During their spring flight season, free-ranging male cecropia moths lived a maximum of 12 days (one of 124 recaptured moths of 387 released moths). The number of survivors declined precipitiously after day five; five to seven days is probably the usual life span. The recaptured moths did not have different initial weights than those that were not recaptured. The larger the moth the more absolute weight it lost and the faster it lost weight during the first few days. A moth lost about 20% of its weight during the first night of flight and accumulated about a 40% weight loss during the remainder of its life

Janzen, D. H

Sternburg, J. G

Waldbauer, G. P

English

ValpoScholar

Longevity and Weight Loss of Free-flying Male Cecropia Moths, \u3ci\u3eHyalophora Cecropia\u3c/i\u3e (Lepidoptera: Saturniidae)

Valparaiso University

The Great Lakes Entomologist Volume 18 Number 4 - Winter 1985 Number 4 - Winter 1985 Article 1 December 1985 Longevity and Weight Loss of Free-flying Male Cecropia Moths, Hyalophora Cecropia (Lepidoptera: Saturniidae) G. P. Waldbauer University of Illinois J. G. Sternburg University of Illinois D. H. Janzen University of Pennsylvania Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Waldbauer, G. P.; Sternburg, J. G.; and Janzen, D. H. 1985. "Longevity and Weight Loss of Free-flying Male Cecropia Moths, Hyalophora Cecropia (Lepidoptera: Saturniidae)," The Great Lakes Entomologist, vol 18 (4) Available at: https://scholar.valpo.edu/tgle/vol18/iss4/1 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. 1985 THE GREAT LAKES ENTOMOLOGIST 133 LONGEVITY AND WEIGHT LOSS OF FREE-FLYING MALE CECROPIA MOTHS, HYALOPHORA CECROPIA (LEPIDOPTERA: SATURNIIDAE) G.P. Waldbauer, I J.G. Sternburg,l and D.H. Janzen2 ABSTRACT During their spring flight season, free-ranging male cecropia moths lived a maximum of 12 days (one of 124 recaptured moths of 387 released moths). The number of survivors declined precipitiously after day five; five to seven days is probably the usual life span. The recaptured moths did not have different initial weights than those that were not recaptured. The larger the moth the more absolute weight it lost and the faster it lost weight during the first few days. A moth lost about 20% of its weight during the first night of flight and accumulated about a 40% weight loss during the remainder of its life. Adult saturniid moths do not feed and live only a few days in captivity (Rau and Rau 1912. 19 ~: Janzen, 1984). The details of their brief adult lives have not been studied with free-living adults. Here we ask how long free-flying adult male cecropia moths live in nature and how much weight they lose as they age. This information is important to understanding how resource harvest as a larva is integrated with the duration of the non-feeding post-larval stages, and how weight loss influences flight dynamics (Janzen 198~1. Cecropia. Hmlophora cecropia (L.) (Lepidoptera: Saturniidae), ranges over the United States and southern Canada east of the Rocky Mountains (Ferguson 1972, Lemaire 1978). Its natural history and ecology have been most intensively studied in Illinois (e.g., Marsh 19~1. Waldbauer and Sternburg 1973, Sternburg et al. 1981). As part of the Illinois studies. the rv.o senior authors released, weighed, and individually marked newly emerged adult males in the contiguous cities of Champaign and Urbana during the natural 1968 cecropia tlight season (rnid-~lay to early July). Many were reweighed after being recaptured in traps baited with virgin females. Adult ca.LOpias usually emerge from the cocoon about 5 h after sunrise (ca. 1000 h). Emergence is delayed on cool days. They crawl a few centimeters to a place where the wings can expand and then remain there until sunset. Shortly after sunset both newly emerged and old males make a dispersal tlight that, judging by the activities of caged males. may continue for as l ng as an hour. The newly emerged virgin females are inactive until an hour before da\\n: then they evert the gland that produces the sex attractant pheromon<:. The males. again active at this time. seek out the females by flying to the pheromone source. These activities cease at d wn. Pairs stay coupled about 16 h, until the following sunset. The males then disperse and the females fly for the first time, seeking oviposition sites. ~lated f males make oviposition flights every night but are not known to mate or release sex pheromon<: again. ~lated males continue to disperse just after sunset and to fly in search of unmated females just before dawn each day (Waldbauer and Stemburg 19791. :Depanrnem of Emornology. l"ruYersity of Illinois. Crbana. IL 61801. -Depanrnem of Biology. l"ni\ersity of Pennsyhania. Philadelphia, PA 19104. 