Aphelinus Albipodus Research Articles

Comparative evaluation of biological control programs and chemical pesticides for managing insect and mite pests in cucumber greenhouses: a sustainable approach for enhanced pest control and yield

BackgroundCucumber plants are susceptible to several economically damaging pests, including whiteflies, aphids, thrips and spider mites. This study aimed to evaluate the efficacy of two biological control programs, utilizing different releases of bio-agents, in comparison with chemical control method. The bio-agents used were the aphid parasitoid Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae), the green lacewing Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae) and the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) in two release rates; low and high. Additionally, a chemical pesticides treatment was included for comparison in managing the pests in cucumber greenhouses during the winter seasons of 2022 and 2023, in Egypt. Abundances of whitefly, aphids, thrips and spider mites were recorded weekly throughout the study.ResultsThe aphid population in the greenhouse with high release rate (BIO 2) showed the highest reduction, with percentages of 84.55 and 89.88% in 2022 and 2023, respectively. Both greenhouse with low release rate (BIO 1) and BIO 2 exhibited significant reductions in the whitefly population, with proportions of 71.31 and 72.01% in 2022, and 82.05 and 85.94% in 2023, respectively. The thrips population also experienced notable reductions in both BIO 1 and BIO 2 greenhouses, with percentages of 72.08 and 75.71% in 2022, and 59.93 and 61.38% in 2023, respectively. However, the pesticide treatment demonstrated the lowest reduction in populations of aphids, whitefly and thrips in both seasons. Nevertheless, in all treatments in the two evaluated seasons, the high release rate of the predatory mite, P. persimilis (15 individuals/m2), proved to be highly effective in maintaining the mite populations below the economic threshold level. However, the population density of the two-spotted spider mite, Tetranychus urticae Koch. (Acari: Tetranychidae), increased in the pesticide-treated greenhouse, indicating the development of resistance to pesticides. Although the tested programs resulted in similar yields, the biological control approach offered the advantage of pesticide-free produce and reduced production costs.ConclusionFor pest management in cucumber growing in greenhouses during winter, it is recommended to use biological control agents at a low release rate at the early occurrence of pests. This approach can help minimize pest populations effectively.

Interaction of Myzus spp. (Hemiptera: Aphididae) with their Food Plants, Parasitoids and Predators in Northeast Bihar

The article examines the association of aphids along with their food plants, parasitoids and predators in varying ecological conditions for the possible use in biological control programs. Aphids are small, sap-sucking insects and they are considered an important pest of agricultural and horticultural plants due to sucking of vital nutrients and transmitting viral diseases. During the survey, 41 species of aphids were recorded on 122 plant species in northeast Bihar. Three species of Myzus viz., M. ascalonicus, M. persicae and M. variants were recorded. M. persicae was recorded on 36 food plants from December to April but its peak population was observed during February and March. Five species of parasitoids (Aphelinus albipodus, Aphelinus gossypii, Aphidius colemani, Binodoxys indicus, Diaeretiella rapae, Lipolexis oregmae), five species of coccinellid predators (Cheilomenes sexmaculata, Coccinella septempunctata, Coccinella transversalis, Micraspis discolor, Scymnus pyrocheilus) and three species of syrphid predators (Dideopsis aegrota, Ischiodon scutellaris, Melanostoma orientale) were recorded on M. persicae. Among these, three parasitoids (B. indicus, L. oregmae, A. gossypii), four coccinellids predators (C. sexmaculata, C. septempunctata, C. transversalis, S. pyrocheilus) and two syrphid predators (D. aegrota, I. scutellaris) were observed abundantly in all localities with a high rate of parasitization/predation on M. persicae.

