Reproductive maturation in the large pine weevil Hylobius abietis: the relative importance of larval and adult diet.

摘要

Larval and adult Hylobius abietis (L.) can feed and, in the case of the adults, cause commercially significant damage to many species of conifer. The present study aimed to evaluate the impact of larval and adult feeding on different host plants on subsequent reproductive fitness. Hylobius abietis larvae were reared on logs of four host species known to vary in suitability for development; Pinus nigra ssp. laricio, Picea sitchensis, Larix kaempferi and Pseudotsuga menziesii. Adult females were collected on emergence and allocated to complete maturation feeding on one of four seedling conifer species, P. nigra spp. laricio, P. sitchensis, P. menziesii and Larix x marschlinsii. It was assumed that variation in both larval and adult host plant quality had the potential to influence subsequent reproductive behaviour. The time taken for females to attain reproductive maturity was assessed, and reproductive output was measured over an average period of 17 days. The best predictor of the time to attain reproductive maturity was found to be the initial adult body weight. This was strongly related to the larval host species, with the largest adults emerging from P. nigra ssp. laricio. The time taken to begin oviposition was in the range 10-49 days (mean 23 days). The subsequent mean rate of oviposition for individual females was in the range 0.1-3.7 eggs per day. Egg volumes varied between and within individual females, in the range 0.241-1.079 mm3. The species of seedling provided for maturation feeding had no significant impact on reproductive behaviour over the course of the experiment. It is possible, however, that the quality of the adult diet might exert a greater influence on behaviour over a longer period because H. abietis is a relatively long-lived species.