Habitat management is a form of conservation biological control, that includes strategies such as the provision of alternative prey for natural enemies. One example is the "banker plants" strategy, which consists of introducing cereals with aphids in horticultural crops. It is usually combined with parasitoid releases. In this work we evaluated whether aphid-infested barley as "banker plants" enhances native populations of aphidophagous syrphids and extends the residence time of Episyrphus balteatus (De Geer) following release. The work was performed in four replicated sweet-pepper commercial greenhouses in the southeast of Spain. Barley was sown, and infested with the aphid Rhopalosiphum maidis (Fitch). Visual censuses were performed to record released individuals of E. balteatus (marked on the thorax before release) and naturally occurring hoverflies. At the end of the experiment leaf samples were taken to the laboratory, and the immature syrphids were reared for identification. The occurrence of syrphids that come from outside the greenhouse was significantly increased by the presence of the infested barley plants. From a total of 506 observations of adult native syrphids, 81% were Sphaerophoria rueppellii (Wiedemann). We did not find significant differences between control plots and those provided with banker plants in their probabilities to retain released specimens of E. balteatus. Of the syrphids collected at immature stages from the barley leaves, we did not record any E. balteatus, and 100% of the specimens were identified as S. rueppellii. We conclude that the banker plant strategy is effective in attracting natural populations of syrphids into sweet pepper greenhouses, but not in keeping released individuals of E. balteatus in the greenhouses long enough to lay eggs. We suggest that the E. balteatus release method should be amended.
We studied the importance of forest structure (shape, edge length and orientation) and the crop mosaic (percentage of crops in the total land cover, within 100 and 2000 m from the forests) to the dynamics of an aphidophagous hoverfly Episyrphus balteatus. Adults were collected by Malaise traps located within and on the south- and north-facing edges of 54 forests. In winter, E. balteatus was only found on south-facing edges because of the greater insolation and temperature. In summer, it was more abundant on north-facing edges because of the abundant presence of flowers. In spring, more adults were found on long and south-facing edges than on northern edges. The presence of shrubs within 2000 m also positively affected abundance. In autumn, abundance was positively associated with length of the north-facing edge and forest shape. Emergence traps revealed that in southern France, E. balteatus may overwinter in the larval or puparial stage in forest edges. Overwintering was earlier reported only in adults. Landscape structure, length of forest edges and probably presence of shrub fallows, influence abundance of Episyrphus balteatus.
In Europe there are only a few species of the syrphid fly Microdon, which live in the nests of various genera of ants. For most of these rare flies, details of their biology, larval behaviour and relationships with their hosts are still not yet well known. In this paper we present data on the life cycle, feeding behaviour and growth pattern of Microdon myrmicae, a social parasite of Myrmica ants and compare it with two species of Maculinea butterflies similarly parasitizing Myrmica ant colonies. M. myrmicae has three larval instars and overwinters as a third instar. Eggs and 1st instar larvae are ignored by ants, which indicate that they are “chemically insignificant”. 2nd and 3rd instar larvae feed on small ant brood. M.myrmicae larvae grow rapidly from May to July and later in the year the host colony only serves as shelter for overwintering. Like Maculinea alcon, larvae of M. myrmicae are numerous in Myrmica nests and more numerous than those of Maculinea teleius. Since the larvae of Microdon feed on an abundance of young ant brood, they experience low level of scramble competition and although many may develop in an ant’s nest they have probably little effect on host colony fitness., Magdalena Witek ... [et al.]., and Obsahuje seznam literatury
Eumerus purpurariae, described from the Canary Islands (Atlantic), has been reared from the stems (platyclades) of the cactus Opuntia maxima (the first known host) on Nueva Tabarca, a Mediterranean island close to the Iberian coast. The egg, larva and puparium of E. purpurariae, as well as its life cycle on the above host-plant are described. The feeding behaviour of the larva in relation to the cephalopharyngeal skeleton morphology is analysed. Based on the present data, comparative table containing the main morphological characteristics of the injurious Eumerus species of the Palaearctic region is presented.
Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field., Brecht Ingels ... [et al.]., and Obsahuje seznam literatury
In this study we analyzed the inter-specific relationships in assemblages of syrphids at a site in northern Italy in order to determine whether there are patterns in diurnal co-occurrence. We adopted a null model approach and calculated two co-occurrence metrics, the C-score and variance ratio (V-ratio), both for the total catch and of the morning (8:00–13:00) and afternoon (13:00–18:00) catches separately, and for males and females. We recorded discordant species richness, abundance and co-occurrence patterns in the samples collected. Higher species richness and abundance were recorded in the morning, when the assemblage had an aggregated structure, which agrees with previous findings on communities of invertebrate primary consumers. A segregated pattern of co-occurrence was recorded in the afternoon, when fewer species and individuals were collected. The pattern recorded is likely to be caused by a number of factors, such as a greater availability of food in the morning, prevalence of hot and dry conditions in the early afternoon, which are unfavourable for hoverflies, and possibly competition with other pollinators. Our results indicate that restricting community studies to a particular time of day will result in certain species and/or species interactions not being recorded., Manuela D´Amen ... [et al.]., and Obsahuje seznam literatury
This study is a revision of the Iberian Merodon Meigen, 1803 species, including an illustrated key, a discussion of taxonomic characters and a morphological diagnosis for all included species. Descriptions are provided for nine new species: M. antonioi sp. n., M. arundanus sp. n., M. cabanerensis sp. n., M. crypticus sp. n., M. hurkmansi sp. n., M. legionensis sp. n., M. longispinus sp. n., M. luteihumerus sp. n. and M. quercetorum sp. n. The taxon M. escorialensis Strobl, 1909 is redescribed and lectotype is designated. Lectotypes are designated for four taxa: M. albifrons Meigen, 1822; M. spinipes obscuritarsis Strobl in Czerny & Strobl, 1909; M. spicatus Becker, 1907; and M. spinipes grossus Gil Collado, 1930. Three varieties are redefined and considered as valid species: M. obscuritarsis Strobl in Czerny & Strobl, 1909 (as var. of spinipes); M. grossus Gil Collado, 1930 (as var. of spinipes); M. unicolor Strobl in Czerny & Strobl, 1909 (as var. of aeneus). The following new synonymies are proposed: M. affinis Gil Collado, 1930 syn.n. (= junior synonym of M. longicornis Sack, 1913); M. lusitanicus Hurkmans, 1993 syn.n. (= junior synonym of M. serrulatus Wiedemann in Meigen, 1822); M. andalusiacus Paramonov, 1929 syn.n., M. bolivari Gil Collado, 1930 syn.n., M. hispanicus Sack, 1931 syn.n. (= all three are junior synonyms of M. unguicornis Strobl in Czerny & Strobl, 1909); M. spicatus Becker, 1907 syn.n. (= junior synonym of M. chalybeus Wiedemann in Meigen, 1822); M. fuerteventurensis Barkemeyer, 2002 syn. n. (= junior synonym of M. obscuritarsis Strobl, 1909); and M. spinipes grossus (Gil Collado, 1930) syn.n. (= junior synonym of M. albifrons Meigen, 1822). Status of M. serrulatus Wiedemann in Meigen, 1822 is revised. Four species: M. longicornis Sack, 1913, M. pumilus Macquart, 1849, M. ottomanus Hurkmans, 1993 and M. segetum (Fabricius, 1794) are new for the Iberian Peninsula. Male genitalia are illustrated for all the species and a key of the 34 Iberian species (+ M. hurkmansi sp. n.) for males and females (except for the unknown female of M. longispinus sp. n.) is appended. Distribution and biological data for the Iberian species are also included. A brief zoogeographic discussion is also presented. The level of endemism of genus Merodon on the Iberian Peninsula is extremely high (almost 50%).
The foraging behaviour of beneficials such as aphidophagous predators depend largely on volatile compounds emitted by potential preys. Even if polyphagous predatory species are considered, all the potential preys are not systematically localised and accepted. In this work, chemical cues from different aphids and plants, each alone or in association, were studied to elucidate their role in prey location. Using a four-arm olfactometer, attraction of combinations of three aphid (Megoura viciae, Acyrthosiphon pisum and Aphis fabae) and one plant (Vicia faba) species for Episyrphus balteatus larvae was observed. Predatory hoverfly larvae were attracted by all tested stimuli in the presence of aphids, whatever the species. Whole or crushed aphids and also aphids on bean plant parts were attractive to syrphid larvae, but the host plant alone did not present any infochemical role for E. balteatus. Identification and quantification of the volatile releases from aphid and plant species, alone or in association, were performed using SPME and GC-MS methods. Aphid alarm pheromone, (E)-β-farnesene, was found in the volatile pattern of each aphid and was tested for its role as an effective kairomone for the hoverfly.
Pollinating insects are important and therefore, it is important to be able to assess and monitor changes in their abundance. Consequently, it is essential that the methods used to collect data have some level of precision and are accurate. In the present study, two commonly used methods: colour pan-traps and sweep netting along transects, were compared. A total of 1775 specimens of 120 species of four insect families were caught in twelve clear-cuts in southern Sweden. Overall, Lepturinae (Cerambycidae; 5 species) and Cetoniidae (Scarabaeidae; 2) were trapped in larger numbers by pan-traps and Syrphidae (62) and Apoidea, both social (10) and solitary (41), by sweep netting. The catches of none of the above groups of insects by the two methods were correlated. These results show that the composition of catches of the two methods are very different, which has implications when choosing a method for sampling or monitoring and comparing and analysing published data.
Eristalis pertinax varies seasonally, with the spring morph more hairy than the summer morph. We measured the size and the venation of the wings of the seasonal morphs. Wings of the spring morph were significantly larger than those of the summer morph and those of females were larger than those of males. There were also significant differences between the morphs in wing venation and their allometric relationship. The differences between sexes were larger than differences between seasonal morphs. The allometry can account for the sexual dimorphism but not seasonal dimorphism. The differences between seasonal morphs in wing shape were relatively large with very few intermediate individuals. The differences were comparable to those between two related species of Syrphidae. Genetic analyses based on markers in nuclear and mitochondrial genomes unequivocally revealed that spring and summer morphs of E. pertinax form a single population and should not be regarded as separate taxa. Thus seasonal variability in this species is a rare example of polyphenism in Diptera., Lukasz E. Mielczarek, Andrzej Oleksa, Katarzyna Meyza, Adam Tofilski., and Obsahuje bibliografii