Laboratory Efficacy of Selected Species of Entomopathogenic Nematodes Against Blueberry Mealybug, 1995

Abstract

Abstract Experiments were conducted in plastic Petri dishes (35 mm diam.) filled with coarse sterile sand mixed with distilled water (10% water by weight). A single final instar mealybug on a small piece of fresh blueberry root was buried in the center of each dish. Nematodes were added in a drop of distilled water (50 u.1) applied away from the center of the dish. Different doses of nematodes were applied using the dilution method in which a series of mixtures of nematodes in water was prepared at the appropriate densities for each experiment. In Experiment 1, three species of nematodes, Steinernema carpocapse (All strain), S. glaseri (NC strain) and Heterorhabditis bacteriophora (HP88 strain), were tested at doses of 10, 50, 100, and 500 infective juveniles (ijs) per dish. Mealybug mortality was assessed at 2- and 5-DAT. Each treatment (species/dose/exposure period) was replicated 12 times. Replicates where the mealybug could not be located were omitted from the study. In Experiment 2, we tested S. feltiae (Australia strain) and H. bacteriophora (HbNJ strain) at 50, 100, 500, and 1000 ijs per dish at an exposure period of 5 d, and replicated 24 times per treatment. In both experiments, after treatment application, the dishes were placed in a large food storage box with damp paper towels to maintain a high humidity, and incubated at 25°C. The nematodes for all experiments were reared in Galleria mellonella larvae and used within two weeks of emergence into white traps.