roles in insect-plant interactions, such as the defensive β-glucosidase and β-thioglucosidase (so-called myrosinase). However, knowledge about the expression profiling and function of glycoside hydrolase family 1 members in a specialist pest of crucifers Plutella xylostella is still limited. In this study, 13 putative glycoside hydrolase family 1 members of P. xylostella were identified based on the sequence characteristics, while no myrosinase activity was detectable in P. xylostella using gas chromatography-mass spectrometry (GC-MS). Expression profiling of these glycoside hydrolase family 1 members identified the midgut-specific gene Px008848 that is induced by host plant. Further experiments revealed that the in vitro expressed Px008848 protein had β-glucosidase activity and the survival rate of the larvae feeding on wounded Arabidopsis thaliana leaves declined when leaves were treated with purified Px008848 protein. When CRISPR/Cas9-based homozygous mutant larvae of Px008848 and wild-type larvae were respectively transferred onto the A. thaliana, the larval survival rate of the mutant larvae was significantly higher than that of the wild-type individuals. Our work showed that certain insect glycoside hydrolase family 1 gene may have negative effect on the development of larvae feeding on the host plant, which broadened our understandings on the evolutionary function of this gene family in the insect-plant interaction.

Genome-Wide Identification and Expression Profiling of the Wnt Gene Family in Three Rice Planthoppers: Sogatella furcifera, Laodelphax striatellus, and Nilaparvata lugens.

The Wnt gene family plays essential roles in regulating many developmental processes, including the maintenance of stem cells, cell division, and cell migration. The number of Wnt genes varies among species. Due to the diversity and importance of their functions, the Wnt gene family has gained extensive research interest in various animal species from invertebrates to vertebrates. However, knowledge of the Wnt gene family is limited in rice planthoppers. Three planthopper species, the white-backed planthopper (Sogatella furcifera Horvath), the small brown planthopper (Laodelphax striatellus Fallén) and the brown planthopper (Nilaparvata lugens Stål) (Hemiptera: Delphacidae), are devastating specialist pests of rice and cause serious damage to rice plants. To better study the evolution and function of the Wnt gene family in rice planthoppers, we identified 8 Wnt family genes in three rice planthoppers with both genomic and extensive transcriptomic resources available. We conducted a systematic analysis of the three kinds of rice planthoppers and analyzed the dynamic patterns of gene conservation, as well as Wnt gene loss and duplication. The expression profiles in different developmental stages of S. furcifera and different adult organs and tissues of L. striatellus provide preliminary functional implications for the Wnt genes in rice planthopper. This study presents the first genome-wide study of the Wnt gene family in rice planthoppers, and our findings provide insights into Wnt function and evolution in rice planthoppers.

Non-host habitat at local and landscape scales promotes overwintering success of a specialist insect pest

Incorporating non-crop habitats around cropping fields is often promoted to enhance biodiversity and deter crop pests. However, few studies have investigated how these habitats influence the overwintering success of pest populations. In this study, we investigate how a specialist insect pest, the asparagus beetle (Crioceris asparagi, Coleoptera: Chrysomelidae), uses local and landscape resources for overwintering. We surveyed beetles in 2019–2020 at 11 asparagus farms in Michigan, USA, and conducted experiments to compare overwintering survival of adult beetles in five substrates commonly found in asparagus agroecosystems. We compared the overwintering number of beetles across three habitat types: asparagus field, weedy margin, and woodlot. Overwintering asparagus beetle abundance was highest within sites with deciduous leaves and decomposing asparagus stalks. We found a negative relationship between the abundance of dead trees in adjacent woodlots and adult beetle abundance. We then expanded beyond the woodlots with a landscape analysis conducted at multiple spatial scales. Landscape analysis indicated that deciduous forest within 1250 m of sites increased beetle abundance in focal asparagus fields, while asparagus production at spatial scales greater than 1500 m suppressed their populations. Our findings indicate that certain specialist pests, like asparagus beetles, depend on host resources for overwintering, but non-host habitat from the surrounding landscape is also important to their success. Practically, removal of host and non-host debris (leaf litter) from asparagus fields may lead to decreased survival and lower pest pressures. In addition, crop-dominated landscapes may not require in-field habitat management of overwintering substrates to the same extent as more diverse landscapes with higher proportions of non-host habitat (deciduous forest). Ultimately, we argue that the net positive and negative impact of increasing non-host habitat at the landscape level should be considered when developing integrated pest management strategies for specialists at the local scale.