A survey of aphid parasitoids and hyperparasitoids (Hymenoptera) on six crops in the Kurdistan Region of Iraq

In this study, we surveyed aphids and associated parasitoid wasps from six important crop species (wheat, sweet pepper, eggplant, broad bean, watermelon and sorghum), collected at 12 locations in the Kurdistan region of Iraq. A total of eight species of aphids were recorded which were parasitised by eleven species of primary parasitoids belonging to the families Braconidae and Aphelinidae. In addition, four species of hyperparasitoids (in families Encyrtidae, Figitidae, Pteromalidae and Signiphoridae) were recorded. Aphelinus albipodus (Hayat & Fatima, 1992), A. flaviventris (Kurdjumov, 1913), A. varipes (Förster, 1841) (Aphelinidae), Aphidius rhopalosiphi (De Stefani, 1902), A. uzbekistanicus (Luzhetzki, 1960), (Braconidae) and Alloxysta arcuata (Kieffer, 1902) (Figitidae) were recorded in Iraq for the first time. The results represent the first survey of these interactions in this region and form the basis for understanding crop-aphid-parasitoid-hyperparasitoid networks and for future biological control actions.

Population dynamics and species composition of maize field parasitoids attacking aphids in northeastern China

Maize, Zea mays L., is the most abundant field crop in China. Aphids are the most economically damaging pest on maize, particularly in the maize agri-ecosystems of Jilin Province, northeastern China. Parasitic wasps are important natural enemies of aphids, but limited information exists about their species composition, richness and seasonal dynamics in northeastern China. In this study, the population dynamics of maize aphids and parasitoid wasps were assessed in relation to each other during the summer seasons of two consecutive years, 2018 and 2019. We selected maize fields in the Changchun, Songyuan, Huinan and Gongzhuling areas of Jilin Province. Four species of aphids were recorded from these maize fields: Rhopalosiphum padi (L), Rhopalosiphum maidis (Fitch), Aphis gossypii Glover and Macrosiphum miscanthi (Takahashi). The dominant species in each of the four areas were R. maids (Filch) and R. padi in Changchun, R. padi in Songyuan, A. gossypii and R. padi in Huinan, and A.gossypii and R. padi in Gongzhuling. We delineated a species complex made up of primary parasitoids and hyperparasitoids associated with maize aphids. The primary parasitoids Lysiphlebus testaceipes, Binodoxys communis and Aphelinus albipodus together formed approximately 85.3% of the parasitoid complex. Pachyneuron aphidis, Phaenoglyphis villosa, Syrphophagus taeniatus and Asaphes suspensus made up the hyperparasitoids. Of the primary parasitoids, L. testaceipes was the dominant species (81.31%). Of the hyperparasitoid group, P. villosa was the dominant species (68.42%). Parasitism rates followed the fluctuation of the aphid population. The highest parasitic rate was observed during the peak period of cotton aphids. In this paper, the occurrence dynamics and dominant species of aphids and the dynamics of parasitic natural enemies of aphids in maize fields in Jilin Province are, for the first time, systematically reported. This study provides important information for the establishment and promotion of aphid biological control in maize fields.

BIO-ECOLOGICAL STUDY OF FEW SPECIES OF APHIS LINN. IN NORTHEAST BIHAR AND THEIR ASSOCIATION WITH FOOD PLANTS AND NATURAL ENEMIES FOR POSSIBLE USE IN THE BIOLOGICAL CONTROL

Aphids are small, soft bodied, polyphagic and polymorphic sap sucking insects. During the extensive survey of different localities of 10 districts of northeast Bihar in different seasons, 41 species of aphids were recorded on more than 122 plant species belong to 35 families. Among these, only 09 species of Aphis viz., Aphis affinis Del Guercio, Aphis craccivora Koch, Aphis fabae Scopoli, Aphis glycine Matsumura, Aphis gossypii Glover, Aphis nasturtii Kaltenbach, Aphis nerii Boyer de Fonscolombe, Aphis puniceae Passerini and Aphis spiraecola Patch were recorded in the target area. The maximum number of plants were infested by A. gossypii (46 plants), followed by A. craccivora (36 plants), A. nasturtii (18 plants) and A. spiraecola (18 plants). Six species of coccinellids (Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius, Micraspis discolor (Fabricius), Pseudospidimerus circumflexa var. testaceus (Weise) and Scymnus pyrocheilus (Mulsant) and six species of syrphid predators (Allograpta javana (Wiedemann), Asarkina ericetorum (Fabricius), Episyrphus balteatus (DeGeer), Ischiodon scutellaris (Fabricius), Melanostoma orientale (Wiedemann) and Paragus serratus (Fabricius)) were recorded on Aphis spp. in the target area. Seven species of parasitoids viz, Aphelinus albipodus Fatima & Hayat, Aphelinus basilicas Fatima & Hayat, Aphelinus gossypii Timberlake, Aphelinus sp., Aphidius sp., Binodoxys indicus Subba Rao & Sharma and Lipolexis oregmae (=scutellaris) (Gahan) were also recorded on Aphis spp. in the target area. Six species of predators (C. sexmaculata, C. septempunctata, C. transversalis, E. balteatus, I. scutellaris and P. serratus) and three species of the parasitoids (A. gossypii, B. indicus and L. oregmae) were found abundantly on Aphis spp. in the target area and may be utilised in the biological control programme after further study

