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

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.

Implementing wood ants in biocontrol: Suppression of apple scab and reduced aphid tending

“…If this holds true, it is important to provide continuous access to artificial sugar sources, which calls for the development of automated reliant systems that can effectively distribute continuous sugar access to trees in large-scale plantations. 40 If the addition of protein to sugar solutions can be avoided, as seen in this study, this is preferable as it increases the ants' incentive to hunt for protein-rich prey, including pest insects. On the other hand, if protein addition is needed for homopteran control, the protein/carbohydrate ratio must be kept under what is required by the ants to maintain predation pressure on other pests.…”

“…We believe the discrepancy between our two studies on wood ants in apples is based on the fact that sugar feeders may have been depleted for short periods during the first study (when this happens ants immediately switch back to aphid farming), which was never the case in the current study. If this holds true, it is important to provide continuous access to artificial sugar sources, which calls for the development of automated reliant systems that can effectively distribute continuous sugar access to trees in large‐scale plantations 40 . If the addition of protein to sugar solutions can be avoided, as seen in this study, this is preferable as it increases the ants' incentive to hunt for protein‐rich prey, including pest insects.…”

“…A number of studies have successfully tested if feeding with artificial sugar sources can effectively distract ants from attending harmful plant sap feeding homopterans on crop plants, including apples, vine, citrus, olives and pumpkins. 17,[34][35][36][37][38][39][40][41] In these studies carbohydrates have been offered as sucrose solutions, mixed sugar solutions or solutions based on honey, and in various carbohydrate concentrations. All studies led to decreased levels of aphid tending and most studies also detected reduced homopteran abundance on the crop plants.…”

Alien vs. herbivore: ant-mediated plant defense as an option for biological control of leafcutter ants

“…While the success of this method depends on the specific ant-hemipteran combination (Del-Claro and Oliveira 1993;Offenberg et al 2019), sugar feeders placed in Spanish vineyards inhabited by Lasius grandis (Forel), Pheidole pallidula (Nylander) and Plagiolepis schmitzii (Forel) ants lowered the abundance of the vine mealybug Planococcus ficus (Signoret), Hemiptera, Pseudococcidae, up to 72% (Beltrà et al 2017). Similarly, predation and parasitoidism of vineyard and citrus mealybugs augmented when sugar solution was offered to disrupt antmealybug mutualisms (Parrilli et al 2021;Pérez-Rodríguez et al 2021). Sugar supplementation can also produce diet shifts, by which ants start preying on their hemipteran partners (Offenberg 2001).…”

“…are employed as biological pest control agents in tropical tree crops (Offenberg 2015;Thurman et al 2019). Recent studies show that ant-mediated plant protection can also be encouraged by supplementation of sugar feeders that attract ants of various genera to trees in temperate apple and pear orchards (Parrilli et al 2021;Pérez-Rodríguez et al 2021;Offenberg et al 2019;Schifani et al 2020). This kind of conservation biological control supports and conserves natural enemy populations and could be a sustainable pest management tool in the future.…”