The insecticidal activity of parasiticide residues in dung of cattle treated with a sustained release eprinomectin formulation was examined, and an improved eprinomectin dung residue extraction ...method is presented. Emergent insect abundance and richness were significantly reduced in all post-treatment intervals (7, 14, 28, 56, 84, 112, and 140 d), relative to pre-treatment. Emergent insect diversity was reduced for between 84 and 112 d post-treatment. Collembola were not affected by residues. Chemical analyses subsequently documented residues of eprinomectin in dung of each collection period post-treatment at levels expected based on previously reported excretion profiles for this product. Cattle subcutaneously injected with this product excreted residues that reduced dung-breeding insect emergence for 5 mo post-treatment. The consequences of these long-term non-target effects to pasture ecosystems are not known.
Residues of veterinary parasiticides in dung of treated livestock have nontarget effects on dung-breeding insects and dung degradation. Here, we review the nature and extent of these effects, examine ...the potential risks associated with different classes of chemicals, and describe how greater awareness of these nontarget effects has resulted in regulatory changes in the registration of veterinary products.
Following the introduction of cattle, exotic dung beetles (Coleoptera: Aphodiidae, Geotrupidae, Scarabaeidae) were imported into the Antipodes (Australia and New Zealand) and North America (primarily ...the United States) to accelerate the degradation of cattle dung on pastures. The history of dung beetle introductions between the two regions is similar but has not previously been assessed: this is important as new introductions are continuing in the regions. Here, we review these introduction programs, report on their current status, and discuss methodological advances. In doing so, we examine the accidental introduction of exotic (i.e., adventive) species and the contribution of both deliberately introduced and adventive species to endemic dung beetle faunas. Further, we provide a list of pest and parasite species whose populations can be reduced by dung beetle activity. We also identify a combined total of 37 introduced and 47 adventive dung beetle species that have become established in the Antipodes and North America, with exotic species dominating dung beetle assemblages from pasture habitats. Climatic and edaphic matches, the size of founding populations, abiotic and biotic stressors, and the time of year when releases are made are all critical determinants that affect the success of dung beetle introduction programs. Finally, we discuss opportunities, plus the risks and challenges associated with dung beetle introductions. We hope that this review will aid in the success of future introduction programs, either to enhance ecosystem services in areas that they are needed, or potentially to reestablish native species in regions where they have been extirpated.
Abstract
Insect larvae typically moult to grow, but here we investigate insect larvae that moult to shrink; that is, retrogressive moulting or retrogressive development. We demonstrate this ...phenomenon in khapra beetle,
Trogoderma granarium
Everts (Dermestidae), among the world's most invasive pests of stored grains and cereal products, and a quarantine pest of interest for many countries. Larvae survived a 3‐month period of starvation, moulting up to six times and reducing their body mass by about half, on average. When reprovisioned with food, most larvae resumed the normal trajectory of development and pupated within a month. Thus, retrogressive development is a mechanism that may favour species whose resources exhibit feast‐or‐famine dynamics. By enabling survival during periods of privation, retrogressive development contributes to the invasiveness of the khapra beetle by allowing them to persist for long periods in empty storage facilities or empty containers used for international grain shipments.
