Behavioural responses and changes in biology of rice leaffolder following treatment with a combination of bacterial toxins and botanical insecticides

• Published in: Chemosphere (Oxford) 2006-09, Vol.64 (10), p.1650-1658
• Main Authors: Nathan, Sengottayan Senthil, Kalaivani, Kandaswamy, Murugan, Kadarkarai
• Format: Article
• Language: English
• Subjects: Animals; Bacillus thuringiensis; Bacillus thuringiensis subsp. thuringiensis; bacterial insecticides; Bacterial Toxins - toxicity; Behavior, Animal - drug effects; Behaviour; bioassays; Biological and medical sciences; Biological control; Biology; Biopesticide; botanical insecticides; Cnaphalocrocis medinalis; Control; crop damage; fecundity; Female; Fundamental and applied biological sciences. Psychology; insect behavior; insect control; insect development; insect pests; insecticidal properties; Insecticides - toxicity; larvae; leaf-folding behavior; leaves; Lepidoptera; longevity; Male; molting; Mortality; Moths - drug effects; Moths - physiology; Neem; neem seed extract; Oryza sativa; Phytopathology. Animal pests. Plant and forest protection; plant extracts; Protozoa. Invertebrates; pupae; Pyralidae; Rice leaffolder; Vitex; Vitex negundo
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2006.01.037

Ingestion of the bacterial toxins Bacillus thuringiensis (Berliner) sub sp kurstaki, neem seed kernel extract and Vitex negundo L. (Lamiales:Verbenaceae) leaf extract to the rice leaffolder (RLF), Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae), resulted in altered leaf-folding behaviour and biology. In laboratory experiments, treatment with plant extracts and bacterial toxins suppressed leaf folding behaviour of C. medinalis. Larvae fed lower doses moulted into progressive instars, but in the late fourth to early fifth instars, spinning behaviour completely stopped, feeding was reduced and larvae regurgitated a sticky, semisolid substance that occluded the tunnel in which the pupae were formed. With the combination of Btk and botanicals, average leaf consumption was decreased by a factor of two even at reduced concentrations when compared with controls. Duration of larval and pupal stages, adult longevity and fecundity were more affected by treatment with the combination of bacterial toxins and both botanicals than by the treatment with the bacterial toxins or botanicals individually. All larvae died in the treatment of bacterial toxins and both botanicals combined.