Discovery of Aphis ruborum (Hemiptera: Aphididae) and Aphelinus varipes (Hymenoptera: Aphelinidae) on Cultivated Strawberry in Mississippi, USA.

An adventive aphid and novel host-parasitoid association from cultivated strawberry (Fragaria × ananessa Duch. cv. Chandler; Fragaria × ananessa Duch. cv. Camarosa) in Mississippi, USA are reported herein. The aphid, first detected in high tunnel cultivation, was found predominately on newly emerged, not fully developed leaflets of daughter plants in the Fall of 2016. By 2017, aphids and their associated mummies were observed on fully developed leaflets on mother plants of both cultivars. The aphid was identified as Aphis ruborum (Börner & Schilder) using morphology and DNA barcoding studies. In addition, DNA barcoding identified parasitoid adults emerging from aphid mummies as two cryptic species, Aphelinus varipes (Foerster) and Aphelinus albipodus Hayat and Fatima. Occurrence of A. ruborum in Mississippi represents a new state record and the eastern-most established record in the United States. The A. ruborum - A. varipes or A. albipodus host-parasitoid association is reported for the first time anywhere in the world.

Evaluation of Aphis glycines as an Alternative Host for Supporting Aphelinus albipodus Against Myzus persicae on Capsicum annuum cv. Ox Horn and Hejiao 13.

Bank plant systems provide effective biological control for pests infesting commercially important crops. Aphids cause physical damage to crops by feeding on the leaves, as well as transmitting damaging viral diseases. To develop a bank plant system to control aphids that damage vegetable crops, we initially reared the parasitoid Aphelinus albipodus (Hayat and Fatima) on the soybean aphid, Aphis glycines (Matsumura) reared on the soybean plant, Glycine max (L.) that was elected as the alternate host. Parasitoid adults that emerged from A. glycines were allowed to parasitize second instar nymphs of the aphid Myzus persicae (Sulzer) which were reared on sweet pepper and chili pepper leaves. The results showed that A. albipodus females feeding and parasitizing M. persicae nymphs reared on sweet pepper lived for 18.9days, with an average fecundity of 337.3 progenies/female, while females feeding and parasitizing on M. persicae nymphs reared on chili pepper lived for 18.8days, with an average fecundity of 356.2 progenies/female. There were no significant difference in the development time and reproduction of A. albipodus individuals parasitizing M. persicae nymphs reared on sweet pepper and chili pepper plants. The intrinsic rate of increase (r), net reproductive rate (R 0), net aphid killing rate (Z 0), and finite aphid killing rate (θ) of A. albipodus parasitizing sweet pepper and chili pepper M. persicae was 0.2258days-1, 171.7 progeny adults, 222.6 aphids, and 0.4048 and 0.2295days-1, 191.8 progeny adults, 243.3 aphids, and 0.4021, respectively. Our results suggested that A. glycines could serve as an effective alternative host for supporting A. albipodus against M. persicae infesting sweet pepper and chili pepper.