ಅಮೂರ್ತ
ಕೀಟಗಳ ಲಾರ್ವಾಗಳು ಸಾಮಾನ್ಯವಾಗಿ ಹೊಸ ಬೆಳವಣಿಗೆಗೆ ದಾರಿ ಮಾಡಿಕೊಡಲು ತಮ್ಮ ದೇಹದ ಹೊರಪೊರೆಯನ್ನು ಚೆಲ್ಲುತ್ತವೆ. ಆದರೆ, ಇಲ್ಲಿ ನಾವು ಕೀಟಗಳ ಲಾರ್ವಾಗಳು ತಮ್ಮ ದೇಹವನ್ನು ಸಂಕುಚಿತಗೊಳಿಸಲು ಪೊರೆ ಬಿಡುವುದನ್ನು ತನಿಖೆ ಮಾಡುತ್ತೇವೆ. ಅಂದರೆ, ಹಿಮ್ಮುಖ ಮೌಲ್ಟಿಂಗ್ ಅಥವಾ ಹಿಮ್ಮುಖ ಅಭಿವೃದ್ಧಿ. ನಾವು ಈ ವಿದ್ಯಮಾನವನ್ನು ಖಾಪ್ರ ಜೀರುಂಡೆ, ಟ್ರೊಗೊಡರ್ಮಾ ಗ್ರ್ಯಾನೇರಿಯಮ್ ಎವರ್ಟ್ಸ್ (ಡರ್ಮೆಸ್ಟಿಡೆ) ನಲ್ಲಿ ಪ್ರದರ್ಶಿಸುತ್ತೇವೆ. ಇದು ವಿಶ್ವದ ಅತ್ಯಂತ ಆಕ್ರಮಣಕಾರಿ ಕೀಟಗಳಲ್ಲಿ ಒಂದಾಗಿದ್ದು, ಸಂಗ್ರಹವಾಗಿರುವ ಧಾನ್ಯಗಳು ಮತ್ತು ಏಕದಳ ಉತ್ಪನ್ನಗಳಲ್ಲಿಕಾಣಿಸಿಕೊಂಡು ಆರ್ಥಿಕ ನಷ್ಟವನ್ನು ಉಂಟು ಮಾಡುತ್ತದೆ. ಅದಲ್ಲದೆ, ಈ ಕೀಟವು ಹಲವು ದೇಶಗಳಿಗೆ ಕ್ವಾರಂಟೈನ್ ಆಸಕ್ತಿಯ ಕೀಟವಾಗಿದೆ. ನಮ್ಮ ತನಿಖೆಯಲ್ಲಿ ಈ ಕೀಟದ ಲಾರ್ವಾಗಳು ಮೂರು ತಿಂಗಳ ಹಸಿವನ್ನು ತಡೆದುಕೊಂಡು, ಮೂರರಿಂದ ಆರು ಬಾರಿ ಪೊರೆಯನ್ನು ಬಿಟ್ಟು, ಸರಾಸರಿ ಅರ್ಧದಷ್ಟು ದೇಹದ ದ್ರವ್ಯರಾಶಿಯನ್ನು ಕಡಿಮೆಗೊಳಿಸಿಕೊಂಡವು. ಆಹಾರದೊಂದಿಗೆ ಮರುಹೊಂದಿಸಿದಾಗ, ಹೆಚ್ಚಿನ ಲಾರ್ವಾಗಳು ಸಾಮಾನ್ಯ ಬೆಳವಣಿಗೆಯ ಪಥವನ್ನು ಪುನರಾರಂಭಿಸಿ, ಮತ್ತೆ ಒಂದು ತಿಂಗಳೊಳಗೆ ಪ್ಯೂಪೆಗಳಾಗಿ ಪರಿವರ್ತನೆಗೊಂಡವು. ಹೀಗಾಗಿ, ಹಿಮ್ಮುಖ ಅಭಿವೃದ್ಧಿಯು ಒಂದು ಕಾರ್ಯವಿಧಾನವಾಗಿದ್ದು, ಅದು ಸಂಪನ್ಮೂಲಗಳು ಸಮೃದ್ಧಿ‐ಅಥವಾ‐ಕ್ಷಾಮದ ಕ್ರಿಯಾತ್ಮಕತೆಯನ್ನು ಪ್ರದರ್ಶಿಸುವ ಕೀಟದ ಜಾತಿಗಳನ್ನು ಬೆಂಬಲಿಸಬಹುದು. ಹಸಿವಿನ ಅವಧಿಯಲ್ಲಿ ಬದುಕುಳಿಯುವಿಕೆಯನ್ನು ಸಕ್ರಿಯಗೊಳಿಸುವ ಮೂಲಕ, ಹಿಮ್ಮುಖ ಅಭಿವೃದ್ಧಿಯು ಖಾಪ್ರಾ ಜೀರುಂಡೆಯ ಆಕ್ರಮಣಶೀಲತೆಗೆ ಕೊಡುಗೆ ನೀಡಿ, ಖಾಲಿ ಶೇಖರಣಾ ಸೌಲಭ್ಯಗಳಲ್ಲಿ ಹಾಗೂ ಅಂತರಾಷ್ಟ್ರೀಯ ಧಾನ್ಯ ಸಾಗಣೆಗೆ ಬಳಸುವ ಪಾತ್ರೆಗಳಲ್ಲಿ ದೀರ್ಘಕಾಲ ಉಳಿಯಲು ಅನುವು ಮಾಡಿಕೊಡುತ್ತದೆ.
