Flower strips enhance predators in sugar beet fields

Aphids, Aphis fabae Scopoli and Myzus persicae Sulzer are important pests of sugar beet, causing direct damage through phloem feeding as well as transmitting Beet Yellows Virus (BYV). Both species have a very broad host range including many wild plant species. As chemical control options are increasingly constrained by insecticide resistance and legislation, it is crucial to find alternative methods of pest regulation. Conservation biological control can be used to augment natural enemy populations in arable fields by manipulating the ecological infrastructure around the field. This study investigated highly diverse, native flower strips for conservation biological control in sugar beet crops. A split plot design was used to compare the effects of flower strips with a grass margin control. Assessments of aphids and natural enemies were conducted in three transects in each treatment, at 2, 6, 12 and 24 meters from the margin. Abundance and species richness of foliar predators was found to be higher near the flower strip up to 12m from the margin. Myzus persicae was generally scarce in the fields, with no effect of the flower strip in either year, and no symptoms of BYV were found in any of the fields. The mean colonization by A. fabae was significantly higher adjacent to the flower strip in 2023 but did not exceed the damage threshold in either treatment. The aphid to predator ratio was significantly lower on plants adjacent to flower strips in 2022, indicating that flower strips enhanced predator abundance relative to aphid populations. The present study shows that flower strips promote foliar predator populations in the adjacent fields and can lead to a higher predator to aphid ratio indicating an aphid control potential but did not significantly affect the already low aphid densities in the two years of study.