Host distribution, larviposition behaviour and generation time ofSarcophaga penicillata(Diptera: Sarcophagidae), a parasitoid of conical snails

Abstract

Host characteristics, hyperparasitism, larviposition behaviour and generation time of Sarcophaga penicillata Villeneuve a parasitoid of the conical snail, Cochlicella acuta Müller (Mollusca: Helicidae) in southern France are described. Only snails which aestivated on vegetation were found to be parasitized by S. penicillata. Sarcophaga penicillata preferred C. acuta which were both significantly higher off the ground and larger in size than the population averages. Of the 2768 snails collected at the study site, 4% (112) were parasitized by S. penicillata, of which 36.6% (41) failed to emerge while 34% (38) were hyperparasitized. The predominant hyperparasite was Novitzkyanus cryplogaster Bouček (Hymenoptera: Pteromalidae) which was responsible for 79% (30) of the hyperparasitism. Larvipositing S. penicillata were observed to fabricate a hole in the epiphragm of resting snails in which they deposited one larva. After larviposition, female S. penicillata remained with the freshly parasitized snail a mean time ± SE of 25.2 ± 10.3 min. It is suggested that this may be an adaptive response to avoid superparasitism. The mean generation time of S. penicillata when reared in the laboratory was 18 days, indicating that more than six generations are possible during summer in the south of France. During winter, S. penicillata enters diapause in the pupal stage within a host snail for up to 6 months. The possible utility of S. penicillata as a biological control agent of introduced conical snails is discussed.

Phylogeny ofHeteronychia: the largest lineage ofSarcophaga(Diptera: Sarcophagidae)

“…According to Keilin (), Sarcophagidae associated with snails are either saprophagous or ‘doubtful parasites’; Villeneuve () hypothesized that saprophagous or necrophagous life habits may have evolved from an original parasitic strategy. Possible true parasitoids of snails may well exist amongst the flesh flies, as in the cases exemplified by Rostand () for Sarcophaga ( Heteronychia ) filia Rondani, by Lopes () for Titanogrypa ( Sarconeiva ) fimbriata (Aldrich), by Muma (, ) and Reeves, Pape & Adler () for Lepidodexia ( Johnsonia ) elegans (Coquillet), by Stegmaier () for Helicobia morionella (Aldrich) and Peckia ( Sarcodexia ) lambens , by Lopes () for Lepidodexia ( Notochaeta ) malacophaga (Lopes), by Coupland & Baker () for Sarcophaga ( Heteronychia ) villeneuveana (Enderlein), by McKillup & McKillup (, , ) and McKillup, McKillup & Pape () for Sarcophaga ( Sarcorohdendorfia ) megafilosia Pape, McKillup & McKillup and Sarcophaga ( Sarcorohdendorfia ) meiofilosia Pape, McKillup & McKillup, by Pérez‐Moreno () for Sarcophaga ( Heteronychia ) javita (Peris, González‐Mora & Mingo), and by Sinha & Nandi (, as Liosarcophaga choudhuri [sic]) for Sarcophaga choudhuryi .…”

“…( Het. ) villeneuveana , which has been extensively studied particularly in Australia where it has been introduced as a biological control agent of pest snail species (Coupland, ; Coupland & Baker, , ; Carter & Baker, 1997a, 1997b; Baker, , ; Cowie, ; Leyson et al ., ; Coupland & Barker, ; Lawrence, Leonard & Baker, ; all as ‘ Sarcophaga penicillata Villeneuve’). Further research, particularly on their larval biology, is necessary to assess whether these species are all true parasitoids (as often stated in the literature without further biological information) or more similar to predators, and whether parasitism, where present, is obligate or facultative.…”

Parasitism of Parapodisma grasshopper species by the flesh fly, Blaesoxipha japonensis (Hori) (Diptera: Sarcophagidae)

“…As a result, a density-dependent decrease in puparium weight was detected, but was significant only in female hosts. These findings suggest that fly larvae engage in exploitative competition for food resources as do other parasitoid flies (Coupland and Baker, 1994;Danyk et al, 2000).…”

The presence of high numbers of empty shells in anthropogenic habitats is insufficient to attract shell adopters among the insects

“…This life cycle is thought to be linked to the life cycle of their main hosts, Theba spp. and Cernuella spp., as these snails oviposit in the autumn and die shortly after (Coupland & Barker, ). Although it was reported to pupate on or in the soil, here we report this fly as abundantly reared from the shells themselves.…”