1Waldbauer et al.: Longevity and Weight Loss of Free-flying Male Cecropia Moths, <i>Published by ValpoScholar, 1985134 THE GREAT LAKES ENTOMOLOGIST VoL 18, No.4 MATERIALS AND METHODS The moths emerged from overwintered cocoons that had been collected in Champaign­Urbana or reared outdoors from local stock as described by Waldbauer and Sternburg (1973). All cocoons were held until emergence at ambient outdoor conditions. The moths emerged synchronously with the wild population, putting our traps in competition with a large population of wild females (Sternburg and Waldbauer 1969, Fig. 4). Males were released on the day they They were first numbered in sequence with a waterproof felt pen on the underside left hind wing and then weighed o the nearest 10 mg between 1300 and 1500 h, long after they had excreted the meconium. Some dribbled a bit of meconium afterward. These were reweighed except for a few that dribbled slightly at the time of release. The males were released between 16 May and 30 June in a park near the center of Champaign-Urbana. Those released in daylight (40%) were put in trees or shrubs where they were hidden by foliage. Those released around dusk (60%) were tossed into the air and llew off. The number of moths recaptured and the number reweighed differs because five recaptured moths that had been damaged by birds were not reweighed. The traps (Sternburg and Waldbauer 1969) were constantly baited with at least two virgin females that were replaced at least every three days. A trap at the home of GPW was 2.9 km west of the release point Another, at the home of JGS, was 3.9 km east of the release point. The area between the traps consists mostly of urban residential areas with many trees and shrubs. At the lime of the study i  had a large wild cecropia population (Sternburg et aL 1981). The traps were examined daily. Recaptured males were reweighed at the laboratory between 1300 and 1500 hand re-released at the trap in which they had been caught. in late afternoon at the GPW trap and just after dark at the lGS trap. If released in daylight at the lGS trap, they were attacked by blue jays (Cyanocitta cristata) and common grackles (Quiscalus quiscula). Release time had no significant effect on the probability of recapture; at the GPW and l S traps, 38.5% and 36.0% respectively, of the re-released moths were recaptured at least once more (x2 0.016, P = 0.9, 1 d.t., continuity corrected) . RESULTS Of the 387 released males, 68% were not recaptured. Of the remaining 124 (32%), 99(79.8%) were first caught in the GPW trap, 24 (19.4%) in the lGS trap, and one (0.8%) in a more distant trap in the country. Only one moth appeared at two traps. The GPW trap was closer to the release point. but we believe it caught more moths mainly because it was west of it. The prevailing winds were from the west, and males must tly upwind in search of females (Wilson and Bossert 1963). Figure I shows that males varied in how long they circulated in nature before they were first recaptured. About 80% of the 124 recaptured males were first caught within four days, but one did not appear until the 12th day. The most recaptures (including re-recaptures) occurred on the third and fourth nights after release (Fig. I), but 30% of them occurred five or more days after release. The results were affected by competition from free-living females that were releasing sex attraetant pheromone during the experiment, and a similar but ecologically less relevant experiment done when wild cecropia females are absent (July and August) would probably give different results. The weight loss data for 119 males that were recaptured 180 times are combined in Table 1. The live weight of all moths at the time of release varied from 1.05 to 4.48 g (x = 2.41 g, SD 0.65). The mean initial live weight of the moths that were not recaptured was 2.46 g (SD 0.65) while the mean initial live weight of those that were recaptured was 2.33 g (SD 0.64); the difference is not significant (t = 1.821,385 d.f., 0.01 < P < 0.05). The moths that were recaptured on the fifth or later nights had an initial mean 2The Great Lakes Entomologist, Vol. 18, No. 4 [1985], Art. 1https://scholar.valpo.edu/tgle/vol18/iss4/11985 THE GREAT LAKES ENTOMOLOGIST 135 40 no. re leased =387 no recaptured =124 % recaptured =32.0 I 2 3 4 5 6 7 8 9 10 II 12 Days After First Release 1. 	