Syrphid Larvae Research Articles

Larval development and voracity of Eupeodes americanus (Diptera: Syrphidae): comparison of the focal prey Aphis gossypii (Hemiptera: Aphididae) and the banker prey Rhopalosiphum padi (Hemiptera: Aphididae).

Unlike European species, the potential of Nearctic syrphids as biological control agents is still poorly studied. However, the American hoverfly, Eupeodes americanus (Wiedemann), has recently demonstrated promising traits as a biocontrol agent, notably against the foxglove aphid, Aulacorthum solani Kaltenbach, on pepper. The present study aims to extend our knowledge of the American hoverfly by evaluating its potential as a biocontrol agent in a banker plant system against the melon aphid, Aphis gossypii Glover, in a greenhouse cucumber crop. The preimaginal development and voracity of E. americanus were compared when preying upon the focal prey/pest (A. gossypii) or the banker prey (bird cherry-oat aphid, Rhopalosiphum padi L.) by daily observations of larvae from egg to adult. Preimaginal development time, survival rate, and occurrence of deformation were similar on both prey species. The weight of third instar and pupae, however, washigher for larvae that fed on the banker prey. The ad libitum voracity of the syrphid larvae was generally very high and did not significantly differ between prey species, except for the third-instar larvae which consumed more focal prey. Results suggest that a banker plant system involving the bird cherry-oat aphid may be a promising tactic for utilizing E. americanus for melon aphid biocontrol.

Predation of syrphid larvae (Diptera: Syrphidae) on thrips in onion fields intercropped with barley

Predation of syrphid larvae (Diptera: Syrphidae) on thrips in onion fields intercropped with barley

Influence of Abiotic Factors on Population of Aphid Complex and Its Coexisting Natural Enemies in Mustard Agroecosystem

A field experiment was conducted to determine the population build-up of mustard aphid and their natural enemies in relation to abiotic factors at TCA, Dholi during the Rabi season of 2018-19 and 2019-20 respectively. The incidence of mustard aphid started in the 2nd and 3rd SMW of 2019 and 2020 respectively and reached maximum in 8th SMW in both the years. However, the predatory activity of coccinellids, syrphid larvae and spiders were started from 3rd SW with their peak activity at 3rd and 4th week of February in both the years. Mustard aphid population exhibited positive correlation with maximum temperature (0.347 & 0.543), minimum temperature (0.317 & 0.152) and negative correlation with relative humidity (-0.083 & -0.479) during 2019 & 2020 respectively and rainfall (-0.35) during 2020. However, natural enemies viz., coccinellids, syrphid larvae and spiders exhibited positive correlation with Tmax, Tmin, rainfall and negative correlation with RH in both the years.

Two-way predation between immature stages of the hoverfly Eupeodes corollae and the invasive fall armyworm (Spodoptera frugiperda J. E. Smith)

Since its 2018 invasion of eastern Asia, the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) has become a key pest in local maize production. Though pesticides have been widely used to mitigate the initial S. frugiperda attack, biological control is receiving ample attention as a desirable, environmentally-sound alternative to chemical control. Hoverflies (Diptera: Syrphidae) are abundant natural enemies in Chinese maize fields and have been observed to consume S. frugiperda larvae. In this study, we use laboratory assays to study the two-way interaction between immature stages of S. frugiperda and the endemic syrphid Eupeodes corollae. To mimic natural conditions, assays were performed in the presence of fresh maize leaves. Those 2nd or 3rd instar larvae of E. corollae preyed on 1st and 2nd instar S. frugiperda larvae with a Holling type III response, consuming a respective theoretical maximum of 43.48 and 83.33 larvae over a 24-h period. Conversely, once S. frugiperda larvae reached 3rd instar, they exhibited aggressive behavior and equally preyed on syrphid larvae with a Holling type III response. Those 5th and 6th instar larvae of S. frugiperda consumed a respective 16.39–19.23, 6.02–19.61 and 6.76–8.26 of 1st, 2nd and 3rd instar E. corollae larvae per day. Though our results await field-level validation, S. frugiperda agonistic (i.e., defensive) and consumptive behavior towards resident natural enemies such as E. corollae possibly degrades biotic resistance and raises its invasion potential. Our findings shine new light on the interaction between lepidopteran herbivores and their natural enemies, and can help advance the development of conservation biological control and other integrated pest management (IPM) strategies against S. frugiperda in China and abroad.

