Evaluation of In2Care® mosquito stations for suppression of the Australian backyard mosquito,Aedes notoscriptus

Abstract

Aedes notoscriptus is a container-breeding mosquito endemic to Australia that vectors arboviruses and is suspected to transmit Mycobacterium ulcerans, the cause of Buruli ulcer. Localised control measures for this species are limited by its high dispersal capability. Here we evaluated the effectiveness of the In2Care system in controlling Ae. notoscriptus. The In2Care system suppresses mosquito populations via the entomopathogenic fungus, Beauveria bassiana, and the insect growth regulator pyriproxyfen, the latter of which is autodisseminated among larval habitats by contaminated mosquitoes. A field trial was conducted using 110 In2Care stations in a 50,000 m2 target area and the results were compared to four control areas that did not receive the In2Care treatment. Efficacy was evaluated by comparing egg counts and measuring larvicidal impact in surrounding breeding sites. Laboratory experiments were conducted to validate the effect of B. bassiana on adult survival. Field results showed that six weeks after the In2Care stations were deployed, treatment site ovitraps contained 43% fewer eggs than control site ovitraps, and 33% fewer eggs after ten weeks, indicating that the In2Care system was able to reduce the population of Ae. notoscriptus. Population reduction remained evident for up to three weeks after In2Care stations removal. Treatment site ovitraps had significantly fewer Ae. notoscriptus eclosing than control site ovitraps, confirming the pyriproxyfen autodissemination feature of the stations, and an average reduction of 50% in adult eclosion was achieved. Adult mosquitoes had a significantly shorter lifespan after exposure to B. bassiana. The strategy has potential for suppressing Ae. notoscriptus populations.