Varietal Influence and Off-Season Occurrence of Asian Rice Gall Midge Orseolia oryzae (Wood-Mason) and its Parasitoid Platygaster oryzae (Cameron) Saran R.1,*, Rani W. Baby2, Kalyanasundaram M.1, Vanniarajan C.3 1Dept. of Agricultural Entomology, TNAU, AC & RI, Madurai-625104 2Sethu Bhaskara Agricultural College and Research Foundation, Karaikudi-630306 3Dept. of Plant Breeding and Genetics, TNAU, AC & RI, Madurai-625104 *email: saranagri1989@gmail.com
Online published on 23 December, 2016. Abstract The influence of rice varieties on the parasitoid activity serves as a strong management strategy in the integrated management of Asian rice gall midge management. Hence, a field trial was laid out at college farm, Agricultural College and Research Institute, Madurai during September 2015 to January 2016 with selected rice varieties (commonly cultivated in regular crop season) viz., TN 1, ANNA4, ADT36, IR 20, MDU3, MDU 5, TPS 3 and TKM 6 tofind out the influence of different varieties on pest and parasitoid activity in regular crop season (September-January) and off-season occurrence of the same in the fallow season (January-April) The gall midge as well as the parasitoid activity was higher on all the varieties at 60 days after planting (DAP) than at 30 DAP. On TN 1 the maximum damage and parasitoid activity observed on 60 DAP were 28.36 and 50.18 per cent respectively. On 60 DAP; comparatively higher parasitoid activity was recorded on other varieties except MDU 3 and MDU 5 whichexpressed a minimum of 29.31 and 33.47 per cent. The pupal weight was maximum (1.28 mg) on TN 1 and thiswas on par with the weight of the pupa reared from IR 20 and ADT 36(1.23 and1.16 mg respectively) and the pupal weight was the lowest when reared from MDU 3 (0.60 mg. The maximum number of adults(53.00) emerged from TN1 reared maggot followed by ANNA 4 (46.00), ADT 36 (45.30) and IR 20 (43.00). No significant difference was observed between the size of the parasitized galls on different varieties and it ranged from 13.87 to 17.03 cm. The midge as well as the parasitoid multiplied on the rice sprouting during the fallow season. Among the five varieties observed, TN 1 recorded the maximum midge damage (23.37%) followed by ANNA 4 (18.26%), IR 20 (16.71%). Lowest per cent was noted on the resistant varieties, MDU 3 (8.58%) and MDU 5 (9.30%). The mean parasitization was comparatively higher at five days after harvest and the maximum (66.34%) was observed on TN 1, followed by ADT 36 (63.20%) while minimum parasitization was noted on the moderately resistant MDU 3 (34.38%) and MDU 5 (35.50%) varieties. No parasitoid activity was seen on known weed hosts observed during the study period. Top Keywords Asian rice gall midge, Varietal influence, Off-season occurrence, Platygaster oryzae, Orseolia oryzae. Top |