Banker plants promote functional biodiversity and decrease populations of the cabbage whitefly Aleyrodes proletella

AbstractIn this study, potential banker plant systems against the cabbage whitefly Aleyrodes proletella Linnaeus (Hemiptera: Aleyrodidae) were developed under controlled conditions. The two most promising banker plant systems, that is, the parasitoid Encarsia tricolor Förster (Hymenoptera: Aphelinidae) either with Aleyrodes lonicerae Walker on European columbine (columbine system) or with Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) on Hokkaido squash (pumpkin system), were further evaluated in the field. Although the pumpkin system produced three times more parasitoids than the columbine system, both banker plants led to an 1.5‐fold increase in A. proletella parasitism rates. However, only the pumpkin system increased the abundance of syrphid larvae on cabbage by 61.5% and reduced A. proletella populations on average by 4.4%–25.8% depending on the respective assessment date. In conclusion, the pumpkin system revealed to be a promising (supplementary) control measure against A. proletella. Options for further improvement and standardization of the pumpkin system as well as a potential implementation in cabbage production are discussed.

Dual ecosystem services of syrphid flies (Diptera: Syrphidae): pollinators and biological control agents

With increasing worldwide pressure on bee pollinator populations and an increase in insecticide resistance amongst pest insects, there is a growing need for diversification of pollinator and pest control systems. Syrphid flies (Diptera: Syrphidae) contribute ecosystem services to agroecosystems through their supporting roles as crop pollinators and predators of pests. Adult syrphids are important pollinators with high floral visitation rates and pollen carrying capacity, while predatory syrphid larvae are natural biological control agents, reducing aphid populations in both field and laboratory conditions. The present challenge is to determine whether syrphid flies have the potential for application as pollinators and in integrated pest management (IPM) schemes as biological control agents. Currently, there are gaps in research that are hindering the use of syrphids as dual service providers. Such gaps include a lack of knowledge of syrphid floral preferences, the role and viability of adult syrphids as pollinators in natural and agro-ecological pollinator networks, and the predatory efficiency of larvae in field and greenhouse conditions. By reviewing relevant literature, we demonstrate syrphids flies have the potential to be used as pollinators and biological control agents. This article is protected by copyright. All rights reserved.

Identification of the Klambothrips myopori (Thysanoptera: Phlaeothripidae) Predator Complex in California.

To identify the predator complex of the invasive thrips, Klambothrips myopori, on its ornamental host plant Myoporum laetum, field surveys were conducted at three sites in southern California over the period of 1 y. Five insect orders and five spider families were represented in the survey. Although the most abundant groups differed among collection sites, syrphid larvae, anthocorids, Chrysoperla spp., Franklinothrips orizabensis Johansen (Thysanoptera: Aeolothripidae), and one spider family (Salticidae) were all collected at each site. Based on the field surveys, Orius spp. and Chrysoperla spp. were identified as possible key natural enemies of K. myopori. Laboratory studies were then conducted to determine the consumption rates of Orius insidiosus Say (Hemiptera: Anthocoridae) and Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) at constant densities of K. myopori and to define the functional responses of the predators. Both predators consumed more second-instar larvae than other prey stages. Orius insidious displayed a type II functional response, while C. rufilabris displayed both type II and type III depending on prey stage. Generally speaking, O. insidiosus and C. rufilabris consumed a higher proportion of prey at lower pest densities, implying that in an augmentative control program using these commercially available natural enemies, predators could be released early in the year when host plants begin to flush and thrips populations are low to suppress population growth.