Assessment of Age, Gender, Mating Status, and Size on Single and Repeat Flight Capabilities of Heilipus lauri Boheman (Coleoptera: Curculionidae)

Heilipus lauri Boheman (Coleoptera: Curculionidae) is a specialist pest of avocado fruit and is considered an incursion risk for U.S. avocado producers. At the time work reported here was undertaken the flight capabilities of H. lauri were unknown. Consequently, proactive studies were undertaken to quantify aspects of this pest’s flight capabilities to inform potential future control efforts. Flight mill studies were conducted in a quarantine laboratory to measure the dispersal capacity of H. lauri with respect to gender, mating status, and size on the single and repeat flight capabilities of weevils. Gender, mating status, and size did not significantly affect measured flight parameters. Average total distances flown and flight velocity, and mean maximum flight bout distances and durations significantly declined as weevil age increased and when weevils engaged in repeat flights. Survivorship rates were significantly reduced as the number of successive flights undertaken increased. The distribution of total average flight distances flown and total cumulative flight distances flown was platykurtic. The implications of these findings are discussed in terms of developing incursion management plans.

Within-Canopy Distribution of Stenoma catenifer (Lepidoptera: Elachistidae) Infestation in Avocado Orchards

Native to the neotropics, the avocado seed moth Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) is a specialist pest of the family Lauraceae and considered one of the most important pests of avocados worldwide. However, little is known regarding its spatial distribution within a single tree. Therefore, we designed a study to evaluate the effects of canopy height and aspect (i.e., side of the tree) on fruit infestation by S. catenifer larvae in avocados. The study was conducted in three commercial organic avocado orchards located in São Paulo, Brazil. At each orchard, 40 fruit from 30 random trees were sampled weekly from October 2017 through February 2018, evaluating the number of fruits infested by S. catenifer larvae at three tree heights (bottom, middle, and top). In addition, fruits on the ground were also sampled. We also evaluated the effect of the side of the tree where the fruits were collected, i.e., whether they were on the side facing the east (sunrise) or the west (sunset). Within the avocado canopy, the level of fruit infestation by S. catenifer larvae was significantly higher at the top of the trees than in the middle and bottom. Fruit on the ground had lower levels of infestation than those on the tree canopy. The level of fruit infestation was also higher on the side of avocado trees facing the east (sunrise). Understanding the within-tree distribution of S. catenifer will help to better target monitoring and control activities against this pest in avocados.

Foliar Aphid Herbivory Alters the Tomato Rhizosphere Microbiome, but Initial Soil Community Determines the Legacy Effects