Evaluation of the demographic potential of Aphelinus albipodus (Hymenoptera: Aphelinidae) with Aphis glycines (Homoptera: Aphididae) as alternate host at various temperatures

Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae) is a parasitoid wasp that uses aphids as hosts and is a candidate for biological control of aphids that infest commercially important crops. To determine the ideal conditions for large-scale reproduction of A. albipodus, a leaf disc method was used to compare the life history of A. albipodus parasitizing Aphis glycines L. (Homoptera: Aphididae) at 20, 24, 28 and 32 °C. The results were analyzed using the age-stage, two-sex life table and showed that the developmental duration and longevity of A. albipodus decreased significantly with increasing temperature. The mean generation time (T) also decreased as the temperature increased. In contrast, the intrinsic rate of increase (r) of A. albipodus increased with rising temperatures. The net reproductive rate (R 0) showed a more complicated pattern, first increasing in higher temperatures and then dropping off at the highest temperature. We employed bootstrap techniques for estimating the variance and standard error of the population parameters. The r increased significantly as the temperature increased, and R 0 at 28 °C was significantly higher than at 32 °C. Overall, our results showed that 28 °C was the most suitable temperature for reproduction of A. albipodus with A. glycines as the host.

The toxic effect of camphor vapour against Aphis craccivora Koch (Hemiptera: Aphididae) and some of its natural enemies

Fumigant toxicity of camphor was studied against the aphid Aphis craccivora Koch and three associated natural enemies, i.e. Coccinella undecimpunctata L., Aphelinus albipodus Hayat & Fatima and Aphidius colemani Viereck. Aphis craccivora was the most tolerant one compared with all tested natural enemies as the recorded LC50 values were 12.71, 6.33, 1.16 and 0.48 mg camphor/liter space for the above mentioned insects, respectively. Subjecting newly emerged adults of A. craccivora to LC25 of camphor vapor significantly reduced female longevity from 17.6 to 6.45 days and reduced the female daily progeny from 4.44 to 1.93 nymph / female, which resulted in a reduction in productivity as finite rate of increase decreased from 1.57 to 1.14 female / female / day. Aphids that survived after subjection to LC50 were found to have significantly higher amount of acid phosphatase and G. S-transferase than non-treated aphids. Inversely, Survived aphids were found to have significantly less amount of β-esterases and alkaline phosphatase than nontreated aphids; while no significant difference was found in case of α-esterases. Camphor fumigant can be a candidate as a control agent against A. craccivora but with restriction because of its drawbacks on natural enemies.

Native primary parasitoids and hyperparasitoids attacking an invasive aphid Uroleucon nigrotuberculatum in Japan

AbstractSince the invasion of Uroleucon nigrotuberculatum from North America we searched for parasitoids of this aphid on Solidago altissima in Japan to determine what species of native parasitoids attack the newly invasive aphid. We found three primary parasitoid species: Ephedrus plagiator and Praon yomenae (Braconidae, Aphidiinae) and Aphelinus albipodus (Aphelinidae). We also found eight hyperparasitoid species: Syrphophagus sp. (Encyrtidae), Dendrocerus carpenteri (Megaspilidae), Asaphes suspensus (Pteromalidae) and Pachyneuron aphidis (Pteromalidae) through both E. plagiator and A. albipodus; Phaenoglyphis villosa (Figitidae, Charipinae), Aprostocetus sp. (Eulophidae, Tetrastichinae) and D. laticeps through E. plagiator, and Alloxysta sp. nr brevis (Figitidae, Charipinae) through A. albipodus. Uroleucon nigrotuberculatum is usually attacked by rather polyphagous primary parasitoids, E. plagiator and A. albipodus, in Japan, where an oligophagous parasitoid specialized to allied aphid species is probably absent. The hyperparasitoid community of U. nigrotuberculatum is common to those of the aphids occurring in open field‐type habitats in Japan.

