Thermo Mediated Activity of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) Predating on Rhizoecus amorphophalli Betren (Hemiptera: Rhizoecidae) on Elephant foot yam
Elephant foot yam (Amorphophallus paeoniifolius Dennst.) tubers are infested with Oriental mealybug, Rhizoecus amorphophalli Betren in storage. The pest sucks and de-saps the cell content of tubers. It causes 10-15% infestation on the tubers leading to reduced vitality. The coccinellid, Cryptolaemus montrouzieri Mulsant is a potential predator of R. amorphophalli. Studies were carried out to determine the optimum temperature required for C. montrouzieri for controlling R. amorphophalli in storage. At 30°C, the population of R. amorphophalli was found to increase faster than at 20°C and 25°C. The population growth was not favoured at 35°C. The C. montrouzieri was found voraciously feeding R. amorphophalli at 25°C. Feeding activity of the C. montrouzieri declined between 30°C and 35°C. The temperature higher than 30°C was not conducive for survival of the predator and significant mortality was recorded at 35°C (P< 0.01). Studies revealed that the temperature range between 25°C and 30°C in storage is most suitable for release of C. montrouzieri for successful control of R. amorphophalli.
Elephant Foot Yam, Feeding Potential, Temperature, Cryptolaemus montrouzieri, Rhizoecus amorphophalli.
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