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

Abstract

Aedes notoscriptus (Skuse) is a container-inhabiting mosquito endemic to Australia that vectors arboviruses and is suspected to transmit Mycobacterium ulcerans, the cause of Buruli ulcer. We evaluated the effectiveness of the In2Care(R) station, which 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(R) stations in a 50,000 m2 area and results were compared to four control areas that did not receive the treatment. Efficacy was evaluated by comparing egg counts and measuring larvicidal impact in surrounding breeding sites. Laboratory experiments validated the effect of B. bassiana on adult survival. Results of this field trial indicate that, six weeks after the In2Care(R) stations were deployed, treatment site ovitraps contained 43% fewer eggs than control site ovitraps, and 33% fewer eggs after ten weeks, suggesting that the In2Care(R) station was able to reduce the egg density of Ae. notoscriptus. Population reduction remained evident for up to three weeks after In2Care(R) stations were removed. Treatment site ovitraps had significantly fewer Ae. notoscriptus eclosing than control site ovitraps, confirming the pyriproxyfen autodissemination feature of the stations. An average reduction of 50% in adult eclosion was achieved. Exposure to B. bassiana resulted in four-times higher mortality among adult mosquitoes. Additionally, using fresh In2Care(R) nettings led to an 88% decrease in average survival compared to four-week-old nettings. The use of In2Care(R) stations has potential for suppressing Ae. notoscriptus egg density.