Abstract:
The toxicity of three insecticides, carbaryl, malathion and permethrin, to the European honey bee (Apis mellifera L.) and the Asian hive bee (Apis cerana F.) were studied at 18๐C, 25๐C and 32๐C by using the topical application and feeling method. The results of LD50 were evaluated and analysed by probit analysis program. The topical application method was conducted at 18๐C, 25๐C and 32๐C showed that the LD50 (numbers in parenthesis are lower-upper range, at significant level 95%) of carbaryl were 0.16 (0.13-0.20), 0.24 (0.14-0.33) and 0.22 (0.18-0.28); of malathion were 0.092 (0.083-0.100), 0.100 (0.082-0.120) and 0.180 (0.170-0.190); of permethrin were 0.0095 (0.0069-0.0120), 0.023 (0.020-0.026) and 0.130 (0.100-0.160) μg/bee respectively, in the European honey bee. Under these particular circumstances in the Asian hive bee, The LD50 were 0.052 (0.031-0.100), 0.100 (0.089-0.120) and 0.090 (0.078-0.100) μg/bee for carbaryl; 0.032 (0.021-0.047), 0.072 (0.066-0.078) and 0.064 (0.053-0.080) μg/bee for malathion; 0.015 (0.013-0.016), 0.043 (0.039-0.048) and 0.130 (0.110-0.160) μg/bee for permethrin. The feeding method was conducted at 18๐C, 25๐C and 32๐C showed that the LD50 of carbaryl were 0.054 (0.044-0.064), 0.220 (0.160-0.270) and 0.500 (0.420-0.600); of malathion were 0.19 (0.15-0.23), 1.20 (0.92-1.80) and 0.44 (0.34-0.54); of permethrin were 0.19 (0.15-0.25), 1.40 (1.0-2.2) and 1.20 (1.0-1.3) μg/bee, respectively, in the European honey bee. The Asian hive bee had the LD50 by feeding method at these temperatures as follows: 0.072 (0.067-0.079), 0.260 (0.210-0.310) and 0.490 (0.310-0.740) μg/bee for carbaryl; 0.20 (0.17-0.22), 0.48 (0.40-0.55) and 0.73 (0.62-0.93) μg/bee for malathion; 0.067 (0.055-0.080), 0.730 (0.600-0.980) and 0.350 (0.260-0.420) μg/bee for permethrin. This research could be concluded that the toxicity of those three insecticides to the two species of Apis was dependent on the temperature, the application method as well as the specific differences of the species. Almost at low temperatures, the toxicity was higher than at high temperatures, but only the carbaryl with the topical application shown no significant differences of toxicity to both species of bees. Likewise, the effect of the topical application was more effective compare to the feeding method, but the exception was the carbaryl that shown higher toxicity in the feeding method to the European honey bee. When topically applied with carbaryl and malathion, the two insecticides were more toxic to the Asian hive bee than the European honey bee whereas permethrin was more toxic to the European honey bee. The feeding method; permethrin was more toxic to the Asian hive bee than the European honey bee at these temperatures; malathion was more toxic to the Asian hive bee than the European honey bee at 25๐C, but at 32๐C the toxicity was more effective to the European honey bee at 25๐C, but at 32๐C the toxicity was more effective to the European honey bee; carbaryl, at 18๐C, was more toxic to the European honey bee than the Asian hive bee.