Differential Responses of the Whitefly Bemisia tabaci Symbionts to Unfavorable Low and High Temperatures
The whitefly Bemisia tabaci complex contains many cryptic species, of which the Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are notorious invasive pests. In our field-collected whitefly samples, MEAM1 harbors an obligate primary symbiont “Candidatus Portiera aleyrodidarum” and two secondary symbionts, “Candidatus Hamiltonella defensa” and Rickettsia sp., whereas MED has only “Ca. Portiera aleyrodidarum” and “Ca. Hamiltonella defensa.” Both “Ca. Portiera aleyrodidarum” and “Ca. Hamiltonella defensa” are intracellular endosymbionts residing in the bacteriomes, whereas Rickettsia sp. has a scattered distribution throughout the host body cavity. We examined responses of these symbionts to adverse temperatures as well as survival of the host insects. After cold treatment at 5 or 10 °C or heat treatment at 35 or 40 °C for 24 h, respectively, the infection rates of all symbionts were not significantly decreased based on diagnosis PCR. However, quantitative PCR assays indicated significant reduction of “Ca. Hamiltonella defensa” at 40 °C, and the reduction became greater as the duration increased. Compared with “Ca. Hamiltonella defensa,” “Ca. Portiera aleyrodidarum” was initially less affected in the first day but then showed more rapid reduction at days 3–5. The density of Rickettsia sp. fluctuated but was not reduced significantly at 40 °C. Meanwhile, the mortality rates of the host whiteflies elevated rapidly as the duration of exposure to heat treatment increased. The differential responses of various symbionts to adverse temperatures imply complex interactions among the symbionts inside the same host insect and highlight the importance of taking the whole bacterial community into account in studies of symbioses.
The authors thank Jie Li and Yun-Qin Li for technical advice and assistance. The authors are also grateful to the five anonymous reviewers for their constructive comments that have helped to improve the paper. This study was financially supported by the National Natural Science Foundation of China (Projects no. 31390421 and 31321063).
- 13.Guay JF, Boudreault S, Michaud D, Cloutier C (2009) Impact of environmental stresstreatment on aphid clonal resistance to parasitoids: role of Hamiltonella defensa bacterial symbiosis in association with a new facultative symbiont of the pea aphid. J Insect Physiol 55:919–926CrossRefPubMedGoogle Scholar
- 26.Zang LS, Liu YQ, Liu SS (2005) A new clip-cage for whitefly experimental studies. Entomol Knowl 42:329–331 (in Chinese with English summary)Google Scholar
- 30.Gottlieb Y, Ghanim M, Chiel E, Gerling D, Portnoy V, Steinberg S, Tzuri G, Horowitz AR, Belausov E, Mozes-Daube N, Kontsedalov S, Gershon M, Gal S, Katzir N, Zchori-Fein E (2006) Identification and localization of a Rickettsia sp. in Bemisia tabaci (Homoptera: Aleyrodidae). Appl Environ Microbiol 72:3646–3652PubMedCentralCrossRefPubMedGoogle Scholar