Journal of Oil Palm Research Vol. 5 No. 2 1993 Dec, p. 92-101 SITI RAMLAH Ahmad Ali*; MOHD BASRI Wahid* ; RAMLE Moslim*
Received: 6 October 1992 Accepted: 22 November 1992
The pathogenicity of Beauveria bassiana (Balsamo) Vuillemin towards bagworm, Metisa plana Wlk. second and fourth instars of Metisa plana Wlk. was confirmed. The larvae were sprayed with different concentrations of conidia suspension and exposed at a temperature of 28±1°C and a relative humidity of 65%-75% and 85%-100% (‘ambient’ and ‘humid’ respectively). The percentage mortality, lethal concentration (LC50) and the leaf area damaged (LAD) were calculated. B. bassiana was capable of infecting both stages of M. plana. The percetage mortality increased with increasing concentration of coxidia suspension. The LC50 of B. bassiana for second instar was 4.2 x 104 conidia/ml under humid, and 1.5 x 106 conidia/ml under ambient moisture conditions. For fourth instar the LC50 was 2.4 x 106 conidia/ml under humid and 2.5 x 107 conidia/ml under ambient moisture conditions. Second instar of Metisa plana Wlk. was thus more susceptible to the pathogen than fourth instar. Increased humidity enhanced the pathogenicity of B. bassiana and lowered the feeding activity of M. plana.KEYWORDS:
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* Palm Oil Research Institute of Malaysia,
P O Box 10620,
50720 Kuala Lumpur, Malaysia.