The presence of Rickettsia is associated with increased susceptibility of Bemisia tabaci (Homoptera: Aleyrodidae) to insecticides.
BACKGROUND
The presence of certain symbiotic microorganisms may be associated with insecticide resistance in insects. The authors compared the susceptibility of two isofemale lines, Rickettsia-plus and Rickettsia-free, of the sweet potato whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) to major insecticides from different chemical groups, including imidacloprid, acetamiprid, thiamethoxam, pyriproxyfen, spiromesifen and diafenthiuron.


RESULTS
While the Rickettsia-plus and Rickettsia-free lines showed no differences in their susceptibility to imidacloprid and diafenthiuron, higher susceptibility of the Rickettsia-plus line to acetamiprid, thiamethoxam, spiromesifen and especially pyriproxyfen was observed. LC(90) values indicated that the Rickettsia-free line was 15-fold more resistant to pyriproxyfen than the Rickettsia-plus line.


CONCLUSIONS
Findings indicate that the infection status of B. tabaci populations by Rickettsia is an important consideration that should be taken into account when performing resistance monitoring studies, and may help in understanding the dynamics of B. tabaci resistance, symbiont-pest associations in agricultural systems and the biological impact of Rickettsia on whitefly biology.
Kontsedalov
Svetlana
S
Department of Entomology, Institute of Plant Protection, the Volcani Centre, Bet Dagan 50250, Israel.
Zchori-Fein
Einat
E
Chiel
Elad
E
Gottlieb
Yuval
Y
Inbar
Moshe
M
Ghanim
Murad
M
D000818:Animals; D005260:Female; D006430:Hemiptera / Q000187:drug effects* / Q000382:microbiology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D012281:Rickettsia; D013559:Symbiosis
D007306:Insecticides; D011725:Pyridines; C055613:pyriproxyfen