Evaluation of large volume yeast interfering RNA lure-and-kill ovitraps for attraction and control of Aedes mosquitoes

Abstract

Aedes mosquitoes (Diptera: Culicidae), principle vectors of several arboviruses, typically lay eggs in man-made water-filled containers located near human dwellings. Given the widespread emergence of insecticide resistance, stable and biofriendly alternatives for mosquito larviciding are needed. Laboratory studies have demonstrated that inactivated yeast interfering RNA tablets targeting key larval developmental genes can be used to facilitate effective larvicidal activity while also promoting selective gravid female oviposition behaviour. Here we examined the efficacy of transferring this technology toward development of lure-and-kill ovitraps targeting Aedes aegypti (L.) and Aedes albopictus (Skuse) female mosquitoes. Insectary, simulated field and semi-field experiments demonstrated that two mosquito-specific yeast interfering RNA pesticides induce high levels of mortality among larvae of both species in treated large volume containers. Small-scale field trials conducted in Trinidad, West Indies demonstrated that large volume ovitrap containers baited with inactivated yeast tablets lure significantly more gravid females than traps containing only water and were highly attractive to both A. aegypti and A. albopictus females. These studies indicate that development of biorational yeast interfering RNA-baited ovitraps may represent a new tool for control of Aedes mosquitoes, including deployment in existing lure-and-kill ovitrap technologies or traditional container larviciding programs.

Keywords: Aedes aegypti; Aedes albopictus; Trinidad West Indies; arbovirus; behaviour; larvicide; oviposition.

Fig. 1.

Assessment of gravid Aedes female attraction to yeast-baited ovitraps. (a) Map of Trinidad showing location of University of West Indies campus (star) in St. Augustine; (b) 10 L ovitraps; (c) locations of paired ovitraps (stars) on the University of West Indies campus; (d) total number of mosquito eggs collected by each trap pair with relative distribution between water-only control and yeast-baited traps.

Fig. 2.

Weekly egg collection (mean±SE) of water-only control and yeast-baited 10 L ovitraps, and relative proportions of Aedes aegypti and Aedes albopictus. Rainfall (mm) data from Piarco airport (~8 km from UWI) are included for general reference. *No data collected due to disruption caused by an earthquake.

Fig. 3.

Population density and point estimates of preference for the yeast-baited ovitrap in each experimental pair. Black circles indicate the point estimates of the preference for the treated trap at each experimental pair, ${\rho }_{d,i}$. The plotted density shows the population density of preference parameters, Beta(3.5, 10.9). The black dashed line shows the population mean and the red dotted lines show the 95% confidence interval for the distribution.