Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) and natural enemy relations as influenced by straw mulch, Bacillus thuringiensis and esfenvalerate insecticide

Studies were conducted to determine the effects of straw mulch, Bacillus thuringiensis var tenebrionis (Bt) and esfenvalerate (Asana) on Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), a pest of potato, and on natural enemies Podisus maculiventris (Say), Perillus bioculatus (F) (Hemiptera: Pentatomidae) and Lebia grandis Hentz (Coleoptera: Carabidae). Adult beetles were significantly (P=0.05) fewer on potato with or without mulch but which were sprayed with Bt and Asana than on the checks. Larvae and natural enemies were more on Bt and non-insecticide treatments than on plants in esfenvalerate plots. Treatment means, however, were not significant (P=0.05). Mulch and Bt suppressd beetle population and preserved good levels of indigenous beneficial insects. We recommend that mulch and Bt can be applied within an integrated pest management programme for L. decemlineata.

Les recherches ont ete menees pour determiner les effets de paillis, de
Bacillus thuringiensis var tenebrionis (Bt), et esfenvalerate (Asana)
sur Leptinotarsa decemlineata (Say) (Coleoptere: Chrisomelidae), une
peste de la pomme de terre, et sur les ennemis naturels Podisus
maculiventris (Say), Perillus bioculatus (F) (Hemiptera:
Pentatomidae) et Lebia grandis Hentz (Coleoptera: carabidae). Les scarabees
adultes etaient significativement (P=0.05) peu nombreux sur la pomme de terre
avec ou sans paillis arrosee de Bt et d'Asana que sous controles. Les larves
et ennemis naturels etaient plus nonbreux sur Bt et traitements sans
insecticides que sur les plantes en parcelles d'esfenvalerate. Cependant, les
differences des traitements n'etaient pas significativement differentes (P =
0.05). Le paillis et le Bt ont supprime la population des scarabees et a
preserve les insectes indigenes benefiques. Nous recommandons, par
consequent, que le paillis ete le Bt soient utilises dans un programme de
lutte integree contre la peste L. decemlineata.