Improved monitoring of vine weevil (Otiorhynchus sulcatus) adults

Abstract: Knowledge of when vine weevil adults are likely to be actively feeding and laying eggs within crops is important if monitoring efforts and controls are to be correctly timed. Previously there was conflicting information on the minimum temperature required for egg laying with 12 °C having been suggested by some authors as a lower threshold. Results presented here indicate that egg laying and feeding may continue at temperatures as low as 6 °C.There are a range of tools with which to monitor for the presence of vine weevil adults within crops. Growers often use simple devices such as corrugated card or grooved boards. Results from a replicated semi-field study indicate that monitoring tools differ widely in both the numbers of weevils they record and how reliably they indicate the presence of a population of vine weevil adults. A commercially sold vine weevil trap (ChemTica, Heredia, Costa Rica) recorded significantly more weevils and was more reliable than corrugated card or grooved boards.