Ultra-low volume application of spinosad (Natular 2EC) larvicide as a residual in a tropical environment against Aedes and Anopheles species

Authors: Gibson, Seth; Linthicum, Kenneth - Ken; Aldridge, Robert; Golden, Frances; PONGSIRI, ARISSARA - Armed Forces Research Institute Of Medical Sciences; KHONGTAK, PATCHAREE - Armed Forces Research Institute Of Medical Sciences; PONLAWAT, ALONGKOT - Armed Forces Research Institute Of Medical Sciences

Submitted to: Journal of the American Mosquito Control Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2018
Publication Date: 3/28/2018
Citation: Britch, S.C., Linthicum, K., Aldridge, R.L., Golden, F.V., Pongsiri, A., Khongtak, P., Ponlawat, A. 2018. Ultra-low volume application of spinosad (Natular 2EC) larvicide as a residual in a tropical environment against Aedes and Anopheles species. Journal of the American Mosquito Control Association. 34(1):58-62. doi:10.2987/17-6692.1.
DOI: https://doi.org/10.2987/17-6692.1

Interpretive Summary: In tropical regions such as Thailand, mosquitoes that can transmit dengue, such as Aedes aegypti and Ae. albopictus, or malaria, such as Anopheles dirus and An. minimus, to humans exploit abundant, hidden, and often minute pockets of standing water for development of immatures. These habitats for immatures as a whole are effectively impossible to identify, eliminate, and treat by hand with larvicides, which are pesticides specifically designed to kill immature mosquitoes. They can be treated at the area level in part using liquid larvicides applied for instance with ultra-low volume (ULV) spray equipment. Unfortunately, mosquito control resources are typically limited and it may not always be possible for integrated vector management (IVM) actions such as ULV larvicide applications to be synchronized with high-risk periods of mosquito development. One improvement to the IVM process could be to develop larviciding techniques to pre-treat areas while dry that are rich in habitat that tends to collect standing water. This investigation shows that a particular biologically-derived larvicide, Natular 2EC, under a combination of field and laboratory conditions shows promise as an effective long-term residual against four medically important mosquito species. This larvicide could be applied as a residual to dry areas that are known to collect water and potentially still be effective after rains or irrigation to enhance protection of humans within a diverse IVM program. This investigation also demonstrates, for the first time, efficacy of Natular 2EC against An. minimus and An. dirus.

Technical Abstract: We investigated the efficacy of a liquid larvicide, Natular 2EC® (spinosad), applied with ULV as a residual during the dry season in southeastern Thailand against 4 medically important species, Aedes aegypti, Ae. albopictus, Anopheles dirus, and An. minimus. We found that this larvicide could be applied as a residual to dry areas known to collect water and potentially still be effective after rains or irrigation, which could increase the flexibility and efficiency of an integrated vector management program targeting these species. This investigation also demonstrated, for the first time, efficacy of spinosad against An. minimus and An. dirus.