Food quality of Ephestia eggs, the aphid Rhopalosiphum padi and mixed diet for Orius majusculus

We studied the food quality of the aphid Rhopalosiphum padi to the pirate bug Orius majusculus using Ephestia eggs as high‐quality comparison prey. Several performance parameters were tested on individuals that had been reared and maintained on each of the two single‐prey diets or on a mixed diet. All fitness parameters were lower in individuals fed aphids only, indicating poor food quality of this prey. Compared with the pure Ephestia egg diet, the mixed diet enhanced teneral mass, while adult survival and female starvation tolerance were negatively affected and all other traits were unaffected. Body protein proportions were constant across diets, whereas lipid proportion was low in the aphid treatment. Preference for aphids was lower following a monotypic aphid diet than when reared on Ephestia eggs or a mixed diet. The results confirm that R. padi is low‐quality food for O. majusculus as it is for other generalist predators, even though O. majusculus may contribute significantly to population suppression of the aphid.

本研究以麦蛾（Ephestia）卵作为优质对照猎物，探究麦二叉蚜（Rhopalosiphum padi）作为大眼花蝽（Orius majusculus）猎物的食物品质。本研究针对分别取食两种单猎物（麦二叉蚜、麦蛾卵）日粮及混合猎物日粮的试虫，测定了多项生长表现参数。仅取食蚜虫的试虫各项适合度参数（fitness parameters）均更低，表明该猎物的食物品质较差。与纯麦蛾卵日粮相比，混合日粮可提升试虫的初羽重（teneral mass），但会对成虫存活率及雌虫耐饥饿能力产生负面影响，其余性状则无显著变化。不同日粮处理下试虫的体蛋白占比均保持稳定，而蚜虫饲喂组的体脂占比偏低。取食单一蚜虫日粮的试虫对蚜虫的取食偏好性，低于取食麦蛾卵或混合日粮的试虫。本研究结果证实，麦二叉蚜（Rhopalosiphum padi）对大眼花蝽（Orius majusculus）而言属于低品质猎物，其对其他广食性捕食者亦然；尽管大眼花蝽可对该蚜虫种群起到显著的抑制作用。