Molecular phylogenetics and reproductive incompatibility in a complex of cryptic species of aphid parasitoids

We infer the phylogeny of a complex of cryptic species and populations of parasitic wasps and examine how reproductive incompatibility maps onto the molecular phylogeny. We used four nuclear (28S-D2, ITS1, ITS2, ArgK) and two mitochondrial (COI, COII) gene regions to analyze relationships among populations in the Aphelinus varipes species complex (Hymenoptera: Aphelinidae) from throughout Eurasia (France, Georgia, Israel, China, Korea and Japan) and from three aphid hosts (Aphis glycines, Diuraphis noxia and Rhopalosiphum padi; Hemiptera: Aphididae). A combined analysis of 21 genotypes of Aphelinus resulted in six most-parsimonious trees, and successive approximations character-weighting selected two of these as best supported by the data. All six gene regions were necessary to fully resolve the relationships among taxa. Four clades within the A. varipes complex were distinguished: (1) Aphelinus kurdjumovi, (2) Aphelinus hordei, (3) Aphelinus atriplicis, Aphelinus varipes, and Aphelinus albipodus, and (4) Aphelinus certus (populations from China, Korea, and Japan). Based on rates of nucleotide substitutions, these clades diverged between 78 and 526 thousand years ago during a period of repeated glaciations in Eurasia. In laboratory crosses, A. kurdjumovi, A. hordei, and A. varipes were reproductively incompatible with one another and all other populations. A. atriplicis was incompatible with these three species, but not with A. certus. The populations of A. certus from China, Japan, and Korea were reproductively compatible with one another but not with the other populations. Thus, with one exception, entities that were phylogenetically distinct were also reproductively incompatible with one another. Our evidence on molecular differentiation and reproductive incompatibility supports recognition of at least five cryptic species in the A. varipes complex. We discuss likely reasons for the high rate of speciation in this complex.

Dynamic egg maturation strategies in an aphid parasitoid

Abstract Females of the parasitoid Aphelinus albipodus both lay more eggs on younger stages of their aphid host, Aphis glycines, and contain more mature eggs in their ovaries when held with these younger host stages. This suggests that egg maturation is more rapid in the presence of younger host stages. Three factors explaining the difference in the egg loads of A. albipodus females exposed to various host stages are examined. These are (i) the number of host‐feeding meals; (ii) the number of eggs laid; and (iii) the host stage utilized. Together, these factors explain 69% of the variance in A. albipodus egg load. The number of host‐feeding meals taken by females is a strong predictor of egg load. More host meals are taken on young hosts, suggesting that host feeding contributes to the trend of faster egg maturation in the presence of younger hosts. Host stage has a strong impact on egg load even when the effect of host feeding is accounted for. There is no evidence for an effect of the oviposition rate on egg load. The results indicate that egg maturation by A. albipodus is dynamic; females mature eggs faster when in the presence of preferred hosts. It is hypothesized that this allows A. albipodus females to more closely match their reproductive effort to reproductive opportunities.

Hymenopteran parasitoids and dipteran predators of the invasive aphid Diuraphis noxia after enemy introductions: Temporal variation and implication for future aphid invasions

Shifts in prevalence and abundance of hymenopteran parasitoids and dipteran predators, Diuraphis noxia , and other aphids were measured in the west-central Great Plains of North America, April–September, in 2001 and 2002, corresponding to over a decade after first detection of D. noxia and first release of D. noxia enemies. Significant temporal shifts in enemy species prevalence and diversity were detected in this study and more broadly during an 11 year time span. At any given time, some species were relatively common. One parasitoid had been predominant throughout ( Aphelinus albipodus ), two had shifted in dominance ( Lysiphlebus testaceipes and Diaeretiella rapae ), three parasitoids had been detected infrequently ( Aphidius avenaphis , Aphidius matricariae , and Aphelinus asychis ), one parasitoid was detected in the 1990s but not during 2001 and 2002 ( Aphelinus varipes ), two predatory flies occurred at occasional significant levels ( Leucopis gaimarii and Eupeodes volucris ), and two parasitoids may have been minor members of the fauna ( Aphidius ervi and Praon yakimanum ). Aphid populations detected were usually very low or not detected, precluding estimation of percent parasitism. The best evidence of suppression was observations of parasitoids in the rare case of D. noxia exceeding economic thresholds, which complemented past studies using high aphid densities. The D. noxia enemies detected were primarily endemic or long-time residents derived from previous introductions. This enemy community may provide flexibility in responding to a future aphid invasion, allowing more strategic use of biological control and other pest management approaches.

