The sex of dogwood borer pupae and pupal exuviae can be easily differentiated based on characteristics of the fused terminal abdominal segment. In males, it is composed of segments 8- 10 and has three distinct rows of posteriorly projecting spines. By contrast, in females, the fused terminal abdominal segment is composed of segments 7-10 and has four distinct rows of posteriorly projecting spines

Bergh, J. Christopher

Leskey, Tracy C

English

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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Publications from USDA-ARS / UNL Faculty U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska 2003 A Simple Character for Sex Differentiation of Pupae and Pupil Exuviae of the Dogwood Borer (Lepidoptera: Sesiidae) Tracy C. Leskey USDA-ARS J. Christopher Bergh Virginia Polytechnic Institute and University Follow this and additional works at: https://digitalcommons.unl.edu/usdaarsfacpub  Part of the Agricultural Science Commons Leskey, Tracy C. and Bergh, J. Christopher, "A Simple Character for Sex Differentiation of Pupae and Pupil Exuviae of the Dogwood Borer (Lepidoptera: Sesiidae)" (2003). Publications from USDA-ARS / UNL Faculty. 360. https://digitalcommons.unl.edu/usdaarsfacpub/360 This Article is brought to you for free and open access by the U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Publications from USDA-ARS / UNL Faculty by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.  378 Florida Entomologist  86(3) September 2003 A SIMPLE CHARACTER FOR SEX DIFFERENTIATION OF PUPAE AND PUPAL EXUVIAE OF THE DOGWOOD BORER (LEPIDOPTERA: SESIIDAE) T RACY  C. L ESKEY 1   AND  J. C HRISTOPHER  B ERGH 21 USDA-ARS, Appalachian Fruit Research Station, 45 Wiltshire Road, Kearneysville WV, 25430 2 Department of Entomology, Virginia Polytechnic Institute and University, Alson H. Smith, Jr. AREC595 Laurel Grove Road, Winchester, VA 22602 The dogwood borer,  Synanthedon scitula  (Har-ris) (Lepidoptera: Sesiidae), has the broadest hostrange of all species of Sesiidae and is an economi-cally important pest of numerous ornamental,fruit and nut trees (Engelhardt 1932; Eichlin &Duckworth 1988; Johnson & Lyon 1991). Dogwoodborer has become an important indirect pest of ap-ple in the eastern United States and Canada(Riedl et al. 1985; Warner & Hay 1985; Weires1986; Pfeiffer & Killian 1999; Kain & Straub2001) due to increased plantings on clonal, size-controlling rootstocks in high-density apple or-chards (Riedl et al. 1985; Kain & Straub 2001).These rootstocks promote formation of adventi-tious root primordia or burr knots near the graftunion at the base of the tree (Rom 1970, 1973) thatappear to be preferred oviposition sites for femaledogwood borer (Riedl et al. 1985; Warner & Hay1985; Kain & Straub 2001). Continuous infesta-tions lead to larval feeding over consecutive sea-sons resulting in consumption of burr knot tissueand feeding in the cambial layer, ultimately lead-ing to tree death from girdling (Weires 1986). Theincreasingly important pest status of dogwoodborer has led to recent research efforts into man-agement options (Kain & Straub 2001) as well asrefinement of the pheromone-based monitoringsystem (Bergh & Leskey 2003). Adult male and fe-male dogwood borers can be differentiated by themore robust abdomen with mostly yellow colora-tion on ventral segments four, five and six, and themore yellow brush-like anal tuft of females (Eich-lin & Duckworth 1988). Sex differentiation of thepupal stage of dogwood borer has never been de-scribed specifically, but a generalized descriptionof pupae of sesiid species by Eichlin & Duckworth(1988) indicates that pupae are highly modified tofacilitate extrication from host plant tissue, withdouble rows of posteriorly projecting spines on ab-dominal segments 2-6 and on segment 7 of males,and single rows on remaining segments 8-10.Pupae and pupal exuviae of dogwood borerwere obtained by excavating larvae from burrknot tissue of apple trees with obvious signs of in-festation including frass and entry wounds in Jef-ferson and Berkeley Counties, WV, USA. Larvaewere reared individually in the laboratory on gen-eral purpose Lepidopteran diet (Bioserv, French-town, NJ) in an environmental chamber at 25°Cand 14L:10D. We followed 20 pupae to adulthoodand determined the sex of moths, as described byEichlin & Duckworth (1988). The pupal exuviaeleft by each moth was then examined under LeicaGZ4 (7-30 × ) and Nikon SMZ 1500 (7.5-112.5 × ) ste-reomicroscopes for sex-related differences in pu-pal characteristics. These differences were thenconfirmed on live pupae. Microscopic examinationrevealed distinct differences between sexes in theFig. 