Studies on the damage level of the weevil Rhynchites cribripennis in olive fruits

Abstract: Among the insect pests of olives, those damaging the fruit are considered to be of highimportance as their damage can directly affect the quality and the quantity of the oil produced. Insome areas in the Mediterranean region the weevil Rhynchites cribripennis (Coleoptera:Attelabidae) is considered as a potentially important pest of olive crops. The damage produced bythis weevil is due to the feeding holes that the adults cause in the flesh of the young olive fruit.This kind of damage can lead to significant fruit drop and subsequent significant yield losses. Inthis study, the damage level (percentage of fruit drop, the number of feeding holes on the fruitand weight loss of olives fruit) was investigated in association with a wide range of pest densities(0, 1, 2, 3, 4, and 5 adults) in cage experiments. The trials were conducted on the variety“Koroneiki” in south-western Peloponnesus. In average, in each treatment 186, 231, 244, 383,451, 497 olives were initially enclosed in each cage, at the end of the anthesis. The totalpercentage of the dropped fruit was highest (78% and 75%, mean ± SE) in the cages with thehighest pest densities (i.e. 5 and 4 adults, respectively). These percentages were reducedfollowing the decrease of the pest density. In the control cages the percentage of fruit drop was18%. These analyses showed that the final number and the total weight of the olives weresignificantly reduced with the increase of the pest densities. The importance of these results in theestimation of the economic injury level of this pest is discussed.