Abstract
The effects of pesticides on the economical character of the administered generation and the next generation of silkworms were examined using four pesticides: MPP, lead arsenate, MAFA and DPTH.
The lowest concentration of chemicals which produced undesirable effects on cocoon weight, cocoon shell weight, and number of eggs laid when the silkworms were fed the chemicals during the 5th instar was about 63ppm for MPP and lead arsenate, and about 65 and 100ppm for MAFA and DPTH, respectively. Even when the silkworms were reared for eight generations while being fed the chemicals at these concentrations continuously during the 5th instar, the economical character of all generations was affected to the same, degree as the first, generation; the effect not being intensified or mitigated with the generation. The generation raised without pesticides after consecutive generations with the chemicals administered showed recovery of economical characters that had been made undesirable.
No resistance against these chemicals was seen in the next silkworm generation.
Silkworms administered MPP for consecutive generations at a concentration slightly higher than the lowest undesirable-effect producing concentration of 125ppm showed a poorer ability to hatch, and those administered lead arsenate at the same concentration showed a poorer pupation rate with increasing generations. The former could not be reared after 6 generations, and the latter after 4.
