Functional and numerical responses of Amblydromalus limonicus and Neoseiulus cucumeris to eggs and first instar nymph of tomato/potato psyllid (Bactericera cockerelli)

Abstract

The tomato/potato psyllid (TPP), Bactericera cockerelli, is a serious pest of some agricultural and ornamental plants, especially of the Solanaceae family. It has been an invasive species in New Zealand since 2006, heavily impacting the potato and tomato industry. The functional and numerical responses of the phytoseiid predators Amblydromalus limonicus and Neoseiulus cucumeris were examined by offering a range of prey densities (two, four, eight, 12, 16, 20, 24 and 28 TPP eggs or 1st instar nymphs) and compared on a capsicum leaf disc under 25 ± 1ºC, 85% ± 5% RH and a 14:10 h light: dark (L:D) photoperiod. Both species displayed a type 2 functional response when fed on eggs or 1st instar nymphs of TPP, indicating an increase in the number of prey killed with an increase in prey population density. The results were analysed by using a logistic regression and Holling disc equation. A. limonicus had a higher attack rate for both eggs (0.05 ± 0.01) and 1st instar nymphs (0.06 ± 0.01) than N. cucumeris, which had an attack rate of (0.03 ± 0.01) for eggs and (0.02 ± 0.01) for 1st instar nymphs of TPP. N. cucumeris had a longer handling time for both eggs (3.68 ± 0.67 hrs) and 1st instar nymphs (2.50 ± 0.79 hrs) compared with A. limonicus, with a handling time of (1.74 ± 0.23 hrs) for eggs and (1.15 ± 0.15 hrs) for 1st instar nymphs. A. limonicus consistently produced significantly more eggs than N. cucumeris across all densities when fed on either eggs or 1st instar nymphs of TPP. However, the results showed the lack of numerical response of both predator species to prey density. The stronger functional response of A. limonicus to TPP eggs and 1st instar nymphs indicates that this species can potentially be a more effective biocontrol agent of TPP than N. cucumeris.