Acceptability of cultivars of highbush Blueberry at varying temperatures by adult black vine weevils (Col.: Curculionidae)

Abstract

Adults of the black vine weevil,<i>Otiorhynchus (Brachyrhinus) sulcatus</i>  (F.), fed and oviposited at normal, expected rates when fed excised foliage of the acceptable highbush blueberry cultivars, June and Stanley, in variable temperature regimes of 7 to 15, mean 10; 12 to 19, mean 15; and 16 to 29, mean 22C. However, on the unacceptable cultivars, Cabot and Weymouth, they laid some eggs at the high and very few eggs at the medium regimes, whereas in earlier work they laid no eggs at a constant 20C. These results indicate that Cabot and Weymouth provide barely adequate nutrition to the weevils and that environmental stresses such as a constant 20C demand more nutrients than the unacceptable cultivars can provide. Variable conditions, probably due to a lower turn-over rate during the cool periods, allow the insect to obtain the nutrients necessary for fat body development and some oviposition.