Evaluation of Aqueous Solution of Neem Seed Extract Against Liriomyza sativae and L. trifolii (Diptera: Agromyzidae)1

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Abstract
Aqueous solutions of neem seed extract applied on leaves were evaluated for antiovipositional and insecticidal effects against the leafminers Liriomyza sativae Blanchard and L. trifolii (Burgess). All experiments but one were conducted with the primary leaves of Henderson bush lima bean as the host. Significantly fewer eggs were laid by L. trifolii females in neem-treated foliage than in water-treated foliage; such a difference in oviposition was not seen for L. sativae. However, larval mortality of both species shortly after hatch was high (100% for L. trifolii. 98.2% for L. sativae). Further work indicated that 2-to 6-h-old neem residues on leaves repelled adult L. sativae. thus reducing oviposition, but that 22-h-old residues were not appreciably repellent. Neem applied as a 0.1 % solution on leaves was active against 1- to 3-day-old L. sativae eggs (by killing larvae hatching from those eggs) as well as against all three larval instars. Against L. sativae eggs and larvae, neem was highly effective as 0.1 and 0.05% solutions (91 to 100% mortality) and moderately effective as a 0.025% solution (49 to 92% mortality). Neem applied on leaves was effective for up to 7 days in killing larvae hatching from eggs, but its effectiveness declined steadily from day 0 after application (86% mortality) to day 7 after application (44% mortality). Adults caged for 25 h with foliage freshly dipped in 0.1% neem extract showed no adverse effects. Similarly, neem extract (0.1%) applied on chrysanthemum leaves showed that adult L. trifolii were slightly inhibited from making ovipositor punctures in leaves. Leaf-miners failed to develop, however, and the neem-treated leaves contrasted with the control leaves, which contained numerous mines.

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