Research Article |
Corresponding author: Komi K.M. Fiaboe ( kfiaboe@icipe.org ) Corresponding author: Jose Fernández-Triana ( cnc.braconidae@gmail.com ) Academic editor: Gavin Broad
© 2017 Komi K.M. Fiaboe, Jose Fernández-Triana, Faith W. Nyamu, Komi M. Agbodzavu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Fiaboe K, Fernández-Triana J, Nyamu F, Agbodzavu K (2017) Cotesia icipe sp. n., a new Microgastrinae wasp (Hymenoptera, Braconidae) of importance in the biological control of Lepidopteran pests in Africa. Journal of Hymenoptera Research 61: 49-64. https://doi.org/10.3897/jhr.61.21015
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A new species of Microgastrinae, Cotesia icipe Fernández-Triana & Fiaboe, sp. n., is described from eastern Africa. It was reared in Kenya as a solitary parasitoid from two major amaranth pests, Spodoptera littoralis (Boisduval, 1833) and S. exigua (Hübner, 1808); study of specimens in collections also revealed its presence in four other countries in the Afrotropical region (Madagascar, Saudi Arabia, South Africa, and Yemen). Morphological, molecular and biological characters are used to describe the new species and to distinguish it from all 12 previously described species of Afrotropical Cotesia. Cotesia icipe shows potential in the biological control of key Lepidopteran pests in small scale farming conditions in Africa.
Microgastrinae , Cotesia , Spodoptera , biological control, Africa
The subfamily Microgastrinae (Hymenoptera, Braconidae) is the single most important group of parasitoid wasps attacking caterpillars, with many species used or being considered as biocontrol agents against Lepidopteran pests in agriculture and forestry (
There are 12 species of Cotesia recorded from the entire Afrotropics (
This paper describes a new species of Cotesia from Kenya (also present in other Afrotropical countries), which has been found to be important in the biological control of two major amaranth pests, Spodoptera littoralis and S. exigua (Lepidoptera, Noctuidae). The parasitoid was found during various field studies carried out by the International Centre of Insect Physiology and Ecology (icipe), in the scope of developing an IPM programme against amaranth pests in East Africa. In Kenya, specimens of the new species were collected from different locations where the project activities are carried out and there is a potentially much wider distribution. The new species is compared to the other 12 species of Cotesia previously recorded from the Afrotropical region, and diagnostic characters to recognize it are provided.
Specimens of the new species were collected from different locations in Central Kenya: Yatta, (01.23044°S; 37.45789°E) and Mwea (0.6309°S; 37.35117°E); Kitengela (1.6°S; 36.85°E) and Thika (1.00269°S; 37.07858°E). The material has been deposited in the International Centre of Insect Physiology and Ecology, Nairobi, Kenya (icipe), the Canadian National Collection of Insects, Ottawa (
Morphological terms and measurements of structures follow those used by
Seven specimens (including the holotype and paratypes, with voucher codes CNC507547-CNC507553) were sampled for DNA barcodes (the 5’ region of the cytochrome c oxidase I (CO1) gene, Hebert et al. 2003). DNA extracts were obtained from single legs using a glass fibre protocol (
Photos were taken with a Keyence VHX-1000 Digital Microscope, using a lens with a range of 10–130 ×. Multiple images were taken of a structure through the focal plane and then combined to produce a single in-focus image using the software associated with the Keyence System. Plates were prepared using Microsoft PowerPoint 2010.
A map with the distribution of the species was generated using SimpleMappr (
Original descriptions and/or authenticated specimens of the 12 Cotesia species previously recorded for the Afrotropical region were checked. In the Detailed diagnosis section below, the new species is compared individually with all other species previously described from the Afrotropics, and diagnostic characters to separate it from all of them are presented. Morphological comparisons are based mostly on female specimens, as male Microgastrinae often are difficult to identify (e.g.,
A neighbor-joining tree (K2P) of all specimens in the Barcoding of Life Data System (BOLD) currently associated with the new species (BIN BOLD:ABZ7318) was generated using the capabilities available in BOLD (for an explanation of the BIN concept see
Female, Kenya,
There are 10 DNA barcodes in BOLD from Madagascar, Saudi Arabia, South Africa and Yemen (Fig.
Metasoma with T3 dark brown to black centrally, yellow laterally; hind legs mostly yellow, except for metacoxa (mostly black, with small yellow spot on apical 0.1), brown spots on apical 0.1 of metafemur (dorsally), apical 0.1 of metatibia dark brown, and metatarsus entirely dark brown; tegula and humeral complex yellow; fore wing with most veins brown. Besides coloration, C. icipe has scuto-scutellar sulcus with eight carinae; T1 almost parallel-sided, very slightly widening towards posterior margin; T2 relatively small, quadrate and not covering the entire surface of the tergum, and T3 1.3x as long as T2 length. The above combination of characters is sufficient to separate the species from all other described species of Afrotropical Cotesia, but see the Detailed diagnosis section below for one-to-one comparisons of C. icipe versus every other species. Beyond morphological characters, from a molecular perspective there is also sufficient information to recognize the new species. Eight out of the 12 previously described Afrotropical species of Cotesia have DNA barcodes available in BOLD (Fig.
Female (Fig.
Male (Fig.
