The impact of three mealybug species on life table parameters of vedalia beetle, Rodolia cardinalis ( Mulsant ) (Coleoptera: Coccinellidae).

Document Type : Original Article

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Plant Protection Dept., Faculty of Agriculture, South Valley University, Qena, Egypt

Abstract

This study aimed to measure survivorship and fecundity of the vedalia beetle, Rodolia cardinalis (Mulsant) reared on three mealybug species (Icerya purchasi Maskell, Planococcus ficus (Signoret)and Pseudococcus longispinus (Targioni-Tozzetti)). The experiment was conducted under laboratory conditions, life table and population parameters were established to evaluate survivorship in all stages of the vedalia beetle life cycle. Results obtained from this experiment showed that the highest rates of death were recorded in the immature stages (larval stages) for all prey was 42.86, 45, 44.11 % and the total mortality was 57.69, 62.11, and 50 % on I. purchasi, P. ficus and P. longispinus respectively. Fertility tables recorded that the reproductive rate R0  of the population was 139.98, 81.10, 37.70 and mean generation time T was 35.85, 44.71, 44.03 and the intrinsic rate of increase r was 0.14, 0.09, 0.08 and the population doubling time DT  was within 4.95, 6.93,8.66 day for three mealybug species respectively. Based on the mentioned results, it could be proved that the survivorship curve of Rodolia cardinalis (Mulsant)belongs to a diagonal model curve, which indicates a humble rate of death during life stages and piecemeal reduction when moving toward adulthood with a significant influence of nutrition preference for I. purchasi comparative with P. ficus and P. longispinus.

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