Abstract
Simple SummaryThis study examined the behavioral and antennal effects of heterocyclic amines (HCAs) on forager honey bees. Behavioral changes related to feeding were initially characterized using a video-tracking protocol in which individual foragers were exposed to HCA-treated food sources within a Petri dish arena. The most efficacious HCA was then tested in a field study using a high-tunnel arena to determine whether repellent effects could be observed on a larger number of foragers to a treated food source. The same HCA was then tested in the field on both melon flowers and knapweed bundles to observe whether repellency was conserved in a more agriculturally realistic scenario. Finally, electroantennogram (EAG) experiments were conducted to document whether the honey bee olfactory system was detecting these compounds. These findings suggest that HCAs could provide an active approach to deter honey bee foragers from feeding on treated agricultural crops.The productivity and survival of managed honey bee colonies is negatively impacted by a diverse array of interacting factors, including exposure to agrochemicals, such as pesticides. This study investigated the use of volatile heterocyclic amine (HCA) compounds as potential short-term repellents that could be employed as feeding deterrents to reduce the exposure of bees to pesticide-treated plants. Parent and substituted HCAs were screened for efficacy relative to the repellent N,N-diethyl-meta-toluamide (DEET) in laboratory and field experiments. Additionally, electroantennogram (EAG) recordings were conducted to determine the level of antennal response in bees. In video-tracking recordings, bees were observed to spend significantly less time with an HCA-treated food source than an untreated source. In a high-tunnel experiment, the HCA piperidine was incorporated in a feeding station and found to significantly reduce bee visitations relative to an untreated feeder. In field experiments, bee visitations were significantly reduced on melon flowers (Cucumis melo L.) and flowering knapweed (Centaurea stoebe L.) that were sprayed with a piperidine solution, relative to untreated plants. In EAG recordings, the HCAs elicited antennal responses that were significantly different from control or vehicle responses. Overall, this study provides evidence that HCAs can deter individual bees from food sources and suggests that this deterrence is the result of antennal olfactory detection. These findings warrant further study into structure–activity relationships that could lead to the development of short-term repellent compounds that are effective deterrents to reduce the contact of bees to pesticide-treated plants.
Highlights
A recent risk assessment found that 161 pesticide residues have been been identified inhives bee hives across the world, of which insecticides comprised fungiidentified in bee across the world, of which insecticides comprised
The amount of time spent by bees in the feeding zones with heterocyclic amine (HCA)- or DEET-treated sugar-agarose cubes had the following rank order of effectiveness based on statistical significance: control > piperazine = pyrrolidine > pyrrole = piperidine = DEET (Figure 4A)
Bees were recorded in the feeding zone of the untreated control sugar-agarose cubes for 505 ± 5 sec, whereas bees exposed to the DEET-treated sugar-agarose cubes were in the feeding zone for 16 ± 4 sec
Summary
Introduction InsectInsectpollination pollinationservices servicesare areestimated estimatedto toprovide provide $20$20 billion billion in in annual annual benefits benefits to to the the agricultural agriculturalsectors sectorsin in both both EuropeEurope and and NorthNorth America, America, with with the the annual annual benefits benefits to to agriculture agricultureglobally globallyestimated estimatedat at $212$212 billion billion [1].[1]. $20 billion billion in in annual annual benefits benefits to to the the agricultural agriculturalsectors sectorsin in both both Europe. North America, America, with with the the annual annual benefits benefits to to agriculture agricultureglobally globallyestimated estimatedat at $212. Pesticide pesticide exposure exposure from from the the widespread use of agrochemicals in food production can have deleterious effects on widespread use of agrochemicals in food production can have deleterious effects on honey honey bee colonies [2,3]. A recent risk assessment found that pesticide residues have bee colonies [2,3]. A recent risk assessment found that 161 pesticide residues have been been identified inhives bee hives across the world, of which insecticides comprised fungiidentified in bee across the world, of which insecticides comprised. Exposure to pesticides produce ef25%, 25%, herbicides
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