Parasitism of Autumnal Morphs of the Soybean Aphid (Hemiptera: Aphididae) byBinodoxys communis(Hymenoptera: Braconidae) on Buckthorn

Abstract

Ann, Entomol. Soc. Am, 104(5): 935-944 (2011); DOI: 10,1603/AN10172 ABSTRAGT The soybean aphid. Aphis glydnes Matsumura (Hemiptera: Aphididae), is both heteroecious and holocyclic, seasonally alternating between buckthorn {Rhamnus spp.), (the primary, overwintering host) and soybean, Glydne max (L.) Merr, (the secondary host). Recently, a classical biological control program for this invasive pest has been implemented in Norih America using the Asian aphidiine braconid wasp Binodoxys communis Gaban. Two critical, related questions regarding the overwintering biology of B, communis are 1) does the para.sitoid maintain fidelity to A. glydnes throughout the aphid life cycle and follow it to its primary host; and, if it does, 2) is parasitoid migration facilitated by phoretic movement within buckthorn-specific winged aphids? In the laboratory, we compared B. communis parasitism on several different autumnal morphs of A. glydnes: winged gynoparae (fall migrants) and their oviparous offspring on buckthorn, fourth-instar alatoid nymphs that would form either gynoparae or summer migrants on soybean, and third-instar gynoparous alatoid nymphs on soybean. We also introduced gynoparae and B. communis onto caged buckthorn plants in southeastern Minnesota to examine autumnal parasitism under natural conditions. In both the laboratory and field, parasitism rates of oviparae were much higher than those of gynoparae. In addition, B. communis rarely completed development on fourth-instar alatoid nymphs. Although wasps successfully developed on third-instar gynoparous nymphs, these hosts mummified before forming wings. These results suggest that although at least one buckthorn-specific morph of A. glydnes seems suitable for B. communis parasitism, it is unlikely that alate-mediated dispersal of immature parasitoids is an adaptive strategy to locate Rhamnus in this species.

Sex‐specific dispersal by a parasitoid wasp in the field

“…Alternatively, females could be reacting to increased proportions of winged A. glycines in soybean during early and mid‐August, which constitutes the peak summer migration period for this aphid (Schmidt et al., ). Laboratory studies have shown that B. communis performs poorly on A. glycines alates (Wyckhuys et al., ; Asplen et al., ), such that emigration could be a response to decreasing host quality.…”

“…Here, we examined sex‐specific dispersal behavior in the open field by Binodoxys communis (Gahan) (Hymenoptera: Braconidae: Aphidiinae: Trioxini), a solitary endoparasitoid wasp recently imported to North America from Asia as a biological control agent against the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae: Aphidinae: Aphidini) (Heimpel et al., ; Ragsdale et al., ). Despite verification of B. communis reproduction in caged and open‐field soybeans, there is no evidence of population establishment by this parasitoid in North America (Heimpel et al., ; Asplen et al., ; Gariepy et al., ). The dispersal ability of B. communis may be especially important to its establishment because its host, A. glycines , alternates seasonally between using soybean in summer and buckthorn ( Rhamnus spec.)…”

“…in winter (Ragsdale et al., ). As soybean plants are annually grown crops harvested in early autumn, the most plausible overwintering strategies for this parasitoid are either year‐round fidelity to A. glycines (by overwintering within aphids on buckthorn) or seasonal host alternation to overwinter within one or more unknown aphid species (Asplen et al., ), each of which requiring successful parasitoid emigration from soybean for successful long‐term population establishment.…”

Environmental Consequences of Invasive Species: Greenhouse Gas Emissions of Insecticide Use and the Role of Biological Control in Reducing Emissions

“…Classical biological control, in which exotic natural enemies of soybean aphid are imported from its native range could reduce or even eliminate the need to apply insecticides if successful [19]. To date however, no classical biological control has been successfully established [18,66,67]. …”

Larval Hitch-Hiking and Adult Flight Are Two Ways of Aphidiinae Parasitoids Long-Range Dispersal

“…JiangLin and FuDe (2004) demonstrated that the parasitoid Lysiphlebia japonica (Ashmead) (Hymenoptera: Braconidae: Aphidiinae) do not parasitize alate Aphis gossypii (Glover) (Hemiptera: Aphidoidea) and prefer to parasitize second and third instars. Asplen et al (2011) considered that dispersal inside its winged hosts was unlikely in Binodoxys communis (Gahan) (Hymenoptera: Braconidae: Aphidiinae), a parasitoid of the soybean aphid, Aphis glycines (Matsumura) (Hemiptera: Aphidoidea). However, Feng et al (2007) and Huang et al (2008) evidenced cases of parasitoid dispersal (Hymenoptera: Braconidae: Aphidiinae) within the winged aphid Myzus persicae (Sulzer), Brevicoryne brassicae (L.), and Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphidoidea).…”