The Boxelder Bug

This factsheet describes the appearance, behavior, and control of the boxelder bug, a common pest around and occasionally on and in Maryland homes

Neonicotinoid Insecticide Imidacloprid Causes Outbreaks of Spider Mites on Elm Trees in Urban Landscapes

BACKGROUND: Attempts to eradicate alien arthropods often require pesticide applications. An effort to remove an alien beetle from Central Park in New York City, USA, resulted in widespread treatments of trees with the neonicotinoid insecticide imidacloprid. Imidacloprid's systemic activity and mode of entry via roots or trunk injections reduce risk of environmental contamination and limit exposure of non-target organisms to pesticide residues. However, unexpected outbreaks of a formerly innocuous herbivore, Tetranychus schoenei (Acari: Tetranychidae), followed imidacloprid applications to elms in Central Park. This undesirable outcome necessitated an assessment of imidacloprid's impact on communities of arthropods, its effects on predators, and enhancement of the performance of T. schoenei. METHODOLOGY/PRINCIPAL FINDINGS: By sampling arthropods in elm canopies over three years in two locations, we document changes in the structure of communities following applications of imidacloprid. Differences in community structure were mostly attributable to increases in the abundance of T. schoenei on elms treated with imidacloprid. In laboratory experiments, predators of T. schoenei were poisoned through ingestion of prey exposed to imidacloprid. Imidacloprid's proclivity to elevate fecundity of T. schoenei also contributed to their elevated densities on treated elms. CONCLUSIONS/SIGNIFICANCE: This is the first study to report the effects of pesticide applications on the arthropod communities in urban landscapes and demonstrate that imidacloprid increases spider mite fecundity through a plant-mediated mechanism. Laboratory experiments provide evidence that imidacloprid debilitates insect predators of spider mites suggesting that relaxation of top-down regulation combined with enhanced reproduction promoted a non-target herbivore to pest status. With global commerce accelerating the incidence of arthropod invasions, prophylactic applications of pesticides play a major role in eradication attempts. Widespread use of neonicotinoid insecticides, however, can disrupt ecosystems tipping the ecological balance in favor of herbivores and creating pest outbreaks

Neonicotinoid Insecticides Alter Induced Defenses and Increase Susceptibility to Spider Mites in Distantly Related Crop Plants

Chemical suppression of arthropod herbivores is the most common approach to plant protection. Insecticides, however, can cause unintended, adverse consequences for non-target organisms. Previous studies focused on the effects of pesticides on target and non-target pests, predatory arthropods, and concomitant ecological disruptions. Little research, however, has focused on the direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid insecticides, one of the most important insecticide classes worldwide, suppress expression of important plant defense genes, alter levels of phytohormones involved in plant defense, and decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants.Using cotton (Gossypium hirsutum), corn (Zea mays) and tomato (Solanum lycopersicum) plants, we show that transcription of phenylalanine ammonia lyase, coenzyme A ligase, trypsin protease inhibitor and chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly 200% in the field experiment.Our findings are important because applications of neonicotinoid insecticides have been associated with outbreaks of spider mites in several unrelated plant species. More importantly, this is the first study to document insecticide-mediated disruption of plant defenses and link it to increased population growth of a non-target herbivore. This study adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects and suggests that the direct effects of insecticides on plant defenses should be considered when the ecological costs of insecticides are evaluated

Supplement 1. Effect sizes and species traits used in the species abundance meta-analysis.

<h2>File List</h2><div> <p><a href="species_effect_sizes.csv">species_effect_sizes.csv</a> (MD5: 814d3f03927e6dcb0a9cf28c7ea4b5da) </p> </div><h2>Description</h2><div> <p>The file, species effect sizes.csv, presents data utilized in the species abundance meta-analysis. Included are details on the publications used for the analysis (record ‘ID’, ‘Author’, ‘Year’, ‘City’, ‘Country’). Species names are given as per the original publication (‘Given.Name’) along with any modifications to the name due to spelling errors, synonyms, or taxonomic revisions (‘Binomial.Accepted’). All names were verified using Lorenz (2005); an asterisk in the Binomial. Accepted column indicates names that were not listed as accepted names in Lorenz (2005). ‘Subfamily,’ ‘Tribe,’ and ‘Subtribe’ are given, again using Lorenz (2005). Ecological traits were recorded at the species-level: ‘Body.Size’ (median length, in mm), ‘Wing.Morph’, ‘Habitat.Specific’ (listing particular details on habitat use), ‘Habitat.Category’ (used for the analysis), and ‘Trophic.Level.’ The effect size used in the analysis is given as the log response ratio (‘LRR’).</p> </div

Appendix A. A table with the abundance of generalist predators (excluding spiders), spiders, the 10 most abundant predator taxa, and the Stephanitis specialist, summed across 10 dates sampled in 1994, on azaleas in structurally simple and complex urban landscapes.

A table with the abundance of generalist predators (excluding spiders), spiders, the 10 most abundant predator taxa, and the Stephanitis specialist, summed across 10 dates sampled in 1994, on azaleas in structurally simple and complex urban landscapes

Host Plant Use by the Invasive Halyomorpha halys (Stål) on Woody Ornamental Trees and Shrubs.

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive plant-feeding insect native to eastern Asia. This herbivore is highly polyphagous, feeding on and damaging diverse plants, including field crops, vegetables, tree fruits, and ornamentals. Woody ornamental plants provide early- and late-season resources for adults emerging from and returning to overwintering sites, as well as feeding and breeding sites for H. halys throughout the growing season. In this study, we quantify the use of diverse plants by H. halys in two commercial nurseries in Maryland, recording data on the abundance of egg masses, early and late instar nymphs, and adults over a three-year study period. Our specific goals were to provide a quantitative comparison of the use of diverse plant species and cultivated varieties, identify non-hosts that could be used to create landscapes refractory to H. halys, and determine whether the use of plants varied across life stages of H. halys or the taxonomic status of plants. We found broad use of diverse plants in this study, identifying 88 host plants used by all life stages of H. halys. We also highlight the 43 plant taxa that did not support any life stage of H. halys and are thus classified as non-hosts. Interestingly, some of these plants were congeners of highly-used plants, underscoring high intrageneric and intraspecific variation in the use of plants by this polyphagous herbivore. We discuss how the selective planting of non-hosts, especially gymnosperms, may aid in reducing the agricultural and nuisance pest status of this invasive insect

Relationship between <i>Halyomorpha halys</i> abundance and plant taxonomic status across stink bug life stages.

<p>Model estimated mean abundances (and 95% CI) are plotted for egg masses, early instar nymphs, late instar nymphs and adults. For each life stage, angiosperms supported significantly more stink bugs than gymnosperms based on Tukey’s HSD comparisons (α = 0.05) indicated by different letters above the bars.</p