Variability in host plant chemistry: behavioural responses and life-history parameters of the Colorado potato beetle (Leptinotarsa decemlineata)

Abstract

Many studies investigating effects of plant chemicals on herbivore performance have reported contradictory results, perhaps because of possible interaction between different chemicals. Also, a herbivore's performance is not necessarily consistent with its food or oviposition preference. Our aim was to investigate simultaneously antibiosis (larval growth and survival) and antixenosis (oviposition and feeding preferences) responses in herbivore to three plant chemicals, of which one is expected to have positive and two are expected to have negative effects. Antibiosis was measured by correlating the nitrogen and glycoalkaloid levels in host plants to the survival and adult size of Leptinotarsa decemlineata, by rearing larvae on whole plants of three potato varieties. Although host plants differed in their glycoalkaloid levels, survival rate and adult body size did not differ among beetles reared on different potato varieties. This suggests that beetles are quite robust for differences in both foliar α-chaconine and foliar α-solanine content. However, differences in antixenosis were found although they could not be directly predicted from the leaf chemistry. Females preferred to lay their eggs on the variety with high α-solanine content (Nevsky) towards which males showed a tendency to feeding preference. Overall, our results confirm that beetles are well adapted to the chemical defences of potato plants as potato varieties did not significantly affect beetle performance, but differences in oviposition preference may still result in major differences in the amount of damage inflicted on plants in the fields.

Quantitative genetic approach for assessing invasiveness: geographic and genetic variation in life-history traits

“…3). This atypical finding is not likely to arise from the lack of competition over food since the same result is found in various environmental conditions (Forister et al 2007;Lyytinen et al 2007). Rather the strong selection by pesticides (during early larval stages) as well as harvesting of potatoes twice (making food resource limited) in the season could have decoupled these traits.…”

Sweet Potato Resistance to <I>Euscepes postfasciatus</I> (Coleoptera: Curculionidae): Larval Performance Adversely Effected by Adult's Preference to Tuber for Food and Oviposition

“…This means there was discordance between these numbers (i.e., differences in preference for food and for oviposition in adults). Such discrepancy in the preference for food and oviposition is known between plant species and other insect species (e.g., Walsh 2003, Lyytinen et al 2007, Oliveira et al 2007, Azerefegne and Solbrec 2010, as well as between plants in one species (Nahrung and Allen 2003). As only tubers were used to evaluate resistance in this study, characteristics in the tuber alone would have determined weevil preferences.…”

Managing the Colorado potato beetle; the need for resistance breeding

“…Solanum chacoense produces an abundant level of steroidal glycoalkaloid compounds, leptines and leptinines (Mweetwa et al 2012). Leptines and leptinines can inhibit the development of CPB (Kowalski et al 1999a;Lorenzen et al 2001) and significantly affect oviposition preference of adult beetles (Lyytinen et al 2007). Tomatine and aglycone solanidine, two other glycoalkaloid, have also been reported for their role in resistance to CPB (Barbour and Kennedy 1991;Kowalski et al 2000).…”