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广西西瓜嫁接苗培育时间在每年的12月至翌年3月,大多采用塑料大棚作为苗圃,地点集中,育苗数量大,为美洲斑潜蝇的繁衍、越冬、危害创造了条件,使成为西瓜嫁接苗圃的首要害虫.1998年冬至1999年春,广西热作所内的西瓜嫁接苗圃,遭受美洲斑潜蝇的危害比历年严重.一、危害症状和情况以幼虫危害砧木葫芦苗为主,瓜苗出土后不久即可受害.幼虫在子叶表皮下取食叶肉,形成蛇形弯曲虫道.1龄幼虫取食量较小,虫道细小如白线状;2龄幼虫取食量增大,虫道变宽;3龄幼虫取食量最大,占总取食量的78%以上,虫道尾部特宽.2～3龄幼虫呈鲜黄色,透过表皮,清晰可见.被害子叶一般有虫1～3头,多的可达5头,叶色变黄,容易枯萎.受害严重的砧木不能用于嫁接.
Guangxi watermelon grafted seedlings growing time in December of each year to March the following year, most of the plastic greenhouses as nurseries, the location of focus, nursery large number of breeding for the American Leafminer fly, overwinter, creating the conditions for harm, so as to become watermelon grafting nursery Of the major pests.From the winter of 1998 to the spring of 1999, watermelon grafting nursery in Guangxi Institute for Hot Work suffered a more serious harm than ever.A, the risk of symptoms and conditions to larvae of rootstock gourd seedlings shortly after the emergence of melons The larvae fed on the epidermis of the cotyledons and formed serpentine curved worm larvae.The feeding amount of the first instar larvae was small and the larvae were small as white line.The feeding amount of the second larvae increased and the larvae widened The third instar larvae had the highest food intake, accounting for more than 78% of the total food intake, and the tracheid tail was extra wide. The second to third instar larvae were bright yellow and were clearly visible through the epidermis. , Up to 5 more, leaf color turns yellow, easy to wilt.Determination of serious rootstock can not be used for grafting.