Experimentally guided development of a food bait for European fire ants

• Published in: Entomologia experimentalis et applicata 2021-09, Vol.169 (9), p.780-791
• Main Authors: Hoefele, Danielle, Chalissery, Jaime M., Renyard, Asim, Gries, Gerhard
• Format: Article
• Language: English
• Subjects: Ants; Apples; Aroma; Baits; Bananas; Carbohydrates; cost‐effective; Crickets; Drying; Essential nutrients; European fire ants; Field tests; Food; food bait; Food preservation; Foraging behavior; foraging ecology; foraging response; Formicidae; Fruits; insect pest management; Insecticides; invasive species; lethal food; Lipids; Myrmica rubra; Myrmicinae; Nests; Nutrients; Pollen; Proteins; Seeds; Shelf life; Sunflowers
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1111/eea.13053

Deployment of lethal food baits could become a control tactic for the invasive European fire ant (EFA), Myrmica rubra L. (Hymenoptera: Formicidae), because foraging ants carry the lethal food to their nest and share it with their nest mates, ultimately causing the demise of nests. Our objective was to develop a food bait that elicits a strong foraging response from EFAs, has extended shelf life, and is cost‐effective to produce. To develop a bait composition with ‘ant appeal’, we ran two separate field experiments testing pre‐selected carbohydrate sources (oranges, apples, bananas) and protein/lipid sources [tuna, pollen, sunflower seeds, mealworms (Tenebrio molitor L., Coleoptera: Tenebrionidae)]. Whereas foraging EFAs responded equally well to the three types of carbohydrates, they preferred mealworms to all other protein/lipid sources. In a follow‐up laboratory experiment, the combination of apples and mealworms elicited a stronger foraging response from EFAs than either apples or mealworms alone. To help reduce bait ingredient costs, we tested house crickets, Acheta domesticus (L.) (Orthoptera: Gryllidae), as a less expensive mealworm alternative and found crickets and mealworms comparably appealing. Addressing the shelf life of baits, we tested freeze‐dried and heat‐dried apple/cricket combinations. Rehydrated freeze‐dried baits proved as appealing as fresh baits and superior to rehydrated heat‐dried baits, suggesting that freeze‐drying may retain essential nutrients and/or aroma constituents. Insecticide‐laced baits had no off‐putting effect on foraging responses of worker ants and caused significant mortality. As freeze‐drying is expensive, further research should investigate the preservation of moist food baits or the development of dry baits that are hydrated prior to deployment. Our objective was to develop a food bait that strongly appeals to European fire ants (EFAs), has extended shelf life, and is cost‐effective to produce. Apples (carbohydrate source) in combination with mealworms (protein/lipid source) elicited the strongest foraging response from EFAs. Addressing the shelf life of baits, we tested freeze‐dried and heat‐dried apple/cricket combinations and showed that rehydrated freeze‐dried baits proved as appealing as fresh baits. Insecticide‐laced baits did not reduce foraging responses of worker ants and caused significant mortality.