New study just out shows that the full benefits of pollinators can only be realized in crops that have adequately controlled plant pests. Further, this fact is usually left out when the value of pollinators in increasing fruit yield is calculated.

Excerpts

We found evidence that suppression of lowbush blueberry fungal diseases and insect pests interacted with pollination of the crop to significantly increase fruit set and average ripe fruit weight. This interaction had two dimensions. First, the response of plant fruit set to increased pollination was highest in the presence of fungicides and insecticides. 

Second, when pollination was limited, low fruit set resulted in increased fruit weight, but only when fungicides and insecticides were used. Both findings suggest that yield effect due to loss of pollination in this crop is greatest when insect pests and diseases are controlled, or in other words, that increased pollination cannot compensate for losses from pests and diseases (Lundin et al., 2013). 

Our results agree with those of another recent study that suggests that the benefits accrued from pollination are linked to the pest and disease management of the plant (Lundin et al., 2013).

One of the broader implications of our findings is to call into question current approaches to estimating the financial value of benefits delivered by pollinating insects to agriculture. 

Rather than an attempt to calculate the marginal benefits of pollinators in concert with the marginal costs associated with these benefits, the traditional methodology essentially calculates the economic benefits lost if pollinators suddenly vanished, in essence under the circumstances of a pollinator ‘supply shock’ (Muth & Thurman, 1995). This approach completely discounts the contributions of other interacting inputs.

increased fruit set at harvest was only possible if 100% pollination was combined with the ‘full input’ treatment. Furthermore, increases in fruit weight among the remaining treatments were only realised in the ‘full input’ plots. These results suggest that the value accorded to pollinator activity in blueberries is strongly dependent upon pest and disease management of the crop.

A.P. Melathopoulos, P. Tyedmers & G.C. Cutler.  (2014)  Contextualising pollination benefits: effect of insecticide and fungicide use on fruit set and weight from bee pollination in lowbush blueberry. Annals of Applied Biology ISSN 0003-4746

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