Based on 4,000+ parasitism cases observed under laboratory condition at icipe in Kenya, C. icipe is a solitary larval endoparasitoid of Spodoptera littoralis (Boisduval, 1833) and Spodoptera exigua (Hübner, 1808) (Lepidoptera, Noctuidae). It was successfully reported to attack those two noctuid species tested on amaranth. However, it failed to parasitize three Crambidae species tested on the same host plant: Spoladea recurvalis (Fabricius, 1775), Udea ferrugalis (Hübner, 1796) and Herpetogramma bipunctalis (Fabricius, 1794). Further studies of host range are warranted to explore the full potential of the new species in the biological control of key pests in small scale farming conditions in Africa. The female prefers ovipositing on second instar host larvae. The development time from egg to adult is two weeks and ovipositing females fed with honey can live more than two weeks at 25°C (our unpublished data).
Afrotropical: Kenya, Madagascar, Saudi Arabia, South Africa, Yemen (Fig.
Currently (as of September 2017) there are in BOLD 19 available sequences from five Afrotropical countries: Kenya (9 sequences), Madagascar (1), Saudi Arabia (3), South Africa (1) and Yemen (5). Although we could not examine the specimens from Saudi Arabia or South Africa, their sequences are identical to the rest, and thus we consider them all to represent the species Cotesia icipe. They belong to BIN BOLD:ABZ7318; however, that BIN is likely to contain more than one species, as the sequences currently assigned to it are grouped in different clusters (Fig.
Neighbor-joining tree (K2P) of all specimens in the Barcoding of Life Data System (BOLD) currently associated with BIN BOLD:ABZ7318 (for explanation on the BIN concept see Methods of this paper). The cluster highlighted in Yellow in the tree shows the specimens considered in the present paper as Cotesia icipe.
Neighbor-joining tree (K2P) of Afrotropical species of Cotesia in the Barcoding of Life Data System (BOLD) with over 500 base pairs; data accessed on September 2017. Specimens named as “Cotesia jft52” in BOLD actually belong to the species Cotesia icipe (cluster highlighted in Yellow), and specimens named as “Cotesia jft68” in BOLD actually belong to the species Cotesia chrysippi (Viereck, 1911).
We dedicate this species to the “International Centre of Insect Physiology and Ecology (icipe)” for its long-term promotion of Integrated Pest Management and for building the capacity of thousands of African young scientists over the years in insect sciences.
Additionally, and to facilitate future work on the group, we detail below how each of the other 12 species of Cotesia previously described from the Afrotropics individually differ from C. icipe.
Cotesia bignellii (Marshall, 1885) has metasoma (entirely) and hind legs (mostly) dark brown, very different from the body color of C. icipe as detailed above. C. bignellii also parasitizes a different family of Lepidoptera hosts (Nymphalidae) and it is mostly distributed in Europe (
Cotesia chrysippi (Viereck, 1911) parasitizes a different family of Lepidoptera hosts (Nymphalidae) (
Cotesia decaryi (Granger, 1949) is only known from Madagascar and probably represents a local endemic from that country. It parasitizes a different family of Lepidoptera hosts (Lasiocampidae) (
Cotesia flagellator (Wilkinson, 1930) is only known from Uganda (
Three related species, Cotesia flavipes Cameron 1891, Cotesia sesamiae (Cameron, 1906) and Cotesia typhae Fernández-Triana, 2017, have all been recently revised in
Cotesia pistrinariae (Wilkinson, 1929) has a strongly narrowed T1 centrally, which is unique among all known species of Cotesia; extensive illustrations of pistrinariae can be found in
Cotesia vestalis (Haliday, 1834) has T1 clearly widening towards posterior margin and T2 covering most of the tergum dorsally, both tergites are also much more coarsely sculptured than in C. icipe; the coxae (especially pro- and mesocoxae) are also darker colored as compared to icipe. There are many host records attributed to this species (
Cotesia vanessae (Reinhard, 1880) is mostly a Palearctic species, recently found to have spread into the Nearctic (Hervet et al. 2014), and only marginally distributed in Africa (
Of all described Afrotropical species Cotesia ruficrus (Haliday, 1834) looks most similar to C. icipe from a morphological perspective; however, it has T1 clearly wider at posterior margin as compared to anterior margin (almost the same width in C. icipe); T2 covers most of the tergum surface; and vein R1 in fore wing is comparatively much shorter, about the same length of pterostigma, and with the distance between end of vein R1 and the end of vein 3RSb being more than 0.4 × the length of vein R1 (in C. icipe the vein R1 in fore wing is comparatively much longer, clearly longer than pterostigma length, and with the distance between end of vein R1 and the end of vein 3RSb being less than 0.2 × the length of vein R1); also, the overall coloration is lighter and more reddish than in C. icipe. Furthermore, from a biological point of view, C. ruficrus is a gregarious parasitoid while C. icipe is a solitary parasitoid. Numerous host records, some of them certainly inaccurate, are attributed to C. ruficrus (
Cotesia rugosa (Szépligeti, 1914) presents the most difficult case to assess, as it is only known from the male holotype, collected in 1912 at an altitude of 2,000 m, on the western side and near of Mount Kenya (
The finding of the new species C. icipe is of particular interest because it successfully attacks Noctuids of the genus Spodoptera (
The research at icipe was carried out with financial support from the German Federal Ministry of Economic Cooperation and Development (BMZ). The participation of JFT was supported by project AAFC-STB-1558 ‘Arthropod systematics research in support of Canadian Agriculture’. Gavin Broad (NHM) and an anonymous reviewer provided valuable suggestions to improve the manuscript.
Tree for Barcode Index Number – BOLD:ABZ7318
Data type: molecular data
Tree Result – Search: Sample IDs; Seq Length(500 bp); Include public records (170 records returned) (170 records selected)
Data type: moleculara data