'New species association' biological control?: Three coccinellid species and an invasive psyllid pest in New Zealand

Classical biological control programmes generally involve some type of evolutionary relationship where predator and prey species have co-evolved. The 'new species association' approach is based on the ecological principle that uses a natural enemy species which has not coevolved with a pest species. The objective of this laboratory-based study was to investigate the potential for a new species association between three naturalized coccinellids, Scymnus loewii, Cryptolaemus montrouzieri, and Cleobora mellyi, and the invasive tomato-potato psyllid (TPP), Bactericera cockerelli. Two experiments were conducted to determine consumption rate and feeding behaviour of adults and 4th instar larvae of the coccinellid species on mixed instars of TPP, using tomato and potato leaflets, and a no-leaflet control. S. loewii, consumed relatively few TPP (< 10 over 24h), and spent less time feeding compared to the two larger species. C. montrouzieri consumed up to 30 TPP over 24h, depending on leaf type and predator life stage. Larvae spent a greater proportion of time stationary on tomato leaflets and less time searching compared to adults. C. mellyi adults and larvae were the most voracious predators of TPP, consuming up to 100 TPP over 24h compared to the other two coccinellids. Adults spent more time feeding on the control (56%) and potato leaflets (30%) than on tomato leaflets. Larvae spent 79% more time feeding on the control, compared to the potato (24%) and tomato (14%) treatments. The results of this study suggest that a new species association exists between the three coccinellid species and TPP.