در شرايط آزمايشگاهي )LEPIDOPTERA:PHYCITIDAE( ANAGASTA KUEHNIELLA)ZELLER( مطالعه و تعيين تعداد سنين شب پره مديترانه اي آرد،

Determining the Number of Larval Instars of the Mediteranean Flour Moth,Anagasta kuehniella (Lepidoptera : Phycitidae), in Laboratory conditions

Having knowledge about different developmental stages of a species and determining the number of its nymphal or larval instars is a very important factor in entomological studies. In population and toxicological studies, it is of very importance that we know the above topics and be able to recognize each of larval or nymphal instars. for instance, in a toxicological study, using larvae or nymphs belonging to different instars will produce incorrect results, because of their possible different sensivity. Studies carried out by entomologists, especially H.D. Dyar, have shown that the size of a sclerotinized part of body, especially head capsule, increase linearly in successive developmental instars and has a constant rate that varies from 1.3 to 1.7. In present study, we studied the number of larval instars of the Mediterranean flour moth, Anagasta kuehniella, on its rearings on wheat flour and under laboratory conditions. Number of larval instars were studied by two methods of ".direct observations" and "measuring head capsule width and using Dyarʹs rule". Five instars were observed by the first method. In the second method, means of head capsule width of 1st to 4th instar larvae were 197. 288. 435 and 727 mium, respectively, and for 5th male and female larvae were 1114 and 1139um, respectively. Dyarʹs rule constants were determined as 1.461, 1.510, 1.671. 1.532 and 1.66. respectively. These results indicated that according to Dyarʹs rule, there are five larval instars in this species. Comparison of the results obtained by these two methods indicates that the Dyarʹs rule can be used for determining the number of and recognizing the larval instars of A. kuehniella under laboratory conditions.