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Vol. 5, No. 3-4, September-December 1991 185 Color identification of economically important Spodoptera larvae in Honduras (Lepidoptera: Noctuidae) S Passoa USDftJAPHISlPPQ 8995 E. Main Street Bldg. 3, Room 109 Reynoldsburg, OH 43068 Abstract Spodopterafrugiperda (J. E. Smith), S. exigua (HUbner), S.lati(ascia (Walker), S. ornithogalli (Guenee), S. dolichos (Fabricius), S. sunia (Guenee), and S. eridania (Cramer) are commonly associated with crops in Honduras. A key to these species with color illustrations ofrare and typical forms is presented. Potential problems in identifying Spodoptera species are discussed. Additional key words: morphology. Noctuoidea Introduction mens are misidentified (Figures 9.1, 9.4, and 11.2 label three forms of S odo tera lati ascia as S. pests throughout the world (Kranz etal. 1977, Hill ] 975) At least eight species are known to occur in 1 Honduras. Spodoptera frugiperda (J. E. Smith), azzom e al. mcorrect y la e ed a p oto- Spoooptera exigua (Hubner), Spodoptera lati{Q.scia graph ofS. 8unia as S. eridania. PNalker), and 8podoptera sunia (Guenee) are eon This work should facilitate identification of sidered economically important pests whereas common Spodoptel a 1m vae in Honduras by pI esen- Spodoptera eridania Wratner), Spodoptera orni- ~~;e~~;~:~~~~~o:o~~~~:~:~:~o~;:i~:~~ thogalli (Guenee), and Spodoptera dolichos (Fabri cius) are rarely abundant enough to cause serious allow accfrate identification of most Spodoptera damage to Honduran crops (Passoa 1983). An adult Spodoptera androgea (Cramer) was collected onthe north coast of HondUIas (La Lima, DepaItment of impossible. Cortes) in October, but its larva is unknown. The host range of Spodoptera is very wide including Methods and Materials most vegetable crops and several basic grains (passoa Most ofthe specimens used in this study were 1983, Andrews 1984, King and Saunders 1984). eoIIeeted in Honduras, Central Ameriea, from 1979 Information on the distribution, phenology, Span- 1981. Additional specimens from Ohio, Illinois and ish common names, biology, and control ofSpodoptera Florida were also studied. Field-collected larvae spp. can be found in the works cited above. were photographed, reared to adult, and then iden- In spite ofa logical and thorough study by Levy tified with Todd and Poole (1980). Eggs laid by and Habeck (19'76), workers in Latin America female moths in captiVity proVided another source sometimes have trouble identifying Spodoptera of larval material. Beans (Phaseolus vulgaris L.), lanae. Two examples illustrate this problem. In sweet potato (Ipomoea halalas (L.) Poir.) or wheat King and Saunders (1984), several Spodoptera speci- germ artificial dietwere all accepted by Spodoptera 186 Insecta Mundi larvae in laboratory feeding trials Larval speci- 1. Dorsal pInacula usuallyconspicuous (Figs. 12, 14) mens were killed in a 9:1 mixture of 80% ethanol but sometimes pale in the green form (Fig. 13), and glacial acetic acid by volume, then tranSfurred their diameter equal to or greater than the dia- to 80% ethanol after 24 hours for permanent stor- meter ofthe abdominal spiracles dorsum ofab age. Larval terminology follows Stehr (1987). The dominal segments granulated under a magnification of25 power or greater (Fig. 4) . ~~oe;:~k:d~rl~:al::~~~;::~:::;:,:~;;~ .............. Spoduptera fru8iperda (J. E. Smith) I'. Dorsal ~inaculanever cons~icuous.theirdiameter the most common synonyms are mentioned under each species, for a more complete list see Todd and Poole (1980). 2. Abdominal segments neyer with dorsal triangular markingl3 pattern consists of a series ofdorsal dashes (Fig; 6) or, more commonly, an inegular spot, if present, is on the mesothorax (Fig. 1) ventral tonofibrillary platelets between abdominal prolegs form a "Y" with a short stem about as long as the anns (Fig. 9) . .......................... Spodoptera exigua (Hubner) 2'. Abdominal segments with at least one pair of dorsal triangular markings (Figs. 2, 11, 23) 1. Four abdominal prolegs present (larva not a lateral spot, ifpresent, is on the first abdominal segment (Figs. 2, 19) ventral tonofibrillary plate ~o~) lets between abdOminal prolegs form a straight 2. 