The efficacy of biological control of Greenhouse whitefly ( Trialeurodes vaporariorum Westwood (1856) (Hemiptera: Aleyrodidae) by three natural enemies, Encarsia formosa Gahan (1924), Eretmocerus warrae Naumann & Schmidt (2000) (Hymenoptera: Aphelinidae) and Nesidiocoris tenuis Reuter (1895) (Hemiptera: Miridae), may be reduced by interactions between the species. I quantified host discrimination between the parasitoids through examination of multiparasitism (interspecific), superparasitism (intraspecific), and selfsuperparasitism (on own parasitism). The choice to host feed increases adult resources, whilst reducing oviposition resources. Host feeding contributes to whitefly control, but may destructively interfere with parasitoid population sizes. I report the level of host feeding and feeding preferences on parasitized and nonparasitized nymphs by the parasitoids. Comparative control by the two parasitoids, separately and together, is presented to determine if multiple or single introductions are more effective to achieve control. Feeding preferences by the omnivorous predator, N. tenuis, were analysed for potential interference on the establishment of En. formosa.

Laboratory choice experiments were conducted, using all parasitoid combinations (pairs of interspecifics, conspecifics, or the same parasitoid), where females had to choose between nonparasitized or parasitized whitefly nymphs, with treatments of a delay between the first and second parasitoids of 0 or 1 hr, or 1 day. All combinations showed the ability to host discriminate, and a preference for feeding and ovipositing on nonparasitized whitefly nymphs. Multiparasitism occurred in 19%, superparasitism in 7% and self-superparasitism in 4% of ovipositions by the parasitoids. Laboratory choice tests were conducted using N. tenuis, with a choice between parasitized or nonparasitized whitefly nymphs or pupae. These tests showed no preference between feeding on parasitized or nonparasitized whitefly nymphs, indicating N. tenuis may impact on En. formosa establishment. Caged tomato plants, in a greenhouse, were inoculated with whitefly; parasitoids were then released into the cages using a full factorial design, with four replicates of all treatments. All combinations of parasitoids decreased whitefly numbers relative to control, with no significant difference between the treatments. This demonstrates that En. formosa and Er. warrae are compatible as biological control agents in multiple introductions.

Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25-50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.