Nursery, Greenhouse, and Landscape News

Use of Entomopathogenic Nematodes to Control Leafminers in Ornamental Plants

Recent investigations with Liriomyza trifolii, an important leafminer of chrysanthemum, showed that the nematode Steinernema carpocapsae (All strain) enters mines through the oviposition hole in the mine to attack leafminer larvae. All larval stages and the prepupa are susceptible to this nematode. Most of the nematodes (92%) entered via the anal openings and the remainder entered via the mouth. Nematodes failed to kill pupae.

A second study showed that the ability of All strain S. carpocapsae to enter mines and kill larval miners was dependent on the relative humidity during the 48 hours following treatment. In greenhouse conditions under ambient relative humidity (50-91%) mortality ranged from 24-43%. In a fog house, with a relative humidity of >92%, mortality of leafminers was >65%. A comparison of nematode species and strains in the laboratory found both highly virulent and less virulent strains. Field tests in a fog house found the All strain of S. carpocapsae and a Hawaiian isolate of S. feltiae (MG-14) were superior to other isolates.

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