异色瓢虫对苜蓿上豌豆蚜和牛角花齿蓟马的捕食效能及捕食偏好性

Predatory Functional Response and Predation Preference of Ladybeetle Harmonia axyridis to Acyrthosiphon pisum and Odontothrips loti on Alfalfa

异色瓢虫是我国苜蓿重要的天敌昆虫,豌豆蚜和牛角花齿蓟马是严重为害苜蓿的刺吸类害虫。为探究异色瓢虫对豌豆蚜和牛角花齿蓟马的生防潜力,室内测定了异色瓢虫1~4龄幼虫和雌成虫分别对豌豆蚜2~3龄若蚜和牛角花齿蓟马成虫的捕食功能反应及猎物捕食偏好性。结果表明,不同龄期的异色瓢虫对两种害虫的捕食功能反应均符合HollingⅡ模型。异色瓢虫4龄幼虫对豌豆蚜2~3龄若蚜的捕食能力最强,雌成虫次之,异色瓢虫1~3龄幼虫的捕食能力随龄期减少而逐渐降低。另外,异色瓢虫雌成虫对牛角花齿蓟马成虫的捕食能力最强,其次为4龄幼虫,3龄幼虫和2龄幼虫的捕食能力较弱。不同龄期的异色瓢虫分别对豌豆蚜2~3龄若蚜和牛角花齿蓟马成虫的搜寻效应均随猎物密度的增加而降低。当猎物豌豆蚜若蚜和牛角花齿蓟马成虫以3种不同数量比例(豌豆蚜:蓟马=40:80头、60:60头、80:40头)共存时,异色瓢虫4龄幼虫对猎物的选择性指数(D)均大于1,表明4龄幼虫对豌豆蚜表现较强的正捕食偏好性;但异色瓢虫雌成虫对猎物的选择性指数均小于1,表明雌成虫对两种猎物无明显的捕食偏好。综上表明异色瓢虫对苜蓿豌豆蚜若蚜和牛角花齿蓟马成虫具有较好的控制能力,尤其是异色瓢虫4龄幼虫与雌成虫对两种猎物具有很强的捕食能力且优于1~3龄幼虫。当两种猎物共存时,异色瓢虫4龄幼虫偏好取食豌豆蚜2~3龄若蚜。

The multicolored Asian ladybird beetle Harmonia axyridis is an important predatory natural enemy in alfalfa fields in China.The pea aphid Acyrthosiphon pisum and the thrip Odontothrips loti are two serious piercing-sucking pests in alfalfa fields.In this study,predatory functional response and predation preference were measured to clarify the biological control potential of H.axyridis towards A.pisum and O.loti.Briefly,the2~(nd)—3~(rd) instar nymphs of A.pisum and adults of O.loti were provided as prey for 1~(st)—4~(th) instar larvae and the female adults of H.axyridis,respectively.The results showed that the predatory functional response of the larvae and female adults of H.axyridis feeding on both of two prey species fitted with the HollingⅡmodel.Feeding on A.pisum nymphs,the 4~(th) instar larvae of H.axyridis displayed the highest predation ability,followed by the female adults.Meanwhile,the predation ability of the 1~(st),2~(nd),and 3~(rd )instar larvae gradually decreased with the reduction of developmental stage.When feeding on O.loti adults,the female adults of H.axyridis exhibited the highest predation ability,followed by the 4~(th) instar larvae,while the 2~(nd) and 3~(rd) instar larvae showed relatively low predation ability.Feeding on A.pisum nymphs and O.loti adults,the searching efficiency of the 1~(st)—4~(th) instar larvae and female adults of H.axyridis decreased with increasing prey density.When H.axyridis 4~(th) instar larvae and female adults were fed A.pisum nymphs and O.loti adults at different ratios (40:80,60:60 and 80:40),the 4~(th) instar larvae preferred A.pisum with a predation preference index (D)1,whereas the female adults showed no preference with a predation preference index (D)1.In conclusion,H.axyridis has great control ability against the2~(nd)—3~(rd) instar A.pisum nymphs and O.loti adults,and the 4~(th) instar larvae and female adults exhibit especially higher predation capability compared to the younger larvae.The 4~(th) instar larvae of H.axyridis prefer A.pisum nymphs when they coexisted with O.loti adults.