A sound trap for Aedes albopictus (Skuse) male surveillance:Response analysis to acoustic and visual stimuli

Aedes albopictus (Skuse) is one of the most invasive mosquito species capable of transmitting various harmful pathogens to humans. Failure of vector control strategies against this species requires the development of new effective vector control methods. Among the alternative genetic control measures under development, the sterile insect technique (SIT) is today receiving a renewed interest as a possible effective tool to be integrated in an area-wide pest management approach. The monitoring of the abundance, distribution, movements and ratio of released sterile and wild fertile males is a fundamental requirement for the successful management of any pest control activities integrating an SIT component. Although several traps exist for adult female mosquito surveillance and population control, effective methods to monitor large quantities of non-biting males were less researched in the past and more difficult to obtain. In this study we analyzed the response of A. albopictus males to various sound stimuli produced with different volumes and frequencies in association with visual cues for the optimization of male catches. The production of modulated frequencies continuously varying within the typical female sound emission range (500-650Hz) showed the best results for a sound pressure level between 75 and 79dB measured at the speaker level. The black color of the trap, however, seems decisive to attract males in the vicinity of sound traps and the combined effect produced by these stimuli is additive. We also observed that males increase their response to acoustic stimulation up to 4days of age and then show a continuous and progressive decline of their sound responsiveness. A plastic sound trap prototype capable of producing the most effective sound stimuli tested at laboratory conditions showed a good A. albopictus males' attractiveness in the field despite a reduced use of color stimuli. The use of sound stimuli therefore appears to be a promising prospect to increase the capture rate of A. albopictus males in new or in already existing mosquito traps.