Modeling Distribution and Abundance of Soybean Aphid in Soybean Fields Using Measurements From the Surrounding Landscape

Abstract

Soybean aphid (Aphis glycines Matsumura) is a severe pest of soybean in central North America. Outbreaks of the aphid in Ontario are often spotty in distribution, with some geographical areas affected severely and others with few or no aphid populations occurring in soybean for the duration of the season. A. glycines spend summers on soybean and overwinter on buckthorn, a shrub that is widespread in southern Ontario and is commonly found in agricultural hedgerows and at the margins of woodlots. A. glycines likely use both short distance migratory flights from buckthorn and longer distance dispersal flights in the search for acceptable summer hosts. This study aims to model colonization of soybean fields by A. glycines engaged in early-season migration from overwintering hosts. Akaike's information criterion (AIC) was used to rank numerous competing linear and probit models using field parameters to predict aphid presence, colonization, and density. The variable that best modeled aphid density in soybean fields in the early season was the ratio of buckthorn density to field area, although dramatic differences in relationships between the parameters were observed between study years. This study has important applications in predicting areas that are at elevated risk of developing economically damaging populations of soybean aphid and which may act as sources for further infestation.

Biology and Economics of Recommendations for Insecticide-Based Management of Soybean Aphid

“…Soybean fields should be scouted on a regular basis because soybean aphid populations can increase rapidly (Hodgson et al 2012;McCornack et al 2004;Ragsdale et al 2007), particularly when winged aphids migrate within and between fields (Costamagna et al 2013). Early-season (i.e., May through mid-July) scouting should focus on fields that have histories of early colonization by soybean aphids, particularly early-planted fields and fields near buckthorn, Rhamnus spp., the overwintering host of soybean aphid (Bahlai et al 2010). More fields should be scouted as soybean aphid populations develop throughout the growing season and plants begin to enter reproductive (R) stages.…”

Evolution of Soybean Aphid Biotypes: Understanding and Managing Virulence to Host-Plant Resistance

“…Of the aphids that remain on buckthorn, alates are eventually formed, perhaps by a density dependant mechanism , and migrate to soybean fields. The colonization of soybean from buckthorn remains complicated in both the timing and the influence of landscape, particularly the proximity to buckthorn Bahlai et al 2010). Ragsdale et al (2004) noted that colonization occurred in only 4 of 42 locations of soybean aphid infested buckthorn stands that contained potted soybean plants.…”

“…Random mortality during the spring colonization of soybean suggests that colonization of soybean may be restricted or most important at small spatial scales, dependant on buckthorn abundance and proximity. Using population dynamic modeling and the Akaike's information criterion (which compares the likelihood of competing models), Bahlai et al (2010) showed that, indeed, the presence or absence of buckthorn was highly related to soybean aphid colonization, and the estimated number of buckthorn shrubs best predicted aphid density, although the distances explored were less than 5km. As soybean aphids likely use both short and long distance dispersal (Zhang et al 2008;Michel et al 2009) expanding these models across larger distances would improve the ability of identifying buckthorn source populations for soybean colonization.…”

“…distribution of buckthorn) the likelihood of virulent genotypes spreading may be low. While the movement and migration patterns of the soybean aphid are becoming clearer (Michel et al 2009;Bahlai et al 2010), a lack of understanding on the genetics of virulence hinders the ability to accurately predict hostplant resistance sustainability.…”

Modelling the spread of European buckthorn in the Region of Waterloo

“…In the 2003 soybean aphid outbreak in Iowa it has been estimated that more than a quarter of a billion dollars was lost due to lost yield and spraying costs (Pilcher et al, 2005). A study by Bahlai et al, (2010) found that the ratio of buckthorn density to field area was the most important factor for predicting the early-season density of soybean aphids. Buckthorn is considered to be an important source for oat crown rust spores in temperate areas (Heimpel et al, 2010;United States Department of Agriculture, 2008).…”