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Journal of the Lepidopterists' Society 32(3), 1978, 175-177
SCELIODES LAISALIS (PYRALIDAE): DESCRIPTION OF THE MATURE LARVA AND NOTE ON ITS FEEDING HABIT
E. O. Ogunwolu
Entomology Division, National Cereals Research Institute, P.M.B. 5042, Ibadan, Nigeria
ABSTRACT. Mature laboratory-reared and field-collected larvae of Sceliodes laisalis Wlk. (Pyralidae) are examined and described and the chaetotaxy illustrated. A brief note on the feeding habit of this species, an economic pest of Solarium fruits in southwestern Nigeria, is given.
Taxonomy of immature insects has long been neglected in Nigeria; mostly, general descriptions of immature stages are contained in publications on the biology of some species. Where a complex of species is involved, most taxonomic studies and identifications were of adults. In contributing to the growth of taxonomy of immatures, I here describe the larva of Sceliodes laisalis Wlk. and illustrate its chaetotaxy. Its feeding habit is also described.
Sceliodes laisalis, widely distributed in southwestern Nigeria (Akinlo-sotu, 1977), is an economic pest of the garden egg fruit, Solarium macro-carpon L. and S. melongena L. (Solanaceae). Larvae reduce the quality and quantity of the fruits and the seeds.
My descriptions are based on 15 field collected specimens and 25 larvae reared in the laboratory. In the following description, names of setae follow Hinton (1946). To describe the feeding habit at Ibadan, I examined fruits of ten S. macrocarpon and S. melongena cultivars and those of Capsicum annuum L., C. frutescens L., and Lycopersicum esculentum Mill, for Sceliodes attack.
Description of Larva
General. Length 16.0-22.4 mm, mean = 17.6 mm; width 3.0-4.1 mm, mean = 3.3 mm. Head yellowish brown often with dark brown maculation; ocellar area deep brown, a fuscous band occurs from post-occiput narrowing towards but not reaching the ocellar area (Fig. IB). Prothoracic shield pale with brown spots and deep brown areas postero-medially; mesothorax suffused with brown; thoracic legs brown. Abdomen pink dorsally excepting the deep brown anal shield; venter pale. Setal pinacula light brown. Spiracles circular, yellowish with brown rim; prothoracic and 8th abdominal spiracles each larger than the others.
Head (Fig. 1A). Width 1.1-1.5 mm, mean zr 1.2 mm; subspherical in frontal view. Adfrontal suture reaching the acutely angled vertex. Labrum shallow and emarginate, mandible with 5 teeth, all but the distal one pointed (Fig. 5), mesal surface with 4 ridges.
Each of the first, second and the sixth ocellus larger than the others; the second ocellus closer to the first than to the third. Posterior seta P2 about % the length of PI;
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Journal of the Lepidopterists' Society
Figs. 1-5. Chaetotaxy of Sceliodes laisalis larva. 1, head, frontal view (A) and lateral view (B); 2, thoracic segments; 3, first, sixth through ninth abdominal segments; 4, anal shield; 5, right mandible.
this inserted about mid-length of the head. Seta PI closer to adfrontal seta AFl than to AF2. Distance from AF2-AFa puncture one-third to one-half that from AF2-AF1. Fa punctures well below frontal setae Fl; distance between these one-half to three-fourths that between clypeal setae C2. A2, A3, and LI setae obtuse angled. Vertical setae VI slightly antero-ventrad from V2; this closer to V3 than to VI. Ocellar seta Ol close to the 3rd ocellus, 02 seta ventrad from the 1st ocellus. Distance from genal seta Gl-Ga puncture less than % that between Ol-Oa puncture.
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Thorax (Fig. 2). Seta MxDl outside prothoracic shield. On this seta XD2 dorsad from and closer to SDl than to XDl. On meso- and metathorax each of dorsal and subdorsal setae on the same pinaculum; lateral seta L3 postero-dorsad from LI; distance from MV2-MV3 about one-third that from MV3-V1. On mesothorax MSD1 and MSD2 on the same pinaculum but on separate pinacula on metathorax. Pro-thoracic coxae close but not touching, mesothoracic coxae about the coxal width apart, and the metathoracic coxae generally more than the coxal width apart.
Abdomen (Fig. 3). Dl and D2 pinacula equal in size and closer on the 8th than other segments. On the 9th segment, dorsal setae D2 on the same pinaculum; Dl, a thin seta, is slightly closer to SDl or equidistant between D2 and SDl. Seta MD1 antero-ventrad from Dl on segments 1-8; lateral pinaculum larger on the 8th than on the other segments.
Subventral setae. 1: 3: 2: 1:1 on segments 1, 2, 7-9, respectively. Distance between VI pinacula on the 7th segment more than 2x that of the 9th segment.
Anal shield (Fig. 4). Rounded posteriorly, SDl setae slightly to well above Dl setae. Prolegs on segments 3-6 with crochets, in biordinal mesoseries, respectively numbering 16-22, mean = 19; 17-22, mean = 20; 17-23, mean = 22; and 18-24, mean = 22; and on anal proleg, 14-17, mean = 16.
Description of Feeding Habit
In feeding, larvae tunnel within the fruit which shows no external sign of damage while larvae are small. The mature larvae exit through holes made on the fruit. These holes serve as entry sites for decay organisms, whose activities eventually cause fruit rot. The cultivars of S. macrocarpon and S. melongena sampled (n = 5 for each) were all attacked by Sceliodes larvae. Two to five larvae were found within each fruit. I found no Sceliodes larvae in fruits of Capsicum annuum, C. frutescens, and Lycopersicum esculentum and neither did Akinlosotu (1977), but Davis (1964) recorded these as hosts of Sceliodes cordalis (Dbld.) larvae.
Literature Cited
Akinlosotu, T. A. 1977. A check list of insects associated with local vegetables in Southwestern Nigeria. Univ. Ife. Inst. Agr. Res. Bull. 8 (In press).
Davis, J. J. 1964. The egg fruit caterpillar. Queensld. Agr. J. 90: 76-78.
Hinton, H. E. 1946. On the homology and nomenclature of the setae of lepidop-terous larvae, with some notes on the phylogeny of the Lepidoptera. Trans. Roy. Entomol. Soc. 97: 1-37.