Aboveground herbivory can impact the root-associated microbiome, while simultaneously different soil microbial communities influence herbivore performance. It is currently unclear how these reciprocal top-down and bottom-up interactions between plants, insects and microbes vary across different soils and over successive plant generations. In this study, we examined top-down impacts of above-ground herbivory on the rhizosphere microbiome across different soils, assessed bottom-up impacts of soil microbial community variation on herbivore performance, and evaluated their respective contributions to soil legacy effects on herbivore performance. We used Macrosiphum euphorbiae (potato aphid) and Solanum pimpinellifolium (wild tomato) to capture pre-domestication microbiome interactions with a specialist pest. First, using 16S rRNA sequencing we compared bacterial communities associated with rhizospheres of aphid-infested and uninfested control plants grown in three different soils over three time points. High aphid infestation impacted rhizosphere bacterial diversity in a soil-dependent manner, ranging from a 22% decrease to a 21% increase relative to uninfested plants and explained 6–7% of community composition differences in two of three soils. We next investigated bottom-up and soil legacy effects of aphid herbivory by growing wild tomatoes in each of the three soils and a sterilized “no microbiome” soil, infesting with aphids (phase one), then planting a second generation (phase two) of plants in the soil conditioned with aphid-infested or uninfested control plants. In the first phase, aphid performance varied across plants grown in different soil sources, ranging from a 20 to 50% increase in aphid performance compared to the “no microbiome” control soil, demonstrating a bottom-up role for soil microbial community. In the second phase, initial soil community, but not previous aphid infestation, impacted aphid performance on plants. Thus, while herbivory altered the rhizosphere microbiome in a soil community-dependent manner, the bottom-up interaction between the microbial community and the plant, not top-down effects of prior herbivore infestation, affected herbivore performance in the following plant generation. These findings suggest that the bottom-up effects of the soil microbial community play an overriding role in herbivore performance in both current and future plant generations and thus are an important target for sustainable control of herbivory in agroecosystems.

Love thy neighbors? Beneficial and pest arthropod populations in a pear and cherry orchard landscape

Neighboring vegetation in an agricultural landscape can impact pest and beneficial arthropod populations in tree fruit orchards. In a pear monocrop region (such as Wenatchee WA, northwestern United States), the concern is that specialist pests can migrate from orchard to orchard and maintain an area-wide high population. In a mixed landscape region (such as Hood River OR, NW USA), the concern is that chemical control measures against invasive pests in nearby cherry orchards can disrupt biological control in pear orchards by killing beneficial arthropods. Specifically, we asked whether surrounding pear and cherry area cover (% in 1 km2), presence of adjacent cherry orchards, and pesticide impact scores influenced the abundance and richness of common pests (pear psylla and two-spotted spider TSS mites) and beneficial arthropods (the parasitoid wasp Trechnites insidiosus and generalist predators) in pear orchards in OR and WA. Pests and beneficial arthropods were collected in pear plots in OR and WA in 2016–2018 using a combination of methods (sticky cards, beat trays, leaf samples). A generalized linear mixed model revealed that surrounding pear cover area did not affect any of the outcome variables. Surrounding cherry cover had variable effects on pest and beneficial abundance in different regions and years, such as a negative correlation with predator abundance (OR 2016), a positive correlation with parasitoid abundance (WA 2017), and higher pear psylla abundance in cherry-adjacent pear plots (OR 2018). Furthermore, a quantile regression showed that pear orchards with low surrounding cherry cover had high variance in parasitoid abundance, while pear orchards with high surrounding cherry cover had consistently low parasitoid abundance. Pesticide impact scores negatively influenced predator and parasitoid abundance and beneficial richness in WA, but not in OR. Pear plots with higher pesticide impact scores had higher TSS mite abundance (in both OR and WA 2018), but did not affect pear psylla abundance. A redundancy analysis (RDA) showed that beneficial population assemblages tended to cluster away from pear plots with high pesticide impact scores. This study shows how landscape and chemical control practices can have variable impacts on pear orchards located in different regions.

Contrasting effects of host crops and crop diversity on the abundance and parasitism of a specialist herbivore in agricultural landscapes

