Effect of Melia azedarach L. extract on Liriomyza sativae (Diptera: Agromyzidae) and its biocontrol agent Diglyphus isaea (Hymenoptera: Eulophidae)

Abstract

The chinaberry tree, Melia azedarach L., is known to have different effects on insect pests and their biological control agents. We studied the effects of extracts of mature and immature M. azedarach fruits on survival of the vegetable leafminer Liriomyza sativae Blanchard and the parasitoid Diglyphus isaea (Walker) under laboratory conditions. Survival of first instar larvae was tested by exposing female leafminers to treated and untreated cowpea seedlings with Melia extracts. Initiation of mines and survival of those first instars to pupation and adulthood were recorded. Seedlings infested with third instar larvae or with larvae 4 d post-parasitism by D. isaea were dipped in plant extracts. Survival to pupation and successful emergence of adult leafminers or parasitoids was recorded. In the test using first instars, there were few initiated larval mines on plants treated with the extract of immature fruits. Consequently, fewer leafminers survived to pupation on plants treated with the latter extract than on plants in other treatments. Survival of larvae on plants treated with extracts was not significantly different from that of the control. Leafminer survival to pupation on plants exposed to D. isaea alone was significantly lower than survival on the control plants. However, there was no significant difference in survival to pupation between the treatment with M. azedarach extract alone, the combined treatment of the parasitoid and M. azedarach extract, and the control. Percent of parasitism was similar in presence and absence offrait extracts. Thus, the use of extracts of M azedarach would be compatible with biological control by the parasitoid D. isaea that contributes to lower leafminer populations.