Metasyrphus Corollae Research Articles

Efficacy of Some Predators and Lecanicillium lecanii Fungus in Controlling of Aphis gossypii (Glover) and Myzus persicae (Sulzer) in Potato Crop

Lokma, N., A.A.A. Saleh, S.A.M. Amer and M F.M. Zawrah. 2023. Efficacy of Some Predators and Lecanicillium lecanii Fungus in Controlling of Aphis gossypii (Glover) and Myzus persicae (Sulzer) in Potato Crop. Arab Journal of Plant Protection, 41(2): 152-160. https://doi.org/10.22268/AJPP-041.2.152160 This study was conducted to evaluate the efficiency of predators and Lecanicillium lecanii suspension as bicontrol agents against Myzus persicae and Aphis gossypii in potato crop, whereas Aphis gossypii had two peaks in the third week of March and April in 2020 and 2021 seasons. In addition, M. persicae had two peaks for both seasons in the fourth week of March and third week of April in 2020 and in the third week of March during 2021. The common predators observed in potato fields were: Coccinella undecimpunctata L., Chrysoperla carnea Steph., Coccinella septumpunctata, Metasyrphus corollae F. and Cydonia vicina isis (Muls.). Regarding potato predators, one peak was found in the second week of March (60 predators/25 leaves) during the 2020 season, and two peaks were found in the third week of March and second week of April (53 and 38 predators/25 leaves, respectively), in 2021 season. On the 8th day after treatment, the entomopathogenic fungus L. Lecanii produced maximum aphid mortality at highest concentration of 108 conidia/ml and 50% concentration of fungal metabolites for both M. persicae and A. gossypii. Meanwhile, L. lecanii 50% metabolites solution had more latent effect by decreasing the longevity and the number of nymphs than when using the spore suspension of 108 conidial/ml. Keywords: A. gossypii, M. persicae, aphid predators, Lecanicillium lecanii, potato.

A new slow‐release formulation of methyl salicylate optimizes the alternative control of Sitobion avenae (Fabricius) (Hemiptera: Aphididae) in wheat fields

Some defects, such as the short persistence and lower release stability of methyl salicylate (MeSA), must be resolved before efficient field application. To enhance the utilization efficacy of MeSA, a slow-release MeSA alginate bead was designed and tested to measure its release rate in a laboratory environment and to obtain insights into its ecological effects in wheat fields. In laboratory tests, both the 2.5 and 10 mL formulations of MeSA alginate beads (hereafter referred to as MeSA 2.5 and MeSA 10) release stably and continuously for at least 15 days, whereas pure MeSA does so for only ∼ 7 days. In field experiments, both the MeSA 2.5 bead and the MeSA 10 bead reduce the abundance of Sitobion avenae significantly and attract Metasyrphus corollae compared with the control. In addition, the effect of MeSA 10 beads is significantly greater than that of MeSA 2.5. The MeSA alginate bead we manufactured could be an efficient slow-release formulation. The MeSA 10 bead had a significantly greater effect on S. avenae population suppression, partly by attracting M. corollae in fields. © 2018 Society of Chemical Industry.

SURVEY OF MAIN INSECT SPECIES ASSOCIATED WITH CERTAIN MEDICINAL AND AROMATIC PLANTS AT AWLAD-SAKR DISTRICT, SHARKIA GOVERNORATE

