Jb. Coupland et G. Baker, HOST DISTRIBUTION, LARVIPOSITION BEHAVIOR AND GENERATION TIME OF SARCOPHAGA-PENICILLATA (DIPTERA, SARCOPHAGIDAE), A PARASITOID OF CONICAL SNAILS, Bulletin of entomological research, 84(2), 1994, pp. 185-189
Host characteristics, hyperparasitism, larviposition behaviour and gen
eration time of Sarcophaga penicillata Villeneuve a parasitoid of the
conical snail, Cochlicella acuta Muller (Mollusca:Helicidae) in southe
rn France are described. Only snails which aestivated on vegetation we
re found to be parasitized by S. penicillata. Sarcophaga penicillata p
referred C. acuta which were both significantly higher off the ground
and larger in size than the population averages. Of the 2768 snails co
llected at the study site, 4% (112) were parasitized by S. penicillata
, of which 36.6% (41) failed to emerge while 34% (38) were hyperparasi
tized. The predominant hyperparasite was Novitzkyanus cryptogaster Bou
cek (Hymenoptera: Pteromalidae) which was responsible for 79% (30) of
the hyperparasitism. Larvipositing S. penicillata were observed to fab
ricate a hole in the epiphragm of resting snails in which they deposit
ed 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 super
parasitism, 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. p
enicillata 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.