Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis |
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| Authors: | Nathan S Senthil Chung Paul Gene Murugan K |
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| Institution: | (1) Dept. of Environmental Engineering, Chonbuk National University, 561 756 Jeonju City, Chonbuk, South Korea;(2) Dept. of Zoology, Bharathiar University, 64 1046 Coimbatore, Tamil Nadu, India |
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| Abstract: | The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides
and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and
bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP)
and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe
at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction
in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect
was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced
in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides
are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found;
(iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic
pesticides in controlling RLF.
http://www.phytoparasitica.org posting Sept. 28, 2004. |
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| Keywords: | Biopesticide Bacillus thuringiensis Bt neem Vitex negundo Cnaphalocrocis medinalis enzyme ACP ALP ATPase |
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