γ Ray Dosimetry and Mating Capacity Studies in the Laboratory on <I>Aedes albopictus</I> Males

Abstract

In Italy, Aedes albopictus Skuse is currently recognized as the most dangerous mosquito, and as currently applied conventional control methods gave unsatisfactory results, we are developing alternative strategies such as the sterile insect technique. To find the optimal sterilizing dose, male pupae were exposed to different doses of gamma rays in the range 20-80 Gy, generated by a Cesium-137 source. The effects of male pupal age at irradiation and gamma ray dose on adult male emergence, sterility level, longevity, and mating capacity were evaluated, and dose-response curves of residual fertility were calculated. Radiation tests were also performed on female pupae to observe their reproductive capacity in case of accidental release. Results confirmed that the age at which the male pupa is irradiated is an important factor that affects the longevity of the adult, whereas the effect of age on the induced sterility level is less pronounced. When male pupae older than 30 h were irradiated, the longevity of the adults was not affected by doses up to 40 Gy. The 40-Gy dose appeared sufficient to induce high level of sterility (>99%) at any male pupal age for all the strains tested. The duration of coupling and the number of mated females per male appeared to be affected by the radiation received by male pupae only at doses higher than 40 Gy. The female pupae were more sensitive to radiation than male pupae, with strong reduction in fecundity and fertility at 20 Gy and complete suppression of oviposition at higher doses.

Declining malaria, rising of dengue and Zika virus: insights for mosquito vector control

“…In particular, the majority of the studies focused on the sexual behaviour of medically important Aedes species focused on comparisons of insemination ability in sterilized and wild males (e.g. Balestrino et al 2010;Wiwatanaratanabutr et al 2010;Boyer et al 2011;Oliva et al 2012;Bellini et al 2013;Hamady et al 2013;Moretti and Calvitti 2013;Madakacherry et al 2014), without behavioural quantification of courtship and mating events (but see Oliva et al 2013;Benelli 2015c;Benelli et al 2015). Notably, limited information is also available on the potential molecules mediating aggregation and mating dynamics in mosquitoes (Cabrera and Jaffe 2007;Fawaz et al 2014;Pitts et al 2014).…”

Mating Competitiveness ofAedes albopictusRadio-Sterilized Males in Large Enclosures Exposed to Natural Conditions

“…Male sterilization occurs at the pupal stage at the SantÕAnna Hospital of Ferrara by gamma rays (Balestrino et al 2010). It is well-known that the mating competitiveness of mass reared radiosterilized males can be affected by two kinds of problems: 1) Possible reduction of the Þtness because of the inbreeding conditions induced by the rearing under artiÞcial conditions, which may cause a decrease in genetic diversity with a loss of the genotypes more adapted to natural conditions (Coppel and Merlins 1977, Asman and Reisen 1987, Hansson and Westerberg 2002, Red and Frankham 2003.…”

“…Although it is assumed that competitiveness studies conducted in large enclosures can provide more reliable indication than laboratory studies conducted in small cages as regard to the real competitiveness of the sterilized males under Þeld conditions, no information is available on the best size of the enclosure and on the speciÞc requirements of different mosquito species. Balestrino et al (2010), in laboratory studies, found an exponential relationship between radiation dose and induced sterility, but the deÞnition of the optimal radiation dose (the dose at which the radiated males have the highest capacity to induce sterility into a wild population for a certain period of time) requires further investigations both through semiÞeld and Þeld studies.…”

Impact of environmental factors on mosquito dispersal in the prospect of sterile insect technique control

“…In addition to [23], we consider a parameter λ s that indicates the level of fertility of sterile males. In fact, depending on the radiation dose, the sterile male is not necessarily fully sterilized [5,7]: only for doses greater or equal to 40 Gy, Aedes males become fully sterile, i.e. λ s = 0.…”

“…Thus, we set λ s = 0.1. According to , [5]), with appropriate sugar supply, sterile males live on average 11.6 days, which implies M ms = 1/11.6. The sexual competitivity is set as f s = 0.7, [7].…”