Landscape complexity affects herbivores in agroecosystems, but consequences on pest control services are variable. Carryover effects of landscape composition in previous years on herbivore control may be important, but have been seldom assessed. Understanding landscape complexity effects at different temporal and spatial scales is important to improve sustainable pest control services. We examined the effect of agricultural landscape complexity (e.g., the percentage of semi-natural habitats) on cereal leaf beetle (CLB), Oulema melanopus L., and its parasitism by Tetrastichus julis (Walker). From 2014 to 2015, we assessed CLB abundance and parasitism in 54 fields along a gradient of landscape complexity (2–70% of semi-natural habitats) in southern Alberta. We used generalized linear models to test the effects of percentage of crops and semi-natural habitats, and landscape and crop diversity on CLB abundance and parasitism at 0.5, 1, 1.5 and 2 km spatial scales. CLB abundance decreased with higher crop diversity at the 0.5 km scale and increased with CLB host crops in the current and previous years at multiple scales, supporting the resource concentration hypothesis. CLB parasitism increased with CLB abundance and in landscapes with increased canola and alfalfa during a year of low CLB abundance. CLB abundance had contrasting associations with semi-natural habitats: positive with woodlands and negative with pastures. Our study suggests that crop diversity reduces the abundance of this specialist pest in agricultural landscapes likely by a dual effect of reducing host crop area and increasing habitats with resources for parasitoids.

Tree species identity and forest composition affect the number of oak processionary moth captured in pheromone traps and the intensity of larval defoliation

AbstractPure forests are often seen as being more prone to damage by specialist pest insects than mixed forests, and particularly mixed forests associating host and nonhost species. We addressed the effect of tree diversity on oak colonization and defoliation by a major specialist pest, the oak processionary moth (OPM) We quantified the number of male OPM moths captured and larval defoliation in pure stands of two oak host species (Quercus robur and Quercus petraea) and in mixed stands associating the two oak species or each oak species with another nonhost broadleaved species. We conducted two complementary studies to test the effect of host species and stand composition: (i) we used pheromone trapping to compare the number of males OPM captured throughout the distribution of oak hosts in France and (ii) we noted the presence of OPM nests and estimated defoliation in mature forests of north‐eastern France. Oak species and stand composition significantly influenced the number of male OPM captured and defoliation by OPM larvae. Quercus petraea was consistently more attractive to and more defoliated by OPM than Q. robur. Both oak trees were attacked more in pure stands than in mixed stands, in particular mixed stands associating oaks with another (nonhost) broadleaved species. The results of the present study support the view that mixed forests are more resistant to specialist pest insects than pure stands, and also indicate that this trend depends on forest composition. Our study provides new insights into OPM ecology and has potential implications for forest management, including the management of urban forests where OPM causes serious human health issues.

Transient expression of SbDhr2 and MeHNL in Gossypium hirsutum for herbivore deterrence assay with Spodoptera litura

BackgroundSpodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco cutworm or cotton leafworm, is a polyphagous pest which causes considerable damage to cotton (Gossypium hirsutum) and other crops. Herbivore-induced defence response is activated in plants against chewing pests, in which plant secondary metabolites play an important role. Dhurrinase2 (SbDhr2), a cyanogenic β-glucosidase from Sorghum bicolor, is the key enzyme responsible for the hydrolysis of dhurrin (cyanogenic β-glucosidic substrate) to p-hydroxymandelonitrile. Hydroxynitrile lyase (MeHNL) from Mannihot esculanta catalyses the dissociation of cyanohydrins to hydrogen cyanide and corresponding carbonyl compound, both enzymes play a pivotal role in plant defence mechanism.ResultsSbDhr2 and MeHNL genes were expressed individually and co-expressed transiently in cotton leaves. We examined the feeding response of S. litura to leaves in the choice assay. The S. litura population used in this study showed better feeding deterrence to leaves co-expressing both genes compared with the expression of an individual gene.ConclusionOur results suggest that co-expression of SbDhr2 and MeHNL genes in cotton leaves demonstrate feeding deterrence to S. litura. Engineering cyanogenic pathway in aerial parts of cotton would be an additional defence strategy against generalist pests and can be enhanced against specialist pests.

Genetic control of Plutella xylostella in omics era.

