Bioecology of wheat chafers Miltotrogus caucasicus and Tanyproctus ganglbaueri in the western Iran

Abstract

Background and Objectives Large areas of non-irrigated wheat fields have recently gone through the damage caused by growing population of wheat chafers. To study wheat chafers’ population changes and their natural enemies, the larvae, pupae and adults were collected from Kermanshah and Kurdistan provinces. Materials and Methods Sampling and counting of larvae and pupae were done by placing wooden quadrats over the wheat fields and digging soils of the sampled areas. The insect net was employed to capture the adults. The sampling was carried out for three years (2010-2013). Results The two cockchafer species Tanyproctus ganglbaueri and Miltotrogus (Amphimallon) caucasicus (Scarabaeidae) were the most damaging chafers to wheat in western parts of Iran. The dominant species depended on the region and timespan indicating species turnover. The described species of T. ganglbaueri hasn’t been reported yet as a pest worldwide. The highest density of M. caucasicus larvae in Kermanshah province was 5.6 larvae per 0.25 m2 quadrat in mid-April; while in case of T. ganglbaueri 16 larvae per 0.25 m2 quadrat was recorded in March in Kurdistan province. Larvae of T. ganglbaueri started feeding in early February and the peak feeding times occured in March and April. The average adult lifespan of T. ganglbaueri was roughly 43 days. Fungal and bacterial pathogens including Beauveria bassiana, Hirsutella sp. and Bacillus sp. were isolated from the wheat chafers. Discussion The relatively different biology of these two pest species has an implication in their timing control actions. More studies on identification and revision of wheat scarabs in different climates of Iran is needed.