七星瓢虫成虫对枸杞木虱的捕食作用

为了测定七星瓢虫成虫对枸杞木虱4种虫态的捕食作用,分别在室内测定七星瓢虫的捕食功能反应、种内干扰、自身密度干扰、捕食偏好性以及在田间七星瓢虫对枸杞木虱的捕食效果.结果表明: 七星瓢虫对枸杞木虱的捕食功能反应符合Holling Ⅱ型方程,其中对卵的最大捕食量为112.6粒,对1～2龄若虫、3～5龄若虫、成虫的最大捕食量分别为536、415和113.9头;田间罩笼试验结果证明,七星瓢虫成虫在其生长周期30 d内能使枸杞木虱总虫口密度下降80.1%;七星瓢虫对1～2龄枸杞木虱若虫的搜寻效率参数a=0.9451,处理时间参数T_h=0.001865,整体优于卵、3～5龄若虫与成虫,且在每皿100头的猎物密度下七星瓢虫的最大捕食率能达80.2%,益害比参考值为1∶100.七星瓢虫对枸杞木虱的捕食作用受自身密度的影响显著大于种内干扰.在混合猎物密度为每皿100头下,七星瓢虫更偏好木虱成虫,在密度为每皿300头下,七星瓢虫更偏向于木虱若虫.表明七星瓢虫是很有控制潜力的捕食性天敌,人工释放七星瓢虫成虫可有效取食枸杞木虱初孵若虫,降低木虱为害.

Predation of Poratrioza sinica Yang & Li by the adults of Coccinella septempunctata.

To study predation by Coccinella septempunctata adults on 4 stages of Poratrioza sinica Yang & Li, predation functional response, mutual interference, density influence and preference of C. septempunctata on P. sinica were investigated in laboratory and preying effect in field. The study indicated that functional response of adult C. septempunctata to P. sinica could be fitted by Holling Ⅱ model, the daily maximum numbers of P. sinica eggs, 1^st-2^nd instar nymphs, 3^rd-5^th instar nymphs and adults preyed theoretically by the adult C. septempunctata were 112.6, 536, 415 and 113.9, respectively. In 30 days of adult’s life cycle, density of P. sinica inside cages could be decreased by 80.1% in the field. Searching efficiency of C. septempunctata to P. sinica 1^st-2^nd instar nymphs was 0.9451 and processing time was 0.001865, which were better than those of other stages. The maximum rate of P. sinica 1^st-2^nd instar nymphs preyed was 80.2% as the prey density was 100 heads per dish, so the ratio of predator: prey was 1:100. The density had a greater impact than mutual interference on C. septempunctata. When different stages of P. sinica co-existed equally, C. septempunctata preferred P. sinica adult in 100 heads per dish while P. sinica nymphs in 300 heads per dish. The study showed that C. septempunctata has the potential to be predator of P. sinica and the newly-hatched nymphs could be controlled more effectively by C. septempunctata adult in field.