Hymenopteran parasitoids and dipteran predators of Diuraphis noxia in the west-central Great Plains of North America: Species records and geographic range

Parasitoids and predatory flies were sampled in the wheat production region of the west-central Great Plains (southeastern Wyoming, western Nebraska, and north-central Colorado) of North America using plant material infested with the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae). Samples were taken April through October in 2001 and 2002, which was 15–16 years after first detection of D. noxia and 5–6 years after the last release of natural enemies for its control in this region. The natural enemies detected were (in order of high to low detection frequencies across three states and 2 years): Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae), Eupeodes volucris Osten Sacken (Diptera: Syrphidae), Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae), Leucopis gaimarii Tanasijtshuk (Diptera: Chamaemyiidae), Aphidius avenaphis (Fitch), Aphidius matricariae Haliday, Diaeretiella rapae (M’Intosh), Aphidius ervi Haliday, Praon yakimanum Pike and Starý (Hymenoptera: Braconidae, Aphidiinae), and Aphelinus asychis Walker (Hymenoptera: Aphelinidae). The results confirmed establishment of one of the 10 exotic parasitoid species released for D. noxia control (A. albipodus) in the west-central Great Plains. It is unknown whether detection of A. asychis, A. matricariae, and D. rapae can be attributed to exotic introductions or preexisting populations. Other species detected in this study have been previously documented from the western US, although the recognized distributions have expanded for A. avenaphis, L. gaimarii, and P. yakimanum compared to the first few years after initial detection of D. noxia. Thus, there is definitive establishment of one exotic introduced for D. noxia and considerable range expansion of preexisting species that prey upon D. noxia.

Effects of photoperiod and temperature on adult oligopause of Aphelinus asychis and larval diapause of A. albipodus (Hymenoptera: Aphelinidae)

The effects of photoperiod and temperature on the dormancy of two aphid parasitoids in Japan, Aphelinus asychis and A. albipodus, were studied in the laboratory. Adult (reproductive) dormancy was induced in A. asychis under 10L : 14D at moderate temperatures and under 15L : 9D at low temperatures. Dormant adults started oviposition 6–17 d after emergence under 10L : 14D at 15 and 18°C. Transferring newly emerged adults from 10L : 14D at 15 and 18°C to 15L : 9D at 20°C caused an apparent reversal of dormancy induction within 1–2 d. It was believed that adult dormancy in A. asychis conforms to “oligopause” rather than “diapause” sensu Mansingh (1971). Adults of A. asychis showed an apparent variation in abdominal coloration from yellowish brown to black. The proportion of females with dark abdominal coloration was higher under 10L : 14D than under 15L : 9D and high at lower temperatures. We regarded this polyphenism as a part of the “diapause syndrome” because oligopause and abdominal coloration were controlled by the same environmental factors. Aphelinus albipodus entered diapause as last instar larvae. The critical photoperiod for diapause induction was 11–12 h at 18°C, and diapause was terminated within six weeks by cold treatment (10L : 14D, 5°C).

Reproductive compatibility and genetic variation between two strains of Aphelinus albipodus (Hymenoptera: Aphelinidae), a parasitoid of the soybean aphid, Aphis glycines (Homoptera: Aphididae)

Aphelinus albipodus Hayat and Fatima is a potential biological control agent of the soybean aphid, Aphis glycines Matsumura, which is a newly introduced soybean pest in the United States. We compared the reproductive compatibility and molecular genetic variation between two geographic strains of A. albipodus. One strain was collected from soybean aphids in Japan and the other recovered from Russian wheat aphid, Diuraphis noxia (Mordvilko), in the western U.S., populations of which were established with parasitoids imported from Eurasia. We present results of crossing experiments between the two strains, genetic differences based on RAPD-PCR markers, rDNA ITS1 and ITS2 gene sequences, and presence of Wolbachia in the two strains using PCR amplification of the wsp gene. We found no reduction in the production of females in reciprocal crosses between strains, but a significant reduction in fecundity when F1 females stemming from one of the reciprocal crosses were backcrossed to males from either source. The two strains differed by 3.4% in the rDNA ITS1 sequence and by presence/absence of one RAPD-PCR marker from a total of 20 RAPD primers screened, but their rDNA ITS2 sequences were identical. We used restriction enzyme analysis to separate the strains by differential digestion of the ITS1 PCR product. Wolbachia was present in 100% of males and females of both strains of A. albipodus.

