Mating compatibility and competitiveness of transgenic and wild type Aedes aegypti (L.) under contained semi-field conditions

We conducted the world's first experiments under semi-field conditions (ACL-2 field house) to assess the mating competitiveness of genetically sterile RIDL male mosquitoes (513A strain). The field house is a state-of-the-art, fully-contained trial facility, simulating the living space for a household of 2-4 people in Peninsular Malaysia. Ten genetically sterile RIDL male A. aegypti mosquitoes competed with ten wild type males inside this field house to mate with ten wild type females. Hatched larvae from mated females were screened under a fluorescent microscope for genetic markers to determine if they were fathered by RIDL male or wild type male, and all results were cross-checked by PCR. Two such experiments were conducted, each repeated sufficient number of times. All strains were on a Malaysian lab strain background for the first experiment, while the RIDL males alone were on a recently-colonised Mexican strain background for the second experiment. A total of 52 % of the matings were with RIDL males in the first experiment, while 45 % of the matings were with RIDL (Mexican) males in the second experiment. Statistically, this is not significantly different from 50 % of the matings expected to take place with RIDL males if the latter were as competitive as that of the wild type males. This shows that A. aegypti RIDL-513A has excellent mating competitiveness under semi-field conditions, verifying earlier trends obtained in small lab cages. We also observed high mating compatibility between recently-colonised Mexican RIDL males and lab-reared Malaysian wild type females.