Sugar supplementation affects ant-mealybug mutualism and promotes natural enemies for mealybug control in pineapple systems

Abstract

Honeydew-producing hemipterans establish mutualistic interactions with ants, which collect honeydew while providing protection against natural enemies and other services. Although this association benefits hemipterans, it often exacerbates crop damage by increasing pest abundance. Providing alternative sugar resources has been proposed as a strategy to disrupt these associations, but its effectiveness remains poorly tested in tropical agrosystems. Here, we investigated whether sugar feeders could reduce ant-mealybug mutualism in pineapple (Ananas comosus) fields on La Réunion, where the mealybug Dysmicoccus brevipes, a vector of Pineapple Mealybug Wilt-associated viruses (PMWaVs), poses a major threat to production. We deployed sugar feeders in replicated field plots and monitored ant, mealybug and predator abundances over eleven months, complemented by sentinel prey assays to quantify ant-mealybug interaction rates and mealybug removal. Mealybug abundance was positively associated with ant presence, while sugar supplementation reduced ant abundance by 42% on pineapple plants compared to controls. Predator abundance was 105% higher in supplemented zones, likely due to both direct nutritional benefits and lower ant interference, but declined with distance from feeders. Three ant species, Solenopsis geminata, Pheidole megacephala and Brachymyrmex cordemoyi accounted for most interactions with mealybugs, with species-specific temporal dynamics but no response to sugar supplementation. Sugar supplementation represents a promising management lever, but its effect on mealybug remains context-dependent. Integrating sugar provisioning with complementary agroecological practices, such as biological control and habitat diversification, may maximize its impact and contribute to sustainable management of pineapple mealybug wilt disease.