The present study was conducted to survey the economic insect pests infesting some medicinal and aromatic plants i.e., roselle (Hibiscus sabdariffa L.), thyme (Thymus vulgaris L.) and sweet basil (Ocimum basilicum L.) and their common associated natural enemies as well as pollinators and visitors at Awlad–Sakr district, Sharkia Governorate, Egypt during the two summer growing seasons 2015 and 2016. The results recorded that 29 insect species belongs to 25 families and 10 orders associated with the three studied medicinal and aromatic plants. Destructive insects comprised 17 species belongs to 15 families and 8 orders. Predaceous insects composed 8 species of 6 families and 5 orders. Parasitoids were represented by only one species on sweet basil. Results also cleared that pollinators and visitors included 3 species belong to 3 families and 2 orders. Aphis gossypii Glover, Bemisia tabaci (Genn.) and Empoasca decipiens (Paoli) were the most dominant insect pests on roselle, thyme and sweet basil plants. A. gossypii was the main insect pest on roselle exhibited by general total percentage of 38.19% in the two seasons and B. tabaci of 51.40% on thyme and E. decipiens of 60.48%on sweet basil. The main predaceous insect recorded on the three aforementioned plants was Coccinella undecimpunctata L., representing 72.53, 56.18 and 30.38%, respectively. Yellow sticky board trap proved to be the most effective method for collecting E. decipiens, B. tabaci, Thrips tabaci Lind., Musca domestica L., C. undecimpunctata, Metasyrphus corollae (Fabr.), Chelonus ininatus L. and Culiseta longiarolata (Macq.), while thesweeping net was the pest methodfor collecting Cosmolyce baeticus L., Nezara virdula L., Aphis mellifera L., Philanthus abdelkader Luc. and Egyptica legyptius.Plant sampling technique was effective for estimating A. gossypii and Iceria aegyptiac Douglas.

SURVEY OF CERTAIN INSECTS INFESTING MAIZE CROP AND BIOLOGICAL ASPECTS OF THE PARASITOID, BRACON BREVICORNIS WESM. (HYMENOPTERA: BRACONIDAE) REARED ON SESAMIA CRETICA LED. UNDER LABORATORY CONDITIONS.

The present study was conducted during two successive seasons in the period from 2011 to 2012 to survey some aphids species Rhopalosiphum maidis (Fitch)., Rhopalosiphum padi (Linnaeus)., Aphis gossypii (Glover). , leafhoppers species Empoasca decipiens (Paoli), Empoasca decedens (Paoli) , Cicadulina chinai (Ghaui) , Balclutha hortensis (Lindb) and Cicadulina bipunctella zeae (China), planthoppers species namely Sogatelle vibix (Haupt) and S. furcifera (Horv.) and two stem borersSesamia cretica Led, Ostrinia nubilalis Hun infesting maize plants and their associated predators.The ecto-larval parasitoid species, Bracon brevicornis Wesm . was reared in the laboratory on full grown larval of the corn borer, S. cretica Led. Some biological aspects of parasitoid were studied. Total developmental period of immature stages (egg – adult) lasted 16.05 days. Average number of deposited eggs / female was 209.08 eggs. Mean number of eggs deposited per host larva was 8.19 eggs. Sex ratio (male: female) was 1 : 0.54 when the parasitoid was reared on S. cretica grown larvae . The results indicated that increase of the parasitoid density, increased the number of host larva parasitized, fecundity and total progeny, while the sex ratio (female %) was decreased. Adult longevity was affected by temperature and food supplied. Four predators were associated with these insects on maize. These predators were Coccinella undecimpunctata , Metasyrphus Corollae , Chrysoperala carnea and true spiders

Oviposition preference of two hoverfly species in response to risk of intraguild predation

Two experiments were performed in the laboratory to understand the relationships between oviposition preference and larval performance of the two predatory hoverfly species, Episyrphus balteatus de Geer and Metasyrphus corollae Fabricius. We first conducted laboratory experiments to understand the nature and relative strengths of intraguild predation between the larvae of three ladybird species, Harmonia axyridis Pallas, Propylea japonica Thunberg, and Scymnus posticalis Sicard, and two predatory hoverfly species. The interactions between larvae of the three ladybird and two hoverfly species differed depending on the species and developmental stages involved: the relationships between H. axyridis or S. posticalis and the two hoverfly larvae tended to be asymmetric with H. axyridis being a superior species and S. posticalis an inferior species, although the reverse was true for each of these two species when small larvae were paired with large larvae of the hoverflies. The ladybird, P. japonica, had both asymmetric and symmetric relationships depending on the hoverfly species with which it interacted. Secondly, we tested the preference and performance hypothesis for hoverflies, by determining whether hoverfly oviposition preference was related to the risk of intraguild predation posed by the presence of a ladybird larva in an aphid colony. Oviposition preference in relation to larval performance of the two hoverflies differed between the species: E. balteatus females tended to adjust their rate of eggs laying in response to the presence of ladybird larvae, while similar responses of M. corollae females were weak. The relationship between oviposition preference and larval performance in hoverflies is discussed.

