Food transport of red imported fire ants (Hymenoptera: Formicidae) on vertical surfaces

Authors: QIN, WENQUAN - South China Agricultural University; LIN, SHUCONG - South China Agricultural University; CHEN, XUAN - South China Agricultural University; Chen, Jian; WANG, LEI - South China Agricultural University; XIONG, HONGPENG - South China Agricultural University; XIE, QINXI - South China Agricultural University; SUN, ZHAOHUI - South China Agricultural University; WEN, XIUJUN - South China Agricultural University; WANG, CUI - South China Agricultural University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2019
Publication Date: 3/1/2019
Citation: Qin, W., Lin, S., Chen, X., Chen, J., Wang, L., Xiong, H., Xie, Q., Sun, Z., Wen, X., Wang, C. 2019. Food transport of red imported fire ants (Hymenoptera: Formicidae) on vertical surfaces. Scientific Reports. 9:3283.

Interpretive Summary: Due to their aggressiveness and venomous sting, red imported fire ants are a significant threat to humans, wildlife, crops, and livestock. Bait technology is an important component in fire ant management. The success of bait technology relies greatly on our understanding on fire foraging behaviors. Ants are the only group of animals (besides humans) that can collectively transport large food items. Although these behaviors have been extensively investigated on horizontal surfaces, few studies dealt with food transport on vertical surfaces. Red imported fire ants can forage on trees. Our studies showed that fire ants can use different strategies to transport food items on tree trunks. Small food items were carried and transported by individual ants, and larger food items were either collectively and directly transported or excised collaboratively first and small particles were then transported individually or collectively. The competition and deadlocks were frequently observed during individual and collective transport respectively. During the excision, groups of ants tightly fixed the food items on the tree trunks by holding the edges of the food items, and some other ants excised the food into smaller pieces. All food items were first transported upward on tree trunks for 1-20 mm, and then moved downward. We also investigated the effects of food placement, food shape, particle sizes, and placement heights on the food transport. Our studies are the first to show how fire ants transport food on a vertical surface, and may provide insights into the development of novel fire ant baiting systems that can be placed on tree trunks.

Technical Abstract: Ants are the only group of animals (besides humans) that can collectively transport large food items. Although these behaviors have been extensively investigated on horizontal surfaces, few studies dealt with food transport on vertical surfaces. Red imported fire ants, Solenopsis invicta Buren can forage on trees. Our studies showed that S. invicta used multiple strategies to transport food items on vertical surfaces (tree trunks). Small food items (1×1×1 mm sausage) were carried and transported by individual ants, and larger food items were either collectively and directly transported (3×3×1 mm) or excised collaboratively first and small particles were then transported individually or collectively (5×5×1 or 8×8×1 mm). Competition and deadlocks were frequently observed during individual and collective transport respectively. During excision, groups of ants tightly fixed the food on the tree trunks by holding the edges of the food item, while other ants excised the food into smaller pieces. All food items were first transported upward on tree trunks for 1-20 mm, and then moved downward. We investigated the effects of food placement (placed on a platform or fixed on tree trunk), food shape (cubic or flaky shaped), particle sizes (0.45-1, 1-2, 2-3, or 3-4 mm), or placement height (20, 80, 150 cm) on the food transport on tree trunks. Our studies are the first to show how fire ants transport food on a vertical surface, and may provide insights into the development of novel fire ant baiting systems that can be placed on tree trunks.