Gut sugar analysis in field-caught parasitoids: Adapting methods originally developed for biting flies

The ability to determine the presence and identity of sugars in the guts of adult parasitoids in the field would aid researchers in addressing long-standing problems in parasitoid ecology. Until very recently, however, gut sugar analyses have not been carried out on parasitoids. This is despite the development and use of methodologies for gut sugar analyses in biting flies (mosquitoes, sand-flies, black-flies, horse- and deer-flies, and biting midges) for decades. Methods used have been the cold anthrone test for the detection of gut sugars, and various forms of chromatography for the identification of gut sugars. We review the use of these methods in biting fly research and then describe the nascent field of gut sugar analyses in parasitoids. Both cold anthrone and chromatography tests have begun to be used on field-caught parasitoids, and we describe progress from our own work. We used cold anthrone on the aphid parasitoid Aphelinus albipodus (Hymenoptera: Aphelinidae), and results from one field study show that approximately one-fifth of individuals tested were positive for gut sugars. The characteristics of the field site point to the primary source of these gut sugars as being aphid honeydew. We also analysed the gut contents of Diadegma insulare (Hymenoptera: Ichneumonidae), a parasitoid of diamondback moth. In this case, HPLC analyses showed that over 85% of field-captured individuals had fed upon sugars. These same analyses suggested that honeydew may have been a major source of the gut sugars in this case also, but the sugar profiles suggest some nectar feeding. Understanding the importance of various sugar sources on parasitoid activity and effectiveness will facilitate the incorporation of sugar sources in habitat manipulation programmes as a part of IPM.

Prospects for Importation Biological Control of the Soybean Aphid: Anticipating Potential Costs and Benefits

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.

Prospects for Importation Biological Control of the Soybean Aphid: Anticipating Potential Costs and Benefits

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 Forster (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.

Patch and prey utilization behaviors by Aphelinus albipodus and Diaeretiella rapae (Hymenoptera: Aphelinidae and Aphidiidae) on Russian wheat aphid (Homoptera: Aphididae)

Abstract The patch and host utilization behaviors of the parasitoids Diaeretiella rapae (Kurdjumov) and Aphelinus albipodus (Hayat and Fatima) in relation to the Russian wheat aphid, Diuraphis noxia (Mordvilko), were examined on wheat plants. Individual female parasitoids were observed for 1 h after arriving on a wheat plant with varying D. noxia densities. The total amount of time spent on the leaf and the number of occasions a parasitoid left the leaf were dependent on aphid densities for D. rapae . In contrast, A. albipodus remained on a plant for almost the entire hour irrespective of aphid densities. After 1 h on the wheat plants, single D. rapae females produced up to 31 progeny from 40 aphids, while single A. albipodus produced a maximum of six progeny. These results can be explained by the differences between the parasitoids in prey handling times, searching, and host feeding behaviors, and parasitoid physiology. The mean oviposition time for A. albipodus was 119 s compared to 1 or 2 s for D. rapae . The time between attacks was also much greater for A. albipodus at all prey densities, partially a result of this parasitoid feeding on aphids. Our results agree with the observation that A. albipodus has many fewer eggs ready for oviposition compared to D. rapae . Therefore, it is not surprising that A. albipodus remained for extended periods on wheat plants with many aphids, allowing development of additional eggs and parasitization of more aphids. The patch and prey utilization rates by A. albipodus seem likely to limit its rate of spatial spread during a growing season relative to D. rapae .