Differential tolerance of two morphological variants of Culex tritaeniorhynchus (Diptera: Culicidae), a Japanese encephalitis vector, to pyrethroid insecticides in Mysore, India.

Five synthetic pyrethroids, deltamethrin, cypermethrin, permethrin, alpha-cypermethrin, and lambdacyhalothrin, were tested on the larvae of 2 morphological variants of Cx. tritaeniorhynchus collected from Mysore City (ground pools) and outside Mysore (paddy fields), in Karnataka State, India. The morphological characters, ie, length and width of siphon, siphonal index, comb scale numbers, pecten teeth numbers, length of anal gills and anal gill index of larvae of two Cx. tritaeniorhynchus populations were found to be significantly different (p<0.05). To elicit further detail of these two variants, pyrethroid bioassays were undertaken. In general, the toxicity ranking of these pyrethroids tested on the Cx. tritaeniorhynchus variants from Mysore City was deltamethrin > lambdacyhalothrin > cypermethrin > permethrin > alpha-cypermethrin. However, for the rural variety it was deltamethrin > lambdacyhalothrin > alpha-cypermethrin > permethrin > cypermethrin. Of the 5 pyrethroids tested, deltamethrin was the most effective on both variants. Alpha-cypermethrin and lambdacyhalothrin were respectively 2.17 and 2.09 times more effective on the city variety (p<0.05), based on LC50 values. The results suggest that, in addition to morphological differences, the 2 tested varieties of Cx. tritaeniorhynchus also differ in susceptibility status.

Entomological studies of Phlebotomus papatasi and P. sergenti (Diptera: Psychodidae) as vectors of cutaneous leishmaniasis in Shiraz, Iran.

Leishmaniasis is considered endemic in 82 countries, including Iran. In order to control the vectors of leishmaniasis, entomological studies, such as fauna, seasonal abundance, nocturnal activity, sex ratio, resting site, etc, are necessary. In this investigation, the species composition of sandflies. and the seasonality and nocturnal activity, sex ratio, and resting site, of Phlebotomus papatasi and P. sergenti, for implementation of future control measures, were surveyed in northeast Shiraz City, southern Iran. Two thousand, five hundred (2,500) adult sandflies were collected from internal and external fixed places by sticky trap. SPSS version 1.3 software was used to analyze the data. Meteorological data were obtained from the meteorological organization in Shiraz. In this investigation, a total of 4 species were recorded: P. papatasi, P. sergenti, Sergentonmyia sintoni, and Ser. dentata. Peak abundance of both P. papatasi and P. sergenti occurred in September, and declined by December. Between sunset and sunrise, the maximum and minimum abundance were found to be at 20 00 hour, and 05 00 or 06 00 hour, respectively. The sex ratio (F/M) of the P. papatasi varied from a high ratio of 10.9: 1 in October, to a low ratio of 1.2: 1 in June. The abundance of sandflies in the external regions was significantly more (p<0.05) than the internal regions in all months except May and June. Using the results of this investigation, health workers in this area can better manage the control and prevention of cutaneous leishmaniasis.