1. (A) Caudal view of entire pupal exuviae (10×) and (B) lateral view (50×) of fused terminal abdominal seg-ment (segments 8-10) with 3 rows of posteriorly projecting spines of the pupal exuviae of the male dogwood borer.Arrows indicates suture between fused segments. Scientific   Notes 379 fused terminal abdominal segment. In males, thisfused segment is composed of segments 8-10 andhas three distinct single rows of posteriorly pro-jecting spines (Fig. 1). By contrast, in females, it iscomposed of segments 7-10 and has four distinctsingle rows of posteriorly projecting spines (Fig.2). These differences allow easy and accurate sexdifferentiation of dogwood borer pupal exuviaeand pupae. The total number of rows of spines onthe abdomen of both males and females was inagreement with the generalized description of pu-pae of sesiid species (Eichlin & Duckworth 1988).Female and male pupae had 14 and 15 rows, re-spectively. However, Eichlin & Duckworth (1988)made no mention of variation among species withregard to the presence of fused abdominal seg-ments and/or the number of rows of spinespresent on the fused abdominal segments. Countsof the total number of rows of spines on the abdo-men of pupae as described by Eichlin & Duck-worth (1988) could be used to differentiate pupalsex. However, this method is more cumbersomeand potentially less reliable because of the greaternumber of rows to be counted and because the sec-ond row of spines on abdominal segments 2 and 3is fairly subtle on the dogwood borer, contributingto misidentifications.Our method of sexing pupae was very usefulfor determining the gender of adults to be used inlaboratory experiments studying mating behav-ior of the dogwood borer. Furthermore, this char-acter was useful in identifying the sex of pupalexuviae recovered from apple trees in commercialorchards to establish seasonal phenology and toexamine protandry. Sexual dimorphism of thefused terminal abdominal segments of pupae ofother sesiid species may exist, although it was notexamined in this study.We thank Starker E. Wright for preparing pho-tographs, and Jean Englemann and Torri Thomasfor excellent technical assistance. We thank Dr.Henry Hogmire and Dave Kain for reviewing anearlier version of this manuscript.S UMMARY The sex of dogwood borer pupae and pupal ex-uviae can be easily differentiated based on char-acteristics of the fused terminal abdominalsegment. In males, it is composed of segments 8-10 and has three distinct rows of posteriorly pro-jecting spines. By contrast, in females, the fusedterminal abdominal segment is composed of seg-ments 7-10 and has four distinct rows of posteri-orly projecting spines.R EFERENCES  C ITED B ERGH , J. C.,  AND  T. C. L ESKEY . 2003. Refining the pher-omone based monitoring system for dogwood borer,pp. 69-75.  In  Proceedings of the 78th Annual Cumber-land-Shenandoah Fruit Workers Conference. J. C.Bergh (ed.), 5-6 December 2002, Winchester, VA.E ICHLIN , T. D.,  AND  W. D. D UCKWORTH . 1988. Sesioidea:Sesiidae, pp. 1-176.  In  R. B. Dominick et al. [eds.],The moths of America North of Mexico fascicle 5.1.Wedge Entomological Research Foundation, Wash-ington, D.C.E NGELHARDT , G. P. 1932. Business proceedings of theeastern branch of the American Association of Eco-nomic Entomologists. J. Econ. Entomol. 25: 293-294.J OHNSON , W. T.,  AND  H. H. L YON . 1991. Insects that feedon trees and shrubs, 2nd ed. Comstock, Ithaca, NY.K AIN , D.,  AND  R. W. S TRAUB . 2001. Status of borers in-festing apple burr knots and their management inNew York orchards. NY. Fruit. Quart. 9: 10-12.P FEIFFER , D. G.,  AND  J. C. K ILLIAN . 1999. Dogwoodborer (Lepidoptera: Sesiidae) flight activity and anFig. 2. (A) Caudal view of entire pupal exuviae (10×) and (B) lateral view (50×) of fused terminal abdominal seg-ment (segments 7-10) with 4 rows of posteriorly projecting spines of the pupal exuviae of the female dogwood borer.Arrows indicates suture between fused segments. 380 Florida Entomologist  86(3) September 2003 attempt to control damage in ‘Gala’ apples usingmating disruption. J. Entomol. Sci. 34: 210-218.R IEDL , H., R. W. W EIRES , A. S EAMAN ,  AND  S. A. H OYING .1985. Seasonal biology and control of the dogwoodborer,  Synanthedon scitula  (Lepidoptera: Sesiidae)on clonal apple rootstocks in New York. Can. Ent.117: 1367-1377.R OM , R. C. 1970. Burr knot observations on clonal applerootstocks in Arkansas. Fruit Var. Hort. Dig. 24: 66-68.R OM , R. C. 1973. Burr knot characteristics of six clonalapple rootstocks. Fruit Var. J. 27: 84-86.W ARNER , J.,  AND  S. H AY . 1985. Observations, monitor-ing, and control of clearwing borers (Lepidoptera:Sesiidae) on apple in central Ontario. Can. Entomol.117: 1471-1478.W EIRES , R. 1986. Five years research and experiencewith control of dogwood borer and related burr knotproblems. Compact Fruit Tree 19: 86-89.

A Simple Character for Sex Differentiation of Pupae and Pupil Exuviae of the Dogwood Borer (Lepidoptera: Sesiidae)

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A Simple Character for Sex Differentiation of Pupae and Pupil Exuviae of the Dogwood Borer (Lepidoptera: Sesiidae)

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