Prey preference and reproduction of predatory mites, Amblybromalus limonicus and Neoseiulus cucumeris, on eggs and 1st instar nymphs of the tomato/potato psyllid

Abstract

ABSTRACTThe tomato/potato psyllid (TPP), Bactericera cockerelli, a serious pest that causes significant damage to important economical and ornamental plants and crops in North America, has been an invasive species in New Zealand since 2006. This study is one of a series of experiments in the laboratory and greenhouses to compare and evaluate the efficiency of two commercially available species of predatory mites (Amblydromalus limonicus and Neoseiulus cucumeris) as potential biocontrol agents of TPP. The objectives of this laboratory study are to determine (1) the predation and reproductive rates of each predatory mite species feeding on eggs and 1st instar nymphs of TPP under choice and no-choice conditions and (2) if there is a difference in predator preference for eggs or 1st instar nymphs of TPP between the two predatory mite species. Under no-choice conditions, A. limonicus young females consumed on average 6.17 ± 0.44 eggs and 6.77 ± 0.32 1st instar nymphs of TPP whereas N. cucumeris young females consumed 3.47 ± 0.36 eggs and 3.20 ± 0.29 1st instar nymphs of TPP per day. On an egg-only diet, A. limonicus had a much higher reproductive rate (0.93 ± 0.19 eggs laid per day) compared with N. cucumeris (0.17 ± 0.07 eggs laid per day). On a 1st instar nymph-only diet, the average number of eggs laid was reduced for both species: A. limonicus laid 0.47 ± 0.10 eggs per day compared with N. cucumeris, who laid 0.13 ± 0.06 eggs per day. Both A. limonicus (preference index 0.68 ± 0.04) and N. cucumeris (preference index 0.74 ± 0.06) showed a preference for eggs of TPP when given a choice of 10 eggs and 10 1st instar nymphs of TPP. In addition, A. limonicus had a much higher reproductive rate (1.23 ± 0.20 eggs laid) compared with N. cucumeris (0.30 ± 0.08 eggs laid) under choice conditions. The results from this study confirmed that N. cucumeris and A. limonicus could feed and reproduce on eggs and 1st instar nymphs of TPP. While A. limonicus has shown previously that it could feed and reproduce on TPP, this is the first report on the predation and reproduction of N. cucumeris on eggs and 1st instar nymphs of TPP. This is significant, given that A. limonicus is not commercially produced in USA and New Zealand where TPP is a major pest, whereas N. cucumeris is commercially produced and much cheaper in both countries.