Abstract
Abstract Two insecticidal tests were conducted from 11 Apr to 13 May in research greenhouses in Beltsville, MD. Cinerarias were grown from seed in Promix BM™ for 2 mo in square plastic pots (10 × 10 cm at top). For the first test, a group of 24 randomly chosen plants were placed in a cage under lighrts (16h light:8h dark) with approximately 75 adult Liriomyza trifolii for 24 h. Plants were then removed from the cage, all leafminers were removed from the plants, and The media in each pot was drenched with 150 ml of either water or one of 3 concentrations of neem seed extract (see table). There were 6 plants per treatment. Concentrations of neem seed extract were prepared by diluting neem seed concentrate (sample Al 3-42845 (AN 4.57); Insect Chemical Ecology Laboratory, ARS, USDA, Beltsville, MD 20705) with water to yield the desired percentage (weight/volume). The concentrate contained 2300 ppm azadirachtin, an insecticidal constituent of neem seed extract. After drenching, plants were returned to the greenhouse. First mstar mines (2.5 cm in length) were counted. When larvae reached third instar, all leaves from all plants were harvested. Leaf area of each plant was measured, and the number of reared pupae and adults was counted. A second test was begun 1 wk after the start of the first, and differed from it only in that rather than being drenched, the plants were sprayed with water or one of 3 concentrations of neem seed extract (see table).
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