Ingested insecticide to control Aedes aegypti: developing a novel dried attractive toxic sugar bait device for intra-domiciliary control

Abstract

Background: Illnesses transmitted by Aedes aegypti (Linnaeus, 1762) such as dengue, chikungunya and Zika comprise a considerable global burden; mosquito control is the primary public health tool to reduce disease transmission. Current interventions are inadequate and insecticide resistance threatens the effectiveness of these options. Dried attractive bait stations (DABS) are a novel mechanism to deliver insecticide to Ae. aegypti. The DABS are a high-contrast 28 inch 2 surface coated with dried sugar-boric acid solution. Aedes aegypti are attracted to DABS by visual cues only, and the dried sugar solution elicits an ingestion response from Ae. aegypti landing on the surface. The study presents the development of the DABS and tests of their impact on Ae. aegypti mortality in the laboratory and a series of semi-field trials. Methods: We conducted multiple series of laboratory and semi-field trials to assess the survivability of Ae. aegypti mosquitoes exposed to the DABS. In the laboratory experiments, we assessed the lethality, the killing mechanism, and the shelf life of the device through controlled experiments. In the semi-field trials, we released laboratory-reared female Ae. aegypti into experimental houses typical of peri-urban tropical communities in South America in three trial series with six replicates each. Laboratory experiments were conducted in Quito, Ecuador, and semi-field experiments were conducted in Machala, Ecuador, an area with abundant wild populations of Ae. aegypti and endemic arboviral transmission. Results: In the laboratory, complete lethality was observed after 48 hours regardless of physiological status of the mosquito. The killing mechanism was determined to be through ingestion, as the boric acid disrupted the gut of the mosquito. In experimental houses, total mosquito mortality was greater in the treatment house for all series of experiments (P < 0.0001). Conclusions: The DABS devices were effective at killing female Ae. aegypti under a variety of laboratory and semifield conditions. DABS are a promising intervention for interdomiciliary control of Ae. aegypti and arboviral disease prevention.

Exploring the utility of social-ecological and entomological risk factors for dengue infection as surveillance indicators in the dengue hyper-endemic city of Machala, Ecuador

“…Houses in good repair limit exposure to mosquitoes, and the association between substandard housing structure and arboviral risk has been repeatedly documented in locations beyond Ecuador [49][50][51]. Houses made of cane were a risk factor for dengue, which is consistent with typical housing found in low income areas with active dengue transmission in Ecuador [52]. Generally found in the urban periphery of Machala, housing constructed from cane does not exclude potentially infectious mosquitoes from entering households [12].…”

Applicability of attractive toxic sugar baits as a mosquito vector control tool in the context ofIndia: a review

“…Later, the same results were reported with an even lower concentration of boric acid (0.1%) in TSB solution against Aedes mosquitoes after 10 days exposure in laboratory 4 . Thereafter, several studies were undertaken with boric acid and sugar solution against Aedes and Culex mosquitoes, and > 90% mortality was observed after 48 h exposure under controlled conditions 15, 30, 39, 40 . Although the majority of studies reported significantly high mortality rates of Aedes mosquitoes with boric acid, a few recent studies documented relatively less mortality (50–70%) 23, 24, 33 .…”

“…A study in Ecuador was recently conducted with dried ATSB and showed that this may have better implications for vector control 39 . However, a major shortcoming of current ATSB strategies is the use of fruit juice as an attractant.…”

“…4 Thereafter, several studies were undertaken with boric acid and sugar solution against Aedes and Culex mosquitoes, and > 90% mortality was observed after 48 h exposure under controlled conditions. 15,30,39,40 Although the majority of studies reported significantly high mortality rates of Aedes mosquitoes with boric acid, a few recent studies documented relatively less mortality (50-70%). 23,24,33 Based on the proven efficacy of boric acid with sugar solutions, several field trials were undertaken both outdoors and indoors.…”

“…A study in Ecuador was recently conducted with dried ATSB and showed that this may have better implications for vector control. 39 However, a major shortcoming of current ATSB strategies is the use of fruit juice as an attractant. Within a short period, the chemistry of volatiles from fruit juices changes, ultimately affecting the attraction behaviour in mosquitoes.…”