Cottonwood leaf beetle, Chrysomela scripta, pupae from a laboratory colony were weighed and monitored through adult emergence, oviposition, and mortality to determine if correlations existed between various pupal or adult parameters and fecundity or longevity. Forty-three female cottonwood leaf beetles were monitored. Pupal weight was not a good indicator of fecundity, total oviposition events, number of eggs/beetle/day, or adult longevity. In addition, adult weight showed very low correlation with fecundity, adult longevity, total oviposition events, or number of eggs/beetle/day. However, adult weight was a marginal indicator of the number of eggs/beetle/day, and correlated well with adult body length. Adult longevity could be used to predict fecundity

Coyle, David R

Hart, Elwood R

McMillin, Joel D

English

Valparaiso University

The Great Lakes Entomologist Volume 32 Number 3 - Fall 1999 Number 3 - Fall 1999 Article 2 October 1999 Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity David R. Coyle USDA Forest Service Joel D. McMillin USDA Forest Service Elwood R. Hart Iowa State University Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Coyle, David R.; McMillin, Joel D.; and Hart, Elwood R. 1999. "Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity," The Great Lakes Entomologist, vol 32 (2) Available at: https://scholar.valpo.edu/tgle/vol32/iss2/2 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. THE GREAT LAKES ENTOMOLOGIST1999 107 PUPAL AND ADULT PARAMETERS AS POTENTIAL INDICATORS OF COnONWOOD LEAF BEETLE (COLEOPTERA: CHRYSOMELIDAE) FECUNDITY AI'-ID LONGEVITY David R. Coyle,l Joel D. McMillin2 and Elwood R. Hart3,4 ABSTRACT Cottonwood leaf beetle, Chrysomela scripta, pupae from a laboratory colony were weighed and monitored through adult emergence, oviposition, and mortality to determine if correlations existed between various pupal or adult parameters and fecundity or longevity. Forty-three female cottonwood leaf beetles were monitored. Pupal weight was not a good indicator of fecun­dity, total oviposition events, number of eggslbeetle/day, or adult longevity. In addition, adult weight showed very low correlation with fecundity, adult longevity, total oviposition e ent , or number of eggslbeetle/day. However, adult weight was a marginal indicator f the number of eggs/beetle/day, and correlated well with a ult body length. Adult longevity could be used to pre­dict fecundity. Adult insect performance can be measured in various ways, including survival, pupal weight (Augustin et al. 1997), adult emergence, or fecundity (Miller and Ware 1997). Positive correlations have been determined to exist between pupal weight and adult fecundity in Lepidoptera (Miller 1957, Bessin and Reagan 1990, Spurgeon et al. 1995), Diptera (Hawley 1985, Krainacker et al. 1989), and Hymenoptera (Zhang and Wagner 1991, McMillin and Wagner 1995, Eliason and McCullough 1997). Few studies have explored this relationship Vvithin Coleoptera. To our knowledge, either immediate postpupal or sexually mature pupal or adult weights have not been correlated with cottonwood leaf beetle, Chrysomela scripta F. (ColeoptBra: Chrysomelidae), fecundity or longevity de­spite this estimate being used and reported previously (Augustin et al. 1997). The objectives of this laboratory study were to determine if size parameters could be used as predictors of fecundity (defined as total eggs per female [Ameen and Story 1997]) and longevity in adult female cottonwood leaf beetles. lVL-,\TERIALS AND METHODS A laboratory colony was established in September 1997 from larvae col­lected from a hybrid poplar plantation near the Ames Municipal Water Pollu­tion Control Facility near Ames, Iowa. Beetles were reared in plastic crisper 1 USDA Forest Service, Savannah River Institute, New Ellenton, SC 29809. 2 USDA Forest Service, Forest Health Protection, Rapid City, SD 57702. 3 Department of Entomology, Iowa State University, Ames, IA50011. 4 Department of Forestry, Iowa State University, Ames, IA 50011. 