|
The Cereal Leaf Beetle (''Oulema melanopus'') is a significant crop pest, discovered by Carl Linnaeus in 1758. ==Life History== One generation of this beetle is produced a year. Adults feed before winter and spend most of their overwintering time in protected areas such as wind rows, crop stubble, and tree bark crevices.〔〔〔 Adults mate once the temperature warms to above 9-10 degrees Celsius (or 44.6 degrees F) 〔 and females have a relatively long laying period (about 45–60 days) where they deposit eggs to the underside of leaves.〔〔 The larvae hatch in 7–15 days,〔 and start the most damaging eating of the entire life cycle. These larvae mature in 12–20 days.〔 Larvae are the greatest threat to crops, as they eat the superficial layer of leaves, hindering the leaves' photosynthetic potential.〔〔 According to Kon, Zabik, Webster, and Leavitt, there is also a chemical factor that attracts the beetles to leaves, and that chemical factor is directly related to hydrophobicity.〔〔 Pupation occurs in the ground, with the adults emerging in 20–25 days,〔〔 ready to start the cycle again.〔 Eggs are cylindrical and round, approximately 0.9 mm long and 0.4 mm wide. Eggs are often laid along the mid vein on the underside of leaves. They are bright yellow at first and darken over time, and are partially black when the larvae emerge. The larvae appear white or yellow, are hump-backed, and have a black head and six small legs. They have a defense mechanism in which they smear excrement on their bodies to mask their vibrant color and to deter predators. This gives them a shiny black appearance, as opposed to yellow or white.〔〔〔〔 Adults, on average, are about 5 mm long and have dark blue wing covers and red legs. Their thoraces range in color from red to orange to reddish brown.〔〔〔〔 The biggest distinction between male and female ''O. melanopus'' is the difference in shape of the first abdominal segment. The male’s segment is more narrowly rounded and flat or concave, and it is more broadly rounded and convex in the female. Pupae are rarely seen in fields, as they are dormant at that time. Pupae are approximately 5 mm in length and are yellow, also darkening with time.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cereal leaf beetle」の詳細全文を読む スポンサード リンク
|