Influence of seasonal variation on the biology of lesser grain borer, Rhyzopertha dominica, (Fabricius) on wheat

The life cycle of lesser grain borer, Rhyzopertha dominica, on wheat 1105 was studied for seasonal variation at room temperature during winter at 21±7 ºC in winter and at 28±5 ºC in rainy season. The result shows that more fecundity (306.8±16.36 eggs) was in rainy season as compare to winter (170.8±16.08 eggs). The incubation period was very similar in both seasons i.e. (11.5±3.44 days) in winter and (11.4±1.50 days) in the rainy season. The total larval and pupal period was (35.8± 2.78 days) and the developmental period was (47.2±3.01days) in rainy season as compare to longer (81.7±5.89 days) and (88.62± 2.98 days) in winter, respectively. The seasonal variations also have the impact on the longevity of male: female, which was longer (38.9±3.91: 41.7±3.49 days) in winter and shorter (28.9±2.68: 32.75±2.82 days) in rainy season. The sex ratio was 0.84: 1.04 in winter and 0.90: 1.10 in the rainy season. Higher mean growth index 2.01 was recorded in rainy season and lower growth index 1.02 was observed in winter.