Vol. 10, Special Issue 10 (2021)

Author(s):
R Emaiya, E Sumathi, VG Mathirajan, N Sathiah, SV Krishnamoorthy and K Venkatesan

Abstract:
Coconut rhinoceros beetle, Oryctes rhinoceros (L.) is a serious pest of coconut plantations in all coconut growing states. Rhinoceros beetle feed on growing point of the tree and cause yield loss. It also attacks coconut seedlings through collar region (or) spear leaf and cause lethal to seedlings. Studies on population dynamics of rhinoceros beetle were carried out in juvenile (6 months old) and established coconut garden (10 years old) from March 2021 to August 2021 at Madukkur block and Orathanadu block of Thanjavur District affected by Gaja cyclone. The study on population dynamics revealed that maximum number of rhinoceros beetles/ trap was recorded during 33^rd standard week (August, 2021) in Madukkur block and 32^nd standard week (August, 2021) in Orathanadu block whereas less number of rhinoceros beetles/ trap was recorded during 14^th standard week (April, 2021) in both Madukkur block and Orathanadu block. In Madukkur block, the average number of adult beetles trapped per week in juvenile garden was negatively correlated with maximum temperature (-0.4104) and positively correlated with rainfall (0.6829). In established garden, the weekly mean trap catches was negatively correlated with maximum temperature (-0.5282) and wind velocity (-0.5030) whereas positively correlated with rainfall (0.8164). Plant damage (%) was positively correlated with minimum temperature (0.5521) and rainfall (0.4356), whereas negatively correlated with relative humidity morning (-0.5414) in juvenile garden. In established garden, plant damage (%) was positively correlated with minimum temperature (0.5480) and rainfall (0.4493) whereas negatively correlated with relative humidity morning (-0.5520). In Orathanadu block, the average number of adult beetles collected in traps per week was positively correlated with rainfall (0.7506) in juvenile garden. In established garden mean trap catches positively correlated with rainfall (0.6563) and negatively correlated with wind velocity (-0.4265). Plant damage (%) was positively correlated with rainfall in both juvenile (0.5919) and established garden (0.5811). The results showed that there was significant relationship between rainfall, trap catches and plant damage (%). This study revealed that the rainfall was a main factor that influences the population dynamics of O. rhinoceros.