INTEGRATION BETWEEN INSECT GROWTH REGULATOR NOMOLT AND TWO PREDATORS Metasyrphus corollae F. (Syrphidae : Diptera) AND Coccinella undecimpunctata L. (Coccinellidae : Coleoptera) TO CONTROL Aphis fabae Scop.

The result of the integration study between insect growth inhibitor regulator nomolt and two predators Metasyrphus corollae F. (Syrphidae : Diptera) and Coccinella undecimpunctata L. (Coccinellidae : Coleoptera) to control Aphis fabae Scop. show the significant interaction effect between density of each predator and nomolt to kill percentage of A. fabae at 20 , 40 nymph/plant indicated the significant interaction effect between density of each predator (one and two larvae) and a prey density 20 and 40 nymph/plant its about 100% then 77.70% when we use single larval from each predators in 40 nymph/plant. The best result registered when the killed percentage in Aphis fabae were 85.70% when controlled with nomolt only, comparasim with (53.58, 53.41)% when used biological factor.

Field boundaries as barriers to movement of hover flies (Diptera: Syrphidae) in cultivated land.

Field boundaries play an important role as refuges, food sources and corridors for invertebrates and vertebrates, and increasing farmland fragmentation impacts on these functions. However, hedgerows and other structures can also impede dispersal by flying insects. The current work uses the pollen of Phacelia tanacetifolia in hover fly guts as a marker to assess hover fly movement in farm landscapes. In the United Kingdom and New Zealand, Phacelia pollen was found in the guts of Ephisyrphus balteatus and Metasyrphus corollae (United Kingdom) and Melanostoma fasciatum (New Zealand) at distances up to 200 m from the source, when there were no barriers between the flowers and the traps used to catch the flies. The rate of decline over distance in the proportion of flies containing pollen was similar for the two countries. The extent to which four replicated field boundary types impeded hover fly movement was tested using post-and-wire fences, lines of poplars (Populus spp.) with gaps, dense poplars and controls (no potential barriers). Phacelia was planted on one side of each boundary, and along the centre of the control plots. The relative presence of the pollen in flies on both sides of the barriers showed that both types of poplar boundary restricted the movement of the flies, but the fence had no effect. In a separate experiment, gravid females of M. fasciatum were captured at a greater height on a shade-cloth fence than were non-gravid females and males. The implications of this work include the functioning and persistence of metapopulations and the influence of field boundaries on population recovery of beneficial invertebrates following pesticide-induced mortality. If field boundaries contribute to a temporal asynchrony between pest and natural enemy populations, this needs to be considered along with the well-established roles of boundaries as refugia for, and sources of, beneficial arthropods.

Effect of hunger on yellow water trap catches of hoverfly (Diptera: Syrphidae) adults

Summary1 An experiment was conducted in a winter wheat field using yellow water traps at crop height and at ground level, near to and distant from flowers, to test the hypothesis that such traps are seen as a source of food by flower‐feeding adult hoverflies and are therefore likely to selectively trap hungry individuals. Hoverflies caught in each trap were counted and identified and the amount of pollen in their guts was assessed. Ratios of numbers of hoverflies seen in the wheat crop to numbers caught in nearby traps were compared for the different treatments.2 Most hoverflies were caught in crop‐high traps but they included a high proportion of individuals with empty guts. The taxa were: Episyrphus balteatus (De Geer), Metasyrphus corollae (F.) (these species together accounted for over 90% of the individuals trapped), with Sphaerophoria spp., Syrphus spp., Scaeva pyrastri (L.), Melanostomini and unidentified others making up the rest.3 Significantly fewer hoverflies were captured in low than in high traps. The ratios of numbers trapped to numbers observed, in flower and in no flower treatments would be expected to be the same if the traps were not selective. This was supported for low traps. With high traps, however, there was a highly significant difference between the ratios (71.34 and 126 : 8, respectively).4 Flies captured in high traps had less pollen in their gut than those captured in low ones. At each distance, more E. balteatus captured in high traps were in pollen category 1 (< 20 grains) than in any other category. The opposite state was seen in low trap catches, where most flies were in category 5 (> 5000 grains). Median pollen categories were 2 (21–200 grains) and 4 (1501–5000 grains) for flies caught in high and low traps, respectively.5 The ecological selectivity of traps according to their height and the physiological condition of the targeted individuals is a problem likely to affect many trapping systems apart from the one described in this paper.

