Abstract
To monitor new emergence of males of Culex quinquefasciatus and ealuate the chemosterilizing effect of hempa-treated sound traps, a field experiment was conducted in a 2.2-haresidential area in a suburb of Butterworth, Malaysia, from July 6 to August 25, 1986. In the initial 20-day trapping experiment, an average of 55.6 males were caught per trap per day. The total number aught in 15 traps could be correlated to new emergence of males, which was sampled by a 5-min net sweep. In the following 20-day experiment with 13 sterilant-treated sound traps, 17.1% egg rafts and 7.8% of the eggs in these rafts were sterile, while those in the pretreatment period were 4.2% and 1.8%, respectively. This moderate percentage of sterile egg rafts was expected because of mosquito migration from the unisolated experimental area and possibly because of insufficient attractancy of the sound trap. The low sterility of each egg raft was presumed due to the low efficacy of hempa used and to flowout of the treated sterilant from the upper inside wall of the sound trap which most males contacted.
