Heterodissemination: precision targeting container Aedes mosquitoes with a cohabiting midge species carrying insect growth regulator

Abstract

Background: Management of Aedes albopictus and Ae. aegypti is challenging in large part due to the cryptic nature of their larval habitats. Autodissemination, using conspecific species to transfer pesticide, is unable to provide proactive control. Here we report results from a new hypothesis, heterodissemination, wherein females of the cohabiting non-biting midge, Chironomus decorus, reared in the laboratory, treated with pyriproxyfen, and released to transfer lethal concentrations to shared mosquito larval habitats.Results: Pyriproxyfen-impregnated oil and powder formulations were developed. The average payload for each female midge treated with oil followed by powder formulations was 5.07 ± 0.92 ∼g of active ingredient or 1660 times the median lethal concentration (LC 50 ) for Ae. albopictus or Ae. aegypti in 200 mL of water. Subsequent residue analysis showed pyriproxyfen transference from chironomids, treated with oil formulation only, into water-holding containers up to 2.06 ppb or 171.7 times the LC 50 . Releasing 20 laboratory reared and contaminated Chironomus decorus into a small room resulted in 80.42 ± 0.67% and 75.67 ± 3.14% Ae. albopictus pupal mortality in open and cryptic sentinel ovicups, respectively. Container water volumes ranging up to 4 L did not affect efficacy. In a large field cage, 90.3 ± 2.5% Ae. albopictus mortality was resulted from releasing 100 treated female midges. Releasing 400 contaminated midges into a residential backyard resulted in 74.3% pupal mortality in sentinel ovicups.Conclusions: Room, large field cage and field release trials demonstrated that adult midges reared and treated in the laboratory transfer highly lethal concentrations of pyriproxyfen to Ae. albopictus container habitats. Heterodissemination provides a potential approach for precision, proactive mosquito control, which may draw attention for further studies.

Heterodissemination: precision insecticide delivery to mosquito larval habitats by cohabiting vertebrates

“…Under natural conditions, releasing 400 IGR-carrying midges into a residential backyard resulted in approximately 75% pupal mortality. These control levels are nearly identical to those obtained in the present study which yielded 73.4% mortality 25 . Thus, a slow-release IGR formulation tablet attached to frogs delivered sufficient concentrations of the insecticide to the containers.…”

“…When laboratory reared pyriproxyfen treated midges were released under laboratory or semi-field conditions, approximately 75%-90% of Ae. albopictus pupal mortality was observed 25 . Under natural conditions, releasing 400 IGR-carrying midges into a residential backyard resulted in approximately 75% pupal mortality.…”

“…The autodissemination concept has recently been further extended to “heterodissemination”, defined as the transfer of insecticides into larval habitats using cohabitants but not conspecifics as the delivery vehicles 25 . Invasive Aedes share their container larval habitat with other species, particularly chironomid (non-biting) midges in the Dipteran family Chironomidae.…”

“…Invasive Aedes share their container larval habitat with other species, particularly chironomid (non-biting) midges in the Dipteran family Chironomidae. The container-inhabiting midge Chironomus decorus Johannsen was reared in the laboratory and females coated with the juvenile hormone mimic pyriproxyfen 25 . Contaminated midges released under semi-natural conditions and in a small field study successfully delivered pyriproxyfen into immature mosquito habitats, causing 70–90% pupal mortality 25 .…”