1Coyle et al.: Pupal and Adult Parameters as Potential Indicators of CottonwoodPublished by ValpoScholar, 1999108 THE GREAT LAKES ENTOMOLOGIST Vol. 32, No.3 boxes (27 x 19 x 10 cm) under a constant 16L:8D photoperiod and 24:18°C temperature regime. Beetles were fed greenhouse-grown Populus x euramer­icana var. 'Eugenei' foliage, LPI 1-8 (Larson and Isebrands 1971, Bingaman and Hart 1992). More than 700 pupae were selected systematically from this colony and weighed to the nearest 10-4 g at 1 day postpupation using a Mettler AE 100Analytical Balance (Mettler Instrument Corporation, Hightstown, NJ) in Feb­ruary 1998. Plastic disposable petri dishes (100 x 15 mm) were divided into four sections by using two strips of paper that were cut and placed togeth r to divide the area of the dish into quarters. One piece of moistened Whatman #1 filter paper was placed in each dish to prevent desiccation. One pupa was placed in each of these sections immediately after weighing. Pupa  were held under the aforementioned controlled conditions until adult emergence. Upon emergence, pupal duration, adult weight, and total body length were recorded for each adult beetle. Body w ight was measured using a Met­tler AE 100 Analytical Balance and body length was measured from the ante­rior point of the head to the p sterior point of the elytra. Cottonwood leaf beetles are sexually dimorphic; therefore, visual stimation of body size was used as an indicator of sex. We assumed that larger beetles were females and smaller beetles were males. Two large and two small adults were placed into small plastic containers (9.5 x 7 2 cm) in hopes of obtaining mating pairs. Many C. scripta were sorted and paired unsuccessfully; the only beetles used in this study were those that mated. Waterproof paint was used to paint one, two, three, or four identification dots on he ely ra of the beetles within their respective containers. The dots did not cause any behavioral changes or me­chanical dam ge to the beetles (unpublished data). From these containers, 43 mated pairs were selected for observation. Individual pairs were then placed in separate small plastic containers (9.5 x 7 x 2 cm). Beetle pairs were monitored daily. Fecundity, total oviposition events, an  longevity (from emergence to mortality) were recorded for ea h mated fe­male. Data were analyzed using a correlation and regression analysis (SAS Institute 1985). RESULTS Pupal weights averaged 0.0335 g (± 0.0048 SE) and ranged from 0.0242 to 0.0442 g. Adult weights at emergence ranged from 0.0195 to 0.0371 g, and averaged 0.0263 g 0.0041). Adult females lived up to 34 days postemer­gence, with an adult life span of 22.47 days (± 7.56). All 43 pairs of beetles monitored successfully. Total fecundity ranged from 63 to 1003 eggs/female with n average of 484.5 (± 251.3) eggs. Adult females laid 63.2 (±9.69) eggs/day. Our study showed poor correlation between pupal weight and adult fecun­dity (r2 = 0.08, n =43, F 3.62, P =0.064), total oviposition events (r2 = 0.05, n = 43, F = 2.06, P = 0.159), the number of eggslbeetle/day (r2 0.12, n = 43, F = 5.76, P =0.021), or female adult longevity (r2 = 2.5 10-.3, n =43, F 0.14, P = 0.715). Adult weight correlated poorly with fecundity (r 2 =0.10, n =43, F = 4.64, P = 0.037), total ovipositional events (r2 = 0.07, n 43, F 3.21, P = 0.081), and longevity (r2 0.01, n =43, F =0.56, P = 0.456). Adult length did correlate well with adult weight (r2 = 0.55, n = 43, F::: 50.66, P < 0.001) (Fig. 1). Adult weight showed marginal correlation with the number of eggs/fe­male/day (r2 = 0.19, n = 43, F 9.78, P = 0.003) (Fig. 2). Fecundity correlated well with adult longevity (r2 0.67, n = 43, F = 82.4, P < 0.001) (Fig. 3). 2The Great Lakes Entomologist, Vol. 32, No. 2 [1999], Art. 2https://scholar.valpo.edu/tgle/vol32/iss2/21999 THE GREAT LAKES ENTOMOLOGIST 109 0.04 0.035 Ci-""' 0.03.r::'a;0) 3= ""' 0.025"S "0 « 0.02 0.015 y = 0.0081 x -0.0344 r2 =0.60 + + • • • • ,. • •• 6.5 7 7.5 8 Adult Length (mm) Figure 1. Relationship between adult female C. scripta weight and length (within 24 h postemergence). . 