Steinhauer, N. | bioRxiv Science

bioRxiv2024

Evaluation of efficacy of formic acid and thermal remediation for management of Tropilaelaps and Varroa mites in central Thailand

The western honey bee, Apis mellifera, faces a new threat from the spread of parasitic Tropilaelaps (Tropi) mites, specifically T. mercedesae, which adds additional complexity to an apicultural landscape heavily impacted by Varroa destructor. In this study conducted in central Thailand, we investigated the efficacy of two methods of applying formic acid and a thermal remediation technique in controlling Tropi mites and Varroa, focusing our attention on the reproductive stage of the mites which is restricted to capped brood cells. Results revealed that both formic acid treatments (Formic Pro and liquid formic acid) demonstrated an immediate and substantial reduction in live Tropi and Varroa populations, maintaining near-zero levels for the 3- week duration of the study. In contrast, thermal remediation, employing heating pads, exhibited a more gradual decline, achieving an 85.42% reduction in Tropi mites and a 92.33% reduction in Varroa mites by week three. Notably, heat-treated colonies experienced an unexpected resurgence in mite populations during week two. The findings contribute valuable insights into potential strategies for mitigating the threat of Tropi mites and highlight the urgency of further research to safeguard global honey bee populations.

zoology↗

bioRxiv2019

Regional differences in gene regulation may underlie patterns of sensitivity to novel insecticides in Colorado potato beetle

Agricultural insect pests frequently exhibit geographic variation in levels of insecticide resistance, which are often presumed to be due to the intensity of insecticide use for pest management. However, regional differences in the evolution of resistance to novel insecticides suggests that other factors are influencing rates of adaptation. We examined LC50 bioassay data spanning 15 years and six insecticides (abamectin, imidacloprid, spinosad, cyantraniliprole, chlorantraniliprole, and metaflumizone) for evidence of regional differences in Colorado potato beetle (CPB) baseline sensitivity to insecticides as they became commercially available. We consistently found that CPB populations from the Western USA had the highest baseline sensitivity to novel insecticides, while populations from the Eastern USA had the lowest. Comparisons of gene expression between populations from these regions revealed constitutively elevated expression of an array of detoxification genes in the East, but no evidence of additional induction when exposed to imidacloprid. Our results suggest a mechanism for geographic variation in rates of adaptation to insecticides whereby baseline levels of gene expression determine a populations response to novel insecticides. These findings have implications for the regional development of insecticide resistance management strategies and for the fundamental question of what determines the rate of adaptation to insecticides.

evolutionary biology↗