Sublethal effects of pyriproxyfen, a juvenile hormone analogue, on Plutella xylostella (Lepidoptera: Plutellidae): life table study M. Alizadeh a *, J. Karimzadeh b , G.R. Rassoulian a , H. Farazmand c , V. Hoseini-Naveh a and H.R. Pourian a a Department of Plant Protection, Campus of Agriculture and Natural Resources, University of Tehran, PO Box 4111, Karaj 31587-11167, Iran; b Department of Plant Protection, Isfahan Research Centre for Agriculture and Natural Resources, PO Box 199, Isfahan 81785, Iran; c Department of Agricultural Entomology, Iranian Research Institute of Plant Protection, Tehran, Iran (Received 10 May 2012; final version received 15 May 2012) The sublethal effects of pyriproxyfen (PYR, a juvenile hormone analogue) were investigated for two consecutive generations on life-history parameters, such as developmental time, pupal weight, fecundity, fertility and longevity of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). After topical application bioassay of third instar larvae, the LC 25 and LC 50 values (as sublethal doses) were determined to be 1.49 and 2.01 mg/ml, respectively. The results showed that the egg incubation period, larval and pupal duration times and oviposition period were increased in treated groups compared with the control (treated with distilled water). Pupal weight, adult longevity, fecundity and fertility were significantly reduced in the treatment groups compared with the control. Using the age-stage, two-sex life table analysis, we found that the intrinsic rate of increase (r), finite rate of increase (l), gross reproduction rate (GRR) and net reproductive rate (R 0 ) significantly decreased while the mean generation time (T) and doubling time (DT) increased in two treatment groups compared with the control. In addition, administration of PYR induced morphogenetic abnormalities including untanned pupae, larval–pupal intermedi- ates and various defective adults. The LC 50 value was more effective on all of the above biological characteristics than the LC 25 for both generations, although parents were more affected than the offspring. In general, our results revealed that PYR was highly effective against P. xylostella in the laboratory both directly (causing mortality) and indirectly (disruption of normal growth and develop- ment). We conclude that PYR is an excellent candidate for suppressing populations of P. xylostella through its sublethal effects. Keywords: Plutella xylostella; pyriproxyfen; sublethal concentrations; age-stage; two-sex life tables; sublethal effects; life table Introduction The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most destructive cosmopolitan insect pests of cruciferous plants in many parts of the world (Talekar and Shelton 1993). In many countries, P. xylostella has *Corresponding author. Email: alizadeh@ut.ac.ir Archives of Phytopathology and Plant Protection Vol. 45, No. 14, August 2012, 1741–1763 ISSN 0323-5408 print/ISSN 1477-2906 online Ó 2012 Taylor & Francis http://dx.doi.org/10.1080/03235408.2012.706426 http://www.tandfonline.com Downloaded by [University of Tehran], [M. Alizadeh] at 20:04 12 August 2012