Susceptibility of seedlingPyrusclones to pear sawfly (Caliroa cerasi) (Hymenoptera: Tenthredinidae) damage

Abstract

Pear slugs, the larvae of the sawfly Caliroa cerasi, can cause extensive damage to pear leaves in organic or reduced-spray orchards. Breeding for resistance provides a strategy for the long-term control of this pest. Twenty-two accessions from the Horticulture and Food Research Institute of New Zealand pear breeding programme were selected to cover a range of field-assessed susceptibility to this pest. These were grafted onto Pyrus calleryana seedling rootstock, and the young plants were arranged in a blocked trial design in a ventilated glasshouse. The plants were covered with insect-proof netting, into which adult sawfly were released. The number of eggs per plant did not differ among the susceptibility classes, but the level of damage was related to the predicted level of susceptibility. This study confirmed the existence of variation in the resistance of pear genotypes to pear slug damage.

Insecticidal control and the phenology of cherryslug (Caliroa cerasi(L.)) (Hymenoptera: Tenthredinidae) on organic pears in Central Otago

“…The combination of biological control with cherryslug-resistant clones of Pyrus (Shaw et al 2003) may be a viable long-term management strategy without the need for insecticides.…”