Red Wood Ants Display Natural Aversive Learning Differently Depending on Their Task Specialization.

The adaptive benefits of individual specialization and how learning abilities correlate with task performance are still far from being well-understood. Red wood ants are characterized by their huge colonies and deep professional specialization. We hypothesized that red wood ants Formica aquilonia form aversive learning after having negative encounters with hoverfly larvae differently, depending on their task specialization. We tested this hypothesis, first, by examining whether hunters and aphid milkers learn differently to avoid the nuisance of contacts with syrphid larvae, and, second, by analyzing the difference between learning in “field” and laboratory-reared (naïve) foragers. During the first interaction with the syrphid larva in their lives the naïve foragers showed a significantly higher level of aggressiveness than the members of a natural colony. Naïve foragers applied the “mortal grip,” “prolonged bites,” and “nibbling” toward the enemy with a significantly higher frequency, whereas members of both “field” groups behaved more carefully and tried to avoid encounters with the larva. The aphid milkers, who had a negative experience of interaction with the larva, being “glued” with its viscous secretion, behaved much less aggressively in the follow-up experiments after 10 min and even 3 days, thus exhibiting the shaping of both short- and long-term memories. However, both “field” hunters and naïve foragers demonstrated no signs of aversive learning. These data provide some new insights into the relationship between task specialization and learning performance in ants. Given our previous results, we speculate that scouts and aphid milkers are the most cognitively gifted specialists in red wood ants, whereas hunters and guards are rather brave than smart.

Digital video surveillance of natural enemy activity on Diaphorina citri (Hemiptera: Liviidae) colonies infesting citrus in the southern California urban landscape

The Asian citrus psyllid, Diaphorina citri, is a significant economic pest of citrus because it vectors a bacterium that causes the lethal citrus disease huanglongbing. From 2015 to 2016, digital video recorders were used to identify natural enemy species attacking sentinel immature D. citri colonies deployed monthly at three urban sites in southern California. Natural enemy activity during both daylight and nighttime hours was recorded. To examine the impact of ant-hemipteran mutualisms on biological control efficacy, we compared natural enemy interactions with D. citri colonies that were either fully exposed or protected from walking arthropods with a sticky barrier. Spiders (Aranae), syrphid larvae (Syrphidae), predatory mites (Phytoseiidae), green lacewing larvae (Chrysopidae), thrips (Thripidae), and the introduced parasitoid, Tamarixia radiata, were the dominant natural enemy groups visiting immature D. citri colonies over the course of the study. A significant proportion of syrphid and green lacewing larvae, and T. radiata visits to the sentinel colonies resulted in D. citri attacks. Spiders rarely attacked immature D. citri. Argentine ants, Linepithema humile, were the most common arthropod visiting D. citri colonies across all study sites and ants were active day and night. When ant access to D. citri colonies was restricted, natural enemy abundance and attack rates increased, particularly those by syrphids and T. radiata. This study highlights the importance of natural enemies and ant-psyllid interactions in the biological control of D. citri in urban citrus ecosystems. Therefore, conservation of natural enemies and ant control should be considered for the sustainable management of this pest-disease complex.

Chemosensory genes in the antennal transcriptome of two syrphid species,Episyrphus balteatusandEupeodes corollae (Diptera: Syrphidae)

