title: Bemisia tabaci females from the Mediterranean (Q) species detect and avoid laying eggs in the presence of pyriproxyfen, a juvenile hormone analogue.
abstract: BACKGROUND
  Pyriproxyfen, a juvenile hormone analogue, disrupts embryogenesis, metamorphosis and adult formation in Bemisia tabaci, but does not directly affect adult females. The effect of pyriproxyfen on egg-laying preference and performance of B. tabaci females and the influence of resistance to pyriproxyfen on these reproductive behaviours were studied.
  
  
  RESULTS
  Choice experiments utilising cotton plants treated and not treated with pyriproxyfen revealed a significant preference for egg laying on non-treated plants both by resistant and susceptible females. No-choice assays indicated a reduction of ∼60% in the number of eggs laid on pyriproxyfen-treated plants by both resistant and susceptible females. The reduction in oviposition on treated plants was not accompanied with reduced expression of the vitellogenin gene or a delay in oocyte maturation, but significant accumulation of mature oocytes in the ovaries was observed, and could be reversed by transferring the females to non-treated plants.
  
  
  CONCLUSIONS
  Pyriproxyfen caused reduced oviposition and enhanced mature oocyte accumulation in pyriproxyfen-resistant and pyriproxyfen-susceptible females. These findings can be explained by two alternative mechanisms: pyriproxyfen-regulated physiological arrest of oviposition, involving hormonal regulation of myotrophic factors, or the hierarchy-threshold behavioural theory of host choice, in which pyriproxyfen-treated plants are defined as low-quality hosts. Aspects of application are discussed.
authors.affiliation: Department of Entomology, The Robert H Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Pnina
authors.initials: P
authors.lastname: Moshitzky
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002755:Choice Behavior; D005260:Female; D003368:Gossypium; D006430:Hemiptera / Q000187:drug effects* / Q000502:physiology; D007305:Insecticide Resistance; D007605:Juvenile Hormones / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects; D010058:Oviposition / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology*
chemical_list: D007605:Juvenile Hormones; D011725:Pyridines; C055613:pyriproxyfen
keywords: Bemisia tabaci; egg maturation; juvenile hormone; oviposition arrest; pyriproxyfen