تعيين LD 50 تركيبات بازدارنده سنتز كيتين بر روي لارو سن دوم سوسك كلرادوي سيب زميني Leptinotarsa decemlineata -Col.:Chrysomelidae

Determination of LD50 Value of Chitin Synthesis Inhibitor Compounds on Second Larvae Instars of the Colorado Potato Beetle Leptinotarsa decemlineata (Col.: Chrysomelidae)

In this research was carried out on determination of LD50 value of chitin synthesis inhibitor compounds (Lufenuron 25% EC and diflubenzuron 25% WP) on second larval instars of the Colorado potato beetle Leptinotarsa decemlineata (Say).Was invest igated. The eggs of the insect were collected from fields where located around Urmia University and Nazlo village. Second larval instar was separated by measuring of head capsule width and used in bioassay. In order to,determination of LD50 potatoes planted in plastic vases were used. To study the susceptibility of larvae, with measuring of their feed level, treatment cages were made and definite rates of poison solution were used, then larvae were released in these cages individually. In bioassays, LD50 values of mentioned compounds on second larval instars were determined. The data were analyzed with log-probit transformation using the MSTATC software. The LD50 values of lufenuron and diflubenzuron on second larval instars were estimated 139. 56 and 913. 67 ppm respectively. The results showed that lufenuron was more effective than diflubenzuron to control the pest. On the basis of collected data in this research and the selective nature of chitin synthesis inhibitor compounds we can conclude that these compounds can be used for reasonable control of Colorado potato beetle.