BackgroundPredatory syrphid larvae are an important natural enemy of aphids in cotton agro-ecosystems in China. Their behaviors in prey foraging, localization and oviposition greatly rely on the perception of chemical cues. As a first step to better understand syrphid olfaction at the molecular level, we have performed a systematic identification of their major chemosensory genes.ResultsMale and female antennal transcriptomes of Episyrphus balteatus and Eupeodes corollae were sequenced and assembled using Illumina HiSeq2000 technology. A total of 154 chemosensory genes in E. balteatus transcriptome, including candidate 51 odorant receptors (ORs), 32 ionotropic receptors (IRs), 14 gustatory receptors (GRs), 49 odorant-binding proteins (OBPs), 6 chemosensory proteins (CSPs) and 2 sensory neuron membrane proteins (SNMPs) were identified. In E. corollae transcriptome, we identified 134 genes including 42 ORs, 23 IRs, 16 GRs, 44 OBPs, 7 CSPs and 2 SNMPs. We have provided full-length sequences of the highly conserved co-receptor Orco, IR8a/25a family and carbon dioxide gustatory receptor in both syrphid species. The expression of candidate OR genes in the two syrphid species was evaluated by semi-quantitative reverse transcription PCR. There were no significant differences of transcript abundances in the respective male and female antenna, which is consistent with differentially expressed genes (DEGs) analysis using the FPKM value. The sequences of candidate chemosensory genes were confirmed and phylogenetic analysis was performed.ConclusionsThis research comprehensively analyzed and identified many novel candidate chemosensory genes regarding syrphid olfaction. It provides an opportunity for understanding how syrphid insects use chemical cues to conduct their behaviors among tritrophic interactions of plants, herbivorous insects, and natural enemies in agricultural ecosystems.

Wind‐modulated landscape effects on colonization of Brussels sprouts by insect pests and their syrphid antagonists

Abstract Most crop fields are annually cleared, including arthropod populations. Recolonization depends on the source habitat presence in the landscape and often is affected by weather conditions. The present study identified source habitats and the effects of temperature and prevailing wind direction on colonization of Brussels sprouts by pests and their natural enemies. We sampled arthropods on standardized monitoring plants in 18 landscapes with different areas of potential source habitats. Most abundant pests and antagonists were Aleyrodes proletella, Brevicoryne brassicae, Plutella xylostella and syrphid larvae. Variation in A. proletella colonization was best explained by the upwind area of oilseed rape (positive effect) and temperature (negative effect). Variation in B. brassicae colonization was best explained by the downwind area of oilseed rape (positive effect), whereas no effects on P. xylostella were found. Syrphid colonization was affected by prey abundance only (positive effect). The results of the present study suggest that A. proletella was transported downwind, whereas B. brassicae located host plants during an upwind flight for approximately 1 km. This is remarkable for aphids with often limited upwind flight ability. Consideration of prevailing wind directions improves forecasting of the colonization intensity by pests from important source habitats.

Syrphids feed on multiple patches in heterogeneous agricultural landscapes during the autumn season, a period of food scarcity

Many syrphid larvae are predators and have an important role as biological control agents of pests in agroecosystems. However, adults feed on non-prey resources such as pollen from flowers. Heterogeneous landscapes can provide syrphids with a great biodiversity of plants and ensure the existence of food resources. This is particularly important during periods of food scarcity, such as autumn, for syrphid species that spend those periods as adults. Nevertheless, the feeding habits of syrphid adults in resource-scarce agroecosystems are poorly known. In this study, the pollen consumption and preferences of Eupeodes corollae (Fabricius) and Episyrphus balteatus (De Geer) were analyzed in olive groves and surrounding herbaceous and woody patches in the autumns of 2012 and 2013 in northeastern Portugal. The guts were dissected, and the pollen types were identified and compared with the ground cover plants in the studied patches. Both species consumed and selected pollen types from herbaceous and woody vegetation that occurred in different patches, indicating that they flew between patches. These results highlight the importance of conserving heterogeneous agricultural landscapes to guarantee the existence of food resources for beneficial insects during periods of scarcity.

Individual and combined effects of the generalist Forficula auricularia and the specialist Episyrphus balteatus on Dysaphis plantaginea – are two predators better than one?

