Opius scabriventris (Hymenoptera: Braconidae) is considered an important parasitoid of the leafminer Liriomyza sativae (Diptera: Agromyzidae) in the main melon (Cucumis melo L.) producing areas in Brazil. However, there is no information on the influence of trichomes on melon plant leaves on the parasitoids’ actions. Therefore, the aim of this investigation was to relate the influence of columnar trichome density on melon cultivars in the parasitism of L. sativae larvae by O. scabriventris. The study was conducted in laboratory conditions, in which melon cultivars were infested and the leafminer larvae were subjected to the parasitism. The results demonstrated that trichome density can influence the parasitism of L. sativae larvae by O. scabriventris. Among the studied materials, Piel de Sapo cultivar showed the highest density of trichomes in the leaves (534 trichomes/cm2) and the lowest parasitism (20%).

Opius scabriventris Nixon is an important parasitoid of the leafminer Liriomyza sativae Blanchard in the melon crop (Cucumis melo L.). Knowing the impact of insecticides on this parasitoid may help the integrated pest management, thus allowing recommending insecticides with a lower impact. Therefore, this study evaluated lethal and sublethal toxicities of select insecticides used in the melon crop for controlling leafminers on the O. scabriventris parasitoid. The toxicity of the insecticides was assessed by confining adults of the parasitoid on freshly sprayed plastic containers, under laboratory conditions. The evaluated insecticides were abamectin, chlorantraniliprole, cyromazine, spinetoram, spinosad, in addition to the negative control treatment (distilled water). The sublethal effect of the insecticides was studied through the parasitism of leafminer larvae by surviving parasitoids. Among the evaluated insecticides, abamectin, spinetoram and spinosad were the most toxic to O. scabriventris; while chlorantraniliprole and cyromazine demonstrated low toxicity to the parasitoid, albeit causing reduction in its parasitism capacity.

Knowledge of diversity of natural enemies in agroecosystems is vital for the integrated pest management. However, surveys of beneficial insects (predators and parasitoids) in the melon crop (Cucumis melo L.) in the semiarid region in Brazil are scarce. Thus, the objective of this study was to know the families of predator insects associated with melon crop in a semiarid region in the state of Rio Grande do Norte (RN), one of the main melon producers in Brazil. The survey study was carried out in a commercial melon area, in the municipality of Baraúna (RN). The samples were collected weekly during the cycle of melon, using passive (Pitfall and Moericke traps) and active (sweep net) collection methods. A total of 13 families of predator insects were collected. The families with the highest relative abundances in the passive collection method were Labiduridae (89.53%) and Formicidae (6.91%), while in the active collection method were Chrysopidae (59.81%) and Staphylinidae (20.56%). These families contain important species of predator which can promote crop pest suppression in melon agricultural systems.