Many vegetable crops, however, are self-pollinating, meaning they can produce fruit without the transfer of pollen between flowers. Still, studies have shown that in many of these crops, yield and fruit quality are greater when pollination does occur. Bumblebees and halictid bees, commonly referred to as sweat bees, enhance pollination in tomato, pepper, and eggplant crops through a process known as “buzz pollination” during which the bee vibrates the flower at a specific frequency to dislodge the pollen.
Even crops that do not benefit from insect pollination, like sweet corn, can still serve as an important food source for many pollinators. A recent study examining bee visitation in Maryland sweet corn fields found that honeybees and several species of wild bees frequently visit sweet corn tassels during the pollen shed period. Consideration should therefore be given to protecting pollinators in both insect pollinated and self-pollinating cropping systems.
Choosing insecticides with reduced bee toxicity
Table 1 provides a list of many available insecticides registered for use in vegetable crops along with an associated bee toxicity rating and a selection of pests controlled. Toxicity ratings are based on reported LD50 values, or the reported concentration of each product required to kill 50% of an experimental honeybee population. This table can be used to help identify more pollinator friendly alternatives for controlling many common vegetable pests.
Unfortunately, for some pests there are no pollinator-safe alternatives that provide effective control. In this case, neonicotinoids and/pyrethroids are often the most effective and commonly used products. While all pyrethroids are considered highly-toxic to bees, not all neonicotinoids are equally as toxic. Acetamiprid (Assail) is nearly 100X less toxic to bees than other neonicotinoids and presents a much safer option for pest-control in blooming crops. Acetamiprid, which is a cyanoamidine neonicotinoid, is metabolized more quickly by honeybees and bumblebees than nitro-substituted neonicotinoids like clothianidin (Belay), imidacloprid (Admire), and thiamethoxam (Platinum/Actara). Although some studies have detected several sublethal effects of acetamiprid exposure, they were often at concentrations higher than expected when applied according to the label. For moderately toxic pesticides applied to blooming crops, application timing is an important consideration. Reduce bee exposure and potential impacts by following all label restrictions and making all applications when bees are not actively foraging. Some bees, such as squash bees, become active very early in the morning, so applications made shortly after dark are least likely to result in direct exposure.
Table 1. Bee Toxicity Ratings for Available Insecticides/Miticides in Maryland Vegetables
Additional strategies for protecting pollinators in agricultural landscapes
Providing diverse habitats, including natural areas and wildflower plantings, is also crucial for supporting bee populations. These areas provide additional food, nest sides, and refuge areas from pesticide-treated fields. As a bonus, many other beneficial insects, including insect predators and parasitoids will also benefit from any measures taken to protect and promote wild bees in crop fields.
Sources Consulted:
Intermountain Fruit / Utah State University Extension. Pesticide Toxicity to Honeybees and Pollinators. Intermountain Tree Fruit Production Guide. https://intermountainfruit.org/pesticide-tables/toxicity-pollinators#:~:text=Protecting%20Pollinators%20and%20Beneficials%20from,are%20above%2052%C2%B0F.
Minnesota Department of Agriculture. Pesticides & Bee Toxicity. https://www.mda.state.mn.us/protecting/bmps/pollinators/beetoxicity
Southeast Vegetable Extension Workers. 2025. Southeastern U.S. 2025 Vegetable Crop Handbook. https://vegetables.tennessee.edu/wp-content/uploads/sites/167/2025/01/2025_SEVEG_final_online1.pdf
This article appears on July 14, 2025, Volume 16, Issue 4 of the Vegetable and Fruit News