Biological and chemical characterization of a kairomone excreted by the bean aphids, Aphis fabae Scop. (Hom., Aphididae), and its effect on the predator Metasyrphus corollae Fabr. II‐ Behavioural response of the predator M. corollae to the aphid kairomone

Abstract: The present study shows the importance of aphid‐kairomone as an additional stimulus which arrests and increases the occurrence of the predator M. corollae with the treated plants. This increase in occurrence could assist in the control of the aphid‐pest when applied in the target area. The results are summarized as follows. (1) The first concentration of aphid‐extract (AEC,) stimulated the oviposition of syrphid females much more than the second concentration of hexacosane (C26CII) and the addition of hexacosane to the aphid‐extract did not increase its activity. (2) The experienced syrphid females deposited more eggs with C26CII, AEC1 and with a mixture of both than did the inexperienced females. (3) The aphid‐extract (AEC1) and hexacosane (C26CII) affected the searching behaviour of syrphid females by significantly increasing the path length and the number of turns exhibited. (4) The syrphid females were significantly arrested by plants treated with either C26CII or AEC1. (5) The results confirm that the predator syrphid females have used hexacosane and aphid‐extract as a source of kairomone.

Biological and chemical characterization of a kairomone excreted by the bean aphids, Aphis fabae Scop. (Hom., Aphididae) and its effect on the predator Metasyrphus corollae Fabr. I. Isolation, identification and bioassay of aphid‐kairomone

Abstract: The results obtained are summarized as follows: (1) the active compounds of aphid's odour stimulated the syrphid females to deposit significantly higher percentages of eggs. These chemical compounds could be isolated by the solvent n‐pentane. (2) Gas chromatography mass spectral analysis of n‐pentane fractions of aphid's odour revealed the presence of several active peaks of hydrocarbon compounds. The active peaks ranged from docosane (C22) to octacosane (C28). Also, GC‐mass spectral analysis of n‐pentane fractions of the aphid‐extract supernatant showed the same chain of hydrocarbon compounds which is present in the aphid odour. (3) Bioassay of the different cosane compounds showed that the different concentrations of tricosane, tetracosane, pentacosane and hexacosane have a kairomonal effect on the syrphid females and the second concentration of C23CII, C24CII, C25CII and C26CII stimulated the syrphid females to deposit a significantly higher percentage of eggs. While hexacosane (C26) was the most abundant hydrocarbon compound in aphid kairomone, tricosane (C23) was the most active hydrocarbon compound. (4) Bioassay of the different mixtures of cosane compounds showed that HCM1, HCM2, HCM3, HCM4, HCM5 and HCM6 have a kairomonal effect on the syrphid females. The highest percentage of eggs was laid under the effect of the fourth mixture (HCM4) which contains tricosane (C23), tetracosane (C24), pentacosane (C25), hexacosane (C26) and octacosane (C28). (5) The chain of non‐volatile hydrocarbon compounds of aphid‐kairomone is secreted along with the cornicle secretion which contains volatile compounds. This kairomone stimulate the oviposition of syrphid females when it is received mechanically by the antennae. (6) The present study showed the importance of the different mixtures of cosane compounds as aphid‐kairomone. The use of aphid‐kairomone could be promising in aphid biological control instead of the heavy use of insecticides.

