Miniature bait station sachet system used in simulated field studies in the laboratory and in semi-field trials conducted in Trinidad

Lyophilized yeast (5-HTR.426 or control) containing 40 mg and 0.1% benzoic acid, was combined with 100 μL of Westham Inc Bait (provided by Westham Co., Tel Aviv, Israel). This mixture was placed on a 1.3 cm square of thick plastic sheet and covered with a membrane supplied by Westham Co. The amount of yeast provided in each sachet was reduced to 4 mg for the outdoor semi-field Aedes mosquito trials. The membrane was sealed using a heat sealer to create a miniature membrane feeder (sachet). These sachets were placed either at the bottom of the cage for the simulated field studies in the lab or in a vertical position on the wall of the experimental cage (for outdoor semi-field trials) with the Westham Co. membrane facing inward to facilitate feeding. Simulated field trials using the sachets were conducted in the Indiana University insectary using laboratory strain mosquitoes, while all semi-field experiments in Trinidad were conducted on field strain mosquitoes in the tent enclosure described above during December 2022-January 2023 and June to September 2023. Three-day old adult females of each species were selected and sugar-starved for 24 h in the field setting described above and then allowed to feed for a period of 24 h. Water was provided for the duration of the experiment. Subsequently, the presence of engorged mosquitoes confirmed successful feeding. Daily survival rates were monitored over the next six days. Each experiment was conducted in triplicate. To assess the feeding rates, the G-test of independence was employed, while the survival rates were compared using ANOVA. Dose–response curves for adulticide 5-HTR.426 yeast ATSB were produced and evaluated as described in Mysore et al.⁴³ with the lyophilized yeast and probit analyses performed using SPSS 29.