Trap–treat–release: horizontal transfer of fipronil in field colonies of black carpenter ants, Camponotus pennsylvanicus

Abstract

BACKGROUND: Horizontal insecticide transfer is thought to play an important role in controlling a wide range of urban pests including ants, bed bugs, cockroaches, and termites. Despite decades of research and numerous laboratory studies, horizontal transfer has never been demonstrated in the field. As a result, the importance of horizontal transfer (and the resulting secondary kill) for practical pest management remains unknown. The goal of this study was to provide the first experimental examination of horizontal transfer under field conditions. The specific objective was to investigate horizontal transfer of fipronil in field colonies of black carpenter ants, Camponotus pennsylvanicus. RESULTS: Laboratory experiments demonstrated that fipronil is effectively transferred from treated donors to untreated recipients and causes significant secondary mortality. Fipronil was effectively vectored to untreated ants from donors exposed via residual and direct spray applications, and 100% mortality was achieved with both exposure routes. Furthermore, horizontal transfer continued beyond secondary mortality and resulted in significant tertiary mortality, which has not been previously demonstrated in ants. Field experiments utilized a novel, three-step control method consisting of trap-treat-release and demonstrated that fipronil is effectively transferred when foraging workers are trapped, treated, and subsequently released back into their colonies. CONCLUSION:The current study is the first field demonstration of the importance of horizontal transfer for the control of pest ants. The trap-treat-release method may be an effective alternative to broadcast spray applications and could help alleviate problems such as insecticide run-off, environmental contamination, and non-target effects. This method has the potential to provide effective management of invasive and pest ants and should be further tested across a wider range of ant species, habitats, and active ingredients.

Controlling invasive Argentine ants, Linepithema humile, in conservation areas using horizontal insecticide transfer

“…The horizontal transfer of fipronil may have continued beyond secondary kill and involved higher levels such as tertiary mortality whereby recipients become secondary donors and vector the insecticide to previously unexposed nestmates. Tertiary mortality played a significant role in the horizontal transfer of fipronil in carpenter ants 31 . In a laboratory test, 50 new workers were exposed to 20 workers that died from having contact with a single primary donor and 90% of the workers died in 96 h 31 .…”

“…Tertiary mortality played a significant role in the horizontal transfer of fipronil in carpenter ants 31 . In a laboratory test, 50 new workers were exposed to 20 workers that died from having contact with a single primary donor and 90% of the workers died in 96 h 31 . Because fipronil is toxic in ultra-low (ng) amounts, non-repellent, and readily transferrable among ants, it is likely that tertiary mortality played an important role in the current study.…”

“…Another new development is exploiting social interactions within colonies to promote the spread of insecticides through horizontal transfer. A recent study evaluated a novel control method based on horizontal transfer for controlling black carpenter ants, Camponotus pennsylvanicus 31 . A three-step method consisting of trap-treat-release was used in field experiments and demonstrated that fipronil is effectively transferred when foraging workers are trapped, sprayed with insecticide, and released back into their colonies.…”

“…The goal of the current study was to build on work described in 31 and evaluate a target-specific pesticide delivery system that relies on horizontal transfer to control Argentine ants in South African fynbos. The first objective was to perform laboratory studies to generate quantitative information on factors affecting horizontal transfer, specifically the amount of fipronil transferred from treated to untreated ants and the number of untreated ants killed in interactions with a single treated ant.…”

Larval Aggregation of Heortia vitessoides Moore (Lepidoptera: Crambidae) and Evidence of Horizontal Transfer of Avermectin

“…The horizontal transfer of chemical pesticides is a mode of action that requires a limited amount of pesticides, which can be transferred from pesticide-exposed (treated) individuals to unexposed (untreated) individuals. This method has been widely applied to control the gregarious insects such as termites [18,19], ants [20,21], and bed bugs [22]. Here we hypothesized that the chemical pesticide (i.e., avermectin) can be horizontally transferred within the aggregations of H. vitessoides larvae, and avermectin-transfer bioassays were conducted to verify this under laboratory conditions.…”