Blue willow beetle
{{Short description|Species of beetle}}
{{Speciesbox
| name = Blue willow beetle
| image = Phratora vulgatissima01.jpg
| taxon = Phratora vulgatissima
| authority = (Linnaeus, 1758)
}}
{{Wikispecies|Phratora vulgatissima}}
The blue willow beetle (Phratora vulgatissima), formerly Phyllodecta vulgatissima, is a herbivourous beetle of the family Chrysomelidae. It is dark with a metallic sheen that ranges from a blue color to bronze. It is distinguished from P. vitellinae by the latter more commonly displaying bronze coloration. European Phratora species can be distinguished based on morphology of female genitalia.{{Cite journal| volume = 21| pages = 5–7| last = Sundholm| first = A.| title = Studien über die Gattung Phyllodecta Kirby (Col. Chrysomelidae)| journal = Opuscula Entomologica| date = 1956}}
The larvae undergo three instar stages from hatching to pupation.{{Cite journal|title = Performance of an herbivorous leaf beetle (Phratora vulgatissima) on Salix F2 hybrids: the uimportance of phenolics |journal = Journal of Chemical Ecology|date = 2013-03-01 |pages = 516–524|volume = 39|issue = 4|doi = 10.1007/s10886-013-0266-3|pmid = 23456345|first1 = Mikaela|last1 = Torp|first2 = Anna|last2 = Lehrman|first3 = Johan A.|last3 = Stenberg|first4 = Riitta|last4 = Julkunen-Tiitto|first5 = Christer|last5 = Björkman| s2cid=1714405 }} This beetle is found throughout Europe and Scandinavia,{{Cite book| publisher = Goecke and Evers Verlag| last = Lucht| first = W. H.| title = Die Käfer Mitteleuropas: Katalog| location = Krefeld| date = 1987}} and occurs in China.{{Cite journal| volume = 2| issue = 3| pages = 218–224| last = Chen| first = S. H.| title = On the Chinese species of the Chrysomeline genus Phratora| journal = Acta Zootaxonomica Sinica| date = 1965}}
Ecology
The blue willow beetle is found on willow (Salix) species, whose leaves contain low levels of salicylates{{Cite journal| volume = 52| pages = 517–528| last1 = Köpf| first1 = A.| last2 = Rank| first2 = N. E.| last3 = Roininen| first3 = H.| last4 = Julkunen-Tiitto| first4 = R.| last5 = Pasteels| first5 = J. M.| last6 = Tahvanainen| first6 = J.| title = The evolution of host-plant use and sequestration in the leaf beetle genus Phratora (Coleoptera: Chrysomelidae)| journal = Evolution| date = 1998| issue = 2| doi = 10.1111/j.1558-5646.1998.tb01651.x| pmid = 28568343| s2cid = 24641299| doi-access = free}}{{Cite journal| volume = 61| pages = 25–32| last1 = Kelly| first1 = M. T.| last2 = Curry| first2 = J. P.| title = The influence of phenolic compounds on the suitability of three Salix species as hosts for the willow beetle Phratora vulgatissima| journal = Entomologia Experimentalis et Applicata| date = 1991| doi = 10.1111/j.1570-7458.1991.tb02392.x| s2cid = 84232264}} in fens, carrs and on river banks, but also often in willow short rotation coppice and other agricultural landscapes.{{Cite journal| volume = 111| pages = 57–62| last1 = Kelly| first1 = M. T.| last2 = Curry| first2 = J. P.| title = The biology and population density of the willow beetle (Phratora vulgatissima [L.]) on Salix viminalis in reclaimed cutaway peat| journal = Journal of Applied Entomology| date = 1991| issue = 1–5| doi = 10.1111/j.1439-0418.1991.tb00293.x| s2cid = 86736745}} It often aggregates on host plants.{{Cite journal|title = Spatio-temporal dynamics of willow beetle (Phratora vulgatissima) in short-rotation coppice willows grown as monocultures or a genetically diverse mixture|journal = Agricultural and Forest Entomology|date = 1999-11-01 |pages = 287–296|volume = 1|issue = 4|doi = 10.1046/j.1461-9563.1999.00039.x|first1 = L.|last1 = Peacock|first2 = S.|last2 = Herrick|first3 = P.|last3 = Brain| s2cid=84933651 }} On Salix cinerea, it prefers and is more common on female than male trees despite higher egg predation exerted by the common flowerbug Anthocoris nemorum on female trees.{{Cite journal|title = Plant-sex-biased tritrophic interactions on dioecious willow|last1 = Kabir|first1 = Faisal MD|date = 2015-04-19|journal = Ecosphere|volume = 5|issue = 12|page = 153|doi = 10.1890/ES14-00356.1|last2 = Moritz|first2 = Kim K|last3 = Stenberg|first3 = Johan A|doi-access = free}} It is univoltine in Sweden but can produce multiple generations per year in other parts of its distribution range.{{Cite journal| volume = 2| pages = 1–100| last = Görnandt| first = H.| title = Die Käfergattung Phyllodecta Kirby| journal = Deutsche Entomologische Zeitschrift| date = 1955| doi = 10.1002/mmnd.19550020102}} Proliferation of larvae and egg production varies with vegetation.{{cite journal |title=Effects of host variety on blue willow beetle Phratora vulgatissima performance |author1=L. Peacock |author2= J. Harris |author3=S. Powers |name-list-style=amp |journal=Annals of Applied Biology |volume=144 |issue=1 |year=2004 |pages=45–52 |doi=10.1111/j.1744-7348.2004.tb00315.x}} It overwinters under lichens on trees and under tree bark.{{Cite journal|title = Phenology and population dynamics of willow beetles (Coleoptera: Chrysomelidae) in short rotation coppice willows at Long Ashton|last = Kendall|first = D A|date = 1996|journal = Biofuels Study}} Predators of blue willow beetle eggs include A. nemorum and Orthotylus marginalis. Larval predators include A. nemorum, the bug Rhacognathus punctatus, a syrphid fly (possibly Parasyrphus nigritarsis){{Cite book| publisher = SPB Publishing| volume = 2: Ecological Studies| pages = 147–171 |editor=P. H. Jolivet |editor2=M. L. Cox | last1 = Rank| first1 = N. E.| last2 = Smiley| first2 = J. T.| last3 = Köpf| first3 = A.| title = Chrysomelidae Biology| chapter = Natural enemies and host plant relationships for chrysomeline leaf beetles feeding on Salicaceae| location = Amsterdam| date = 1996}} and the wasp Symmorphus bifasciatus.{{Cite book| publisher = Akademie Verlag| last = Blüthgen| first = P.| title = Die Faltenwespen Mitteleuropas (Hymenoptera, Diploptera)| location = Berlin| date = 1961}} Adult beetles are parasitized by the wasp Perilitus brevicollis{{cite journal |title=Plant-mediated effects of different Salix species on the performance of the braconid parasitoid Perilitus brevicollis |author=J.A. Stenberg |journal=Biological Control |volume=60 |year=2012 |pages=54–58 |doi=10.1016/j.biocontrol.2011.09.004}} and consumed by R. punctatus.
As a pest
In Europe, the blue willow beetle can become a severe herbivore pest on willows.{{cite journal |title=Uncoupling direct and indirect plant defences: Novel opportunities for improving crop security in willow plantations|author1=J. Stenberg |author2=A. Lehrman |author3=C. Björkman |journal=Agriculture, Ecosystems and Environment |volume=139 |issue=4|year=2010|pages=528–533 |doi=10.1016/j.agee.2010.09.013}} For plantations of common osier (Salix viminalis), herbivory reducing biomass production by up to 40% has been estimated.{{cite journal |title=Effects of leaf beetle damage on stem wood production in coppicing willow|author=C. Björkman|author2=S. Höglund|author3=K. Eklund|author4=S. Larsson|name-list-style=amp|journal=Agricultural and Forest Entomology |volume=2 |issue = 2|year=2000|pages=131–139 |doi=10.1046/j.1461-9563.2000.00058.x|s2cid=85412547 }} It is susceptible to Bacillus thuringiensis tenebrionis and also Spinosad when treatment is applied to affected plants.{{cite conference | last1 = Helbig| first1 = C.| last2 = Müller| first2 = M.| last3 = Landgraf | first3 = D. |title=Insect pests in short rotation coppice in Germany—An overview of their effects, risk potential and control measures |book-title=Short Rotation Forestry and Agroforestry: An Exchange of Experience between CDM Countries and Europe |publisher=Benwood Project Consortium |year=2011 |pages=46–56 |citeseerx=10.1.1.432.2300}}