[Effects of sub-lethal dosages abamectin on food intake and digestive enzyme activities of silkworm Bombyx mori L].
Mulberry leaves treated with sub-lethal dosages (LC5, LC10 and LC20) abameetin were fed to the 5th instar larvae of silkworm (Bombyx mori L.), and the food intake and digestive enzyme activities of the larvae were studied by using gravimetric method and measuring enzyme activities. The results showed that sub-lethal dosages abameetin significantly inhibited the growth and food intake of the larvae, with their body mass and its increase rate as well as their relative growth rate being significantly lower than the control, and accompanied with the decreases of food intake, its relative consumption rate, and feces amount. The efficiency of the conversion of ingested food (ECI) and that of the conversion of digested food (EDI) also reduced, but the approximate digestibility (AD) increased significantly. The amylase and sucrase activities in the midgut of the larvae treated with abameetin decreased significantly for a longer time at the beginning, and then recovered to the same as or a higher level than the control, whereas the trehalase activity decreased significantly for a shorter time at the beginning, then increased significantly, and finally recovered to the normal. It was suggested that sub-lethal dosages abameetin had definite toxicity to the silkworm, and the toxic effect was increased with increasing dosage, which could result in the turbulence of silkworm's digestive system, and further, affect its food intake and its growth and development.
Zhu
Jiu-sheng
JS
Shanxi Key Laboratory of Pesticide Science, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China. zjs5963@163.com
Wang
Jing
J
Gao
Hai-yan
HY
Qin
Shu
S
Qiao
Xiong-wu
XW
Han
Ju-cai
JC
D000681:Amylases / Q000378:metabolism; D000818:Animals; D012831:Bombyx / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000187:drug effects*; D007306:Insecticides / Q000633:toxicity; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000633:toxicity; D023382:Toxicity Tests, Acute; D014198:Trehalase / Q000378:metabolism
D007306:Insecticides; C048324:abamectin; D007559:Ivermectin; D000681:Amylases; D014198:Trehalase