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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 x 105 to 3417.65 x 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 x 105 conidia ml-1) followed by MIS7 (0.15 x 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 [ABSTRACT FROM AUTHOR]

Teak (Tectona grandis) is one of the most favoured timbers in the world and is used for many products and services. In north Canara Circle of Karnataka, India the heartwood borer, Alcterogystia cadambae, is found to cause substantial damage to teak trees. From morphometric estimations of larvae collected in the field, and by applying Dyar's law, it was ascertained that there were seven stages of instars. The laboratory rearing using artificial diet also revealed that larvae moulted six times to have seven instars in its larval life. The duration of the first to seventh instar was 32.2, 13.0, 38.0, 31.0, 30.5, 33.0 and 43.0 days respectively. The total larval duration was 207 days. [ABSTRACT FROM AUTHOR]

Species of the entomopathogenic fungus Metarhizium are some of the most promising biocontrol agents against Lepidopteran pests. Laboratory bioassays were conducted to study the virulence of five isolates of Metarhizium sp. against larvae of the polyphagous pest, Spilarctia obliqua (Lepidoptera: Arctiidae). The Metarhizium isolates used in the study were recovered from soil and various insect hosts belonging to Lepidoptera, Coleoptera and Isoptera. Initially, a preliminary assay was carried out involving 18 Metarhizium isolates at a spore concentration 107 conidia ml-1 and five isolates, MIS 1, MIS 2, MIS 3, MIS 8 and MIS 9, which caused more than 50% mortality were chosen for the detailed bioassay. The assay was carried out with four different spore concentrations of each isolate, ranging from 104-107 conidia ml-1. The lethal concentration LC50 of these five isolates ranged from 2.1 × 105 to 38.9 × 105 conidia ml-1. The lethal time LT50 of the isolates ranged from 7.0-8.1, 6.0-7.7, 5.1-6.7, 4.6-5.4 days at concentrations 1 × 104, 1 × 105, 1 × 106, 1 × 107 conidia ml-1 respectively. The most pathogenic among the five isolates was the MIS 2 isolate with the lowest LC50 of 2.11 × 105 conidia ml-1 and LT50 of 4.6, 5.1, 6.0 and 7.0 days respectively at concentrations 1 × 107, 1 × 106, 1 × 105, 1 × 104 conidia ml-1. Isolate MIS 3 was second in effectiveness. These two isolates showed promise for use as biocontrol agents against S. obliqua. [ABSTRACT FROM AUTHOR]