The numbers of adult male cecropia moths that were first recaptured on each day following of e-closion. weight of 2.-!-9 g (SD = 0.71). which is not different from either the entire set of released moths or the entire recaptured subset (by inspection). The moth that was recaptured on the 12th day was one of the heaviest (3.49 g at release), but one recaptured on the 10th day was one of the lightest (2.73 at release). There is no suggestion that heavy individuals ha\<:: different life spans than individuals. ~Iale cecropias lose weight as they age, rapidly at first and more slowly later (Table I, .., and 31. For example. the weight of a male that was recaptured on the first-fifth after release declined 22.6. -1-. 1. and 5% from the original 2.60 g on successive days, day losing 22. 7. 6. 1. and 7C7c of the previous day's weight. For the entire set of recaptured moths. the cumulatiVe a\'erage absolute weight loss stans at 0.38 g and accumulates to 1.09 g by day fiVe. (Sample size for the sixth and following days is too small to merit detailed examination.) These losses represent 16-47% of the weight of the an:rage released moth. Owr the same five-night progression. the standard deviation in absolute weight loss doubles from 0.18 to 0.38. The regression of absolute weight loss initial liVe weight appears to have a progressively steeper slope each day after (Fig. 2). but only day one is significantly different from the other days. It seems clear that the larger the moth. the greater the absolute weight loss per day of life. The correlation coefficients for the first five days of life (Fig. 2) are also high enough t  suggest a real relationship between the rate of weight loss and body weight. The greatest absolute weight loss during the first 24 h was 0.72 g (27% of a 2.68 g moth). while the smallest was 0.18 g (lICC of a 1.62 g moth). The greatest percent loss 3Waldbauer et al.: Longevity and Weight Loss of Free-flying Male Cecropia Moths, <i>Published by ValpoScholar, 1985136 THE GREAT LAKES ENTOMOLOGIST Vol. 18, NO.4 20 5 r= .84 4 r =.86 3 r85 2 days since release r =.78 day since release r =.73 O'-----L-..------~___...J-____ 2 3 4 Moth Initial Live Weight (g) Fig. 2. Relationship of initial live weight (x) to absolute weight (y) loss by free-ranging male cecropia moths that were recaptured 1-5 days after the day of eclosion. The number of moths recaptured and the regression equation for each day are (I) 17, Y -0.2039 O.2768x; (2) 29, Y -0.3682 + 0.4643x; (3) 39. Y = -0.3700 + 0.5047x: (4) 40. Y = -0.1911 0.4927x; (5) 26, Y -0.0864 + 0.47l8x. for the first 24 h was 28% of a 2.55 g moth. For all recaptures after any time, the greatest absolute loss was 2.32 g, which was 52% of a 4.48 g moth by the sixth day after release. The average cumulative loss in body weight per gram is highest on the first day and then levels off at about 0.45 g by day six (Table I, Fig.3). The standard deviation of this parameter also rises rapidly and then approaches an asymptote at about 0.09-0.10. The longer the moth lives, the less it loses per gram of initial weight per day. The regression of percent weight loss against initial live weight (Fig. 3) shows, as did Figure 2, that larger moths lose weight at a faster rate than do small ones, but that this difference seems to be disappearing by the fifth day of recapture (Fig. 3). However, the correlation coefficients are so small (Fig.3) that this relationship must be viewed as very general, rather than one that can be used to predict the behavior of a particular individual. Visual inspection of the actual data points through which the regression lines in Figure 3 pass suggests that the low correlation coefficients are due to great scatter rather than a tight but curvilinear relation­ship being forced onto a straight line modeL DISCUSSION The results show that at least half of the recaptured males survived for five r more days, with one surviving for 12 days. Rau and Rau (1912, 1914) found that mated male cecropias generally had a mean survival offrom 7.52 to 10.85 days when caged