AbstractThe interactions between specialist and generalist natural enemies could affect the success of biological pest control, especially in augmentation programmes. The aim of this laboratory study was to quantitate the individual and combined effects of the generalist predator Forficula auricularia L. (Dermaptera: Forficulidae) and the specialist Episyrphus balteatus De Geer (Diptera: Syrphidae) on the population growth of the rosy apple aphid (RAA), Dysaphis plantaginea Passerini (Hemiptera: Aphididae). The experiment was carried out using apple seedlings with five levels of initial RAA infestation. In most cases, both predator species (alone and in combination) were able to reduce RAA densities or to keep them at their initial level. This suppression effect was greater when RAA densities were low and resulted in near‐complete mortality of the RAA colony after 4–6 days. Without predators, RAA population size almost doubled within 10 days, whereas with predators, RAA population size was reduced by about 20 (alone) and 50% (in combination). Although RAA numbers in the two‐predators treatment were ca. 81% of RAA numbers in the one‐predator treatment for pooled numbers across dates and densities, the difference between the two treatments was not significant. Some predator mortality occurred with first and second instars of the syrphid larvae and only at the two lowest initial RAA infestation levels. This mortality may be explained by inadequate food supply, intraguild predation (IGP) (in 13.3% of the possible cases), or both. However, the incidence of IGP under natural conditions could be even less frequent, as both predators were never observed on the same leaf.

Efficacy of crop cover netting against cabbage pests and their natural enemies and relevance of oilseed rape

Crop cover nets are used in vegetables to reduce damage by pests. Recently, nets with 0.8 mm mesh size were recommended to protect Brassica vegetables from whiteflies, but farmers doubted their efficacy. We compared the impact of different mesh sizes on the abundance of insect pests and their antagonists on Brussels sprout in a field study and considered also important resource habitats, i.e. oilseed rape, in the surroundings. Cabbage whitefly was the most abundant pest followed by peach-potato aphid, cabbage aphid and diamondback moth. Aphid parasitism reached 48 % while syrphid larvae and spiders were the most abundant predatory taxa. The cabbage whitefly was less abundant under 0.8 mm nets in June and August compared to 7 mm nets, while no effect was observed in October. In general cabbage aphid, diamondback moth, syrphids and aphid parasitism were not affected by nets, but peach-potato aphid density increased under 7 mm nets late in the season. In contrast, spiders were less abundant under 0.8 mm than under 7 mm nets. Moreover, only the cabbage whitefly was positively affected by oilseed rape growing. In summary, 0.8 mm nets may be beneficial to reduce colonisation by cabbage whiteflies, especially in early summer and in landscapes with high colonisation pressure. Nets with wider mesh size may be appropriate in landscapes with low colonisation pressure by cabbage whiteflies since 0.8 mm mesh size had the disadvantages to support the peach-potato aphid and hinder colonisation by spiders.

Effect of aqueous extracts of black alder (Alnus glutinosa (LINNAEUS, 1753) GAERTNER, 1791) and elder (Sambucus nigra LINNAEUS, 1753) on the occurrence of Brevicoryne brassicae LINNAEUS, 1758 (Hemiptera, Aphidoidea), its parasitoid Diaeretiella rapae (M’INTOSH, 1855) (Hymenoptera, Ichneumonoidea) and predatory Syrphidae on white cabbage

Abstract The insecticidal and antifeedant effects of aqueous extracts from two common plants (black alder Alnus glutinosa and elder Sambucus nigra) on the occurrence of Brevicoryne brassicae, its parasitoid Diaeretiella rapae and predatory Syrphidae on white cabbage were investigated in 2008-2009. Both extracts reduced the number of cabbage aphids, although the Sambucus nigra extract proved to have a better effect. Differences were seen both in the numbers of winged aphids settling on plants and in the overall numbers of aphids on plants during the entire season. There were no significant differences in the degree of parasitization by Diaeretiella rapae in the three experimental combinations. Eight species of Syrphidae were found in the Brevicoryne brassicae colonies: Episyrphus balteatus, Sphaerophoria scripta, S. rueppelli, S. menthastri, Eupeodes corollae, Scaeva pyrastri, Scaeva selenitica and Syrphus vitripennis. The dominant species was Episyrphus balteatus. The largest numbers of syrphid larvae and pupae were collected from cabbage aphid colonies on the control plants. Smaller numbers were recorded on the plot where the cabbages were sprayed with the Sambucus nigra extract. The results of this study indicate that botanical insecticides based on S. nigra have the potential to be incorporated into control programmes for the cabbage aphid.

