Ecological Interactions Affecting the Efficacy of Aphidius colemani in Greenhouse Crops

Abstract

Aphidius colemani Viereck (Hymenoptera: Braconidae) is a solitary endoparasitoid used for biological control of many economically important pest aphids. Given its widespread use, a vast array of literature on this natural enemy exists. Though often highly effective for aphid suppression, the literature reveals that A. colemani efficacy within greenhouse production systems can be reduced by many stressors, both biotic (plants, aphid hosts, other natural enemies) and abiotic (climate and lighting). For example, effects from 3rd and 4th trophic levels (fungal-based control products, hyperparasitoids) can suddenly decimate A. colemani populations. But, the most chronic negative effects (reduced parasitoid foraging efficiency, fitness) seem to be from stressors at the first trophic level. Negative effects from the 1st trophic level are difficult to mediate since growers are usually constrained to particular plant varieties due to market demands. Major research gaps identified by our review include determining how plants, aphid hosts, and A. colemani interact to affect the net aphid population, and how production conditions such as temperature, humidity and lighting affect both the population growth rate of A. colemani and its target pest. Decades of research have made A. colemani an essential part of biological control programs in greenhouse crops. Future gains in A. colemani efficacy and aphid biological control will require an interdisciplinary, systems approach that considers plant production and climate effects at all trophic levels.

Optimizing aphid biocontrol with the predator Aphidoletes aphidimyza, based on biology and ecology

“…It is also necessary to deepen our understanding of how chemicals used in greenhouse production affect the population dynamics of A. aphidimyza ; even those considered as ‘compatible’ by current IOBC standards may cause sublethal or latent effects …”

“…37,109 It is also necessary to deepen our understanding of how chemicals used in greenhouse production affect the population dynamics of A. aphidimyza; even those considered as 'compatible' by current IOBC standards may cause sublethal or latent effects. 110 The greenhouse environment has also seen rapid technological change in recent years, including the use of LED lights (with different emission spectra/heat signatures to traditional high-pressure sodium lamps), as well as CO 2 supplementation and changes that are likely to come in the face of climate change and in response to the rising cost of heating and cooling. For example, horticulture scientists in the north-eastern USA have been experimenting with growing ornamentals at cooler temperatures to save on heating costs in cooler months, and dynamic climate regimes are being explored as ways to reduce costs or boost production.…”

Identification of Conditions for Successful Aphid Control by Ladybirds in Greenhouses

“…Aphid parasitoids are sometimes used for this purpose [14]; in recent years, mass-reared hymenopteran parasitoids (Family Aphidiidae, and Family Aphelinidae) have become the option of choice, rather than predators [15,16]. However, there are several drawbacks to using aphid parasitoids.…”

Biological Control Outcomes Using the Generalist Aphid Predator Aphidoletes aphidimyza under Multi-Prey Conditions

“…More testing is needed to confirm this quantitatively, though weekly or biweekly preventative releases is how this biocontrol agent is generally employed in ornamental/vegetable greenhouse crops for aphid control in North America [7]. With our current understanding of this natural enemy, under current greenhouse growing conditions, the best use of A. aphidimyza in a curative capacity may be to augment control by more specific aphid natural enemies (e.g., parasitoids such as Aphidius colemani and A. ervi , which are not considered 100% reliable for aphid control in greenhouse crops either) [39,40]. More research is needed into factors that optimize or reduce the performance of A. aphidymza in greenhouses (e.g., host-plant effects, climate, risks of intra-guild predation, etc.)…”