Soybean aphid, Aphis glycines Matsumura, a native of eastern Asia, was first discovered in North America in July 2000 in Wisconsin and subsequently in a total of 10 North Central U.S. states by September 2000. Currently, soybean aphid has spread to 20 U.S. states and three Canadian provinces, putting >60 million acres of soybean at risk to crop injury caused by this exotic insect. The life history of this species has been studied by a number of entomologists and crop protection specialists, and here we provide a summary of the observations made by ourselves and our colleagues. The soybean aphid has been observed at all stages of a heterecious holocyclic life cycle and seems to be adapting to a large geographic area of the North Central United States. Soybean aphid uses native and exotic primary hosts found in North America, specifically Rhamnus cathartica L. and Rhamnus alnifolia L’Hér. The aphid’s principal secondary host is soybean, Glycine max (L.) Merr., but there seems to be a lengthy gap in early spring between the production of alatae on buckthorn (Rhamnus spp.) and the occurrence of soybean. In the fall when soybean is senescing, a biological bottleneck is created as the aphid must develop sexual morphs on soybean that emigrate back to the primary host to complete the sexual phase of its life cycle. During the summer, A. glycines is prone to develop winged morphs during any generation on soybean, which puts much of the soybean crop at risk of invasion by this exotic species, even if the insect does not overwinter locally. The integrated pest management challenges presented by the aphid require a deeper understanding of its biology as it adapts to North America.

Since the discovery of the soybean aphid, Aphis glycines Matsumura, in North America in the summer of 2000, a great deal of interest has developed in the biology, ecology, and control of this insect in its native range of eastern Asia. Although there is a wealth of literature on A. glycines that could help guide the efforts of North American entomologists, much of it is written in Chinese. Here, we review the Chinese-language literature on the biology, ecology, natural enemies, and control of the soybean aphid in China.

The invasion of soybean aphid, Aphis glycines Matsumura, into soybean (Glycine max L.) production areas of the northcentral United States has generated substantial concern over the ultimate impact of this pest on domestic agriculture. To evaluate the potential extent and severity of its invasion in the United States, we examined possible pathways for the arrival of the insect, considered the likelihood for establishment in different regions of the United States, and described patterns of spread. Historical records of aphid interceptions by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service suggest that populations of soybean aphid most likely arrived in the United States from Japan or China, either carried by an international airline passenger or associated with horticultural cargo. Two methods of climate comparison suggest that the aphid may ultimately be present in all soybean producing areas of the United States. However, the severity of infestations within these areas is likely to vary considerably in space and time.

Aphis glycines Matsumura shares its hosts with two other aphid species, Aphis nasturtii Kaltenbach and Aphis gossypii Glover. Tables of characters and photographs are provided to assist in the separation of these three species. A photographic plate showing a gynopara, male, ovipara, and late summer apterous vivipara of A. glycines is included.

Eleven species from the family Rhamnaceae, including both species exotic and native to North America, were tested for their acceptability to the fall migrants of the soybean aphid, Aphis glycines Matsumura. Two species, Rhamnus cathartica L. and Rhamnus alnifolia L’Héritier were accepted and had overwintering eggs deposited on them. Eggs survived the winter, and colonies developed on both hosts in the spring. R. alnifolia is a new overwintering host for the soybean aphid.

A field survey of soybean aphid, Aphis glycines Matsumura, and its natural enemies was conducted during summer 2002 in Langfang, northern China (116.4° E, 39.3° N). Aphids colonized soybean when plants were still small in early July. After a lag of 2 wk, aphid density increased rapidly in late July, reaching a peak of 114 ± 46 aphids per five soybean plants on 1 August. The population declined to a plateau immediately after this peak and then declined again starting in mid-August, although a second small peak occurred in late August. The finite rate of increase varied from zero- to five-fold, and the aphid seemed to be limited by natural enemies. The main species of natural enemy were the aphid parasitoid Lysiphlebus sp., the aphid predators Propylaea japonica (Thunberg), Scymnus (Neopullus) babai Sasaji, and Paragus tibialis (Fallén). In a field exclosure experiment, A. glycines density in small-mesh cages peaked three-fold higher than in large-mesh cages and 12-fold higher than on uncaged plants, indicating that natural enemies did indeed limit aphid density.

