Facultative predation of Apolygus lucorum on Aphis gossypii

The polyphagous plant bug, Apolygus lucorum (Hemiptera: Miridae) is a key pest of several agricultural crops in China, including cotton, Chinese date and grape. With occasional reports of A. lucorum preying upon small insects and insect eggs, this mirid is thought to be zoophytophagous. In this study, we explored A. lucorum feeding habits under laboratory and field conditions. In the laboratory, predation of A. lucorum on the cotton aphid (Aphis gossypii) corresponded to a Holling type II functional response. Predation levels did not differ between male and female individuals. Also, A. lucorum nymphs did not successfully develop into adults when solely fed A. gossypii, in comparison to nymphs that were allowed access to cotton leaves. Nymphal survival rate when solely offered plant material was much lower than on the mixed diets. In addition to laboratory experiments, we screened for evidence of A. gossypii feeding amongst field-collected mirids. A specific A. gossypii primer was designed using cytochrome oxidase subunit (COI) gene. Among 309 A. lucorum adults collected from cotton fields, A. gossypii target DNA was found in 17 individuals, amounting to 5.5%. The above results demonstrate the zoophytophagous nature of A. lucorum and constitute a basis for further assessment of the ecological role of A. lucorum in other agricultural systems.