Flower strips promote natural enemies, provide efficient aphid biocontrol, and reduce insecticide requirement in cotton crops

Manipulating border flower strips is an effective method of conservation biological control , and can promote natural enemies and boost biocontrol services in agroecosystems. However, few studies have compared the effectiveness of flower strip establishment versus chemical control , and how far from border strips into fields does pest control remain efficient. We conducted a two-year experiment in cotton plots to compar e three pest management measures for cotton aphids in China: (1) sown border s of flower strips , (2) chemical control using imidacloprid with border flower strip replaced by a cotton strip, and (3) control treatment: no insecticide applications and border flower strip replaced by a cotton strip. We monitored the abundances of aphids and natural enemies in border strips and at different distances away from border strips into cotton plots. Abundances of cotton aphids' natural enemies including ladybeetles , predatory bugs, lacewings, and hoverflies were significantly higher in border flower strips than in border cotton strips. Importantly, aphid abundances were lower in cotton plots with flower strips than cotton plots treated chemically in 2020 , and about similar in 2021. They were also lower by 57 % and 34 % compared to the control plots in 2020 and 2021 , respectively . Moreover, efficient pest suppression in cotton plots with flower strips was achieved as far as 10.5-14.6 m away from the strip into the plots (the maximum distance sampled). Our study demonstrates a high degree of effectiveness of flower strips in promoting natural enemy abundances and aphid suppression, and reducing the need for insecticide use in cotton crops.