Biological control of homopteran pests of conifers in Africa.

Day, Roger; Kairo, M. T. K.; Abraham, Y. J.; Kfir, Rami; Murphy, Sean T.; Mutitu, K.E.; Chilima, C. Z.; Neuenschwander, Peter; Borgemeister, Christian; Langewald, J.

doi:10.1079/9780851996394.0101

Cited by 21 publications

(17 citation statements)

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“…This is a consequence of the often very narrow genetic diversity of exotics when only few planting materials were transferred from the species' centres of origin. One example is the poor performance of Rwandan Grevillea robusta provenances as compared to wild Australian ones (Kalinganire and Hall 1993), another the invasion of the cypress aphid Cinara cupressivora and the woolly adelgid Pineus boerneri in exotic conifer plantations in eastern and southern Africa (Day et al 2003). Greater tree diversity including 'plastic' indigenous tree species buffers farming systems against the mentioned challenges, which is of particular importance in the face of climate change (Dawson et al 2011).…”

Section: Introductionmentioning

confidence: 98%

Exotic tree species displace indigenous ones on farms at intermediate altitudes around Mount Kenya

et al. 2011

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Agroforestry systems are potentially suitable for conservation of tree genetic resources. Farmers around Mt. Kenya usually integrate trees into their farm. Large parts of these trees seem to be of exotic origin, whereas indigenous species have priority for conservation. This study aimed at determining on-farm richness, composition and frequency of indigenous and exotic woody species around Mount Kenya to assess the suitability of farms for the conservation of indigenous tree species. 265 onfarm plots of 0.5 ha size each were selected in 18 different agro-ecological zones by using a stratified sampling scheme. All woody species within the plot were recorded with their local and scientific names. Total species richness was 424 (including 306 indigenous ones), mean richness per plot 16.5 species (including 8.8 indigenous ones). Eight out of the 10 most frequent species were exotic ones with Grevillea robusta from Australia ranking first (found on almost 76% of the surveyed farms). The proportion of indigenous species increased with increasing aridity and temperature. Dominance of exotic species was found at farms of humid mid-and highlands. Ordination analysis revealed that mostly exotic species contributed to separation of farms in the highlands and upper midlands, whereas indigenous species in the lower midlands and lowlands. As the frequencies of most indigenous trees were low, only parts of the surveyed farms can contribute to conservation of tree genetic resources, particularly the less intensively managed farms of the more arid lands. Farmers' access to knowledge on valuable indigenous tree species and to quality seedlings of these trees need to be improved to increase indigenous species' frequencies on farms and possibly to replace some of the exotic species in the future.

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Section: Introductionmentioning

confidence: 98%

Exotic tree species displace indigenous ones on farms at intermediate altitudes around Mount Kenya

et al. 2011

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“…However, we cannot conclude whether our results indicate a genetic shift towards higher inherent resistance to P. pini or towards better adaptation to the local environmental conditions that might also reduce the susceptibility to P. pini. Stress and unfavourable environmental conditions are known to make trees more susceptible to P. borneri (Chilima & Leather, 2001;Day et al, 2003). McClure (1982) reported that Pineus coloradensi (Gill.…”

Section: The Icelandic First-generation Provenancesmentioning

confidence: 99%

“…The effects of infestation on trees are needle shedding, reduced needle length and loss of growth increment (Day et al ., ). Barnes et al .…”

Section: Introductionmentioning

confidence: 97%

“…The effects of infestation on trees are needle shedding, reduced needle length and loss of growth increment (Day et al, 2003). Barnes et al (1976) found high variability in the susceptibility of different Pinus spp.…”

Section: Introductionmentioning

confidence: 99%

“…Natural enemies have been shown to be able to effectively control population levels and damage of Pineus spp. (Day et al, 2003). CABI (2018) lists natural enemies of Pineus spp., although none of those species had been recorded in Iceland in the late 1980s (Ólafsson, 1991).…”

Section: Introductionmentioning

confidence: 99%

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The effect of the pine woolly aphid (Pineus pini) on survival, growth and natural selection in Scots pine (Pinus sylvestris) in Iceland

Heiðarsson¹,

Sigurðsson

Davidsson³

et al. 2020

Agri and Forest Entomology

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Scots pine Pinus sylvestris was originally introduced to Iceland in the beginning of the 20th Century. Extensive plantings started in the late 1940s and, in total, 2–3 million Scots pine seedlings were planted, mainly originating from two counties in northern Norway. Part of this plant material was imported as seedlings. Pine woolly aphid Pineus pini was introduced to Iceland before 1940, most likely on imported seedlings in 1937. High mortality of Scots pine, concurrent with high infestation of the pine woolly aphid, was observed in Iceland during the late 1950s and 1960s and planting was discontinued. Provenance trials with Scots pine were established in Iceland in 2004–2006. They consisted of 15 provenances from Norway, four from Finland, four from Scotland, one from Russia, one from the Austrian Alps and three first generation Scots pine provenances from Iceland, collected from survivors of the epidemic in the 1950s and 1960s. In total, there were 28 provenances. The Icelandic provenances had significantly lower P. pini infestation than all the provenances of non‐Icelandic origin, which indicates that natural selection in Scots pine in Iceland has occurred in favour of individuals less susceptible to P. pini.

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