Diamondback moth, Plutella xylostella (L.), is a specialist pest on cruciferous crops of economic importance. The large-scale use of chemical insecticides for the control of this insect pest has caused a number of challenges to agro-ecosystems. With the advent of the omics era, genetic pest management strategies are becoming increasingly feasible and show a powerful potential for pest control. Here, we review strategies for using transgenic plants and sterile insect techniques for genetic pest management and introduce the major advances in the control of P. xylostella using a female-specific RIDL (release of insects carrying a dominant lethal gene) strategy. Further, the advantages of gene drive developed in combination with sex determination and CRISPR/Cas9 systems are addressed, and the corresponding prospects and implementation issues are discussed. It is predictable that under the policy and regulation of professional committees, the genetic pest control strategy, especially for gene drive, will open a new avenue to sustainable pest management not only for P. xylostella but also for other insect pests.

An online interactive identification key to common pest species of Aspidiotini (Hemiptera, Coccomorpha, Diaspididae), version 1.0.

Aspidiotini is a species-rich tribe of armored scale insects that includes several polyphagous and specialist pests that are commonly encountered at ports-of-entry to the United States and many other countries. This article describes a newly available online interactive tool that can be used to identify 155 species of Aspidiotini that are recognized as minor to major pests or that are potentially emergent pests. This article lists the species and features included with a description of the development and structure of the key. The interactive key is free to access at https://idtools.org/id/scales/aspidiotini/about_index.php.

Distribution models for Ascia monuste and the host Brassica oleracea var. capitata

AbstractThe butterfly Ascia monuste L. (Lepidoptera: Pieridae) is a specialist pest of brassica crops in neotropical regions where it significantly impacts crop production. Understanding the actual and potential distribution of the pest and its hosts in current and future climates may help government agencies to mitigate and manage potential incursions. Here, we use MaxEnt algorithm to model the current distribution of both A. monuste and its host, Brassica oleracea var. capitata L. (cabbage) and then model the likely impact of projected climate change (RCP 4.5 and 8.5 scenarios) on their potential future distributions. While A. monuste is currently restricted to the American continent, we show that under current conditions the potential distribution of both the butterfly and cabbage includes areas of Africa, Asia, Oceania and Europe to some extent. The annual temperature range and mean annual temperature were the strongest predictors of the distribution of both species. Under a projected climate change scenario, suitable areas in the tropical climate zone are expected to decrease for both species. However, in temperate regions, the suitable area for cabbage is expected to increase but will remain unsuitable for the pest. Our results highlight the need for strategies to prevent the introduction of A. monuste to other areas of the tropical climate zone and for the development of management practices in the neotropical region.

Effects of Two Cultivated Brassica spp. on the Development and Performance of Diadegma semiclausum (Hymenoptera: Ichneumonidae) and Cotesia vestalis (Hymenoptera: Braconidae) Parasitizing Plutella xylostella (Lepidoptera: Plutellidae) in Kenya.

The diamondback moth (DBM), Plutella xylostella L., is the most destructive pest affecting vegetable production in Kenya and around the world. Parasitoids have shown promising results in lowering the pest populations and damage caused by DBM. However, variations in host plant quality have been reported to have bottom-up effects up to the third and fourth trophic levels. We assessed the effects of two cultivated Brassica varieties (cabbage, Brassica oleracea var. capitata L. cultivar 'Gloria F1' and kale, B. oleracea var. acephala L. cultivar 'Thousand headed') on the development and performance of the specialist pest P. xylostella and two exotic parasitoids Diadegma semiclausum (Hellen) and Cotesia vestalis (Haliday). The exposed larval period of DBM took about 1.5 d longer on kale than cabbage and the total immature development time of both females and males was significantly longer on kale than cabbage. Higher pupal weight and higher fecundity were recorded on DBM fed on kale. Development time of D. semiclausum and C. vestalis was not affected by the host crop as was the parasitism rate of D. semiclausum. Heavier male pupae and larger adults of D. semiclausum, as well as more fecund adults of C. vestalis, were obtained from hosts fed on cabbage. Larger adults of C. vestalis were obtained from herbivores fed on kale. These results show potentially positive effects of host plant allelochemicals that are detrimental to herbivores while promoting parasitoid development and performance, which can be harnessed for the control of DBM.