title: Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities.
abstract: BACKGROUND
  The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia.
  
  
  RESULTS
  The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia-Arsenophonus and Wolbachia-Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real-time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron.
  
  
  CONCLUSIONS
  The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides.
authors.affiliation: Department of Entomology, Institute of Plant Protection, the Volcani Centre, Bet Dagan 50250, Israel. ghanim@agri.gov.il
authors.forename: Murad
authors.initials: M
authors.lastname: Ghanim
authors.forename: Svetlana
authors.initials: S
authors.lastname: Kontsedalov
mesh_terms: D000818:Animals; D005260:Female; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000502:physiology*; D006430:Hemiptera / Q000187:drug effects* / Q000382:microbiology* / Q000502:physiology; D007306:Insecticides / Q000494:pharmacology*; D013559:Symbiosis
chemical_list: D007306:Insecticides