Ant attendance of the cotton aphid is beneficial for okra plants: deciphering multitrophic interactions

Abstract Aphids are pest species of many crops and biocontrol methods are often ineffective. Ant–aphid associations can be mutualistic or antagonistic, with ants increasing or reducing aphid numbers. Within‐species plant variation or other herbivores may further influence these ant–aphid interactions. Okra is an economically important crop in Cameroon. Several okra varieties are grown here and attacked by the facultatively ant‐tended cotton aphid Aphis gossypii. We conducted field and screenhouse experiments where plant variety, ant presence and predator access were manipulated to investigate the multitrophic interactions on okra and their effects on okra yield. In the field, ants did not protect aphids from their natural enemies and syrphid larvae reduced aphids by 42%. Additionally, aphid recruitment of ants reduced chewing herbivore damage by 11% and indirectly increased okra fruit set. We also found aphid numbers, aphid predation by syrphids and chewing herbivory to vary across okra varieties. Finally, in the screenhouse, we recorded a 24% reduction in aphid numbers on plants with ant presence. The present study highlights the importance of direct and indirect biotic interactions for pest biocontrol. Tropical agricultural systems are complex and understanding such interactions can help in designing pest control measures in sustainable agriculture.

Recruitment of aphidophagous arthropods to sorghum plants infested with Melanaphis sacchari and Schizaphis graminum (Hemiptera: Aphididae)

A significant question in biological control is the extent to which indigenous natural enemies might be pre-adapted to exploit invasive species that constitute novel prey. We observed the recruitment of natural enemies to aphid microcosms – pots containing four sorghum plants infested with either Melanaphis sacchari (Zehntner), a newly invasive aphid, or Schizaphis graminum (Rondani), an established pest. The first cohort was monitored in open habitat along a tree line near riparian parkland and urban plantings, and the second, within a sorghum monoculture. Both aphid species were eliminated by natural enemies within 13days in the first cohort, but in the second, M. sacchari reached higher numbers than S. graminum and survived a week longer. Biological control was successful in both cases; neither aphid produced a generation of alates, nor did plants sustain significant damage. Syrphid larvae, primarily Allograpta obliqua (Say), caused most aphid mortality in the first cohort, whereas adult Coccinellidae, primarily Hippodamia convergens Guerin-Meneville, caused most mortality in the second. Eggs and larvae of Chrysoperla carnea Stephens were present in both cohorts, but appeared to suffer more intraguild predation in the first. Flower flies and velvet mites were present only in the first cohort, and flower bugs, only in the second. Aphelinus sp. successfully parasitized both aphids, but Lysiphlebus testaceipes Cresson did not develop in M. sacchari due to their infection with the secondary endosymbiont Hamiltonella defensa (confirmed by DNA analysis). Thus, sorghum infested with M. sacchari attracted the same guild of natural enemies as S. graminum and had similar biological control outcomes. The findings suggest that the capacity of indigenous aphidophagous guilds to respond to, and ultimately control, invasive aphid species may be underestimated.

