An inventory of parasitic Hymenoptera in banana plantations under two pesticide regimes

To evaluate the impact of pesticides used in banana cultivation on beneficial invertebrates, parasitic Hymenoptera were inventoried in six plantations that received conventional applications of herbicides, nematicides, fungicides and insecticides and in two plantations under low-input treatments. To put banana into perspective relative to other monocultures, parasitic Hymenoptera were compared with those found in four other crops: citrus, heart of palm, macadamia and Gmelina arborea. Over 7800 female parasitoids were collected in the inventory. Parasitoid abundance and species richness were greatest in low-input banana, intermediate in the four other monocultures and lowest in conventional banana. Parasitoid abundance and species richness were inversely related to rates of nematicide and insecticide application. Banana plantations had a characteristic parasitoid fauna distinct from the other crops, but there was no distinct parasitoid community associated with low-input vs. conventional banana. Differences in parasitoid richness among farms were not related to: (1) abundance of parasitoids at each site, (2) plantation size or age, and (3) parasitoid host affinities. These results are discussed in the context of historical lepidopteran outbreaks in banana associated with pesticide induced upsets of natural enemy control, and recommendations are offered about how pest management might be altered to minimize impacts on hymenopteran parasitoids.