Entomophaga (1996) 41, 183-210
F. Herard and G. Mercadier (1996)
Natural enemies of Tomicus piniperda and Ips acuminatus (Col., Scolytidae) on Pinus sylvestris near Orléans, France: Temporal occurrence and relative abundance, and notes on eight predatory species
Entomophaga 41 (2), 183-210
Abstract: Ips acuminatus (Gyllenhall) and Tomicus piniperda (L.) were the main scolytid beetles in Scots pine, Pinus sylvestris L., outbreak areas near Orleans, France during 1978-1979. Ips acuminatus attacked thin-bark logs while T. piniperda attacked thick-bark logs. More than 150 species of insects were associated with these scolytids. Forty-five species (31 predators and 14 parasitoids) were confirmed as natural enemies of bark beetles. Three predators were abundant: Thanasimus formicarius L. (Col.: Cleridae), Rhizophagus depressus (F.) (Col.: Rhizophagidae) and Medetera spp. (Dipt.: Dolichopodidae). The first two were especially frequent in galleries of T. piniperda, while Medetera spp. were more abundant in galleries of I. acuminatus. The main parasitoids were Rhopalicus tutela (Walker) and R. brevicomis Thomson (Hym.: Pteromalidae), Coeloides abdominalis Zetterstedt and C. melanostigma Strand, Dendrosoter middendorfi Ratzeburg and D. hartigii Ratzeburg, and Spathius rubidus Rossi (Hym.: Braconidae). These parasitoids are polyphagous. However, C. abdominalis was obtained from T. piniperda but not from I. acuminatus, while S. rubidus and D. hartigii were obtained from I. acuminatus but not from T. piniperda. Temporal and relative abundance of natural enemies of T. piniperda and I. acuminatus were studied. The predators R. depressus and T. formicarius had complementary limiting effects on bark beetles as adults and larvae of R. depressus fed mainly on scolytid eggs, while T. formicarius adults attacked scolytid adults and the clerid larvae preyed upon scolytid larvae. The predatory pressure applied by T. formicarius and R. depressus to T. piniperda early during the spring was later complemented by a series of parasitoids and other predators. This sequential timing of the natural enemies of T. piniperda suggests that the interactions among the guild are more complementary than adverse. Differential timing of the natural enemies in logs infested by I. acuminatus and some evidence of competition between the predators Medetera spp. and parasitoids suggested a less effective control of this scolytid.
Number and duration of larval instars were determined, and measurements of predatory activity were made for Thanasimus formicarius, Rhizophagus depressus, Hypophloeus fraxini Kugelann (Col.: Tenebrionidae), Platysoma frontale Paykull (Col.: Histeridae), and Xylocoris cursitans (Fallen) (Het.: Anthocoridae). Predatory activity was evaluated for last instar larvae and adults of Scoloposcelis obscurella (Zetterstedt) (Het.: Anthocoridae), and for last instar larvae of Medetera sp. and Lonchaea collini Hackman (Dipt.: Lonchaeidae).
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Franck Herard
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
population dynamics/epizootiology
surveys/distribution/isolation
