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Since the 1970s Frankliniella occidentalis has successfully invaded many. Datasheet Type(s); Invasive Species; Pest; Vector of Plant Pest; Natural. Palmer, USA: Alaska Department of Natural Resources. Identification Guide to Thrips Associated with Crops in Australia.
19 November 2019. Datasheet Type(s). Invasive Species. Pest. Vector of Plant Pest.
Natural Enemy. Host Plant. Preferred Scientific Name.Frankliniella occidentalis. Preferred Common Name.western flower thrips. Taxonomic Tree. Domain: Eukaryota. Kingdom: Metazoa.
Phylum: Arthropoda. Subphylum: Uniramia. Class: Insecta. Summary of Invasiveness.Since the 1970s Frankliniella occidentalis has successfully invaded many countries to become one of the most important agricultural pests of ornamental, vegetable and fruit crops globally.
Its invasiveness is. TitleAdultCaptionFrankliniella occidentalis (western flower thrips); adult, showing identifying features. Large postocular setae and with anteroangular setae about equal to anteromarginal setae.Copyright©Stan Diffie/University of Georgia/Bugwood.org - CC BY-NC 3.0 USAdultFrankliniella occidentalis (western flower thrips); adult, showing identifying features. Large postocular setae and with anteroangular setae about equal to anteromarginal setae.©Stan Diffie/University of Georgia/Bugwood.org - CC BY-NC 3.0 US. TitleLeaf damageCaptionFrankliniella occidentalis (western flower thrips); the thrips are barely visible (arrowed) in this image, but the leaf damage on a Verbena spp.
March 2007.Copyright©Chazz Hesselein/Alabama Cooperative Extension System/Bugwood.org - CC BY 3.0 USLeaf damageFrankliniella occidentalis (western flower thrips); the thrips are barely visible (arrowed) in this image, but the leaf damage on a Verbena spp. March 2007.©Chazz Hesselein/Alabama Cooperative Extension System/Bugwood.org - CC BY 3.0 US.
Summary of InvasivenessSince the 1970s Frankliniella occidentalis has successfully invaded many countries to become one of the most important agricultural pests of ornamental, vegetable and fruit crops globally. Its invasiveness is largely attributed to the international movement of plant material and insecticide resistance, both of which have combined to foster the rapid spread of the species throughout the world. Individuals are very small and they reside in concealed places on plants; thus are easily hidden and hard to detect in transported plant material. They reproduce rapidly and are highly polyphagous, breeding on many horticultural crops that are transported around the world.F. Occidentalis is species no. 177 on the list of A2 pests regulated as quarantine pests in the European Plant Protection Organisation (EPPO) region (version 2005-09). It has now reached many countries, and remains a serious threat to crops in those countries that it has not yet reached.
Notes on Taxonomy and NomenclatureAdults in natural populations of this species in western North America exist as a wide range of colour forms. In early spring, and also in montane areas, adult females are commonly almost black in colour, whereas in summer females are primarily yellow with the median area of each abdominal tergite more or less dark. These colour forms often involve differences in body size and proportions, and lengths of setae. Many of these colour and structural variants were named by early workers as different species, thus Frankliniella moultoni Hood was applied to dark individuals in California, but Frankliniella occidentalis was applied to light ones.
Such practices account for most of the 18 names that are now rejected as synonyms.Despite being considered as a single morphologically variable species at present, recent molecular studies have revealed the presence of two distinct genetic types of the western flower thrips. This genetic evidence indicates the two forms are distinct enough to be considered as separate species. However, the two forms have not been formally described as species yet. The two types, which have been designated as the greenhouse (G) and lupin (L) strains are sympatric in their native range of California. Both types have been successful invaders although current records indicate that the greenhouse type is much more widely distributed throughout the world. Given this taxonomic uncertainty, the species F.
Occidentalis is here interpreted in a broad sense as a single variable species. Nevertheless, economic entomologists should be aware that different populations identified under this name can and do exhibit differing biological characteristics, including virus vector ability, thermal tolerances, host plant preferences, fecundity and insecticide resistance. DescriptionEggsOpaque, reniform (kidney-shaped) and about 200 µm long; inserted into the epidermis and mesophyll layer of host plant. Eggs may be laid in leaves, flower structures or fruit.LarvaeThere are two larval instars, which are spindle-shaped, and are creamy-white to yellow in colour. The first- and second-instars can be differentiated by examination of the number and placement of small setae on the abdomen. These setal patterns differ between the sexes for each instar, which allows the sexes to be differentiated.
Larvae are mobile, but they tend to reside in concealed places on plants, such as within flowers or developing leaves, or under the calyx of fruits (; ).PupaeThere are two pupal instars, neither of which feeds. Although capable of movement, neither pupal stage moves about actively unless disturbed. Depending on host plant architecture, western flower thrips may drop to the ground to pupate. The first pupal stage, the propupa has short wing buds and the antennae protrude forward from the head. The pupa has wing buds extending more than half-way along the abdomen, and the antennae curve back over the head. Both pupal stages are usually white to cream coloured.AdultUsually less than 2 mm long, the adult is slender with narrow, fringed wings.
Females have spindle-shaped abdomens, and vary in colour from yellow to brown to nearly black, as described above. The female of the invasive pest strain is typically brownish yellow with dark brown markings medially on the abdomen.
The adult male is smaller than the female, with a narrower abdomen, and is usually yellowish white. Females and males are macropterous (i.e. They have fully developed wings).
In California, three colour forms of F. Occidentalis have been distinguished, pale, intermediate and dark, whose relative abundances differ according to the season and geographic location. In spring, and in montane areas, the dark form predominates, and in this the cuticle of the head and abdomen is blackish brown. It seems likely that this dark form is better able to survive low temperatures, but males are rarely dark. With a good quality 20X hand lens it is possible to see the long setae on the pronotum of adults that are typical of this species, but the structural details by which the genus and species are recognized cannot be seen without a microscope. Occidentalis is naturally abundant in many wild flowers throughout western North America from southern California (and presumably Mexico) into Canada.
In the late 1970s and 1980s, it spread across the USA and Canada. It reached the Netherlands in 1983 and then spread outwards across Europe.
This sudden explosion remains unexplained but is possibly the result of some undetected genetic change in a population on a crop under intensive cultivation and insecticide treatment. Having become well established in Europe and Israel, it spread to the highlands of eastern Africa and subsequently entered New Zealand in 1992 and Australia in 1993. In Australia it has spread around Sydney, Adelaide and Brisbane, but in Western Australia summer temperatures that routinely exceed 40°C may be limiting its spread to the vicinity of Perth. It is present in southern Brazil , and also in the Cameron Highlands of Peninsular Malaysia , and it is becoming more common in tropical lowland countries. In Costa Rica and Colombia, although abundant in screenhouses where chrysanthemums are grown, it remains rare outside on native plants or crops, whereas in Guatemala it has been reported as a pest of field-grown crops. In Florida, USA, it can be abundant in crop fields but becomes progressively less abundant away from crop areas, presumably because of competition from native thrips and predation (;, 2008; ).
Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotesAfricaPresentIntroducedInvasive;;First reported.