Habitat and prey preferences of the two predatory bugs Anthocoris nemorum (L.) and A. nemoralis (Fabricius) (Anthocoridae: Hemiptera-Heteroptera)

Abstract

The annual occurrence and distribution of the predatory bugs Anthocoris nemorum and Anthocoris nemoralis between apple, pear and herbal vegetation, was assessed in three apple orchards in 2001, and in two apple and two pear orchards in 2002. In the laboratory anthocorid prey preference was assessed in two-choice experiments with key pests of apple and pear including pear psyllid, apple psyllid, green apple aphid, rosy apple aphid and red spider mites. Anthocorid predation behavior towards pear psyllids was assessed. Anthocorids were the dominant early season predatory bugs. A. nemorum dominated in apple, while A. nemoralis dominated in pear. A. nemorum was also common in herbal vegetation, especially in mid-summer. Anthocorid numbers were correlated with numbers of collembola, psyllids and aphids in apple, and with numbers of psyllids in pear. A. nemoralis preferred pear psyllid to green apple aphid, while A. nemorum preferred green apple aphid . Both species preferred psyllids to spider mites. The success rate of A. nemoralis in attacking pear psyllids was higher than that of A. nemorum. A. nemorum had two generations in both 2001 and 2002 proving that it can be bivoltine under Danish climate conditions. The mid-summer move by A. nemorum from trees to herbal vegetation suggests that herbal vegetation may maintain A. nemorum in orchards at times of low prey numbers in the trees. Habitat and prey preference trials both identify A. nemorum as a biological control agent of special importance in apple, whereas A. nemoralis is of importance in pear.