Screening of microbial agents for the control of the orchid lema, Lema pectoralis Baly (Coleoptera: Chrysomelidae)

Abstract

Several isolates of Beauveria bassiana, Metarhizium anisopliae, and Bacillus thuringiensis were screened against the orchid lema, Lema pectoralis Baly (Coleoptera: Chrysomelidae), a major pest of Dendrobium and Vanda orchids. The B. bassiana isolates, Bb-1 and AJII-1, were identified as the most promising against the adults but none was effective against the eggs and larvae. The best isolate, Bb-1 had an LT50 of 7.14 and 5.68 d at 107 conidia mL.1, and an LC50 of 2.58 × 105 and 1.77 × 105 two weeks after treatment, in the first and second trials, respectively. Passage of the inoculum in the insect cadaver increased the virulence of isolates. A measure of the time when the insects permanently stopped to feed, i.e., ceased feeding time (CFT), was formulated. At the CFT stage, the insects are unable to cause any further damage. B. bassiana caused cessation of feeding in infected insects up to 2 d prior to their death.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

171-178

Document Type

Article

Subject

Bacillus thuringiensis, Beauveria bassiana, Biological control, Chrysomelid beetle, Dendrobium, Lema pectoralis, Metarhizium anisopliae, Microbial control, Orchid pest, Vanda

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