An assessment of the biological control potential of Heliophanus pistaciae (Araneae: Salticidae) on Nysius natalensis (Hemiptera: Lygaeidae), a pest of pistachio nuts

The predation potential of Heliophanus pistaciae Wesolowska (Araneae: Salticidae) on one of the minor pests of pistachio nuts, Nysius natalensis Evans (Hemiptera: Lygaeidae), and vinegar flies, Drosophila melanogaster Meigen (Diptera: Drosophilidae), was assessed in laboratory and field trials. Laboratory tests were conducted using Petri dishes, and field trials using cotton mesh bags placed over pistachio nut clusters. In feeding tests, female and male H. pistaciae consumed significantly more D. melanogaster than N. natalensis in the first and second days of the experiments. Consumption of N. natalensis by both sexes increased significantly during the second day of the experiments. No such change in consumption rate of D. melanogaster on day 2 was recorded for either sex. Prey preference tests found female H. pistaciae to prefer D. melanogaster (91%) to N. natalensis (9%). Different capture rates may be related to prey size and/or palatability. Field trials found female H. pistaciae (n=20) to kill a mean of 1.05 N. natalensis in a 24-h period. The experiments indicate that H. pistaciae may have a limited role as a biological control agent of N. natalensis, but a combination of predation and effective orchard management should be able to suppress N. natalensis populations below damaging levels in pistachio canopies.