Effects of four pesticides from insect growth regulators against the alder leaf beetle, Agelastica alni (Col.: Chrysomelidae)

Alder leaf beetle, Agelastica alni (Linnaeus, 1758) (Col.: Chrysomelidae) is an important pest of the alder trees in Iran. Both the beetle and its larvae feed on leaves of alder trees causing aesthetical and physiological damage. The toxicity of four commercial insect growth regulators (IGR) including lufenuron, flufenoxuron, hexaflumuron and pyriproxyfen was investigated on the second instar larvae (24 h old) of alder beetle, A. alni using the leaf dip method (for 30 s) under laboratory conditions [25 ± 1 ºC, 75 ± 5% RH and a photoperiod of 14:10 (L: D)]. The experiment was conducted in the toxicology laboratory of Guilan University. SPSS software was used for calculating LC50 values. 72 hours after treatment the insecticides proved to have high toxicity. In addition, these pesticides had negative effects on the morphology of larvae in the molting stage. LC50 values were estimated as 36.37 ppm for lufenuron, 48.35 ppm for flufenoxuron, 68.90 ppm for hexaflumuron and 54.37 ppm for pyriproxyfen, respectively. Abnormal morphological changes such as incomplete formation of the cuticle due to consumption of the pesticides by these larvae were observed. Considering that IGRs are safer to human and environment health, compared to conventional insecticides, these four IGRs especially lufenuron seems to be suitable candidates for development of IPM programs against alder leaf beetle.