Crop Residue and Residue Management Effects on <I>Armadillidium vulgare</I> (Isopoda: Armadillidiidae) Populations and Soybean Stand Densities

Abstract

In general, Armadillidium vulgare (Latreille) are considered nonpests of soybean [Glycine max (L.) Merrill], but changes in soil conservation practices have shifted the pest status of this organism from an opportunistic to a perennial, early-season pest in parts of central Kansas. As a result, soybean producers that rotate with corn (Zea mays L.) under conservation tillage practices have resorted to removing excess corn residue by using controlled burns. In a 2-yr field study (2009-2010), we demonstrated that residue removal in burned compared with unburned plots (measured as previous crop residue weights) had minimal impact on numbers of live and dead A. vulgare, soybean seedling emergence, and isopod feeding damage over time. Specifically, removal of residue by burning did not result in higher emergence rates for soybean stands or less feeding damage by A. vulgare. In a separate study, we found that number of live A. vulgare and residue weights had no consistent relationship with seedling emergence or feeding damage. Furthermore, seedling emergence was not impacted by higher numbers ofA. vulgare in unburned plots, indicating that emergence in this study may have been influenced by factors other than A. vulgare densities. These studies demonstrate that removing residue through controlled burning did not impact seedling emergence in presence of A. vulgare and that residue and feeding damage to seedlings did not consistently relate to A. vulgare densities. Other factors that may have influenced a relationship between residue and live isopod numbers, such as variable moisture levels, are discussed.

Effect of agricultural practices on terrestrial isopods: a review

“…Studies in other continents show that a drought-tolerant species, such as A.vulgare , could have colonised croplands from field margins and boundaries: In Argentina, since the late 1990s A.vulgare has been an abundant and frequent species in agricultural land colonizing broad areas (Trumper and Linares 1999, Saluso 2004, Faberi et al 2011, Villarino et al 2012, Faberi et al 2014). Armadillidiumvulgare is also found in agricultural lands in Illinois and Kansas, USA (Byers et al 1983; Johnson et al 2012) and in the Gauteng Province of South Africa (Tribbe and Lube 2010). Porcellioscaber and Balloniscussellowii Brandt, 1833 are found although less frequently, the latter recorded only in Entre Rios Province, Argentina (Saluso 2004).…”

“…In agroecosystems, these functions are very important to allow the continuation of crop production. In agricultural systems, isopod populations must feed on dead crop residue and weeds (Johnson et al 2012). Different plant species are cultivated in field crops and these are sown and harvested in different seasons through the year.…”

“…The amounts of residues and soil cover thus decrease faster throughout the decomposition period with residues of soybean and sunflower than of wheat and maize. According to Johnson et al (2012) the reduction of maize residue levels had minimal impact on A.vulgare numbers. The density of A.vulgare was similar between fields with a litter layer of wheat and soybean.…”

“…The capacity of isopods to switch between feeding on dead and green living tissues, i.e., herbivorous feeding, in the field has been demonstrated for several decades. Different isopod species have been observed feeding on green living tissues of several plants even if they have another food source as a choice (Paris and Sikora 1965, Byers et al 1983, Szlávecz and Maiorana 1990, Hopkin 1991, Benetti et al 2002; Morisawa et al 2002; Paoletti et al 2008; Farmer and Dubugnon 2009; Tierranegra-Garcia et al 2010, Faberi et al 2011, Miller 2011, Johnson et al 2012, Faberi et al 2014, 2017). In addition, more recently isopods have been reported to exhibit granivory, i.e., feeding on seeds of weeds and crop plants, of some typical plants in agroecosystems (Saska 2008; Koprdová et al 2012, Salvio et al 2012).…”

“…The work addresses the question of what stops both species from attacking living plants and provides evidence that it is, in part, the jasmonate signal pathway. Additionally, when isopod populations increase in agroecosystems intra-specific competition among isopods is induced and in consequence may result in consumption of live plant material as is observed in A.vulgare (Paris and Sikora 1965, Trumper 2001, Saska 2008, Johnson et al 2012, Faberi et al 2014) and in Australiodillobifrons (Paoletti et al 2008).…”