Tetranychus (Tetranychus) truncatus Ehara, 1956

DraboK, Edouard, WaongoK, Antoine, TraoréK, Fousséni, SanonK, Antoine & AugerK, Philippe, 2023, First discovery of Tetranychus truncatus in Africa and new records of spider mites (Prostigmata, Tetranychidae) in Burkina Faso, Acarologia 63 (3), pp. 969-977 : 973-975

Tetranychus (Tetranychus) truncatus Ehara, 1956

Figures 2 A-C

This species has been recorded in 12 countries in the Australasian, Oriental and Palearctic regions ( Migeon and Dorkeld, 2023). The last two countries where it has been reported are India ( Srinivasa et al., 2012) and Bangladesh ( Ullah and Gotoh, 2013) and the country geographically closest to the African continent, where T. truncatus has been recorded, is Iran (e.g. Sadeghi-Namaghi, 2010).

Specimens examined — 13 males, 25 females from A. hybridus, Kamboinsé (12°27′07.1″N 001°33′36.5″W, alt. 297 a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 11-XI-2019 leg. E. Drabo; 2 males, 2 females from Cajanus cajan L. Millsp ( Fabaceae ), Kamboinsé (12°27′24.5″N 001°32′56.9″W, alt. 295 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 26-VI-2019 leg. E. Drabo; 3 males, 5 females from Vigna unguiculata (L.) Walp ( Fabaceae ), Kamboinsé (12°27′21.4″N 001°33′03.1″W, alt. 296 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 26- VI-2019 leg. E. Drabo; 4 males, 9 females from Allium cepa L. ( Amaryllidaceae ), Kamboinsé (12°27′13.0″N 001°33′28.4″W, alt. 297 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 26-VI-2019 leg. E. Drabo; 3 males, 1 female from Zea mays L. ( Poaceae ), Kamboinsé (12°27′20.3″N 001°33′00.1″W, alt. 297 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 26-VI-2019 leg. E. Drabo; 2 males, 3 females from Leptadenia hastata Pers. ( Apocynaceae ), Kamboinsé (12°27′06.0″N 001°33′36.8″W, alt. 296 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 26-VI-2019 leg. E. Drabo; 7 males, 24 females from Corchorus olitorius L. ( Malvaceae ), Kamboinsé (12°27′07.4″N 001°33′36.3″W, alt. 297 m a.s.l.), Ouagadougou (Kadiogo),

Burkina Faso, 11-XI-2019 leg. E. Drabo; 1 male, 3 females from S. lycopersicon, Kamboinsé (12°27′08.1″N 001°33′36.8″W, alt. 297 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 11- XI-2019 leg. E. Drabo; 3 males, 11 females from S. macrocarpon, Kamboinsé (12°27′06.6″N 001°33′36.5″W, alt. 297 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 11-XI-2019 leg. E. Drabo; 6 males, 12 females from S. melongena, Kamboinsé (12°27′05.9″N 001°33′35.4″W,

alt. 297 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 11-XI-2019 leg. E. Drabo; 3 males, 8 females from Ipomoea eriocarpa R. Br. ( Convolvulaceae ), Kamboinsé (12°27′02.1″N 001°33′33.8″W, alt. 298 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 27-I-2020 leg. E. Drabo; 3 males, 12 females from Helianthus annuus L. ( Asteraceae ), Kamboinsé (12°27′09.3″N 001°33′38.1″W, alt. 296 m a.s.l.), Ouagadougou (Kadiogo), Burkina Faso, 15-II-2020 leg. E. Drabo.

Distinctive characters — Female tarsus I with four tactile setae proximal to the proximal pair of duplex setae on tarsus, dorsal striae between setae e 1 and f 1 forming a diamond pattern, ventral striae without lobes, anterogenital striation entire, unbroken (but may be sparse medially), male empodium I claw-like, empodia I-II each with an obvious dorsal spur, shorter on empodia III-IV, shape of the male aedeagus ( Fig. 2A ).

Molecular identification — A BLAST search of the three mite haplotype sequences against the NCBI’s GenBank showed between 99.77% similarity (accession number MG518333.1) and 99.09% with the 56 sequences of T. truncatus .

Remarks — The morphological identification of our specimens of T. truncatus was uncertain because the male aedeagi we observed appeared to be somewhat different to that depicted in the original description by Ehara (1956). The main differences were an obvious indentation present in the aedeagal knob dorsal margin between the two knob projections and a more developed triangular posterior projection ( Fig. 2A ). Nevertheless, thanks to the examination of type specimens of T. truncatus, Seeman and Beard (2011) reported similar variations in the aedeagus shape of this species. However, in the same contribution, they mention that the female anterogenital striation is entire, unbroken, but sometimes sparse medially, whereas in the specimens we examined it is sparse with small breaks medially and more or less dotted in its anterior longitudinal part ( Fig. 2B,C ). Despite these morphological variations, with the use of molecular tools, we were able to obtain a reliable identification of our specimens as T. truncatus .

There is no doubt than T. truncatus represents an important phytosanitary risk in Burkina

Faso and, of course, at the scale of the African continent. Indeed, taking into account its pest status reported in almost all the parts of the world it colonized, particularly in Bengladesh ( Tarikul Islam et al., 2017), China ( Jin et al., 2018), India (Bhaskar and Lenin, 2018), Taiwan

( Ho, 2000), Thailand ( Sakunwarin et al., 2004) and Vietnam ( Hinomoto et al., 2007), its wide range of potential host plants [92 host plants according to Migeon and Dorkeld (2023)], including major crops (e.g. rice, maize, cassava, several Solanaceae but also cotton) and its ability to develop pesticide resistances (e.g. Ullah and Gotoh, 2013 ; Li-Wen et al., 2019), make it a major pest. Our study confirms this in part, as we already found it on 12 different host plants, the majority of which are crops.

Note — New spider mite record for Africa ( Burkina Faso) and new host records on A. hybridus , C. cajan , A. cepa , L. hastata , C. olitorius , S. macrocarpon and I. eriocarpa .

Figures

Figure 2 A–C Tetranychus(Tetranychus) truncatusEhara, 1956. A – variations in male aedeagus of 5 specimens,B–C – female anterogenital striation in two specimens: B – using phase-contrast microscope,C – using DIC microscope. D – Tetranychus urticae Koch, 1835, male aedeagus. Scale bars = 5 µm (A), 10 µm (D), 20 µm (B,C).