Crude aqueous‐extract (kairomone) from Aphis fabae Scop. (Hom., Aphidae) and its effect on the behaviour of the predator Metasyrphus corollae Fabr. (Dipt., Syrphidae) female

Abstract: Female Metasyrphus corollae Fabr., a syrphid predator on the bean aphid Aphis fabae Scop., responded to aqueous extract containing kairomones of the prey. The crude aphid‐extract was topically dropped onto clean leaves of Vicia faba. After application of aqueous‐extract at different aphid densities on the clean leaves, the predator showed variations in oviposition and searching behaviours in comparison with untreated leaves (control). The variations are summarized as follows: (1) the aqueous‐extract of aphids stimulate M. corollae females to lay eggs at all aphid densities. The number of eggs were directly proportional with aphid concentrations; (2) the predator M. corrolae female intensified its searching behaviour by increasing the total path length walked; (3) the number of turns exhibited is significantly higher as compared with those of control; and (4) the retention time spent by M. corollae females with treated plant is much more than that with clean plant at all aphid densities. The present results showed that the aphid aqueous‐extract contains the active ingredients (kairomones) which induce a considerable change in the searching pattern and increase the oviposition rate of the predator syrphid females.

Investigations on the Phytophagous and Predator Insect Species on Stone-Fruits in North-East Agricultural Region of Turkey

Phytophagous and predator insect species were investigated on apricot, peach, plum, morello cherry, and cherry in the North-east Agricultural Region of Turkey during 1991 and 1992. The samples were taken in orchards in Erzurum, Artvin, Erzincan, Igdir and Kars provinces. At the result of this study, 123 phytophagous and 41 predators totally 164 species were recorded in various orders, families and genera. Among phytophagous species, Hyalopterus pruni (Geoffroy) (Aphididae), Pterochloroides persicae (Cholodkovsky) (Lachnidae), Rynchites auratus (Scop.), R. bacchus (L.) (Attelabidae), Anthonomus pomorum (L.) (Curcilionidae), Cydia pomonella (L.) (Tortricidae), Lyonetia clerckella L. (Lyonetidae), Rhagoletis cerasi L. (Tephritidae), and Eurytoma schreineri Schreiner (Eurytomidae) have economic importance as pest on various stone fruits in this region. E. schreineri detected as a new apricot pest in Turkey and infested 20-25% of apricot fruits. R. auratus is the most serious pest of the morello cherry fruits and the rate of infestation is 10-85% . Adults of R. bacchus feed on the apricot fruits and make several holes, in addition, this species nibbles fruit steams and cause drop off up to 90% of fruits in some localites. This study brought out that R. auratus and R. bacchus have economic importance in this region. On the other hand, although Acronicta tridens (D. & S.) (Noctuidae) and Caliroa limacina Retz. (Tenthredinidae) show local distribution they cause important damages in infested orchards. Psylliodes kasyi Lopatin (Chrysomelidae) and E. schreineri are new records for Turkish fauna. Moreover, the larva of Gypsonoma rosaecolana Dbld. (Tortricidae), bore through the flesh of the apricot fruits. Syndemis musculana Hb. (Tortricidae) and Ypsolopha persicella F. (Yponomeutidae) feed on apricot and peach leaves, respectively. Among predator species, Nagusta goedeli (Klt.) (Reduviidae), Anthocoris nemoralis (F.), A. sibiricus Rt. (Anthocoridae), Chrysoperila carnea (Stephens) (Chrysopidae), Scymnus subvillosus (Goeze), Stethorus punctillum Ws. (Coccinellidae), Episyrphus balteatus (DeGeer), Melanostoma mellinum (L.), Metasyrphus corollae (F.) and Sphaerophoria scripta L. (Syrphidae) were dominant species in this region. In addition, preys of some species were also determined.

Natural Enemy Impact on the Abundance of Diuraphis noxia (Homoptera: Aphididae) in Wheat in Southern France

Natural enemy impact on Diuraphis noxia (Mordvilko) abundance was measured with field exclosure experiments in wheat near Montpellier, France, during three springs. Plants were artificially infested with D. noxia; predators, parasitoids, and aphid–home pathogens were excluded from some plants but not others; and subsequent changes in aphid densities were compared by destructive plant sampling. Each year, D. noxia density in all treatments increased and then declined as plant quality deteriorated, but peak densities were 10– to 18–fold higher on closed–caged plants than on open–caged or uncaged plants. Differences in microclimate, emigration, and aphid competition were eliminated as explanations for differences in D. noxia densities. The mortality required to explain differences in dynamics between closed–caged and open–caged/uncaged D. noxia populations was calculated. Natural enemies were sampled in the surrounding wheat to assess their capacity to inflict this required mortality. The predatory coccinellid Coccinellaseptempunctata L. reached densities of 4–16 per square meter and the predatory syrphids Episyrphus balteatus De Geer, Metasyrphus corollae F., and SphaerophOria scripta L. together reached one per square meter. The parasitoids Aphellinus asychis walker, Aphelinus varipes (Foerster), Diaeretiella rapae (McIntosh), and Aphidius matricariae were also abundant. Given predator search capacities and observed parasitism rates, mortality from natural enemies could easily account for the differences in D. noxia densities between closed–caged and open–caged/uncaged plants.

Possible consequences of a specific interaction between predators and parasites of aphids

Empirical data on trophic interactions between the aphid predator Metasyrphus corollae, the aphid parasite Diaeretiella rapae and the aphids Brevicoryne brassicae and Myzus persicae were collected. A skewed curve seemed to express the development of parasitism in the absence of the predator. An increase in the percentage of parasitized aphids of both species occurred at the time of intense feeding by the predator released into the system. A simple mathematical model for this situation was developed. The simulation of interactions between aphids and the parasite corresponded well to the empirically obtained curve. Application of the model to a range of situations was investigated by computer simulations. Its practical value for further considerations and predictions in biological control is demonstrated.

Feeding economy of larvae of a flower fly,Metasyrphus corollae [Dip.: Syrphidae]: Partial consumption of prey

Metasyrphus corollae (F.) larvae ingested aphid contents at a decreasing rate over time because the contents of the aphid became increasingly difficult to obtain as the body of the prey was emptied. Starved larvae usually handled prey longer than wellfed larvae. Younger starved larvae fed longer than older larvae. Larvae starved for 24 h ate the most of a prey. Larvae held prey, on average, until 71% of dry mass was extracted after which the prey carcass was discarded. Prey handling time and amount of each prey consumed were determined by size and hunger of larvae and degree of depletion of prey contents.

Diurnal activity patterns in hoverflies (Diptera, Syrphidae)

Abstract. 1. Time‐budgets are constructed from censuses of hoverflies. Larger species spend less time in flight.2. Most species are active under similar conditions of light intensity, but a shade‐tolerant (Melanostoma scalare Fabr.) and a sun‐loving species (Metasyrphus corollae Fabr.) were identified.3. Large species become active (i.e. move, by flying or feeding) at lower temperatures than small ones, except M.scalare, which is tolerant to cool temperatures. This means that, M.scalare apart, the order of species appearing during the day is size‐dependent, largest first.4. Previous claims about the diel periodicity of syrphids can be reconciled by considering the importance of individual thermal balance.5. Tolerance to low temperatures in small hoverflies is associated with feeding on anemophilous pollen; this may indicate a proline‐fuelled flight.

Why does the hoverfly Metasyrphus corollae migrate?