Next generation sequencing (NGS) increasingly is being used to characterize the gut microbiome of insects to provide insights into the ecology and biology of the host, but results may be confounded ...by co-occurring infections of bacteria genus Wolbachia Hertig, 1936 in the cells of the host. We illustrate this issue using spotted-wing drosophila, Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), as an example. With an assay based on polymerase chain reactions, we detected Wolbachia in 20% of flies collected from sites in British Columbia, Alberta, and Newfoundland and Labrador, Canada. With NGS, we determined that the total microbiome of infected flies was dominated by Wolbachia (mean of 98.8%) with mean values of bacterial richness and diversity 1.4- and 22-fold lower than that of co-occurring, uninfected flies (mean of 0.6% Wolbachia). We review options available to address the confounding factor of Wolbachia, which vary with the presence of infections in the population, the prevalence of infected individuals in the population, and the titre of Wolbachia in infected individuals. Understanding this issue and how it can be resolved is of broad importance, given that an estimated 40% of terrestrial arthropod species harbour Wolbachia infections.
Natural systems of hybridizing plants are powerful tools with which to assess evolutionary processes between parental species and their associated arthropods. Here we report on these processes in a ...trispecific hybrid swarm of Populus trees. Using field observations, common garden experiments and genetic markers, we tested the hypothesis that genetic similarities among hosts underlie the distributions of 10 species of gall‐forming arthropods and their ability to adapt to new host genotypes. Key findings: the degree of genetic relatedness among parental species determines whether hybridization is primarily bidirectional or unidirectional; host genotype and genetic similarity strongly affect the distributions of gall‐forming species, individually and as a community. These effects were detected observationally in the wild and experimentally in common gardens; correlations between the diversity of host genotypes and their associated arthropods identify hybrid zones as centres of biodiversity and potential species interactions with important ecological and evolutionary consequences. These findings support both hybrid bridge and evolutionary novelty hypotheses. However, the lack of parallel genetic studies on gall‐forming arthropods limits our ability to define the host of origin with their subsequent shift to other host species or their evolution on hybrids as their final destination.
Hybrid genotypes that arise between plant species frequently have increased susceptibility to arthropod pests and fungal pathogens. This pattern has been attributed to the breakdown of plant defenses ...('Hybrid susceptibility' hypothesis) and (or) to extended periods of susceptibility attributed to plant phenologies in zones of species overlap and (or) hybridization ('phenological sink' hypothesis). We examined these hypotheses by assessing the susceptibility of parental and hybrid Populus host genotypes to a leaf spot disease caused by the fungal pathogen Septoria musiva. For this purpose, 214 genotypes were obtained from morphologically pure zones of P. balsamifera and P. deltoides, and from an intervening zone of overlap and hybridization on the drainage of the Red Deer River, Alberta, Canada. Genotypes were identified as P. balsamifera, P. deltoides, or hybrid using a suite of 27 species-specific SNP markers. Initially the genetic structure of the hybrid zone was characterized with 27.7% of trees classified as admixed individuals. To test the hybrid susceptibility hypothesis, a subset of 52 genotypes was inoculated with four isolates of S. musiva. Levels of susceptibility were P. balsamifera > F1 hybrid > P. deltoides. A further 53 genotypes were grown in a common garden to assess the effect of genotype on variation in leaf phenology. Leaf phenology was more variable within the category of hybrid genotypes than within categories of either parental species. Leaf phenology was also more variable for the category of trees originating in the hybrid (P. balsamifera - P. deltoides hybrid and parental genotypes combined) zone than in adjacent pure zones of the parental species. The results from the inoculation experiment support the hybrid intermediacy hypothesis. The results from the common garden experiment support the 'phenological sink' hypothesis. These findings have greatly increased our understanding of the epidemiology and ecology of fungal pathogens in plant hybrid zones.
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