at ambient St. Louis conditions during their natural flight period. However, they (1912) found that, while males that emerged in June survived a mean of 10.62 days, males that emerged in April and May survived a mean of 17.40 days, by far the longest mean life span that they found for mated males. The difference is probably due to the cooler temperatures experienced by the early emergers. Although all but two of our moths were recaptured in 4The Great Lakes Entomologist, Vol. 18, No. 4 [1985], Art. 1https://scholar.valpo.edu/tgle/vol18/iss4/11985 THE GREAT LAKES ENTOMOLOGIST 137 4 r= 265°i ~=--_-5 r=.12 40~, I 1 '" <''1 <;;:) ..J ...... I 30r ---~ 3 r=.34 2 days since release r=.40 day since ~ ! release ~ I r=38 1: 20 <I.> 1::q: 10 2 3 4 Moth Initial Live Weight (g) Fig. Re!ati0n,hip (If initial live weight (x) to percent weight loss (y) by free-ranging male cecropia m0U:, thaI .. ere recaptured 15 days after the day of eclosion. The number of moths recaptured :.tnJ l.i:le regre"ion equation for each are I) 17. Y = 7.8783 + 13.23 1:,9Sx: ,3. 39. Y = 25.1394 (4) 40. }' = 32.0828 + 26. }' = 39.t-~1:'(1 I 5362x. June_ the difference between our results and those of the Raus suggests that living free in nature de.::reases longeyitv. The recapmred males probably flew much farther than the minimum 2.9 or 3.9 km distance between the traps and the release point. Before its first recapture and between any a male makes at least one evening dispersal flight and one morning flight in of a female. either of which may continue for an hour. These flights are probably circuitous and long. A searching male could, for example, locate and follow several pheromone trails that e\'entually fade out because another male reaches the female first. Ymati,)n in the longe\'ity of our cecropia males may have been affected by at least the folio"," ing: I II predation: (2) frequency of recapture (recaptured males were protected from predation while they were in the trap or the laboratory); (3) number of days spent in copulo Ithe male expends resources t  fertilize the female, and a pair of moths may be more ~nr'''r,i'nr to predators than a single moth); (4) nutrient and water reserves at the time of I adult cecropia neither feed nor drink); (5) weather, distance flown, and rate of eli.penditure ('f energy. \,~ater. and perhaps other reserves due to variations i  body size; 161 .::hoke of diurnal and nocturnal roosting sites (this could intluence the probability of predation and desiccation!. The data at and do not allow us to examine these causes of variation except to note that there was no relation between initial body and longevity as measured by recapture. However. large moths lost body weight absolutely faster and faster per gram of their body than did smaii moths. As the moths aged. this relationship was accentuated, at least if one <:ompares the first night of tljght with subsequent nights. Perhaps it costs the most to l1y when hea\·iest. or perhaps the moths tly the most on the first night. However. as the moths age. the percent of their body weight lost per night becomes more nearly equal for 5Waldbauer et al.: Longevity and Weight Loss of Free-flying Male Cecropia Moths, <i>Published by ValpoScholar, 1985138 THE GREAT LAKES ENTOMOLOGIST Vol. 18, No.4 Table I Weight loss parameters for recaptured male cecropia moths based on combined data for 119 males that were recaptured 180 times, All losses are expressed in grams. n.07 0.07 0.05 0.05 (UJI O.Ol 12 all initial body weights. Presumably, this is because the non-expendable parts of the moth's flight apparatus are more similar in initial weight across the variation in initial total moth weight than are the initial weights of water, fat, and other expendable resources, ACKNOWLEDGMENTS The Illinois Natural History Survey, through Dr. W. H. Luckmann, provided a screened outdoor insectary and trees on which to rear cecropias. Analysis of the data and preparation of the manuscript were supported largely by NSF grant DEB 80-11558 to D. H. Janzen. LITERATURE CITED Ferguson, D. c., 1972. Bombycoidea (in part). pp. 246-251 in R. B. Dominick et al. (eds,). The moths of America north of Mexico. Fascicle 20.2B. Classey, London, Janzen, D. H. 1984. How to be a tropical large moth: saturniids and sphingids contrasted, Oxford Surveys in Evolutionary Biology, 1:85-140. Lemaire, C. 1978. Les Attacidae Americains ( