Factors in Varietal Susceptibility of Walnut Fruits to Attack by the Walnut-Husk Fly

Haas, A. R. C.

doi:10.1104/pp.12.3.721

Cited by 4 publications

(2 citation statements)

References 4 publications

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“…Therefore, we believe that the observed infestation patterns can be better explained by varying levels of secondary metabolites (allelochemicals) in fruit, in turn determined by cultivar, age of tree or by growing conditions, rather than microclimate. In support of the above, differences in walnut cultivar susceptibility to R. completa have been reported in California (Boyce, 1934;Hass, 1937;Opp & Zermeño, 2001;Coates, 2005). We believe that until more accurate information on the effect of cultivar (plant chemistry) can be gathered, presence absence data, rather than infestation levels, is better suited to make inferences on potential invasion routes.…”

Section: Possible Invasion and Expansion Routesmentioning

confidence: 59%

Is the alpine divide becoming more permeable to biological invasions? – Insights on the invasion and establishment of the Walnut Husk Fly, Rhagoletis completa (Diptera: Tephritidae) in Switzerland

Aluja

Guillén

Rull

et al. 2011

Bull. Entomol. Res.

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The Walnut Husk Fly, Rhagoletis completa Cresson (Diptera: Tephritidae), is native to North America (Midwestern US and north-eastern Mexico) and has invaded several European countries in the past decades by likely crossing the alpine divide separating most parts of Switzerland from Italy. Here, we determined its current distribution in Switzerland by sampling walnuts (Juglans regia L.) in ecologically and climatically distinct regions along potential invasion corridors. R. completa was found to be firmly established in most low altitude areas of Switzerland where walnuts thrive, but notably not a single parasitoid was recovered from any of the samples. Infested fruit was recovered in 42 of the 71 localities that were surveyed, with mean fruit infestation rate varying greatly among sites. The incidence of R. completa in Switzerland is closely related to meteorological mean spring temperature patterns influencing growing season length, but not to winter temperatures, reflecting survival potential during hibernation. Importantly, areas in which the fly is absent correspond with localities where the mean spring temperatures fall below 7°C. Historical data records show that the natural cold barrier around the Alpine divide in the central Swiss Alps corresponding to such minimal temperatures has shrunk significantly from a width of more than 40 km before 1990 to around 20 km after 2000. We hypothesize on possible invasion/expansion routes along alpine valleys, dwell on distribution patterns in relation to climate, and outline future research needs as the incursion of R. completa into Switzerland; and, more recently, other European countries, such as Germany, Austria, France and Slovenia, represent an example of alien species that settle first in the Mediterranean Basin and from there become invasive by crossing the Alps.

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Section: Possible Invasion and Expansion Routesmentioning

confidence: 59%

Is the alpine divide becoming more permeable to biological invasions? – Insights on the invasion and establishment of the Walnut Husk Fly, Rhagoletis completa (Diptera: Tephritidae) in Switzerland

Aluja

Guillén

Rull

et al. 2011

Bull. Entomol. Res.

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“…Alternatively, it is possible that cultivars producing larger fruit may at the same time exhibit reduced levels of secondary metabolites as a result of artificial selection by breeders (Aluja & Mangan, 2008). Before conclusions can be reached, more studies are needed to analyse additional fruit features such as epicarp hardness, ripening stage, pH, and polyphenol content, which have been shown to influence host acceptance and survival in other fly species (Boyce, 1933; Hass, 1937; Pree, 1977; Rull & Prokopy, 2004; Aluja & Mangan, 2008; Papachristos et al., 2008; Rattanapun et al., 2009).…”

Section: Discussionmentioning

confidence: 99%

Influence of walnut cultivar on infestation by Rhagoletis completa: behavioural and management implications

Guillén

Aluja

Rull

et al. 2011

Entomologia Experimentalis Et Applicata

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The walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), has recently invaded Switzerland, Austria, Germany, and France, probably crossing the alpine divide after its initial introduction into Italy. Here, the susceptibility of 36 walnut [Juglans regia L. (Juglandaceae)] cultivars to attack by R. completa was studied in an experimental orchard in Switzerland. Walnut cultivars differed significantly in infestation rates; cultivars that produced large, heavy fruit harboured significantly more larvae than cultivars that produced smaller fruit. Pupal weight was significantly influenced by cultivar, but not by any of the physical properties that we measured. For individual fruit within a cultivar, pupal weight was weakly related to fruit weight and infestation level. Adult longevity was correlated with pupal weight and appeared to be favoured in flies that developed in large‐fruit cultivars. The longevities of adults recovered from different cultivars differed significantly. The shortest longevity was recorded for flies recovered from Geisenheim 1049 (39.2 ± 2.80 days) and the longest for flies recovered from Sheinovo (68.8 ± 21.75 days). Differences in diapause length were also highly significant and varied between 167 ± 5.1 (Esterhazy III) and 257.4 ± 8.21 days (Mayette). These results suggest that (1) across and within cultivars, walnut husk flies prefer to infest (i.e., they develop better in) large, heavy fruit, and (2) offspring that develop in large fruit are likely to accrue fitness advantages over the offspring of females using smaller fruit. Our results provide the basis for subsequent studies on resource defence by males, as they enable a prediction of which type of fruit males should defend more vigorously.

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Resistance of plants to insect attack

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1941

Bot. Rev

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Factors in Varietal Susceptibility of Walnut Fruits to Attack by the Walnut-Husk Fly

Cited by 4 publications

References 4 publications

Is the alpine divide becoming more permeable to biological invasions? – Insights on the invasion and establishment of the Walnut Husk Fly, Rhagoletis completa (Diptera: Tephritidae) in Switzerland

Is the alpine divide becoming more permeable to biological invasions? – Insights on the invasion and establishment of the Walnut Husk Fly, Rhagoletis completa (Diptera: Tephritidae) in Switzerland

Influence of walnut cultivar on infestation by Rhagoletis completa: behavioural and management implications

Resistance of plants to insect attack

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