Life history traits of pest and non‐pest populations in the phytophagous ladybird beetle, Epilachna niponica (coleoptera, coccinellidae)

Abstract

Life history traits of the phytophagous ladybird beetle, Epilachna niponica were compared between a non‐pest population feeding on wild thistle and a pest population feeding on cultivated solanaceous crops, mainly potato. The pest population had larger females, a higher population growth rate, a more continuous oviposition schedule, and a shorter developmental period in the immature stages, compared with the non‐pest population. The two populations showed no clear differences in phenology from spring to autumn, egg mass size, hatchability, and larval survival rate. Significant differences were found in number of eggs laid per female during the first and second periods, and in the developmental period of the immature stages. These life history traits were influenced primarily by food plant. A higher fecundity and shorter immature period appear to be readily altered by the host shift from thistle to potato.

Toward the Development of Novel Long-Term Pest Control Strategies Based on Insect Ecological and Evolutionary Dynamics

“…The results show that pest populations exhibit a continuous ovoposition rate, shorter immature stages, and bigger female body size. Let us now picture a species that is not only very plastic phenotypically, but also extremely diverse genotypically (Shirai & Morimoto, 1997). What could we do to control such a species?…”

A host shift from wild blue cohosh to cultivated potato by the phytophagous ladybird beetle, Epilachna yasutomii (Coleoptera, Coccinellidae)

“…We used 30 days as the summer diapause period of E. yasutomii in accordance with the study of E. niponica (Shirai and Morimoto 1997). When adults emerged, 30 unmated females were transferred individually to plastic dishes (9 cm in diameter, 4.5 cm deep) and supplied with black nightshade (Solanum nigrum L.) leaves.…”

“…(Berberidaceae), "blue cohosh," and Scopolia japonica Maxim. Shirai and Morimoto (1997) compared life history traits of Epilachna niponica Lewis between a nonpest population depending on wild thistle and a pest population feeding on cultivated solanaceous crops. Potato cultivation increased in the mountainous area of central Honshu in the 1930s (Umemura 1984), and thereafter Epilachna ladybird beetles extended their range from wild vegetation to crop fields.…”

“…Epilachna yasutomii Katakura, a close relative to E. niponica, is an appropriate model for such a comparative study between nonpest and pest populations, because the pest population of E. niponica in crop fields is very restricted in distribution and the phenology of wild thistles is quite similar to the overall phenology of solanaceous crops (Shirai and Morimoto 1997). In contrast, E. yasutomii has become a major pest in wide area of Kanto and Tokai districts, central Honshu (Katakura 1981(Katakura , 1997.…”

“…As in the previous study (Shirai and Morimoto 1997), a field census and two laboratory comparisons were conducted. As in the previous study (Shirai and Morimoto 1997), a field census and two laboratory comparisons were conducted.…”