The discovery of the soybean aphid, Aphis glycines Matsumura, in U.S. soybean production systems in 2000 has provided a unique opportunity to study the interaction of a new invader with existing natural enemy communities. One research thrust has been examining the role of predators in soybean aphid dynamics in the Midwest. We discuss the roles of predatory arthropods in field crops and set forth a conceptual model that we have followed to identify key predators in the soybean aphid system. We identify Orius insidiosus (Say) and Harmonia axyridis (Pallas) as potentially key predators and show our findings on their phenology in soybean fields and their impact on soybean aphid population dynamics. Finally, we discuss how this information can be used in integrated pest management programs for soybean aphid and point to gaps in our knowledge where future studies are needed.

We discuss the potential pros and cons of using importation biological control against the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae). Importation of exotic organisms for biological control is never completely risk-free, but the potential negative impacts of not achieving biological control of invasive pests may exceed the risks associated with a biological control introduction. The potential benefits of biological control include reduced insecticide use and a reduced ability of the invasive pest to impact native flora and fauna, and we outline what the scope of these benefits may be for the soybean aphid. The benefits are only accrued, however, if biological control is successful, so the likelihood of successful biological must also be assessed. Accordingly, we outline some issues relevant to predicting the success of importation biological control of the soybean aphid. We also outline the potential risks to nontarget organisms that would be associated with importation biological control of the soybean aphid. Currently, two parasitoid species, Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae) and Lipolexis gracilis Förster (Hymenoptera: Braconidae) have been imported from Asia and have passed through quarantine. We briefly review the biology and host range of these two species. A different strain of A. albipodus that was released against the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), in the early 1990s was also found to attack the soybean aphid in the laboratory and has been redistributed from Wyoming to Minnesota and Wisconsin in field releases against the soybean aphid. We discuss our rationale for going forward with this redistribution.

The genus Tronamyia is described in the tribe Lipochaetini (subfamily Gymnomyzinae) with Asmeringa lindsleyi Sturtevant & Wheeler (new combination) as its type species. The type species had previously been listed as an unplaced species in the tribe Atissini (subfamily Hydrelliinae). In a phylogenetic analysis of the tribe Lipochaetini, Tronamyia is the sister group of Lipochaeta Coquillett, a genus that also occurs along maritime beaches or inland saline or alkaline playas of the New World.

To detect biocontrol agents of the invasive aquatic weed Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), surveys were conducted in the basins of the Paraná and Uruguay rivers in Argentina and the basin of the Amazon river in Peru and Brazil. Among the captured delphacids, Megamelus scutellaris Berg was the most abundant. Berg originally described this species on the basis of a macropterous female. In this contribution, the macropterous and brachypterous male and the brachypterous female are described, and the holotype female is redescribed. Some biological aspects are recorded.

Understanding the population dynamics of a montane/alpine grasshopper species with a disjunct distribution may help to clarify the evolutionary mechanisms of the genus Melanoplus during the Pleistocene era. A total of 215 individuals of one such species, Melanoplus alpinus Scudder, was collected from 43 meadows (5 individuals per meadow) in 10 drainages of four mountain ranges in Wyoming and Montana. This sample structure allows for genetic analysis at four spatial scales: among mountain ranges, among drainages within ranges, among meadows within drainages, and within meadows. We examined whether genetic structuring differed among the sampling scales analyzed and whether present isolation between populations of M. alpinus reflects similar historical isolation. Polymerase chain reaction restriction fragment-length polymorphism analyses were conducted on two mtDNA regions (COI and COII), revealing nine haplotypes among the 215 individuals. DNA sequence analysis of 496 bp of the COI region for 23 individuals representing the various restriction fragment-length polymorphism haplotypes and ranges revealed three major lineages, with divergence rates that have been typically observed between species of Melanoplus. The three lineages may represent three cryptic species or a relatively ancient paraphyly in a single species. Regardless of which of these scenarios is true, analysis of molecular variance suggested that “M. alpinus” was a widely distributed, panmictic species at the end of the last Pleistocene glaciation that has since retreated to montane/alpine meadows of the central and northern Rocky Mountains. The presently fragmented distribution of the species is not indicative of historically similar isolation. The degree of genetic differentiation varied among geographical scales, being greatest among drainages and meadows within mountain ranges. Very little genetic differentiation existed among mountain ranges.

