ABSTRACT Random survey was carried out throughout the valley for species composition of chafer beetles from March 2004 to September 2005. In all twenty two species of white grub beetles were recorded comprising of 7, 7, 4, 1, 2 and 1 species from sub families Melolonthinae, Rutelinae, Dynastinae, Cetoniinae, Sericinae and Geotrupinae, respectively. Studies on light traps, host tree collection and feeding preference of chafer beetles were carried out in two ecosystems i.e. orchard and golf course during the year 2004 and 2005.The pooled data for the two years on light trap (LT) and host tree (HT) collections in orchard ecosystem recorded 15 species, Adoretus simplex was found most abundant (30.58%) followed by Holotrichia longipennis (19.23%), with an over all LT: HT ratio of 1: 1.11. On the basis of LT and HT attraction in Royal Spring Golf Course Srinagar, 16 species were recorded during two years and Heteronychus robustus was found predominant (41.80%) followed by H. longipennis (15.35%) with an over all LT:HT ratio of 1:2.20.
Host plant preference of H. robustus was studied at Royal Spring Golf Course on 16 hosts during the year 2005. Raspberry and chestnut were extremely preferred hosts while as walnut, oak (evergreen) and robinia were found highly preferred, preferred and moderately preferred hosts, respectively on the basis of average number of beetles/branch/night/tree. In vitro studies on host food preference (intake) of H. robustus showed raspberry and chestnut as very high food intake, walnut as high food intake, oak (deciduous) as good food intake and cypress as low food intake hosts, respectively on the basis of per cent food consumption.
Host plant preference of Adoretus simplex in orchard ecosystem was studied on 9 host plants during the year 2005. Chestnut, black raspberry, grape and rose were found extremely preferred, highly preferred, preferred and moderately preferred hosts, respectively on the basis of average number of beetles/branch/night/tree. In vitro studies on host food preference of Adoretus simplex showedchestnut, walnut, oak (deciduous), apple and rose as very high, high, good, low and very low food intake hosts, respectively on the basis of per cent food consumption.
Among different colour regimes of light traps, black light showed significantly highest attraction of adult chafers followed by fluorescent and red light recording 37.90, 28.81 and 16.14 beetles/trap/season, respectively. The height of traps showed a significant effect on the attraction of adult beetles and highest attraction was recorded at 100 cm height (36.33 beetles/trap/season) followed by 50 cm (31.95 beetles/trap/season) which did not differ significantly from each other. However, the attraction was significantly lower at 200 cm height (14.57 beetles/trap/season).
The biology of predominant specie of chaffer beetle (H. robustus) was studied in vitro which showed a single annual generation completing the life cycle in 315-364 days. The egg stage lasted for 8-12 days, grub period for 288-326 days and pupal period 19-26 days.
The susceptibility of white grubs to different entomopathogens and an insecticide, chlorpyriphos 20 EC were evaluated under field conditions at RSGC Srinagar during the year 2004 and 2005. The pooled data recorded Beauveria bassiana (local strain at 1x1012 spores/ml) as the most promising treatment followed by Metarrhizium anisopliae (local strain at 1x1012 spores/ml), recording mortality of 92.19% and 79.23%, respectively 30 days after the treatment. Chlorpyriphos 20 EC (4 litre/hectare) recorded 72.15% mortality, the third effective treatment after Beauveria bassiana and Metarrhizium anisopliae.