Potential Use of Pyriproxyfen for Control ofAedes aegypti(Diptera: Culicidae) in Iquitos, Perú

Abstract

The effects of pyriproxyfen were tested against a local population of Aedes aegypti (L.) in Iquitos, Perú. Bioassays showed that, when applied to late instars, pyriproxyfen prevented adult emergence at extremely low concentrations (LC50 = 0.012 ppb). There was no adult emergence from water sampled from storage tanks that had been seeded with the equivalent of 50-83 ppb (AI) pyriproxyfen. Five months after treatment, despite constant dilution of these tanks, water sampled from these sources continued to be lethal to larvae and pupae. Additional studies, carried out in the laboratory, showed that groups of five or 20 female blood-fed mosquitoes, exposed to residues of approximately 0.003 g (AI) pyriproxyfen/m2, could transfer enough chemical to new oviposition sites to prevent approximately 80% of adult emergence from larvae developing in that previously uncontaminated water. Moreover, although the fecundity of the adult females used as the transfer vehicles in these tests was unaffected, the subsequent eclosion of the eggs that these mosquitoes laid was decreased by 70-90%. It also was shown that, at very high concentrations (>30,000 ppb), pyriproxyfen-treated water sources were as likely to be used as oviposition sites as untreated sources. These data suggest that treated sites might act as sinks for mosquito reproduction and moreover that such sites might act as dissemination sources for the horizontal transfer of larvicides to new environments by mature females. We review the literature on the environmental and human health effects of this compound and discuss its potential for use as a mosquito control agent in the field.

The sterilizing effect of pyriproxyfen on the malaria vector Anopheles gambiae: physiological impact on ovaries development

“…Interestingly Brabant and Dobson [24] showed that methoprene could impair oviposition over two gonotrophic cycles in Ae. aegypti and larval breeding sites treatment with PPF could inhibit larval development up to five months [20]. …”

Pyriproxyfen for mosquito control: female sterilization or horizontal transfer to oviposition substrates by Anopheles gambiae sensu stricto and Culex quinquefasciatus

“…For instance while Itoh and colleagues [13] observed a reduction in number of eggs laid by Ae. aegypti exposed to PPF on the same day of bloodmeal, Sihuincha and colleagues [15] reported that exposure of the same mosquito species at a similar point in time did not affect the number of eggs laid. Only few studies have been done on the effect of PPF on egg-laying and hatching in Anopheles mosquitoes with contrasting findings.…”

“…The auto-dissemination technique has been successfully explored with Aedes mosquitoes in both laboratory and field settings [11-13,15,26,27,59,60]. Field studies have shown that Ae.…”

“…The major effect of PPF on mosquitoes is the inhibition of metamorphosis to prevent emergence of adults from pupae [18,19]. PPF has extremely low toxicity to humans [20], is effective at controlling mosquito larvae at very low doses [16,21] and can persist for up to six months in a variety of aquatic habitat types [15,21-23]. In addition, exposure of larvae to sub-lethal doses of PPF affects the adults’ egg development, egg production and reduces the hatching of eggs [24,25].…”

“…In addition, exposure of larvae to sub-lethal doses of PPF affects the adults’ egg development, egg production and reduces the hatching of eggs [24,25]. Exposure to PPF has been studied extensively in Aedes mosquitoes [11,13,15,26-28] and it has been shown that topical application can also reduce the reproductive capacity of adults [13,15,27,28] depending on dosage and time of exposure in relation to the blood meal [13], which signals the start of egg development [29]. However, inconsistent information on the effect of PPF exposure on egg-laying and hatching of eggs laid can be found for various species requiring more research in this subject area [13,15,30,31].…”