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Herbivory is an important modulator of plant biodiversity and productivity in grasslands, but our understanding of herbivore-induced changes on below-ground processes and communities is limited. Using a long-term (17 years) experimental site, we evaluated impacts of rabbit and invertebrate grazers on some soil functions involved in carbon cycling, microbial diversity, structure and functional composition. Both rabbit and invertebrate grazing impacted soil functions and microbial community structure. All functional community measures (functions, biogeochemical cycling genes, network association between different taxa) were more strongly affected by invertebrate grazers than rabbits. Furthermore, our results suggest that exclusion of invertebrate grazers decreases both microbial biomass and abundance of genes associated with key biogeochemical cycles, and could thus have long-term consequences for ecosystem functions. The mechanism behind these impacts are likely to be driven by both direct effects of grazing altering the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi-trophic interactions between above- and below-ground communities.

The environmental impact of exotic insect pest species is often poorly quantified, making current pest management strategies obsolete. The fall armyworm (FAW) is endemic to the Western hemisphere – where it is considered a major pest of maize – and invasive to Africa, Asia and Oceania since 2016, 2018 and 2020, respectively. FAW's highly polyphagous behaviour and potential expansion of its host range in invaded habitats may put some non-crop flowering plants and their ecosystem services at risk. While its potential for intraguild competition and hybridisation with endemic maize pest species could have important consequences for pest population dynamics and pest management, a FAW inter-strain hybrid – resistant to pesticides – has already been documented in China. Integrated pest management (IPM) combines host plant resistance, agronomic practices and biological control for the long-term prevention of pests. Within invaded areas, a lack of knowledge of FAW's ecological adaptations, the absence of resistant cultivars, and an insufficient build-up of natural enemies provide challenges that translate into research opportunities to support IPM solutions for this exotic pest species. [ABSTRACT FROM AUTHOR]

Overuse of pesticides can result in the development of resistance, secondary pest outbreaks, and pest resurgence due to a reduction in natural enemies. The present study compares the residual toxicity of lambda-cyhalothrin, a relatively nonselective insecticide, with abamectin, indoxacarb, and spinosad, compounds which have been reported to be less harmful to arthropod natural enemies. Two key cosmopolitan pests of crucifer crops, (Plutella xylostella) and (Myzus persicae), and two of their respective hymenopteran parasitoids, (Cotesia vestalis) and (Aphidius colemani) were used as representative pests and natural enemies. The pyrethroid lambda-cyhalothrin was found to be the most persistent toxicant against both pest and both parasitoid species tested, while the lactones abamectin and spinosad were the least persistent toxicants. A leaf wax stripping technique was used to compare the contact toxicity of insecticide residues against adult C. vestalis and A. colemani in the epicuticular wax layer. For each compound, removal of epicuticular wax reduced the 24 h residual toxicity (LC50) of fresh deposits (day 0) by about an order of magnitude against C. vestalis. A second residual toxicity experiment showed that removal of epicuticular wax significantly reduced the residual toxicity of each compound against A. colemani at 0, 7, and 14 d after application, with little or no detectable residual activity for the oxadiazine indoxacarb or abamectin/spinosad respectively after 14 d. The present data supports the view that in addition to the intrinsic toxicity of insecticides to natural enemies, differences in their persistence as foliar residues should also be considered in IPM systems. [ABSTRACT FROM AUTHOR]

The six chlorpyrifos-degrading strains were isolated from the soil and then the pathway of degradation and the ecological factors that govern chlorpyrifos degradation in soil were investigated. The results highlight the potential of the bacterium to be used in the cleanup of contaminated pesticide waste in the environment.

Research has been conducted on the Plutella xylostella, a diamondback moth. The use of the crystalline, solubilized and activated forms of the Bacillus thuringiensis Cry1Ac delta-endotoxin in examining the resistant and susceptible forms of this this moth is described.

Researchers describe populations of the diamondback moth Plutella xylostella that have become resistant to the insecticidal crystal (Cry) proteins of Bacillus thuringiensis. The Cry proteins are believed to be the safest pesticides but some insects are developing resistance to them.