0 setae present on first abdominal seg- line or, morerarely, a"Y" with a'very long stem ment (Fig. 2). compared to the arms (Fig. 10) 3 3. Lateral spotusually present on first abdominal segment(this spotis a practicalmethodofrec- 3. Lateralspotonthefirst abdominal segment, when ognizing Spodoptera larvae in the field) (Fig present, interrupts the subspiraGular line to 2, 26). torm a pale, thInner lIne on the thorax (Fig. 19) 4. Mesothorax with a sclerotized bar connecting if lateral spot and/or subspiracular line are theSD1 setaanda tonofibrillaryplatelet(Fig. absent (F'lgS. 18, 20), then dorsal triangles ot 3). first abdominal segment larger than dorsal tri- No retin 1 m n h m n i angles ot tourth abdomInal segment (F'lg. 17) 3'. Lateralspotonthefirst abdominalsegment, when present, does not inb>mlpt the sUhspiracular line and therefore the line maintains equal in tensity and Width on thethorax compared tothe notch (Fig. 8). abdomen if lateral spot and/or subspiracular 8. Skin smooth under a magnification of25 power line are absent, then dorsal triangles of first (except in Spodoptera frugiperda) and never abdominal segment not larger than dorsal tri- WIth mrcrospmes. 9. Head with an inverted "Y" because adfrontal areas are outlined in white (see discussion under Spodoptel a Ii ugipelda) (Fig. 32). 4 them (Fig. 27), if lines are inconspicuous or absent in darkforms (Figs. 24-25, 28), then area Key to common Spodoptera larvae belowsubdorsal stripewith several longitudinal in Honduras narrowwhitelines(Fig. 24) dorsalmesothoracic (modifiedfrom !HI)'andHabook 1976, Oliverand Chapin markingeither tIiangular, elongate-oval, or semi- 1981, Crumb 1956, and Godfrey 1987) circular (Figs. 11, 32) .. .................. Spodoptera ornithogalti (Quenee) 4.' Dorsal triangles never with a narrow white line passingthroughthem, although a seriesofwhite Vol. 5, No. 3-4, September-December 1991 187 dots may be present (FigS. 31, 34) area below with cutwormsthathave granulated skin and large subdorsal stripe without several longitudinal pinacula, for example, Agrotis ipsilon (Hufnagel). narrow white lines except for the black form of However, cutworms have the adfi'OntaI suture ex S.latifascia (Fig. 34) dorsalmesothoracicmark tendingtothe epicranialnotch(top ofhead) whilein ings semicircular or trapezoidal (Figs. 32, 33), S. frugiperda the adfrontal area extends only half never triangular or elongate-oval 5 that distance. 5. $podOptera ( Laphygma) exigua (HQbner); beet armyworm A heavily-marked form of the beet armyworm wasillustratedbyLevy and Habeck (1976), butthis 5'. color pattern is rare in Honduras. Instead, most of low the tI i,iIlgles OIl th., subdral Ii e(Fig. the larvae are speckled with white on a green 30) 6 6. Mesothmacic dOl sal mmkings usually semicir- present (Fig. 16). SpoMptera exigua canusually be cular (Figs. 32, 34) and smaller than dorsal tri recognized by a lateral spot on the mesothorax (see angles on eighth abdominal segment (Fig. 11) discussion under 8. (rugiperda). However, presened rarely mesothoracic dorsal markings are re- specimens ofS. exigua usually fade in alcohol and placed by a ','mite spot (Fig. 31) .. lose theircolor pattern so mostidentificationsmust ........................ Spodoptera latifascia (Walker) be confirmed with stmctnral characters Among 6'. Mesothoracie dorsal markings trapezoidal (Fig. common noctwds In agrIcUltural fields In Hon 30) and subequal to dorsal triangles on eighth duras, the presellGe ofh'lo subventral setae on the abdominal segment (Fig. 29), these markings never replaced by a white spot .. first abdominal segment (Fig. 2), a sclerotized bar ...................... Sp9doptera doliGR,()s (FabriGius) connecting the mesothoIacic SD 1 seta to a tOllofib- rillary platelet (Fig. 3), the ventral tonofibrillary Discussion platelets intheform ofa ''Y'' with a short stem (Fig. 9), and smooth skin under a magnification of 25 power will Identify S. eXlgua. Spodoptera ( Lapbygma) frugiperda (J. E. Smith); fall armyworm. Spodoptera (-Xylomyges) eridania (Cramer); Usually Spuduptera frugipetda is readily distill- southern armY'tVorm Despiteitsname, the southernarmywonn isnot as common in Honduras as S. frugiperda, S. sunia, orS.latifii,sCia. Sj)odoptgra g1idania has beentradi 15 and 16) because the pale pinacula ofS. frugiper tionally distinguished by the spot on the first ab da are easy to ovetlook, especially in field surveys. dominal segment which interrupts the subspiracu- Cuticular texture can also be used to distinguish larline Lev andHabeck 1976 .However theterm i i ce e Instead, the subspiracular line loses intensity as it passesbelowthelateral spot(Fig. 19). Most8pooop tera larvaehave a lateral spotso thecondition ofthe subspiIacwaI linemustbenoted. TheillustIatiollof wasprobablymisidentifiedasS. eridania becauseof its prominent lateral spot Unfortunately, sometimes the subspiracular line of 8. eridania is pale (Fig. 9) or absent (Fig. 8). Under these circumstances the southern a~~ wonn is difficult to recognize. One character whl appears l1Di<ple to S eridnnin isthe large size oftbe 188 Insecta Mundi dorRal triangles on the first abdominal segment mesothoracicmarkingscanbehelpful inidentifying (Fig. 17). The presenceofa white spotposterodorsad Spodoptera larvae. The mesothoracic spot of S. to the spiraclewasused bY OliverandChapin(1981) ornithogalli

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