Effect Of Host Shift On Growing Development And Symbiotic Bacteria Of Phenacoccus Solenopsis Tinsley

Phenacoccus solenopsis Tinsley is an invasive pest widely distributed all over the world in recent years,which seriously endanger many crops and cause serious economic losses.Invasive insects need to undergo the transformation of host plants during feeding,colonization,and reproduction in a new area.Whether the host plant that feeds is the favorite host of the pest and the ability to adapt to the non-feeding host are closely related to its invasiveness.Microorganisms play important roles in the production,adaptability and defensive ability.Some symbiotic microorganisms are indispensable for maintaining the normal life of the host insect,even specialized into special cell structures or organelles are fixed in the host insects.The colony structure of symbiotic bacteria in insects can be affected by different environments,such as temperature,humidity,and different host plant species.In this experiment,Gossypium hirsutum,Capsicum annuum,Lycopersicon esculentum,and Solanum tuberosum were selected to study the effect of host shift on growth and development of mealybug such as each instar stage,pre-spawning stage,oviposition amount,and longevity.Among them,S.tuberosum was the original host,on which mealybugs were fed more than 10 generations.We used 16 s rDNA sequence high-throughput technology to study the effects of host shift on the structure of symbiotic bacteria of mealybugs.The results are summarized as follows:(1)After shifting to cotton,the stages of 1st,2nd,3rdinstar nymphs were significantly longer than that of the potato.After shifting to tomato,the stages of 1st,2nd instar nymphs were significantly longer than that of the potato.After shifting to pepper,the stages of 1st,2nd,3rdinstar nymphs were significantly longer than that of the potato.Meanwhile,female adult life span was significantly shorter than that of the potato,and the number of oviposition of the adultswas significantly less than that of potato.(2)To understand the effect of host shift on symbiotic bacterial flora among the samples,we selected the representative OTUs,a total of 13 sequences for further analysis.The result showed that,from the species level,the structure of symbiotic bacteria of mealybugs,which had lived on the potato for more than 10 generations,was simple,and the primary symbiotic bacteria,Tremblaya phenacola,accounted for more than 95%.In addition,we also found a nested system consist of T.princeps and an unnamed bacteria belong to Gamaproteobacteria.After shifting to cotton,the structure of symbiotic bacteria in 3rd instar nymphs had little change compared with that of on potato,while that in the adults were more abundant than those in the potato.After shifting to tomato,the structures of symbiotic bacteria in 3rd instar nymphs were more abundant,while that in the adults had little change compared with those in the potato.After shifting to pepper,both the structure of symbiotic bacteria in 3rd instar nymphs and the adults were more abundant than those in the potato.This phenomenon might be caused by the different nutrient content in different host plants phloem juice and the different nutrient requirements for the different developmental stage.