Frankliniella occidentalis (Pergande)

Skarlinsky Ii, Thomas L., 2024, The identification of the flower thrips, Frankliniella Karny (Thysanoptera: Thripidae) intercepted at U. S. ports of entry, Insecta Mundi 2024 (39), pp. 1-64 : 50

Frankliniella occidentalis (Pergande) ( Fig. 43 )

Diagnosis. This species can be variably shaded from pale to dark. Dark specimens can be confused with F.panamensis but differ from the latter by having eyes with many ventral pigmented facets, a shorter abdominal tergite VIII posteromarginal comb and usually lack microtrichia on the upper surface of the hind coxae.

Distinguishing features. Color. Body, intermediate/pale (most common) ( Fig. 43A ) or dark ( Fig. 43B ), forewings pale, legs indistinctly shaded or pale ( Fig. 43A, 43B ). Eyes with many ventral pigmented facets, the darker facets in the 1-1-2 pattern with a longitudinal row of 3 paler pigmented facets that extend from between the inner and medial darker facets to the anterior outer margin ( Fig. 43C ). Structure. Head with the PO1 setae, OC3 setae in position 2B ( Fig. 43D ). Pronotum with 2–4 mAM ( Fig. 43D ). Upper surface of the hind coxae usually without microtrichia. Abdominal tergite VIII posteromarginal comb complete, microtrichia length about the same as the distance between 2 microtrichia.

Interception frequency. Very common.

Region(s) of interceptions. Asia, Australia and the Pacific, Central America and the Caribbean, Europe, North Africa and the Middle East, North America, South America, Sub-Saharan Africa.

Comments. This species, commonly known as the western flower thrips (WFT) was the most frequently intercepted Frankliniella at US ports of entry from 1985 until 2021. Molecular evidence by Rugman-Jones et al. (2010) suggested F. occidentalis consists of two sympatric, morphologically identical species. The authors designated the two molecularly divergent groups as WFT lupin (WFTL) and WFT greenhouse (WFTG). More recently Gunawardana et al. (2017) reported that some Frankliniella have microtrichia on the upper surface of the hind coxae. I subsequently examined some of the Rugman-Jones et al. (2010) DNA voucher specimens and discovered that from the provided female specimens those with the molecular haplotypes L and R from the WFTL group, Rugman-Jones et al. (2010), possess microtrichia on the upper hind coxae. Additionally, these specimens vary in shading, from pale to dark, and the B1 setae on abdominal tergite IX are less than 100 µm.

Figures

Figure 43. A–D) Frankliniella occidentalis. A) Intermediate pale form. B) Dark form. C) Ventral compound eye. D) Head and pronotum.