LAUSR

Simple Summary The papaya mealybug, Paracoccus marginatus, is a polyphagous invasive pest that causes severe damage in China. To improve our understanding of the expansion and prevalence of P. marginatus individuals on host plants, it is important to explore the fitness changes of insects after host plant shifting. In this study, we measured the development, fecundity, and population parameters in P. marginatus individuals over a span of three consecutive generations after being transferred from potato (Solanum tuberosum) to papaya (Carica papaya), sweet potato (Ipomoea batatas), and alligator weed (Alternanthera philoxeroides). Further, the population growth rates of insects on C. papaya, I. batatas, and S. tuberosum in the F2 generation were projected. We found that P. marginatus individuals transferred to C. papaya had higher fitness. When transferred to I. batatas, the fitness of P. marginatus initially decreased in F0 and then rebounded in F1 and F2. Paracoccus marginatus individuals could rapidly expand their populations on the above host plants. However, P. marginatus individuals were unable to complete their development on A. philoxeroides. Our findings provide new insights into the host plant fitness, prevalence, and potential pest control of P. marginatus. Abstract 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.