Modelling reproduction of Plutella xylostella L. (Lepidoptera: Plutellidae): climate change may modify pest incidence levels C.A. Marchioro and L.A. Foerster* Department of Zoology, Universidade Federal do Paraná PO Box 19.020, 81531-990 Curitiba, PR, Brazil Abstract Temperature is considered to be an important abiotic factor influencing insect reproduction. Despite the importance of Plutella xylostella L. (Lepidoptera: Plutellidae) as a pest of brassicaceous crops worldwide, the effects of temperature on its reproduction are not well understood. We evaluated the effect of constant temperatures ranging from 10 to 32.5°C on the reproduction of P. xylostella and developed an oviposition model for the species. The model combined temperature- dependent parameters of total fecundity, age-specific oviposition rate and age- specific survival. Additionally, we modelled population growth as a function of temperature. The estimated parameters allowed us to discuss the possible consequences of global warming on P. xylostella distribution. Temperature affected the length of pre-oviposition after adult emergence, oviposition period, longevity, total fecundity and egg viability. The model predicted that both daily egg production and length of oviposition period decreased at temperatures below 15°C and above 25°C. Population growth increased linearly with temperature in a range from 10°C to 25°C; however, the model predicted a reduction in population growth at temperatures above 28.6°C. Data suggested that temperature plays a critical role in P. xylostella reproduction, and subtle differences in average temperature could have an impact on its population growth. This is especially important in the context of global climate change, which in turn could alter the distribution and abundance of the pest in some regions of the world. Keywords: Diamondback moth, oviposition model, population growth, global warming, temperature (Accepted 7 February 2012) Introduction The reproduction and abundance of insects are affected by the interaction between intrinsic life history traits and extrinsic factors, such as food quality, temperature, photoperiod and moisture (Awmack & Leather, 2002; Malaquias et al., 2010). Among the abiotic factors, temperature may be the most important (Hentz et al., 1998; Sagarra et al., 2000) because it directly affects reproductive parameters, such as the duration of oviposition period, total fecundity and egg viability (Kim & Lee, 2003; Son & Lewis, 2005; Ali & Rizvi, 2008). The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is the most important pest of brassicaceous crops worldwide (Talekar & Shelton, 1993). It has a cosmopolitan distribution, occurring in regions with distinct climates ranging from the cold Himalayan Mountains (Mohan et al., 2009) to the dry heat of Ethiopia (Ayalew & Ogol, 2006). *Author for correspondence Fax: 55 041 32662042 E-mail: foerster@ufpr.br Bulletin of Entomological Research, Page 1 of 8 doi:10.1017/S0007485312000119 © Cambridge University Press 2012