Acta Entomologica Sinica ›› 2016, Vol. 59 ›› Issue (4): 464-471.doi: 10.16380/j.kcxb.2016.04.012

• RESEARCH PAPERS • Previous Articles     Next Articles

Temperature regulates the reproduction mode of Trichogramma embryophagum (Hymenoptera: Trichogrammatidae) by influencing the titer of endosymbiont Wolbachia

CHEN Xi1,2, WANG Li-Yan1,2,*, YANG Zhi-Qiang1,2, ZHAO Chang-Jiang1,2, HE Lin1,2, ZHANG Hai-Yan1,2,*   

  1. (1. College of Agronomy, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China; 2. Key Laboratory of Crop Germplasm Improvement and Cultivation in Cold Regions of Heilongjiang Province Education Department, Daqing, Heilongjiang 163319, China)
  • Online:2016-04-20 Published:2016-04-20

Abstract:  To reveal the effect of temperature on Wolbachia titer and its function in regulating the biological characteristics of host, the relationship between the biological indices of host and Wolbachia titer at different temperatures was evaluated in this study. 【Methods】 Trichogramma embryophagum wasps infected by parthenogenesis-inducing Wolbachia were cultivated under four temperature gradients (22, 25, 28 and 31℃) for five consecutive generations, and the biological characteristics including the reproductive mode and sex ratio were observed. At the same time, the Wolbachia titer was detected by fluorescence quantitative real-time PCR, using the specific primers of the outer surface protein gene (wsp), fructose bisphosphate aldolase gene (fbpA) and glutamyl-tRNA(Gln) amidotransferase subunit B gene (gatB) in Wolbachia. 【Results】 At 22 and 25℃, the reproduction mode of the total five generations of T. embryophagum was not altered, without drones appearing in culture population, and the Wolbachia titer also was not significantly different among five generations. At 28℃, a few of drones were found in F3 generation and the majority of drones appeared in F5 generation significantly, while the Wolbachia titer in T. embryophagum began to decline in F2 generation and decreased significantly till F5 generation. At 31℃, in F2 generation the drones appeared, and in F5 generation all T. embryophagum had restored to the androgenetic parthenogenetic; the Wolbachia titer began to decrease in the F2 generation, decreased significantly in F3 generation and was not detectable by PCR in F5 generation.【Conclusion】 The reproduction mode and Wolbachia titer in parthenogenetic thelytokous Trichogramma can be altered by high temperature, and are affected significantly with the increase of temperature and generation. In other words, the alteration degree of reproductive mode of Trichogramma due to high temperature is negatively correlated with the endoymbiont Wolbachia titer.

Key words:  Wolbachia, Trichogramma embryophagum, temperature, titer, fluorescence quantitative real-time PCR