Facilitation Among Saproxylic Insects Inhabiting Tree Hollows in a Mediterranean Forest: The Case of Cetonids (Coleoptera: Cetoniidae) and Syrphids (Diptera: Syrphidae)

Tree hollows offer an ideal niche for saproxylic insects in mature Mediterranean forests, where Diptera and Coleoptera are the richest groups. Co-occurrence is frequently observed among many species of both groups in these microhabitats, and some of these species have been considered to facilitate the presence of other species by acting as ecosystem engineers. One of the systems that is found in Mediterranean tree hollows is formed by cetonid (Coleoptera: Cetoniidae) and syrphid (Diptera: Syrphidae) larvae. Here, cetonid larvae feed on wood and litter and produce a substrate that is easier to decompose. To assess the possible role of these larvae as facilitating agents for the saproxylic guild, we studied whether the presence of saprophagous Syrphidae inside tree hollows is associated with the activity of cetonid larvae. Furthermore, in laboratory conditions, we tested whether cetonid larvae activity can improve the development and fitness of the saprophagous syrphid species. Our results show that "cetonid activity" was the variable that best explained the presence of saprophagous syrphid species in natural conditions. Myathropa florea (L., 1758) was one of the species most influenced by this activity. The laboratory experiment gave similar results, demonstrating that an enriched substrate with Cetonia aurataeformis Curti, 1913 larval feces improves syrphid larval growth rate and fitness of adults (measured as longer wing length) of M. florea.

Identification of the most common predatory hoverflies of Mediterranean vegetable crops and their parasitism using multiplex PCR

The larvae of many hoverflies (Diptera: Syrphidae) are important polyphagous predators used in integrated pest management programs. Because the accurate identification of preimaginal stages by morphological characters is difficult, we have developed a multiplex PCR to identify the immature and/or adult stages of the most common syrphid species in Mediterranean vegetable crops: Episyrphus balteatus, Scaeva pyrastri, Eupeodes corollae, Meliscaeva auricollis, Sphaerophoria scripta, and Sphaerophoria rueppellii. The latter two species were amplified by the same primer pair due to the high similarity of their cytochrome oxidase subunit I sequences. Additionally, the assay included a primer pair targeting Diplazon laetatorius, a common koinobiont ichneumonid endoparasitoid of predatory syrphid larvae. The multiplex PCR assay proved to be highly specific and sensitive, and it was used to study the assemblage of hoverfly species in larval stage in two Mediterranean lettuce crops in two consecutive years. The molecular analysis revealed that Eu. corollae, Ep. balteatus, and Sph. scripta/Sph. rueppellii were the species present in the investigated fields. Species composition differed depending on sampling date and whether the larvae were collected on the plants or on the ground. The parasitoid D. laetatorius was not detected in any of the analyzed hoverfly larvae, suggesting low-parasitism pressure in the studied syrphid populations. The wide distribution of most of these syrphid species makes this multiplex PCR assay an ideal tool to deepen our knowledge on the ecology of these polyphagous hoverfly species in preimaginal stages and to improve the use of hoverflies to control insect pests.

An unusual, but not unexpected, evolutionary step taken by syrphid flies: the first record of true primary parasitoidism of ants by Microdontinae

Parasitoidism of ants by flies is known only for Phoridae and Tachinidae. We report the first record of a hoverfly (Syrphidae, Microdontinae, Hypselosyrphus) acting as a true primary parasitoid of ants. Previously, larvae of Microdontinae were known only as obligate predators of ant brood. This is also the first host record for any Hypselosyrphus species, the first reliable record of an association between a syrphid fly and a ponerine ant, and the first record of a dipteran parasitoid developing upon the immature stages of ants. We reared adults of Hypselosyrphus trigonus from cocoons of the arboreal ponerine ant, Pachycondyla villosa, nesting in Aechmea bracteata bromeliads in southern Quintana Roo, Mexico, and we succeeded in determining various aspects of the parasitoid's life history. The findings obtained in the present study provide novel insights into the evolutionary transformation and diversification of the feeding habits of microdontine syrphid larvae, from an obligatory, specific predatory association with the ant brood, to parasitoidism of ant prepupae. We also highlight the need for more detailed studies of the interactions of arboreal ants and their parasites. We conclude with an overview of the evolutionary transitions and diversification of larval feeding habits that have taken place within the family Syrphidae. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 462–472.