Feasibility of wing beat sound trap for the control of mosquito vectors.

Early observations suggested that the female sound was a possible cause of mating. Attempts had been made for introduction of female wing beat sound for removal male mosquitoes from the population for the control purpose. The traps emitted female wing beat sound, were set on black clothes as a swarm marker, could collect a large number of male Cx. tritaeniorhynchus in Japan. Those traps were later improved with introduction of two attractants, hamster and dry ice. Consequently, two systems were adopted for efficiency trapping of males and females. A cylinder trap with 350 Hz of wing beat frequency was introduced for male Cx. tritaeniorhynchus collection, while the cage trap with 530 Hz was for female collection. The traps were set every other days after sun set for three weeks in a paddy field. Although there was no decrease of population density, the reduction of parous rate was evident. For future effective control, it may suggest the need to distribute more wing beat sound traps to cover all larva breeding paddy field and near by blood sources. On the other hand, other control methods should be integrated.

A brief survey of phlebotomine sandflies in Thailand.

Sandflies were found in widely scattered localities in Thailand in varied numbers. Daytime resting places for the adults included caves, termite hills, abandoned houses, ancient stone sanctuaries, air-raid shelters, tree hollows, loose bark of dead standing trees and rock crevices. Of fifteen species, P. major major, P. teshi, S. anodontis, S. gemmea, S. hodgsoni hodgsoni, S. perturbans, S. punjabensis and N. vietnamensis were here recorded for the first time in Thailand. P. argentipes and P. major major are interesting in view of their potential as disease vectors.

Plasmodium falciparum infection in Bisazir chemosterilized Anopheles dirus in laboratory studies.

Bisazir, at a 0.5% solution induced sterility in males and at a 1.5% solution in female A. dirus. These sterilizing doses reduced P. falciparum infection in mosquitoes, however, they can still transmit malaria. It is concluded that by the concentration of 1.5 and 2.0% that induced complete sterility in males and females are not safe in sterile-male release programme for the control of A. dirus, unless all females were eliminated prior to release.

DDT-resistant Culex quinquefasciatus: the effect of DDT on the mosquito's size, fecundity and survival.

Resistant strains of Culex quinquefasciatus were selected in the larval stage by exposure to sublethal doses of DDT. The size, body weight and fecundity of DDT-resistant mosquitoes were significantly decreased. There was no significant difference between the longevity of females in the original strain and the DDT selected strains, however, there was a significant difference in the males of the DDT-resistant strains than those of the original strain.

Descriptions of odonate nymphs from Thailand.

The descriptions of odonate nymphs from Thailand are presented. The insects of the Order Odonata both naiads and adults may serve as the second intermediate host of some intestinal parasites in Thailand.