The effect of within-crop floral resources on pollination, aphid control and fruit quality in commercial strawberry

Dual ecosystem services of syrphid flies (Diptera: Syrphidae): pollinators and biological control agents

“…Despite encouraging laboratory results, few field and glasshouse studies have demonstrated a direct reduction of aphid numbers as a result of syrphid predation . Instead, most studies use the presence of syrphid eggs or adults as a proxy for predation under the assumption that a higher density of syrphids necessarily results in lower pest numbers. Of more concern, several studies have found that the number of syrphids in a field is too low or too variable to reduce pest numbers effectively .…”

“…Recent field studies have focused on attracting syrphid adults into crops by planting floral resources . Flowers such as buckwheat ( Fagopyrum esculentum ), cornflower ( Centaurea cyanus ), alyssum ( Lobularia maritima) , coriander ( Coriandrum sativum ), and mint ( Mentha spicata ) are attractive to syrphid adults .…”

“…Flowers such as buckwheat ( Fagopyrum esculentum ), cornflower ( Centaurea cyanus ), alyssum ( Lobularia maritima) , coriander ( Coriandrum sativum ), and mint ( Mentha spicata ) are attractive to syrphid adults . However, syrphid fecundity, larval density and aphid suppression were not affected when additional floral resources were grown on land adjacent to the cropped lands . This may be because of the differing dietary needs of adult and larval syrphids that complicates attempts to provide a syrphid‐promoting habitat.…”

“…Adult female syrphids will make a decision to oviposit in an area more suitable for the larvae over her own requirement or desire for floral resources (nectar and pollen) . Thus, aphid population and density, rather than floral resources available and attractive to adult females, directly affect ovipositional choice and subsequent syrphid larval density . As such, if the goal is to incorporate extra floral resources to encourage adult females to oviposit, and thus benefit from the predatory larvae, then planting extra floral resources is likely not the best method.…”

“…The effectiveness of syrphid pollination in agro‐ecosystems has primarily been examined in horticultural plants in glasshouses, with some more recent studies undertaken in field or semi‐field conditions . Controlled pollination experiments have shown that syrphids, predominantly Eristalis tenax , are useful in increasing seed production of some food crops such as onion, oilseed rape ( B. napus ), sweet pepper ( Capsicum annuum ), strawberry ( Fragaria × ananasa ), and a variety of wild plants . For example, in a glasshouse experiment, sweet pepper ( Capsicum annuum ) plants that were visited by Eristalis tenax had more abundant fruit and higher seed set than the sweet pepper plants that were not visited …”