Biological control is one of the strategies to reduce populations of diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), the major pest of brassica. Entomopathogen-based biopesticides are recommended and used for its control, reducing the constant use of chemical pesticides. Predators and/or fungal entomopathogens have an increasing interest to be used against diamondback moth, and the compatibility of these control agents in the field is important for pest management. Here we experimentally investigate the effects of diamondback moth larvae treated with a biopesticidal formulation of Beauveria bassiana (Balsamo) Vuillemin in the feeding preference and functional response of the ring-legged earwig. We used untreated and B. bassiana-treated diamondback moth fourth instars (over a 24-h period of exposure) and Euborellia annulipes (Lucas) fifth instars. The nymphs were included in choice condition tests and different larval densities to the analysis of feeding preference and functional responses, respectively. Euborellia annulipes nymphs exhibited no feeding preference under choice conditions but presented different types of functional response: Type II on untreated and type III on fungus-treated diamondback moth larvae. The interaction between E. annulipes and B. bassiana observed in our study contributes to the understanding of the predator–prey–pathogen relationships with implications for P. xylostella integrated management strategies.

Rose crops are attacked by many pests, including mealybugs. Although Planoccocus citri is not registered as a main pest of roses in Brazil, it is an increasing problem on roses inside greenhouses. Chrysoperla externa and Cryptolaemus montrouzieri are options against P. citri and other pests on roses, however using two predators in biological control programs may face problems like intraguild predation. This work aimed to assess the consumption of 1 st instar nymphs and adult females of P. citri by adults of C. montrouzieri and 3 rd instar larvae of C. externa, as well as the interaction between these predators when confined together. The following treatments were performed with ten replications in a completely randomized design: 1 -C. externa + 200 nymphs of P. citri; 2 -C. externa + 10 adults of P. citri; 3 -C. montrouzieri + 500 nymphs of P. citri; 4 -C. montrouzieri + 15 adults of P. citri. Each replication was set on rose leaflets inside a Petri dish (9cm Ø). Intraguild interaction was assessed by releasing both predators inside dishes containing 700 nymphs of P. citri. Before the releases, predators stayed 24 hours without food. We evaluated the prey consumption and intraguild predation for three hours. C. externa consumed significantly less (85,4±2,99) nymphs than did C. montrouzieri (387,0±3,02). There was no difference in adult mealybugs consumed, with an average of 1,85±0,19. No intraguild predation was observed, and an increase of 11,8% in consumption was observed when predators were released together compared to the scenario of no competition.