By Katie CameroResearchers already knew neonicotinoids could harm honey bees and other beneficial insects when applied to important crops such as cotton, potato, and citrus. A 2017 study, for example, found the chemicals can poison bees, causing symptoms like paralysis, vomiting, or death when they eat contaminated nectar or pollen, or even crawl over sprayed surfaces. Yet neonicotinoids still account for more than 20% of the world’s insecticide market.
In the new study, scientists wanted to see whether the chemicals could harm these and other insects more indirectly. They looked to the invasive mealybug (pictured), a 6-millimeter-long insect that eats plants typically contaminated with pesticides. As they nosh, the bugs excrete a sticky substance called honeydew, which pollinating insects like hoverflies and parasitic wasps consume.