Fitness of the Papaya Mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), after Transferring from Solanum tuberosum to Carica papaya , Ipomoea batatas , and Alternanthera philoxeroides .

The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), is a polyphagous invasive pest in China. The effect that the shifting of the host plant has on the fitness of a polyphagous pest is critical to its prevalence and potential pest control. In order to assess the fitness changes of P . marginatus after transferal from potato ( Solanum tuberosum (Tubiflorae: Solanaceae)) to papaya ( Carica papaya (Parietales: Caricacea)), sweet potato ( Ipomoea batatas (Tubiflorae: Convolvulaceae)), and alligator weed ( Alternanthera philoxeroides (Centrospermae: Amaranthaceae)), the life table data of three consecutive generations were collected and analyzed using the age-stage, two-sex life table method. The results showed that when P . marginatus was transferred from S . tuberosum to papaya, a higher intrinsic rate of increase ( r ) and finite rate of increase ( λ ) were observed. Paracoccus marginatus individuals transferred to I . batatas had the significantly lower population parameters than those on C . papaya ; however, the fitness recovered for those on I . batatas after two generations. Paracoccus marginatus individuals were unable to complete development on A . philoxeroides . Our results conclusively demonstrate that P . marginatus individuals can readily adapt to C . papaya and I . batatas even after host plant shifting, and are capable of causing severe damage to these hosts.