Study on life parameters of the invasive species Octodonta nipae (Coleoptera: Chrysomelidae) on different palm species, under laboratory conditions.

In southeastern China, the invasion of the nipa palm hispid Octodonta nipae (Maulik) (Coleoptera: Chrysomelidae) results in devastating damage to palms. Host plants play an important role in the population increases and outbreaks of O. nipae. O. nipae could not complete its development on the Majestic palm (Ravenea rivularis Jumelle & Perrier), and females did not lay eggs on Chinese fan palm (Livistona chinensis R. Brown). However, this insect species both completed development and laid eggs on Chinese windmill palm (Trachycarpus fortunei (Hooker) H. Wendland), Canary Island date palm (Phoenix canariensis Chabaud), and pygmy date palm (Phoenix roebelenii O' Brien). The demographic characteristics of O. nipae reared on Chinese windmill palm, Canary Island date palm, and pygmy date palm were compared with an age-stage, two-sex life table. In this study, the developmental periods from egg to adult varied from 42.1 d on Chinese windmill palm to 49.8 d on pygmy date palm. The survivorship from egg to adult on Chinese windmill palm, Canary Island date palm, and pygmy date palm was 77.5, 79.4, and 66.7%, respectively. Although the adult longevity and the mean fecundity for individuals reared on Chinese windmill palm, Canary Island date palm, and pygmy date palm were not significantly different, there were significant differences in the intrinsic rate of increase, the finite rate, and the mean generation time among palm species, and the values of intrinsic rate of increase and finite rate were higher for populations reared on Chinese windmill palm and Canary Island date palm (0.0313 and 1.0318 d(-1) and 0.0278 and 1.0282 d(-1), respectively) and lower for populations reared on pygmy date palm (0.0192 and 1.0194 d(-1)). However, mean generation time was shorter on Chinese windmill palm (124.11 d) and Canary Island date palm (129.62 d) and longer on pygmy date palm (166.03 d). Our study indicated that different hosts affected life parameters of O. nipae, with the most preferred hosts being the Chinese windmill palm and Canary Island date palm. These results may be useful for the design of culture management strategies for O. nipae.

Demographic comparison and population projection of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) reared on sugarcane at different temperatures.

Understanding how temperature affects fitness is important for conservation and pest management, especially in the era of global climate change. Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae) is a worldwide pest of many economically important crops. Although much is known about this pest's life cycle, its adaptability to different temperatures is not fully understood. Here, we used age- and stage-specific life tables to investigate the effects of temperature on fitness-related traits and demographic parameters of R. ferrugineus under eight constant temperature regimens in the laboratory. The growth potential of these populations was also evaluated. The greatest longevity for males and females was 158.0 d at 24 °C and 144.5 d at 21 °C, respectively, but mean total fecundity was the highest at 27 °C. The intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0) increased initially at low temperatures and then decreased. All metrics reached a maximum at 27 °C and a minimum at 36 °C. Mean generation times (T ) decreased across the temperature range with a minimum at 36 °C. Our results indicate that the optimum temperature for growth of R. ferrugineus was approximately 27 °C. Our work will be of value for developing strategies for control management of this pest species.