Document Type : Agricultural Entomology
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Abstract
Flea beetles are serious insect pests of canola throughout Gorgan, Gilan, Zanjan, Khozestan and Markazi provinces. Attacking the plant at early stages results in considerable damages. The life cycle and seasonal population changes of the main species namely Phyllotreta corrugate, was investigated using sticky yellow traps and direct sampling methods in selected fields of Saveh region during 2002-2005. In addition, biological parameters were studied in laboratory conditions (23±2°C & 60±5% RH) simultaneously.
The results revealed that the beetles overwintered as adult under the crop remains, appeared from early to late March in fields and started feeding on different cruciferous host plants. The adults completed feeding, mated, and oviposited individually or in small groups on the soil surface or one cm below it and in host-plant root area. In Saveh, new adults emerged on early June, when winter canola was under harvesting. These adults fed on newly emerged canola and crusiferous weeds for a while, then they aestivated until autumn, when fresh canola seedlings were available. The aestivated adults continued feeding on host plants until early December, when hibernation took place in the population due to climatic conditions. Based on the laboratory results, egg incubation, larval and pupal periods last 6-11, 18-28 and 8-15 days, respectively. This pest is monovoltine in Saveh region.
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