0.045 0.04 • ::§ 0.035 ""'.r:: y =0.0002x + 0.0147 • + •0) . • 'a; r = 0.19 *.0.033= ""' "S 0.025~ +0.02 • 0.015 25 35 45 55 65 75 85 Number of eggs/beetle/day Figure 2. Relationship between adult female C. scripta weight and the num­ber of eggs/beetle/day over the entire duration of ovipositional activity. 8.5 3Coyle et al.: Pupal and Adult Parameters as Potential Indicators of CottonwoodPublished by ValpoScholar, 1999110 THE GREAT LAKES ENTOMOLOGIST Vol. 32, No.3 1200 (j) (ij y = 27.149x -152.55 E 1000 •r2 = 0.67 ••.S:! ... Q) • a. 800 I/) OJ OJ Q) 600 (ij-0 ;!:!. 400:>. ~ "C c:: ::::I 200 0 Q) LL • 0 5 10 15 20 25 30 35 Adult Longevity (days) Figure 3. Relationship between adult female C. scripta longevity and fecun­dity. DISCUSSION In most insect orders, healthy larvae are often the largest larvae (and subsequently pupae), and emerge into the largest adults (Kamata and Igarashi 1995). For insects that do not feed as adults and lay only one clutch of eggs, larger larval size would allow the potential for more eggs to develop during pupation. However, this hypothesis would not necessarily hold true for insects such as the cottonwo d leaf beetle that feed as adults, experience multiple matings, and lay multiple clutches of eggs. The capacity to mate and oviposit multiple times reduces the need for greater size, which also re­duces the probability that size would correlate with fecundity. We found this relationship to be true with C. scripta. Average fecundity values in our study (484.5 ± 251.3 eggs per female) were similar to those obtained in a laboratory study by Burkot and Benjamin (1979) (510.0 ± 152.9). Furthermore, the average number of eggs per cluster (63.2 ± 9.69) was nearly identical to that of Burkot and Benjamin (1979) (64.3 ± 14.7). Head and Neel (1973) observed egg masses of 50-100 eggs per cluster in outdoor caged studies. Field studies by Lowe (1898) (45 eggs per cluster) and Haugen (1985) (55.6 ± 1.9 eggs per cluster) are slightly less than those obtained in this study; this could be attributed to the more opti­mal conditions in the aboratory. Limited food resources and crowding can impact fecundity in chrysomelids (Zvereva et al. 1995). Intraspecific competition among adults for food resources can lead to reduced leaf area consumed per adult, which subsequently can have an impact on beetle health and reproduction (Zvereva et al. 1995). Adult C. scripta are only in competition for food in nature during high population levels (E. R. Hart, personal observation); there wa  no com­petition for food resources in this study. All adult beetles were fed ample fo­liage, and no b etles suffered food shortage or crowding during the course of 4The Great Lakes Entomologist, Vol. 32, No. 2 [1999], Art. 2https://scholar.valpo.edu/tgle/vol32/iss2/21999 111THE GREAT LAKES ENTOMOLOGIST this experiment. In a study by Bauer et al. (1990) adult C. scripta reared on foliage in petri dishes had a shorter life span (33.0 ± 3.4 days) than did adults reared under colony conditions (55 ± 5.8 days). This may have oc­curred in our study, although life spans for insects in the larger laboratory colony were not recorded. Adults in this study had slightly shorter life spans (22.47 ± 7.56 days) than did the insects in the study by Bauer et al. (1990). A linear relationship existed between adult female weight and length. These findings parallel results from other studies (Zhang and Wag er 1991), and result from heavier beetles often being larger beetles; increased size often is expressed through increased body length. Fecundity correlated well with adult longevity. This correlation is evident in other leaf beetles as well (Ameen and Story 1997). Presumably, this relationship results because fe­male beetles with longer lives have more opportunities to ma e and oviposit than do beetles with shorter life spans. Multiple mating increases fecundity in other insect species (Lamunyon 1997), and the opportunity longer-lived cottonwood leaf beetles have to mate multiple times