The bark beetle,Ips grandicollis,disrupts biological control of the woodwasp,Sirex noctilio,via fungal symbiont interactions

Abstract

The corticoid fungus, Amylostereum areolatum, is deposited in pine trees by the woodwasp, Sirex noctilio, at the time of oviposition. This fungus is essential in S. noctilio larval growth and it is also a food source for Beddingia siricidicola, the nematode used for S. noctilio biological control. In recent years, the historically successful biological control programme has been disrupted in Australia by the bark beetle, Ips grandicollis. This study investigated whether the mechanism of this disruption involves a fungus, Ophiostoma ips, which I. grandicollis introduces into trees. In artificial and wood media, A. areolatum was unable to grow in areas occupied by O. ips. The latter fungus was faster growing, especially at 25 °C rather than 20 °C. Larval galleries of S. noctilio in field-collected samples were strongly associated with wood infested by A. areolatum and absent from areas affected by O. ips. The nematode failed to survive and reproduce on O. ips as it can on A. areolatum. Competitive interactions between O. ips and A. areolatum within the trap trees are demonstrated to be key factors in the negative effect of I. grandicollis on S. noctilio biological control programmes.

Pathology, distribution, morphological and genetic identity of Deladenus proximus (Tylenchida: Neotylenchidae) a parasitic nematode of the woodwasp, Sirex nigricornis in the eastern United States

“…In its native range of North Africa and Eurasia, S. noctilio causes little damage to pines and is of minimal concern (Hall, 1968;Spradbery and Kirk, 1978). However, in locations where S. noctilio has invaded non-native pine plantations there is no community of predators, parasitoids and parasites to control the population (but see Yousuf et al, 2014b). As a consequence, populations of invasive S. noctilio have caused catastrophic damage to pine plantations in the southern hemisphere (Carnegie et al, 2005;Carnegie et al, 2006;Coutts, 1965).…”

SirexWoodwasp: A Model for Evolving Management Paradigms of Invasive Forest Pests

“…Such insects may interact with S. noctilio either directly or indirectly by introducing competing fungi (4,88,92,118,124). A. areolatum is a weak competitor against certain fungi that occur as endophytes in Pinus (e.g., Diplodia sapinea in South Africa) or that are introduced by bark beetles in North America and Australia (e.g., Ophiostoma ips introduced by Ips grandicollis and Leptographium wingfieldii by Tomicus piniperda) (55,92,124,127).…”

“…A. areolatum is a weak competitor against certain fungi that occur as endophytes in Pinus (e.g., Diplodia sapinea in South Africa) or that are introduced by bark beetles in North America and Australia (e.g., Ophiostoma ips introduced by Ips grandicollis and Leptographium wingfieldii by Tomicus piniperda) (55,92,124,127). These fungi can affect the rate at which trees die and the wood moisture levels in infested trees, which has indirect negative effects on A. areolatum (124) and on the oviposition behavior of the wasp (89). Apart from their competition with A. areolatum, competing insects can also interfere with management programs (28,34,35,45,46,124,127).…”

“…These fungi can affect the rate at which trees die and the wood moisture levels in infested trees, which has indirect negative effects on A. areolatum (124) and on the oviposition behavior of the wasp (89). Apart from their competition with A. areolatum, competing insects can also interfere with management programs (28,34,35,45,46,124,127). In Australia, for example, colonization of dying trees by I. grandicollis reduces the number of S. noctilio oviposition events, the size of S. noctilio individuals in trap trees, and the level of parasitism of the wasp by D. siricidicola (124).…”

“…Apart from their competition with A. areolatum, competing insects can also interfere with management programs (28,34,35,45,46,124,127). In Australia, for example, colonization of dying trees by I. grandicollis reduces the number of S. noctilio oviposition events, the size of S. noctilio individuals in trap trees, and the level of parasitism of the wasp by D. siricidicola (124). Despite these potential influences on S. …”