Sulfoxaflor exposure reduces egg laying in bumblebees (Bombus terrestris)

Sulfoximine-based insecticides, such as sulfoxaflor, are of increasing global importance and have been registered for use in 81 countries, offering a potential alternative to neonicotinoid insecticides. Â Previous studies have demonstrated that sulfoxaflor exposure can have a negative impact on the reproductive output of bumblebee colonies, but the specific life-history variables that underlie these effects remain unknown. Here, we used a microcolony-based protocol to assess the sub-lethal effects of chronic sulfoxaflor exposure on egg laying, larval production, ovary development, sucrose consumption, and mortality in bumblebees. Following a pre-registered design, we exposed colonies to sucrose solutions containing 0, 5, 10 and 250ppb of sulfoxaflor. Exposure at 5ppb has been previously shown to negatively impact colony reproductive success. Our results showed that sulfoxaflor exposure at 5ppb (lowest exposure tested) reduced the number of eggs found within the microcolonies (He...