A Malaise trap modification for targeted passive sampling of Aphidiinae (Hymenoptera: Braconidae)

Parasitoid wasps in the subfamily Aphidiinae (Hymenoptera: Braconidae) are aphidophagous predators that provide biological control of native and introduced aphid (Homoptera: Aphidoidea: Aphididae) species in a variety of natural, field, and greenhouse settings. Aphidiine wasps are normally best collected by gathering aphid colonies and rearing the adult parasitoids. Because they are aphid-obligate parasitoids, this collecting method allows for targeted active sampling that is directed at confirming the hosts and host plants, and allows for observations of parasitoid behavior and biology in the field. Malaise traps are the primary passive trapping method for collecting aphidiines in the field but trap samples can quickly become overburdened with non-target insects which drastically increases sample sort time, cost per specimen, and increases the potential damage to specimens caused by non-target insects. Here, Townes-style Malaise traps were modified with a mesh exclusion panel to target small aphid-parasitoid wasps of the subfamily Aphidiinae (Hymenoptera: Braconidae) in soybean (Glycine max L.) and adjacent fields. The addition of a mesh excluder greatly increased the number of recoverable and higher quality specimens of wasps, and reduced the number of medium to large-sized non-target insects in samples, prevented preservative dilution caused by excess non-target organisms, minimized damage to the small parasitoids, and reduced overall sample sort time and labor costs.