Pests of coccinia (cocinia grandis (L) voigt) and their management

Abstract

The occurrence, distribution and magnitude of pests of coccinia in ten locations of Kalliyoor Panchayath in Thiruvananthapuram district were studied in a survey conducted at monthly intervals for one year. A field trial was carried out to evaluate the efficacy of various botanicals and chemical insecticides in managing the pests of the crop in the Instructional Farm, College of Agriculture, Vellayani. The results of the survey revealed that the dominant pests in coccinia were scale insect Saissetia hemispherica (Targ.), aphid Aphis spiraecola Patch, fruit fly Bactrocera cucurbitae Coq. and gall fly Lasioptera cephalandrae Mani. The minor pests recorded were leaf footed bug Leptoglossus australis F., pentatomid bug Aspongopus obscurus F., epilachna beetle Henosepilachna vigintioctopunctata F., pumpkin beetles viz., Aulacophora foveicolllis (Lucas), Aulacophora impressa Fabricius, Aulacophora bicolor Weber, vine borer Apomecyna saltator Fabricius leaf folder Diaphania indica Saunders and red spider mite Tetranychus sp. Very low infestation of green stink bug Nezara viridula Linn., mealy bug Ferrisia virgata (Ckll.) and woolly bear Pericallia ricini Fb. The infestation of coccinia by A. spiraecola, L. australis, N. viridula, H. vigintioctopunctata, A. bicolor, A. impressa and Tetranychus sp. was reported for the first time. Location wise variations in the incidence and distribution of the pest were noticed. All the major and minor pests except A. dispersus and Tetranychus sp. were observed through out the year. These pests were found only in summer season. Seasonal occurrence of the pests showed higher population and more damage in summer than rainy season. Five fold increase in the damage was caused by L. cephalandrae in summer. Among the various natural enemies observed, only the spiders were seen in all the locations and throughout the year. Correlation studies revealed strong positive correlation between maximum temperature and population of the pests and extent of damage. Rainfall had significant negative relationship with both population and extent of damage. An important finding of the present investigation was that the galls of L. cephalandrae served as the site for multiplication of B. cucurbitae. Eighty per cent of the fruits and thirty per cent of the galls showed infestation by B. cucurbitae. The number of fruit flies emerged from fruit and gall did not show any variation. Evaluation of botanicals and chemical insecticides against pests and spiders revealed that botanicals were effective in controlling all the pests except S. hemispherica and L. cephalandrae and the chemical insecticides were comparatively more effective in the management of the pests other than L. cephalandrae. Imidacloprid offered long lasting protection of the crop from S. hemispherica and A. spiraecola. All the treatments tried were safe to spiders. The findings of the study clearly indicated that coccinia is severely infested with two hemipteran and two dipteran pests resulting in heavy yield loss. Imidacloprid which was found to be the best treatment could be recommended for the management of the pests especially the hemipteran pests. The treatments failed to manage L. cephalandrae.