may be a factor in the increased fecundity. AJthough the focus of this study was on body size and fe­cundity correlations of adult females, we recognize that body size can have important implications for adult males as well (Tammaru et aL 1996). Future studies could examine the relationship between male body size and mating success. Inbreeding can have negative effects on reproduction (Wildt et aL 1987). This laboratory colony had been sustained since October; experiments took place in February. Some inbreeding may have taken place during this tim , as this was the fourth generation of cottonwood leaf beetles in the laboratory. Additional factors such as rearing conditions or possible microbial contami­nation may have influenced longevity and thus total fecundity (Webber and Ferro 1996, Jackson 1997). Many Populus clonal variations and hybrids are being screened for use in short-rotation woody crop systems. Adult cottonwood leaf beetles may live longer on certain genotypes or selections of Populu than others. Planting Populus clones and hybrids preferred by cottonwood leaf beetle could result in more egg masses and more larvae and could potentially contribute to out­break conditions. Many characteristics, including growth, hardiness, and pest preference and performance need to be taken into consideration when choosing Populus plant material for advancement in regional trials. The per­formance and life expectancy of adult cottonwood leaf beetles is one of these characteristics. For insects that feed as adults and have multiple oviposition events, in­creased larval, pupal, and adult size may b  of little benefit to fecundity, be­cause they will have more than one opportunity to oviposit. Therefore, previ­ous measurements of cottonwood leaf beetle larval performance that used pupal weight (Augustin et aL 1997) may not be entirely relevant, and future studieson larval performance should focus on survival, adult longevity, and actual fecundity. ACKNOWLEDGMENTS We thank Valasia Iakovoglou and Christine Hall for technical assistance Thanks to Rich Faltonson, Iowa State University, for care of foodstock trees and Leah S. Bauer, North Central Forest Experiment Station, USDA Forest Service, East Lansing, MI for supplying cottonwood leaf beetles. Thanks to Julie L. Todd for her helpful review of this manuscript. Funding for this pro­ject was supplied in part by the Oak Ridge National Laboratory, ope ated by 5Coyle et al.: Pupal and Adult Parameters as Potential Indicators of CottonwoodPublished by ValpoScholar, 1999112 	 THE GREAT LAKES ENTOMOLOGIST Vol. 32, No.3 Martin Marietta Energy Systems, Inc. for the United States Department of Energy, contract no. DE-AC05-840R21400, subcontract 19X-SZ269C. J urn l Paper No. J-18475 of the Iowa Agriculture and Home Economics Station, Ames, Iowa. Project No. 3443, and supported by Hatch Act and State of Iowa funds. LITERATURE CITED Ameen, A O. and R. N. Story. 1997. Fecundity and longevity of the yellowmargined leaf beetle (Coleoptera: Chrysomelidael on crucifers. J. Agric. Entomo!. 14: 157-162.Augustin, S., M. R. Wagner, J. Chenault and K. M. Clancy. 1997. Influence of pulp and paper mill wastewater on Chrysomela scripta (Coleoptera: Chrysomelidae) perfor­mance and Populus plant traits. Environ. Entomol. 26: 1327-1335. Bauer, L. S., J. Meerschaert and O. T. Forrester. 1990. An artificial diet for cottonwood and imported willow leaf beetles (Coleoptera: Chrysomelidae) and comparative per­formance on poplar foliage. J. Entomo!. S i. 25: 475-480. Bessin, R. T. and T. E. Reagan. 1990. Fecundity of sugarcane borer (Lepidoptera: Pyralidae), as affected by larval development on gramineous host plants. Environ. Entomol. 19: 635-639. Bingaman, B. R. and E. R. Hart. 1992. Feeding and oviposition preference  of adult cottonwood leaf beetles (Coleoptera: Chrys melidael among Populus clones and leaf age classes. Environ. Entomol. 21: 508-517. Burkot, T. R. and D. M. Benjamin. 