东亚小花蝽对西方花蓟马和二斑叶螨的捕食选择性

多食性天敌对猎物的捕食选择性及猎物密度对天敌捕食的干扰作用直接影响到天敌对不同猎物的控制作用.在实验室条件下研究了东亚小花蝽对西方花蓟马和/或二斑叶螨不同虫态的捕食选择性,以及两猎物中一种猎物的密度变化对小花蝽取食另一种猎物的影响.结果如下:东亚小花蝽5龄若虫和成虫对西方花蓟马2龄若虫的捕食选择性均强于对其成虫,对二斑叶螨的选择性为雌成螨>若螨>幼螨.实验中西方花蓟马2龄若虫是东亚小花蝽最喜好的虫态.二斑叶螨雌成螨密度固定为60头/19.63cm2,西方花蓟马若虫密度从10增加到60时显著地减少了东亚小花蝽对二斑叶螨的取食.反之,固定西方花蓟马同样密度,增加二斑叶螨密度却没有显著改变小花蝽对西方花蓟马的取食.此结果进一步表明,西方花蓟马是东亚小花蝽更喜好的猎物.

The prey preference of Orius sauteri on western flower thrips and two-spotted spider mite

The prey preference of polyphagous predators to different preys and the interference of the prey density greatly affect their control efficiency. Prey preference of the predator Orius sauteri on the western flower thrips, Frankliniella occidentalis (Pergande) and the two-spotted spider mite, Tetranychus urticae Koch, and effects of density of one prey on the predation on the other prey, were studied in the laboratory maintained at (26±1)℃ and 70% RH. Both 5th instar nymphs and adults of O. sauteri prefer to feed on nymphs than on adults of F. occidentalis, whereas prefer to feed on adults than on nymphs or larvae of T. urticae. The second instar larvae of thrips was the most favorite for O. sauteri among all supplied stages of thrips and spider mites. At a fixed density of spider mites (60/19.63cm~2), increasing thrips density from 10 to 60 significantly decreased the predation of spider mites by O. sauteri; however, at a same fixed thrips density, increasing spider mite density didn′t decrease the predation on thrips. These results strongly indicated that F. occidentalis was a more suitable prey than T. urticae for O. sauteri. The western flower thrips, which is a newly invasive species in China, was discussed as to its ecological roles in the intrusive surroundings in context of prey preference of predators.