Influence of Weather on Sugarcane Mealybugs and Their Natural Enemies

An experiment was conducted in two insect-prone areas viz., Bangladesh Sugarcrop Research Institute (BSRI), Pabna and Regional Sugarcrop Research Station (RSRS), Thakurgaon to study the influence of weather on sugarcane mealybugs and their natural enemies during the 2013-14 cropping season. A positive linear relationship was observed between mealybugs infestation with and relative humidity 51% (R2=0.514) but a negative correlation was found with temperature and rainfall. The infestation was higher at Thakurgaon than at Pabna during almost entire cropping season but a little higher at Pabna in November. At Pabna, the lowest infestation (6.30%) was recorded in May and the highest (34.71%) in November. At Thakurgaon, the lowest infestation (7.48%) was found in May and the highest (29.30%) in September. Results revealed that per cent loss in weight of sugarcane was 4.76 to 36.50 at 10% and 100% infestation level in Pabna. On the other hand, 6.57 to 33.55% loss of cane weight was caused at 10% and 100% infestation level in Thakurgaon. The results proved that, as expected, weight loss generally increases with a stronger level of infestation. Different natural enemies viz., parasitic wasps, ladybird beetles, hover flies, brown lacewings, spider, Cryptochaetum sp. were found to be abundant in the study plot during the month of June to August.