1979. The biology and ecology of the cottonwood leaf beetle, Chrysomela scripta (Coleoptera: Chrysomelidae), on tissue cultured hybrid Aigeiros (Populus x Euramericana) subclones in Wisconsin. Can. Entomo!. 111: 551-556. Eliason, E. A and D. G. McCullough. 1997. Survival and fecundity of three insects reared on four varieties of scotch pine Christmas trees. J. Econ. Entomol. 90: 1598-1608. Haugen, D. A 1985. Oviposition preference of the cottonwood leaf beetle, Chrysomela scripta F., on poplar clones, Populus spp. Ph.D. dissertation, Iowa State University, Ames. Hawley, W. A 1985. A high-fecundity aedine: factors affecting egg production of the western treehole mosquito, Aedes sierrensis (Diptera: Culicidae). J. Med. Entomol. 22: 2 0-225. Head, R. B. and W. W. Nee!. 1973. The cottonwood leaf beetle: observations on the biol­ogy and reproductive potential in Mississippi. J. Econ. Entomol. 66: 1327-1328. Jackson, J. J. 1997. Biology ofAphthona nigriscutis (Coleoptera: Chrysomelidae) in the laboratory. Ann. Entomol. Soc. Am. 90: 433-437. Kamata, N. and M. Igarashi. 1995. Relationship between temperature, number of in­stal's, larval growth, body size, and adult fecundity of Quadricalcarifera punctatella (Lepidoptera: Notodontidae): cost-benefit relationship. Environ. Entomo!. 24: 648-656. Krainacker, D. A., J. R. Carey and R. I. Vargas. 1989. Size-specific survival and fecun­dity for laboratory strains of two tephritid (Diptera: Tephritidae) speci s: implica­tions for mass rearing. J. Eeon. Entomo!. 82: 104-108. Lamunyon, 	C. W. 1997. Increased fecundity, as a function of multiple mating, in an arctiid moth, Utetheisa ornatrix. Ecol. Entomo!. 22: 69-73. Larson, P. R. and J. G. Isebrands. 1971. The plastochron index as applied to develop­mental studies ofcottonwood. Can. J. For. Res. 1: 1-11. Lowe, V. H. 1898. Cottonwood leaf beetle, green arsenite. Bull. N. Y. Agric. Exp. Sta. No. 143. 23 pp. McMillin, J. D. and M. R Wagner. 1995. Season and intensity of water stress: Host­6The Great Lakes Entomologist, Vol. 32, No. 2 [1999], Art. 2https://scholar.valpo.edu/tgle/vol32/iss2/2THE GREAT LAKES ENTOMOLOGIST1999 	 113 plant effects on larval survival and fecundity of Neodiprion gilletti (Hymenoptera: Diprionidae). Environ. Entomol. 24: 1251-1257. Miller, C. A. 1957. A technique for estimating the fecundity of natural populations of the spruce budworm. Can. J. Zool. 35: 1-3. Miller, F. and G. Ware. 1997. Preference for and suitability of Asian elm species and hybrids for the adult elm leaf beetle (Coleoptera: Chrysomelidae). J. Econ. Entomol. 90: 1641-1645. SAS Institute. 1985. SAS user's guide: basics, version 5 ed. SAS Institute, Cary, NC. Spurgeon, D. W., P. D. Lingren, T. N. Shaver and J. R. Raulston. 1995. Realized and potential fecundity of the Mexican rice borer (Lepidoptera: Pyralidae) as a function of pupal weight. Environ. Entomol. 24: 94-98. Tammaru, T., K. Ruohomake, and K Saikkonen. 1996. Components of male fitness in relation to body size in Epirrita autumnata (Lepidoptera, Geometridae). Ecol. Ento­mol. 21: 185-192. Webber, D. C. and D. N. Ferro. 1996. Flight and fecundity of Colorado potato beetles (Coleoptera: Chrysomelidae) fed on different diets. Ann. Entomol. Soc. Am. 89: 297-306. Wildt, D. E., M. Bush, K. L. Gcodrowe, C. Packer, A. E. Pusey, J. L. Brown, P. Joslin and S. J. O'Brien. 1987. Reproductive and genetic consequences of founding isolated lion populations. N ure 329: 328-331. Zhang, Z. Y. and M. R. Wagner. 1991. Cocoon and adult parameters predict fec-undity of the pine sawfly Neodipirion fulviceps. Southwest. EntomoL 16: 193-198. Zvereva, E. 	L., M. V. Kozlov, and S. Neuvonen. 1995. Population density and perfor­mance of Melasoma lapponica (Coleoptera: Chrysomelidae) in surroundings of smelter complex. Environ. EntomoL 24: 707-715. 7Coyle et al.: Pupal and Adult Parameters as Potential Indicators of CottonwoodPublished by ValpoScholar, 1999

Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity

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Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity

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