R. H. L. Disney

First occurrences of the Phorid, Megaselia abdita, in forensic cases in Britain

Abstract.  The first two cases of the occurrence of Megaselia abdita Schmitz (Diptera: Phoridae) in human corpses in Britain are reported and a further case of M. rufipes (Meigen). In all three cases the corpses experienced low temperatures.

Duration of development of two species of carrion‐breeding scuttle flies and forensic implications

Abstract.  A procedure for rearing carrion‐breeding scuttle flies (Diptera: Phoridae) under naturally fluctuating temperatures is described. Data on the duration of development of the egg stage, egg plus feeding larval stages, postfeeding larvae and total development from egg to adult, at different temperature regimes (means of daily means) are tabulated for Megaselia giraudii (Egger) and M. rufipes (Meigen). The variation is greater than previously supposed and involves larvae derived from the same egg batch leaving the bait in successive waves. Despite this variation the tables allow the provision of percentage probabilities of estimations of the earliest oviposition dates for specimens collected from a forensic case.

Potential use of Braconidae (Hymenoptera) in forensic cases

Abstract.  The larvae of small Diptera, such as Phoridae, from forensic cases are frequently identified by rearing out the adults. However, parasitoid Hymenoptera are often obtained instead. Rather than discarding these, it is suggested that, with a knowledge of their durations of development, they can be employed as surrogates for their hosts for estimating a minimum postmortem interval. Some data for a forensically important species of Phoridae parasitized by a species of Braconidae are presented.

Scuttle flies (Diptera: Phoridae) of the Canary Islands.

Fifty-four species in 10 genera are listed for the Canary Islands. Megaselia chinyeroensis Disney sp. nov. and Microselia prescherae Disney sp. nov. are described. The hitherto unkown males of Megaselia intermedia (Santos Abreu), Metopina tanjae Disney and Prescher, the putative female of Chonocephalus bentacaisei (Santos Abreu) and the female of Megaselia apozona Schmitz are described. Discovery of errors in the original description of Megaselia striolata Schmitz means that Megaselia canaryae Disney must be synonymized with Schmitzs species.

Studies in European ant-decapitating flies (Diptera: Phoridae): ant alarm pheromone as host finding cue in Pseudacteon brevicauda, a parasite of Myrmica rubra (Formicidae: Myrmicinae)

Pseudacteon brevicauda Schmitz parasitizes Myrmica rubra in the Middle Rhine region in Germany. Female flies are attracted to disturbed ant colonies, where they attack Myrmica workers for oviposition. We experimented with different body parts of the ants, with dissected mandibular glands, and with synthetic gland constituents to locate the source of the fly attractant and the chemical basis of the signal. The attracting kairomone originates from the mandibular glands, which are used by Myrmica ants in alarm communication. Among the gland constituents, the ketones 3-octanone and 3-nonanone attracted and alerted the parasitic flies. The alcohol 3-octanol did not attract flies over long distance but it released an alerting response over short distance. A comparison of the chemical compositions of mandibular glands between ant species, focusing on the bioactive compounds, can explain both host specificity of P. brevicauda and the extension of the host spectrum to the (chemically similar) Myrmica scabrinodis.

Behaviour and activity patterns of the scuttle fly Megaselia oxybelorum Schmitz (Diptera: Phoridae) at nest aggregations of two host digger wasps (Hymenoptera: Crabronidae)

We report on a field study of the behavioural ecology of Megaselia oxybelorum Schmitz at nest aggregations of its hosts, the digger wasps Philanthus triangulum F. and Cerceris arenaria L. (Hymenoptera: Crabronidae). The flies flew across the P. triangulum nesting site both as single individuals and as females and males paired in copula, and the former case was recorded more than twice as often as the latter, while only single individuals were recorded at the C. arenaria site. Individuals both alone and in copula were seen at the P. triangulum site during the day roughly coinciding with the host provisioning activity, while at the C. arenaria site the flys daily activity followed a bimodal trend in contrast to the normal distribution of the host provisioning. Visits of host nests were frequent at the P. triangulum site and null at the C. arenaria site. Single individuals spent less than 1 min inside a nest, while a female entering while still in copula spent generally 1–3 min inside, males exiting after 1–5 s, showing that only in this second case was an oviposition possible. The number of Megaselia oxybelorum increased with increasing host nest density and decreasing nearest neighbour distances of nests. Behavioural patterns of M. oxybelorum, when compared to other Megaselia spp. associated with fossorial Hymenoptera, showed differences possibly related to the biology of the hosts. In addition, some morphological variation within and between host sites are discussed.

Additions to the British list of Megaselia Rondani (Diptera: Phoridae), including two new species, from the crowns of ancient pollarded trees

Among species trapped in the crowns of ancient pollarded trees in southern England are Megaselia russellsmithi Disney sp. n, M. velutinicavus Disney sp. n. and M. henrydisneyi Durska, which is a further addition to the British List. The hitherto unknown females of M. henrydisneyi, M. serrata (Wood) and M. speiseri Schmitz are described. M. gargarans Schmitz and M. basiturgida Disney & Durska are synonymised with M. crassipes (Wood) following recognition of an error in Schmitz’s description of M. gargarans and of other confusions in the literature. http://zoobank.org/urn:lsid:zoobank.org:pub:1CC46F9C-AB02-446C-BF83-4D9529508DFA