171 - Essential oil-based insecticides pose reduced threats to off-target species, such as honey bees (Apis mellifera).

Abstract: Managing mosquito populations is crucial for mitigating the threat they pose on public health. Broad spectrum insecticides, although effective, can have negative impacts on the environment due to their potential toxicity to non-target organisms. Discovering insecticides that effectively control mosquitoes while having little negative impact on beneficial insects is a challenge. Plant based products have often been considered for insect management as alternatives to synthetic insecticides. This potential has been recognized in essential oils due to their large library of chemical constituents, and evidence of insecticidal properties. Additionally, research on these chemistries show evidence of low toxicity to off target species, further supporting the use of these chemicals as supplements for mosquito management. Essential oils can contain many active constituents, which can result in multiple modes of action and potentially reduce insecticide-resistance selection pressures. This study determined the efficacy of multiple plant essential oil-based insecticides, labeled for use against mosquitoes, against honey bees (Apis mellifera). It was hypothesized that certain insecticide formulations would have little impact on honey bees while still maintaining efficacy at reducing mosquito populations. This study found that certain formulations of 25(b) insecticide products posed greater risk to honey bees while others showed little to no negative impact on honey bees. This was demonstrated through direct applications of the insecticide to honey bees at suggested high and low label rates. This study demonstrates the effectiveness and potential of essential oil-based insecticides at managing target pests while reducing off-target effects.