Predicting the temperature‐dependent natural population expansion of the western corn rootworm, Diabrotica virgifera

Abstract

The western corn rootworm, Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), was accidentally introduced near Belgrade in Serbia just before 1992 and from there its expansion into Europe started. We have estimated its mean rate of expansion from 1992 to 2000 to be approximately 33 km year − 1 , using data from the annual surveys of the European and Mediterranean Plant Protection Organisation.We investigated whether or not D. virgifera can establish itself at certain places in Europe, taking its temperature-dependent development into account. We also estimated the time it will take D. virgifera to reach the Netherlands, considering only its dispersal by flight. All life stage transitions of D. virgifera were simulated with the program INSIM to assess whether or not it could establish itself in particular places. In the simulations, we used the available laboratory data on its life history characteristics, as well as a time series (2 -6 years) of daily minimum and maximum temperatures from weather stations across Europe. The temperature-dependent net reproduction resulting from the simulations showed that D. virgifera populations cannot establish themselves at latitudes above 55 ° N.The overall expected velocity of D. virgifera 's range expansion was computed with van den Bosch et al.'s formula [van den Bosch F, Hengeveld R & Metz JAJ (1992) Analysing the velocity of animal range expansion. Journal of Biogeography 19: 135 -150], where the expansion velocity was based on dispersal characteristics and demographic parameters. We predicted that D. virgifera will not reach the Netherlands by flight from the border of its 2000 range before 2018 using this overall expected velocity. The explanation of this late arrival is that the velocity of population expansion decreases in all directions from the centre of its 2000 range due to unfavourable temperatures.Our analysis is an improvement on former analyses in that it uses temperature-dependent life history characteristics. We stress, however, that the lack of knowledge on dispersal behaviour and on the values of life history characteristics in field situations might severely limit the applicability of the predicted velocity.

Biology and temperature requirements of the invasive seed bug Leptoglossus occidentalis (Heteroptera: Coreidae) in Europe

“…In general, DDs can be a useful method to simply predict the number of insect generations in different climatic conditions. Recently, the use of DDs for mapping insect voltinism and potential geographic distribution has been successfully used for insect conservation, pest management, and biological control (Bryant et al 2002;Hemerik et al 2004;Pilkington and Hoddle 2006). In our experiments, CDD for embryonic development calculated by the DD models (STM and SSM) perfectly fits DDs from the Campbell's linear model; however, postembryonic CDD from the DegDay application was moderately underestimated, when compared to the linear model.…”

Generational growth rate estimates of Diabrotica virgifera virgifera populations (Coleoptera: Chrysomelidae)

“…Baufeld and Enzian 2001;Elliott and Hein 1991;Hein and Tollefson 1987;Hemerik et al 2004;Mitchell and Riedell 2001;Mooney and Turpin 1976;Naranjo and Sawyer 1989;Onstad et al 2001a;Onstad et al 2001b;Storer 2003). Nevertheless, most of the aforementioned studies lack detailed analyses on growth rates of this species, or were exclusively based on laboratory data of survival, sex ratio and fecundity.…”

“…The generational time step model of calculated a growth rate of 6.1 for the first generation based on fecundity data, overwintering mortality during the egg stage, mortality during the larval stages and sex ratio. Finally, the model of Hemerik et al (2004) estimated growth rates above 15 for Hungary and Croatia based on temperature-dependent development data of D. v. virgifera. None of these existing models is based on or validated by field-assessed growth rates of D. v. virgifera populations.…”

Alien species in a warmer world: risks and opportunities

“…Plants such as the palm Trachycarpus fortunei have also benefited from milder winter conditions; mean temperatures of the coldest month >2.2 8C in the past few decades have enabled this species to establish fertile populations in the wild [17]. Changes in climatic conditions that result in a prolonged growing and reproductive period often provide alien species with exploitable opportunities [46]. As a consequence, global warming can shift or breach barriers that previously limited spread and thus enable expansion into areas where the species were previously kept in check by climate ( [47,48], but see [49]).…”