## 1 Introduction  
Multitrophic interactions amongst host plants, herbivorous insects and natural enemies that feed on those herbivores can be tightly linked. Insect herbivores can produce a complex defensive response in their host plant [1]. A component of this response is the emission of volatiles that can play both a direct [1] and indirect defense [1] against plant pest. Such emissions are referred to as herbivore-induced plant volatiles (HIPVs). For insect herbivores, the indirect impact of HIPV involves attraction of the herbivores' natural enemies and the volatile response of plants can be unique to the species of herbivorous insects [2,3]. For example, a component of this response is methyl salicate (MeSA), which is released by soybean leaves when fed on by herbivores, such as spider mites (_Tetranychus urticae_ [PERSON]; [4]) and the soybean aphids (_Aphis glycines_ [PERSON] [5]). The invasion of _A. glycines_ introduced a new, economic pest to soybean production in the United States [6]. Both seed-applied and foliar-applied insecticides are the primary tools for preventing yield loss from _A. glycines_ in North America, resulting in a 130-fold increase in the their use for soybean production since the arrival of _A. glycines_ in the U.S. However, a recent U.S. Environmental Protection Agency (EPA) review of the benefits associated with seed-applied insecticides suggest that this tool has no benefit for soybeans production and more specifically for protection from _A. glycines_. Natural enemies can be a significant source of mortality for early summer populations of _A. glycines_ within the U.S. [7], but do not provide consistent biological control to completely replace insecticides. Recently, a field study using artificial sources of MeSA released in soybean fields resulted in a positive effect on the abundance of aphid predators and a negative impact on the abundance of _A. glycines_[8]. To what extent the positive impact of MeSA for the biological control of _A. glycines_ can be further improved with additional HIPVs is not clear. Manipulating predators by combining HIPVs can increase the attraction of predaceous insects, though this increase may involve non-induced volatiles as well [9]. Therefore, a survey of the volatiles produced by soybeans, both induced and non-induced may play a significant role in future studies of HIPVs for management of _A. glycines_. Several classes of volatiles have been identified from soybeans [10, 11, 12, 13] (Table 1) using either Tenax-GC adsorbent or solid phase microextraction (SPME). The use of SPME to sample plant volatiles is attractive for several reasons. Air sampling pumps and solvents are not needed, and the headspace around a material can be readily sampled without maceration or homogenization of the plant material [14]. SPME has been used to sample volatiles from various parts of the soybean plant. [PERSON] _et al._[10] used SPME to detect differences in volatiles emitted from soybean seeds collected at distinct developmental stages. By inserting SPME fibers within sealed vials containing unprocessed soybean seeds, 49 compounds were recovered, 19 of which had not been reported previously from soybeans. [PERSON] _et al._[13]collected volatiles using both SPME fibers and Tenax-GC adsorbent exposed to homogenized soybean leaves. The compounds identified using SPME were similar to those collected with sorbent Tenax [13]. The potential to expand upon the use of SPME in laboratory studies to field studies makes this method of volatile sampling attractive. We investigated the volatile response of soybeans to _A. glycines_ using Carboxen/polydimethylsiloxane (PDMS) 75 \(\upmu\)m SPME fibers. Our objective was to determine if SPME could be used to identify compounds associated with _A. glycines_-infested soybeans grown in the laboratory and in the field. We hypothesize that SPME fibers can detect significant differences in the volatiles released in soybean plants that are non-infested or infested with _A. glycines_.