The infection frequencies and dynamics of three secondary endosymbionts in the laboratory environments on Sitobion avenae (Fabricius) as determined by long PCR

Abstract Stable infections of maternally transmitted secondary endosymbionts in aphids are frequently found in field populations; however, whether this phenomenon changes in artificial lab conditions has not been clear. To investigate, (1): we collected Sitobion avenae (Fabricius) from six different regions and detected the three common secondary endosymbionts ( Regiella insecticola , Hamiltonella defensa and Serratia symbiotica ); (2): we raised Sitobion avenae from Chuzhou, Anhui for 14 months in the laboratory, and analyzed these aphids' DNA using the long PCR protocol after the 1st month, 3rd month, 5th month, 7th month, 9th month, 11th month, 12th month, 13th month and 14th month. The results showed that S. symbiotica and R. insecticola could be detected in all aphid populations, while H. defense were detected in three locations. After reared in the lab, the infection frequencies of Serratia symbiotica did not change across the 14 study months, but the infection frequencies of Regiella insecticola after the 9th month and of Hamiltonella defensa after the 11th month decreased significantly. Additionally, the results show that facultative endosymbiont infections may decline in artificial lab conditions, suggesting that temporal changes of endosymbionts may occur within the host under different environmental pressures. This result may partially explain why different geographic populations harbor a diverse variety of endosymbionts. The results of this study can be helpful in understanding the stability of secondary endosymbionts in Sitobion avenae under long-term reproduction in controlled laboratory conditions.