Rainfall is not a direct mortality factor for anopheline larvae.

Sir, The impact of raindrops has major consequences on the soil surface conditions. The effects of rain drop energy on erosion and infiltration have been investigated (Fernandes et al., 1997). Palmer (1965) found that a thin layer of water increases the effects of raindrop impact force on soil properties; this result has been confirmed by numerical simulation (Huang et al., 1983; Chang & Hills, 1993). During heavy rain, low depth of water in puddles or pools could constitute a hostile environment for the survival of delicate organisms. This question is examined here in the case of one species of mosquito larvae. We know that rain can be injurious for aquatic stages of mosquitoes. After important rain the flow of running water can carry away the mosquito larvae, leading to noticeable mortality for aquatic populations of mosquitoes living usually in stagnant water (Reisen et al., 1989). On the other hand, to our knowledge, the direct impact of raindrops on mosquito larvae remains poorly documented. Considering the apparent full adaptation of larval mosquitoes for living in the water and the success of mosquitoes in wet countries, we has approached this question with two hypotheses. The first one, rainfall has to be strong enough to allow the drops of water to hurt or kill the larvae. The second, the depth of available water has to be selected in order to (i) avoid the spontaneous diving of larvae which would protect them from the drop shocks and, CWG W. J. & HILLS D.J. Sprinkler droplet effects on infiltration.1. Impadt~~Tmuíãtioniï~ JOZLZI ~f In-igatiolz and Drainage Engineering, 1993, 119, 142-156. -