Evaluation of Mosquito Attractant Candidates Using a High-Throughput Screening System for Aedes aegypti (L.), Culex quinquefasciatus Say. and Anopheles minimus Theobald (Diptera: Culicidae).

Abstract

Simple SummaryTrapping mosquitoes can enhance its capture rate by adding attractants such as carbon dioxide or human hosts’ odor-mimicking synthetic blends. Various olfactometers exist to test mosquitos’ behavior, but high-throughput screening system (HITSS)—one of the diffusion assays—has not been applied to developing lures. In this study, six different newly prepared chemical lure candidates (Kasetsart University (KU)-lures) were tested for diurnal Aedes aegypti, nocturnal Culex quinquefasciatus and nocturnal Anopheles minimus, using the HITSS assay. Results showed species-specific different lure preferences; the diurnal species were attracted to KU-lure #1 (29.7%), while both of the nocturnal species preferred KU-lure #6 (68.3% and 74.3% for Cx. quinquefasciatus and An. minimus, respectively). In addition, the selected lure candidates clearly demonstrated dose-dependent reversal responses for each Ae. aegypti and Cx. quinquefasciatus. Our results indicate that the HITSS assay distinguishes potential species-specific lure candidates. In addition, the HITSS assay was equally effective in determining the host-seeking behavior in pyrethroid-resistant and -susceptible strains. Further studies are needed to determine the accuracy of the HITSS assay in large-scale semi-field screen house tests using commercial traps.Several types of olfactometers have been used to evaluate mosquito responses to agents that mimic natural volatiles that repel or attract. The Y-tube olfactometer has been widely used to study repellents and attractants, while the high-throughput screening system assay has only been used to study repellents. Whether the high-throughput screening system assay is suitable for evaluating attractants is unknown. We evaluated the responses to four lactic-acid-based mixtures and two non-lactic-acid-based chemical lure candidates using the high-throughput screening system (HITSS) for three mosquito species (laboratory strains and field populations of both Aedes aegypti (L.) and Culex quinquefasciatus Say.; laboratory strain of Anopheles minimus Theobald) under laboratory-controlled conditions. HITSS assay results showed that KU-lure #1 elicited the greatest percent attraction for pyrethroid-resistant and -susceptible Ae. aegypti. KU-lure #6 elicited the strongest attractive response for pyrethroid-susceptible and -resistant Cx. quinquefasciatus and pyrethroid-susceptible An. minimus. The response to the lures from each species was independent of the pyrethroid susceptibility status (Ae. aegypti, p = 0.825; Cx. quinquefasciatus, p = 0.056). However, a significant difference in attraction to KU-lure #6 was observed between diurnal and nocturnal mosquitoes (Cx. quinquefasciatus vs. Ae. aegypti, p = 0.014; An. minimus vs. Ae. aegypti, p = 0.001). The laboratory-level HITSS assay effectively selects potential lure candidates. Because the host-seeking behavior differs between mosquito species, further studies are needed to develop species-specific attractants. Additional studies in semi-field screen houses using commercial traps are necessary to evaluate the accuracy of these laboratory assay results.