BIOEFFICACY OF METARHIZIUM ANISOPLIAE ISOLATES AGAINST TEAK SKELETONISER PALIGA MACHOERALIS (LEPIDOPTERA: PYRALIDAE)

• Published in: Journal of tropical forest science 2013-07, Vol.25 (3), p.310-316
• Main Authors: Sapna-Bai, N, Remadevi, OK, Sasidharan, TO, Balachander, M, Dharmarajan, P
• Format: Article
• Language: English
• Subjects: Chemical suspensions; Conidia; Forestry research; Fungal spores; Fungi; Insect larvae; Insect pests; Lepidoptera; Metarhizium; Metarhizium anisopliae; Pests; Pyralidae; Tropical forests
• ISSN: 0128-1283

Paliga machoeralis is the most malicious pest of teak responsible for epidemic defoliation of trees in plantations and natural forests. Metarhizium spp. have been a long standing model for biological control reported to have great potential for the management of over 200 insect species. The present study was conducted to evaluate the virulence of M. anisopliae isolates against P. machoeralis in the laboratory. Bioassay of 25 isolates of M. anisopliae was carried out using inoculum concentrations ranging from 103—108 conidia ml-1. The dose-mortality and time-dose-mortality responses for these isolates were determined. Median lethal dose concentration (LC50) values of isolates ranged from 0.11 × 105 to 3417.65 × 105 conidia ml-1. Among the 25 isolates, MIS2, MIS7, MIS1 and MIS3 were found to be more effective with lower LC50 values. MIS2 was the most effective isolate with lowest LC50 (0.11 × 105 conidia ml-1) followed by MIS7 (0.15 × 105 conidia ml-1). Lowest median lethal time (LT50) of 3.4 days was also recorded for MIS2 followed by MIS7 (3.7 days), MIS1 (4.3 days) and MIS3 (4.9 days) at spore load of 107 conidia ml-1. With respect to LC50 and LT50, MIS2 proved to be superior over other isolates. The results indicate prospects of isolates MIS2 and MIS7 in developing biopesticide formulation for management of teak skeletoniser. Paliga machoeralis merupakan perosak jati yang paling teruk dan menyebabkan epidemik peluruhan daun di ladang serta hutan asli. Metarhizium spp. sudah lama diguna untuk kawalan biologi dan mempunyai potensi besar dalam pengurusan lebih 200 spesies serangga. Kajian ini dijalankan untuk menilai kemudaratan isolat M. anisopliae terhadap P. machoeralis di makmal. Bioasai 25 isolat M. anisopliae dijalankan menggunakan kepekatan inokulum 103—108 konidium ml-1. Kematian isolat berdasarkan dos serta masa ditentukan. Kepekatan maut purata (LC50) isolat berjulat antara 0.11 × 105 konidium ml-1 hingga 3417.65 × 105 konidium ml-1. Antara 25 isolat yang dikaji, MIS2, MIS7, MIS1 dan MIS3 didapati lebih berkesan dengan nilai LC50 yang lebih rendah. MIS2 merupakan isolat yang paling berkesan dengan nilai LC50 yang terendah iaitu 0.11 × 105 konidium ml-1. Ini diikuti oleh MIS7 (0.15 × 105 konidium ml-1). Nilai masa maut purata (LT50) yang terendah iaitu 3.4 hari dicerap untuk MIS2 diikuti oleh MIS7 (3.7 hari), MIS1 (4.3 hari) dan MIS3 (4.9 hari) pada kepekatan 107 konidium ml-1. Dari segi LC50 serta LT50, MIS2 nyata lebih berkesan berbanding dengan