The brown citrus aphid, Toxoptera citricida (Kirkaldy), is an important pest of Florida citriculture because it causes feeding damage to citrus and vectors citrus tristeza virus. Parasitoids recovered from brown citrus aphids in Florida include Lysiphlebus testaceipes (Cresson), Lipolexis scutellaris Mackauer, and Aphelinus gossypii Timberlake. Monitoring the levels of parasitism caused by each species is difficult because the parasitoids must be reared out or dissected from the aphid hosts. A simple and quick molecular approach was developed to detect and distinguish these parasitoids developing within the host aphid. Total genomic DNA was extracted from the brown citrus aphid and each of the three parasitoids and the 18S rRNA gene of each species was amplified by polymerase chain reaction (PCR). The PCR products were sequenced to obtain complete gene sequences for each species. The variable regions V2 of the genes were used to design species-specific primers for detecting and differentiating the three parasitoids. The species-specific PCR amplifications discriminated the parasitoid DNAs from each other and from the host DNA. Detection of L. testaceipes DNA within the host aphid was possible in 8% of samples during the first 2 h after parasitoid oviposition; in 66% of samples after 24 h; in 94% of samples after 48 h; and in 100% of samples after 72 h. The PCR approach described in this study provides earlier and more precise detection of parasitism and determination of species than rearing or dissection methods.

The effects of various environmental factors on body color were investigated for nymphs of the American grasshopper, Schistocerca americana (Drury). Two types of body color variation were separately analyzed. In so-called green-brown polyphenism, a green, yellow and reddish background body colors were recognized, though the variation was continuous. The reddish morph was common at low temperatures (e.g., 30 and 34°C), while the green and yellow ones became predominant at high temperatures (e.g., 38 and 42°C). The other factors including humidity, background color and rearing density had little influence on this polyphenism. The variation in intensity of black patterns was also continuous, and greatly influenced by temperature. Nymphs with intensive black patterns occurred at low temperatures and the incidence of such individuals decreased with an increase in temperature. Rearing density had only a moderate effect on the induction of black patterns: nymphs with more black patterns occurred at a higher density, but even under isolated conditions some nymphs developed intensive black patterns.

[His⁷]-corazonin is a neuropeptide that was originally isolated from the American grasshopper, Schistocerca americana (Drury), without known function. The current study was carried out to examine the possible involvement of this peptide in the induction of dark color in nymphs of this grasshopper. Additionally, the effects of a homolog, [Arg⁷]-corazonin, and juvenile hormone (JH) III on body color were investigated. Light-colored nymphs obtained at a high temperature were used for bioassays of the peptides. [His⁷]-corazonin showed a dose-dependent induction of black patterns, but it did not influence the green-brown polyphenism. [Arg⁷]-corazonin that induced black patterns in the injected nymphs was as potent as [His⁷]-corazonin, indicating that the substitute of His by Arg does not influence the dark color-inducing effect. Injection of JH III into reddish nymphs obtained at a low temperature caused them to turn green in a dose-dependent manner, but it had no effect on the expression of black patterns. These results may suggest that [His⁷]-corazonin and JH are involved in the control of black pattern expression and green-brown polyphenism, respectively, in this grasshopper. This is the first study demonstrating a physiological function of [His⁷]-corazonin in this grasshopper.

The immature stages of Calydna sturnula, from the second instar onwards, are described and illustrated from tropical dry forest in the Area de Conservación Guanacaste in northwestern Costa Rica. The foodplant in all cases was Schoepfia schreberi (Olacaceae). Only six of the 219 individual caterpillars and pupae collected during the last 15 yr were parasitized by braconid and chalcid wasps and a tachinid fly. The larval ultrastructure of C. sturnula was studied by means of scanning electron microscopy, with emphasis placed on their prothoracic balloon setae, rare structures in the Riodinidae. The occurrence of larval and pupal balloon setae in the Riodinidae is reviewed. Larval balloon setae are currently known from all three genera of the Helicopini, at least Calydna in the incertae sedis section of the Riodininae, and at least three genera of the Nymphidiini. Larval material was examined for all but one of these genera, and the macro and ultrastructure of their balloon setae are described, illustrated, and compared. Pupal balloon setae are currently known only from Helicopis and Calydna. The balloon setae of Calydna and the genera of the Helicopini are found to be more similar to each other than to those of the Nymphidiini genera. Because balloon setae occur in nonmyrmecophilous (such as Calydna) as well as myrmecophilous species, we hypothesize that they are used to store and disperse a noxious chemical when the caterpillar or pupa is grabbed by a predator, rather than to facilitate a symbiotic relationship with ants, as previously suggested. Internally, balloon setae are filled with a spongy yellowish material that consists of a dense latticework of tiny strands. We suggest that as these strands enter the otherwise hollow external acanthae, the acanthae discharge the noxious chemical when the balloon setae are squeezed.

