TOXICITY OF CRUDE MAIZE EXTRACT ON Panonychus citri (McGREGOR) UNDER LABORATORY CONDITIONS

摘要

The LC50 and sub-lethal effect of crude maize extract were calculated to determine its toxicity on Panonychus citri. The freeze-dried extract re-suspended in water before being applied was used. Serial dilutions were prepared at the concentrations of 2.0, 1.0, 0.5, 0.25, 0.12, 0.06 and 0.03 %, which were sprayed over young females of the mite. The length of the periods of pre-oviposition, oviposition and post-oviposition, the longevity and fecundity of the females surviving the sub-lethal doses of the extract were determined to find out its potential sub-lethal effect. The LC50 was of 0,142% and 0,089 % at 24 and 48 h respectively. The pre-oviposition period of the females sprayed with the sub-lethal concentrations were significantly longer than that of the control. No statistically significant differences were observed for the oviposition and post-oviposition periods. Fecundity values were observed to decrease as the extract concentration increased, but not with significant differences. The results achieved in the present study showed that the crude extract of maize had a marked contact action, but without considerable sub-lethal effects on P. citri.