Abstract. 1. Migration pattern and mass appearance of the hoverfly Metasyrphus corollae (F.) (Diptera, Syrphidae) were investigated on the SE coast of Sweden in 1981. In total, 4433 hoverflies, belonging to fifteen species, were collected in water traps during 4–6 August. All but 2.2% were M.corollae, 3282 specimens being caught on 4 August, 1021 on 5 August and thirty‐five on 6 August.2. The sex ratios (♂/♀) on these dates were 1/1.6, 1/1.3 and 1/1.7. The average dry weights did not significantly differ between sexes (males 4.01 mg, females 4.02 mg).3. M.corollae females were reproductively immature.4. Females mostly had Senecio pollen in their guts while males mainly had Rubus pollen. The average number of pollen grains per specimen was 210 for females and 1100 for males.5. In the summer 1980 aphids were numerous, forming a basis for a high abundance of adult hoverflies (with hibernating larvae) in 1981. Aphid density in 1981 was low and stimuli inducing egglaying were sparse. It is suggested that this pattern of aphid abundance triggers migration in M.corollae and in other aphidophagous species at irregular intervals.

Effect of Prey Availability During Development on the Reproductive Output of Metasyrphus corollae (Diptera: Syrphidae)

We tested the hypothesis that increased prey availability, which results in increased energy consumption and probably lower energetic costs of foraging, increases reproductive output. Larvae of Metasyrphus corollae (F.) (formerly Srphus corollae F.), which are obligate predators of aphids, were individually reared at 19.5 ± 1°C, with 10, 20, 40, or 60 pea aphids offered each day on plants with a surface area of 7.5, 35, or 73 cm2. When more aphids were offered, larvae consumed more and produced heavier pupae. Fecundity of adults reared from these pupae was extremely variable (range, 0–1,488 eggs laid) and depended mostly on adult longevity, not on consumption or pupal weight. More eggs were laid in the first 15 days of adult life by larger adults. Adult longevity depended on the size of the cage in which the adults were kept. Flight had a higher cost against reproduction in small fliesthan in large ones. Differencesbetween the strategy of energy allocation of insects which acquire most of their energy while they are larvae and that of insects which feed while reproducing are discussed.

ヒラタアブの食性について II

In this account a record is given of the food-habits of 12 species of aphidophagous Syrphidae commonly found in crop fields in Nagasaki. Food lists of Ischiodon scutellaris FABR., Paragus quadrifasciatus MEIG., P. tibialis FALLEN, Sphaerophoria cylindrica SAY, Sph, javana WIED., Syrphus torvus O.S. and Epistrophe aino MATS., with notes of their attacking dates of plant-lice, are given. Those of Syrphus ribesii L., S. serarius WIED., S. bilineatus MATS., Metasyrphus corollae FABR., and Epistrophe balteatus DE GEER were previously published by the writer in 1956. The plant-lice attacked by the 12 syrphids amount to 40 species, which belong to 20 genera, Aphis, Macrosiphum, Amphorophora, Capitophorus, Myzus, Rhopalosiphum, Hyalopterus, Macrosiphoniella, Brevicoryne, Phorodon, Pseudocerosipha, Megoura, Acyrthosiphum, Glyphina, Neophillaphis, Periphyllus, Prociphilus, Eulachnus, Lachnus, and Oregma, about 83 per cent of which belong to the tribe Aphidini of the Aphididae, being parasitic on 65 species of plants including common crops. Among these syrphids, Epistrophe balteatus may rank first in attacking as many as 37 species of plant-lice, while Syrphus torvus and Epistrophe aino may be the lowest ranking on the list, devouring merely 4 species of aphids respectively. The nonconcentricity of aphidophagous capacity is also discussed. With regard to to the aphidophagous capacity of syrphids, single aphidophagous capacity may be distinguished from complex aphidophagous capacity, the former consisting of any single species of syrphids and the latter being composed of more than two species of them. Because of their simultaneous employment of single aphidophagous capacity in the destruction of the same or different plant-lice on different kinds of plants, the aphidophagous capacity of syrphids can not be exclusively concentrated on the destruction of a spefcific plant-lice on a specific crop during the same season. Complex aphidophagous capacity, in the same way, can not be exclusively concentrated upon the control of a specific aphid on a specific plant. In other words, during the same season, any single or complex aphidophagous capacity employed in the destruction of a specific aphid on a specific crop may simultaneously be dispersed toward the same or different aphids on different plants.