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Tree Protection Co-operative Programme research group

Tree Protection Co-operative Programme

Pine bark beetle/ Hylastes angustatus

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Hylastes angustatus (Herbst, 1793)

Common NamePine bark beetle/ Hylastes angustatus
Scientific NameHylastes angustatus (Herbst, 1793)
SynonymsBostrichus angustatus Herbst 1973 Hylastes scandinavicus Lekander 1965
OriginEurope (Reay & Walsh 2001, El Khoury et al. 2019)
Distribution in South AfricaEastern Cape, KwaZulu-Natal, Limpopo, Mpumalanga, Western Cape

Symptoms

Of the three pine infesting bark beetles introduced into South Africa, Hylastes angustatus tends to be the most problematic. Severe infestations of this species in newly planted plantations can result in up to 50% seedlings loss due to girdling caused by the under bark boring activities of the beetles and their larvae (Tribe 1992).

Attracted by the volatiles produced by damaged pine, H. angustatus is typically found boring in felled logs or discarded branches within the plantation and is considered a secondary bark beetle of stressed trees. Additionally, in some instances, the beetles can also be found infesting the lateral roots of growing pines and are known to infest trees below ground level. This indiscriminate boring and breeding of the beetles in discarded material within the plantation leads to population booms, from where the beetles spread into newly planted plantations, attracted by volatile cues produced by the seedlings due to post planting stress (Erasmus & Chown 1994).

Biology

In South Africa, H. angustatus is reproductively active from mid-August until early April. The species is most considered a pest of summer rainfall regions as dispersal is timed with the occurrence of rain. However, with later rainfall occurring in the winter rainfall areas, the species is becoming more problematic in the Southern Cape. Due to the long active period of the species, up to three generations can occur in winter rainfall regions per season, and up to five generations can occur in summer rainfall regions (Tribe 1991).

Management

Primarily relies on good silvicultural practices including the removal of slash and pine debris from plantations to prevent the build-up of beetle populations and reducing the levels of seedling damage during planting to prevent the production of volatile cues that attract the beetles.

Gallery

Lateral view of Hylastes angustatus adult (scale = 1mm)
Lateral view of Hylastes angustatus adult (scale = 1mm)