Involvement of Gonolabis distincta in the Control of Root Maggots in Garlic Fields

Garlic root maggots are the main pest of garlic in Qi County, Henan Province, China, which has become an important factor restricting the development of the garlic industry. Earwigs play an important role in controlling root maggots because of their similar ecological niches. In this study, through DNA barcoding and morphological identification, the following root maggots and main earwigs species from Qi County were quickly identified: Delia platura (Meigen), Bradysia odoriphaga Yang et Zhang, Delia antiqua (Meigen), Muscina angustifrons (Loew), Lucilia sericata (Meigan), and the main species of earwigs was Gonolabis marginalis (Dohrn). D. platura was the dominant species and accounted for 98% among all garlic root maggots. The predation ability for each stage of G. distincta on the larvae and pupae of D. platura showed that G. distincta at different developmental stages preyed on both the the larvae and the entire pupae of D. platura. Among them, female adults had the strongest predation ability and the largest daily predation on first instar larvae of gray D. platura (71.25 ± 0.66). First instar nymphs of G. distincta also had a certain predation ability with the daily predation of first instar larvae being (1.85 ± 0.13). The predation ability of G. distincta at different instars on the larvae of the same instar of D. platura increased with the increasing of the instar. For the first to second instar larvae of D. platura, the female adult of G. distincta had the strongest predation ability, followed by the male adult of G. distincta, and then the fifth instar nymph of G. distincta. There was no significant difference in the predation ability between the male and female adults of G. distincta, but the adults' predation capacities were significantly higher than that of the fifth instar nymph of G. distincta. The capacity of the fifth instar nymph of G. distincta was significantly higher than the fourth instar nymph of G. distincta, the fourth instar nymph of G. distincta was significantly higher than the first to third instar nymphs, and there was no significant difference in the predation amount among the first to third instar nymphs. The predation selection experiment indicated that the fifth instar nymphs and the male and female adults of G. distincta showed a positive preference for the first to third instar larvae of D. platura and a negative preference for the pupae of D. platura. Our study provided a preliminary scientific basis for green prevention and control of garlic root maggot.