棉铃虫和烟青虫初孵幼虫对植物顶尖嫩叶的偏好性差异

棉铃虫和烟青虫是一对除寄主范围以外差异极小的近缘种,目前初孵幼虫取食选择对决定两者寄主谱所起的作用尚不明确。为此,本试验选取16种植物(烟草、番茄、辣椒、茄子、棉花5种是共同寄主;月季、菠菜、甘蓝、大葱4种是非寄主;玉米、大豆、花生、黄瓜、胡萝卜、西芹、黑杨7种是棉铃虫寄主),在培养皿两侧分别放入植物顶尖嫩叶和滤纸对照,在中间放置初孵幼虫进行选择,每隔10min观察记录一次结果,持续24h,2h后选择结果呈稳定趋势。结果表明棉铃虫初孵幼虫取食选择范围广,选择玉米、茄子、烟草、大豆、黄瓜、胡萝卜、菠菜、番茄、棉花、西芹、花生、辣椒、大葱这13种植物,这些植物除菠菜和大葱外均为已报道的棉铃虫寄主植物。而烟青虫初孵幼虫取食选择范围窄,选择甘蓝、大豆、烟草、茄子、西芹、番茄6种植物,其中烟草、茄子和番茄为已报道的烟青虫寄主植物。此外,棉铃虫初孵幼虫在除甘蓝外其他植物上的选择率均高于烟青虫,其具备取食多种植物的能力。两者初孵幼虫取食选择对确定各自寄主谱范围做出了重要贡献,但不能完全限定寄主谱,其仍然具备取食寄主谱以外其他植物的能力。

Differences in neonates'host plant preference between Helicoverpa armigera and Helicoverpa assulta

Helicoverpa armigera and H .assulta are a pair of closely-related sister species with a very different host range.It remains elusive whether host plant selection by neonates is a major contributor to their difference in host range.To address this question,we placed neonates of each species in the center of petri dish and observed neo-nates’choice between filter paper (control)and leaf of any of 16 plants that are hosts (tobacco,tomato,red pep-per,eggplant and cotton),non-hosts (China rose,spinach,cabbage and welsh onion)of both species,or hosts of H .armigera (corn,soybean,peanut,cucumber,carrot,celery,and poplars)at every 10 minutes,respectively. Neonates of both species made their choices at 2 h after being placed in the center of a petri dish.H .armigera se-lected 13 out of the 16 plants,including 11 host plants (corn,eggplant,tobacco,soybean,cucumber carrot,to-mato,cotton,celery,peanut and red pepper)and 2 non-host plants (spinach and welsh onion)of this species.By contrast,H .assulta neonates chose only 6 out of the 16 tested plants,including 3 host (tobacco,eggplant and to-mato)and 3 non-host (cabbage,soybean and celery)plants of this species.Moreover,H .armigera neonates had higher selection rate than H .assulta neonates on all the 16 plants except for cabbage.The observed obvious cor-relation between the plant ranges selected by neonates of the two Helicoverpa species and their host range suggests that host plant selection by neonates is an important contributor to their difference in host range.But selection of non-host plants by neonates of both species indicates that host plant selection by neonates is not the only limiting factor to the host range of both species.