Use of Sugar Dispensers to Disrupt Ant Attendance and Improve Biological Control of Mealybugs in Vineyard

Abstract

Simple Summary

Management methods for mealybugs (Hemiptera: Pseudococcidae) alternative to insecticides have been explored in vineyards. Biological control by either wild or released natural enemies can be disrupted by tending ants, which create a strong association with mealybugs. In this paper, sugar dispensers were investigated as an ant management method to enhance parasitization and predation and eventually to reduce mealybug infestations. Field trials showed a reduction of ant activity, an enhancement of the ecosystem services provided by both parasitoids and predators and a decrease of mealybug infestation on grapes. The use of sugar dispensers provided promising results, highlighting its potential to be integrated with inoculative releases for a more sustainable management of mealybugs.

Abstract

Planococcus ficus (Signoret) and Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae) are economically important pests occurring in vineyards, causing severe economic losses for growers and compromising bunch production. The partial effectiveness of insecticides used in controlling mealybug infestations as well as their high impact on the environment and on human health have led to the research of alternative and sustainable control methods, including biological control. Several natural enemies are reported to be effective against mealybugs, but their activity may be hindered by tending ants. These social insects are known to exhibit a mutualistic relationship with mealybugs, resulting in extremely aggressive behavior against beneficial insects. Consequently, this study explored a method to mitigate ant attendance by means of sugar dispensers in order to improve ecosystem services, as well as decrease mealybug infestation in vineyards. Field trials were carried out in four commercial vineyards of Northern Italy infested by mealybugs, in which Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae) and Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) were released as biological control agents. Our results showed that sugar dispensers reduced ant activity and mealybug infestation, leading to a significant enhancement of ecosystem services. The technique showed a great potential in boosting biological control against mealybugs in field conditions, though the field application seemed to be labour intensive and needs to be replicated for a multi-year evaluation.