plants, are mostly unknown. All known immature stages of Merodon feed on underground storage organs (bulbs, rhizomes and corms) of geophytes of the families Asparagaceae, Iridaceae and Amaryllidaceae. Of 160 known Merodon species, to date, the pupal stages have been described for only four: M. equestris (Fabricius), M. bombiformis Hull, M. luteihumerus Marcos-García, Vujić & Mengual, and M. geniculatus Strobl. During field investigations in Đerdap National Park, Serbia, Merodon puparia were found in the ground near the bulbs of Ornithogalum umbellatum L. (Asparagaceae). DNA barcoding revealed that they belonged to the species M. aureus Fabricius and M. avidus (Rossi). Analysis of museum material from the Bavarian State Collection of Zoology in Germany revealed the puparium of an additional species, M. rufus Meigen. In our study we provide for the first time descriptions of the puparia of these three Merodon species. The main diagnostic morphological characters of the pupal spiracles and posterior respiratory processes are described using scanning electron microscopy, and cephalopharyngeal skeletons using binocular microscopy. In addition, puparium morphology of M. aureus, M. avidus and M. rufus is compared with known puparia of four other Merodon species and with the third larval stage of M. hurkmansi Marcos-García, Vujić & Mengual.
The importance of eristaline flies (Diptera, Syrphidae, Eristalini) as pollinators in natural ecosystems and for agricultural crops is well known. However, in‐depth studies on the life cycle of most of these species have yet to be carried out. The aim of this research was to study the life cycle of Eristalis tenax (Linnaeus, 1758) and Eristalinus aeneus (Scopoli, 1763) in order to improve the current rearing system employed at the University of Alicante. The results were analysed using the age‐stage, two‐sex life table method. As one of the main results, the mean duration of the life history of E. tenax and E. aeneus was 46.06 and 65.12 days (d), respectively. The most critical step for both species was found at the beginning of the larval stage (first instar), when the highest mortality was recorded. Population parameters were also analysed and compared. The intrinsic rate of increase (r), the finite rate of increase (λ), the net reproductive rate (R0) and the mean generation time (T) were 0.09 (d−1), 1.09 (d−1), 42.11 offspring and 40.97 d, in the case of E. aeneus and 0.05 (d−1), 1.05 (d−1), 23.13 offspring and 59.23 d, in the case of E. tenax. These results indicate that the current rearing system is more efficient for E. aeneus, which displays a faster population growth. However, some modifications need to be implemented to improve the production of E. tenax.
Eristalinus punctulatus (Macquart, 1847) is a hoverfly (Syrphidae) that is native to Australia. Eristalinus belongs within tribe Eristalini, which is well known for its pollination efficiency. Although there is not much information available about this species, the abundance and floral constancy of this group of flies make E. punctulatus an appropriate candidate for use as pollinating agent. However, like most other eristalines, there is a lack of information regarding basic aspects of its biological cycle, as well as the morphology of the preimaginal stages. In this paper, the morphology of the egg, the first and third larval instars and the puparium of E. punctulatus are described for the first time. A description of the head skeleton is also given to improve understanding of the larval feeding habits of this species. Additionally, a diagnostic key of the third larval instar is provided together with an update of the pupal stage key, including all the Eristalinus species whose preimaginal morphology has already been described. The most noteworthy morphological features of the larva of E. punctulatus are the presence of lappets, the proportions of the anterior spiracles and the number and size of the facets.
The intra-puparial development of 150 pupae of Eristalinus aeneus (Scopoli, 1763) and Eristalis tenax (Linnaeus, 1758) was analyzed. Individuals were obtained from the sixth laboratory generation kept under artificial rearing conditions at the facilities of the University of Alicante (Spain). The experiment was conducted at 25 ± 1 C temperature, 50 ± 5% relative humidity, and 12:12 hr (L:D) of photoperiod. Groups of 10 pupae were collected every 6 hr over 48 hr, after that period, pupae were collected daily until the adult emergence. They were fixed in 5% formic acid and preserved in 70% ethanol. Fixed pupae were dissected and photographed. The chronology and morphological changes that take place during the intra-puparial development in both species were analyzed and compared. Five phases were observed: prepupa, before 6 hr; cryptocephalic pupa, between 6 and 24 hr; phanerocephalic pupa, between 24 and 30 hr; pharate adult, after 30 hr; and the adult imago, restricted to the very end of the development process just before adult emergence. In total, the intra-puparial development lasted 189 ± 4 hr in E. aeneus and 192 ± 3 hr in E. tenax, with the pharate adult the longest phase (some 81% of the total developmental time). These data can be used to develop accurate cold storage protocols during artificial rearing of both pollinator species, avoiding critical events during the development and increasing survival.
Eristalinus aeneus (Scopoli) and Eristalis tenax (L.) (Diptera: Syrphidae, Eristalini) are important pollinator species that can be artificially reared and commercialised. To achieve better control over the pupal development time and adult emergence, cold storage techniques are suitable tools. Insects were reared under controlled conditions: 25 AE 1 °C, 50% r.h., and L12:D12 photoperiod. Pupae of both species were stored at 5 °C at the beginning (early treatments) or at the end (late treatments) of their development for various periods of time (5, 10, 15, 20, or 30 days). Development stopped completely at 5 °C in both treatments, but in general, pupae stored at the beginning of the pupal stage provided better results in terms of survival (adult emergence) and quality of the adults (general morphology). The cold tolerance of E. tenax was lower than that of E. aeneus, with their pupal developmental time successfully extended up to 18 and 23 days, respectively, without compromising survival and morphology. The number and types of morphological alterations due to cold storage were recorded.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.