Influence of azadirachtin, a botanical insecticide, on Chrysoperla carnea (Stephens) reproduction: toxicity and ultrastructural approach

A commercial formulation of azadirachtin (Align) was tested on Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) adults to determine its effects on reproduction. Three methods of exposure were carried out in the laboratory (residual, direct contact and ingestion) with concentrations close to the maximum field recommended concentration in Spain (48 mg AI/liter). Align proved to be harmless to newly emerged adults irrespective of the mode of exposure. Nevertheless, fecundity was reduced in a reversible way in females that have ingested azadiracthin after the onset of oviposition. Fertility was not different from that of controls in all treatments. Additional tests showed that males were not involved in the reduction of oviposition. Electron microscopy studies pointed out that Align interfered with vitellogenin synthesis and/or its uptake by developing oocytes; thus, growing follicles in treated females were significantly smaller that those of the controls. The role of azadirachtin as a compound that may influence several hormonal and protein titers involved in reproduction is also discussed.