Populations of Sancassania mites were collected in Costa Rica from scarabaeid and passalid beetles and cultured. The populations proved to be reproductively incompatible due to postzygotic isolation and show 1.4% difference in domains 2 and 3 of the 28S nuclear rDNA gene, indicating the populations represent distinct species. Because the mites were virtually indistinguishable morphologically, 61 morphological characters of 50 females and 101 characters of 60 deutonymphs of the two species were analyzed. Traditional univariate morphometrics could not separate them. Multivariate analyses of variance (principal component and discriminant function) were used to interpret morphological differences between the two species in relation to factors that influence their morphology in a laboratory and field setting. Principal component analyses were done on size and shape as well as shape variables alone. The discriminant function analysis was done on a reduced subset of shape variables. In both cases, the shape analyses resulted in complete separation of the two species and the characters contributing strongly to the discrimination were used in formal description of the two species, Sancassania salasi sp. nov. and S. ochoai sp. nov. Although deutonymphs of S. salasi taken from field-collected beetles show a significantly smaller magnitude of size variation, they show significant deviation in shape compared with cultured deutonymphs of the same species, a potential problem for correlation of specimens of other Sancassania species from culture and nature. Characters that provide the strongest contribution to these intraspecific shape changes are, therefore, taxonomically unreliable.

Factors affecting egg size variation and its fitness consequences were studied within and among generations of a multivoltine bean weevil, Bruchidius dorsalis (Fahraeus), which exhibits reversed courtship roles. Because the toughness of host plant (Gleditsia japonica Miquel) seed pods varies among weevil generations in the field and it was supposed that seed hardness varies as well, it was hypothesized that female weevils regulate egg size according to seed hardness. To test this hypothesis, egg size was compared among three generations. The overwintering generation of B. dorsalis laid significantly larger (≈ 40% greater volume) eggs than did the other two generations. To assess the effect of paternal nutritional investment on egg size, females were allowed to mate with either well-fed or poorly fed males. During the first half of the 20-d experiment, no significant effect was detected, but during the second half, females that had mated with well-fed males laid significantly and slightly larger (≈4% greater volume) eggs than those mated with poorly fed males. There was much less variation within generations than among generations. Egg size and the drilling ability of hatched larvae were significantly, positively correlated, indicating that larvae that hatched from larger eggs could drill farther into host plant seeds. These results suggest that female weevils regulate egg size according to seasonal changes in the hardness of host plant seeds, and that paternal investment affects within-generation variation in egg size.

The role of semiochemicals in host location by the parasitoid Pteromalus cerealellae (Boucek) was investigated in Y-tube and three-way olfactometers, by measuring responses to stimuli associated with the cowpea weevil, Callosobruchus maculatus. Orientation of mated parasitoid females was measured in response to five stimuli: live virgin female bruchid beetles, solvent extracts of whole body virgin female bruchids, solvent extracts of the oviposition marking pheromone from a glass substrate, previously infested cowpea seeds with adult emergence holes, and uninfested cowpea seeds. All stimuli elicited significantly better responses than those to blank controls. Female parasitoids that had previous exposure to live, virgin beetles and infested seeds exhibited shorter latency and response times to the stimuli than did naïve females. Live, virgin female bruchids and whole body solvent extracts of virgin female bruchids elicited the strongest responses. Comparison of responses in a three-way olfactometer of whole body solvent extracts of virgin female bruchids, infested seeds, and solvent extracts of bruchid oviposition marker pheromone showed that whole body extracts of virgin female bruchids elicited the strongest response by both host-experienced and naïve female parasitoids. The potential for innate responses to host-specific chemical cues and the possibility of female parasitoids using chemical cues from adult hosts are discussed.