What Is the Economic Threshold of Soybean Aphids (Hemiptera: Aphididae) in Enemy-Free Space?

Abstract

Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a serious pest of soybean, Glycine max (L.) Merr., in the North Central United States. Current management recommendations rely on the application of insecticides based on an economic threshold (ET) of 250 aphids per plant. Natural enemies are important in slowing the increase of aphid populations and can prevent them from reaching levels that can cause economic losses. However, biological control of A. glycines is inconsistent and can be affected negatively by the intensity of agricultural activity. We measured the impact of a natural-enemy-free environment on the capacity of the current ET to limit yield loss. In 2008 and 2009, caged microplots were assigned to one of three treatments: plants kept aphid-free (referred to as the control), plants that experienced a population of 250 aphids per plant (integrated pest management [IPM]), and plants that experienced unlimited aphid population growth (unlimited). The population growth rate of aphids in the unlimited treatment for the 10 d after the application of insecticides to the IPM treatment was calculated using linear regression. The linear equation was solved to determine the mean number of days between the ET and the EIL for an aphid population in absence of predators. The number of days was determined to be 6.97 ± 1.11 d. The 2-yr average yield for the IPM treatment was 99.93% of the control treatment. Our study suggests the current soybean aphid ET of 250 aphids per plant can effectively protect yield even if the impact of natural enemies is reduced. KeywordsAphis glycines, soybean, insecticide, economic threshold Disciplines Agriculture | Entomology CommentsThis article is from Journal of Economic Entomology, 104 (3) ABSTRACT Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a serious pest of soybean, Glycine max (L.) Merr., in the North Central United States. Current management recommendations rely on the application of insecticides based on an economic threshold (ET) of 250 aphids per plant. Natural enemies are important in slowing the increase of aphid populations and can prevent them from reaching levels that can cause economic losses. However, biological control of A. glycines is inconsistent and can be affected negatively by the intensity of agricultural activity. We measured the impact of a natural-enemyÐfree environment on the capacity of the current ET to limit yield loss. In 2008 and 2009, caged microplots were assigned to one of three treatments: plants kept aphid-free (referred to as the control), plants that experienced a population of 250 aphids per plant (integrated pest management [IPM]), and plants that experienced unlimited aphid population growth (unlimited). The population growth rate of aphids in the unlimited treatment for the 10 d after the application of insecticides to the IPM treatment was calculated using linear regression. The linear equation was solved to determine the mean number of days between the ET and the EIL for an aphid populatio...

Feeding Preference of Crapemyrtle Bark Scale (Acanthococcus lagerstroemiae) on Different Species

“…Economic thresholds (ET) of plant damages incurred by pest insects are widely used as advisory tools to determine action points for effective treatments [ 80 , 81 , 82 ]. One study showed that soybean aphid has an ET of 250 insects per plant [ 82 ], however, the ET could be lower for CMBS infesting ornamental crops, considering the negative effect on the aesthetic value resulting from defoliation, loss of flowering, and the accumulation of sooty mold [ 2 , 4 , 7 ].…”

Transcriptional responses of tolerant and susceptible soybeans to soybean aphid (Aphis glycines Matsumura) herbivory

“…Since the first introduction of the soybean aphid, Aphis glycines Matsumura, in the early 2000s, it has emerged as a major pest of soybeans. Aphids have now spread to 30 states and several south Canadian provinces (Hartman 2001;Alleman 2002;Venette and Ragsdale 2004;Beckendorf et al 2008;NAPIS 2011) and have caused considerable economic damage to soybean growers (NAPIS 2011;Ragsdale et al 2011;McCarville et al 2011;Ragsdale et al 2007;Venette and Ragsdale 2004). Different strategies have been developed to manage this pest including chemical, biological, and cultural control methods (Wang and Ba 1998;Wang et al 2000;Ostlie 2002;Hill et al 2004;Wu et al 2004;Rutledge and O'Neil 2006;Brosius et al 2007).…”

Effects of Temperature on Survival, Development, and Reproduction of Aphis glycines (Hemiptera: Aphididae) Autumnal Morphs

“…Summer morphs of A. glycines (virginoparae) have been extensively studied with a wealth of research articles on their population dynamics (Liu et al 2004;Fan et al 2017), natural enemies (Costamagna & Landis 2006;Desneux et al 2006;Dieckhoff & Heimpel 2010;Liu et al 2012), host plants (Sun et al 2015;Chen et al 2017;Wang et al 2019), economic thresholds (Ragsdale et al 2007;McCarville et al 2011), etc. However, there is only a limited number of studies dealing with autumnal morphs of A. glycines.…”