Competitive Ability and Fitness Differences between Two Introduced Populations of the Invasive Whitefly Bemisia tabaci Q in China.

Background: Our long-term field survey revealed that the Cardinium infection rate in Bemisia tabaci Q (also known as biotype Q) population was low in Shandong, China over the past few years. We hypothesize that (1) the Cardinium-infected (C⁺) B. tabaci Q population cannot efficiently compete with the Cardinium-uninfected (C⁻) B. tabaci Q population; (2) no reproductive isolation may have occurred between C⁺ and C⁻; and (3) the C⁻ population has higher fitness than the C⁺ population. Methodology and Results: To reveal the differences in competitive ability and fitness between the two introduced populations (C⁺ and C⁻), competition between C⁺ and C⁻ was examined over several generations. Subsequently, the reproductive isolation between C⁺ and C⁻ was studied by crossing C⁺ with C⁻ individuals, and the fitnesses of C⁺ and C⁻ populations were compared using a two-sex life table method. Our results demonstrate that the competitive ability of the C⁺ whiteflies was weaker than that of C⁻. There is that no reproductive isolation occurred between the two populations and the C⁻ population had higher fitness than the C⁺ population. Conclusion: The competitive ability and fitness differences of two populations may explain why C⁻ whitefly populations have been dominant during the past few years in Shandong, China. However, the potential role Cardinium plays in whitefly should be further explored. [ABSTRACT FROM AUTHOR]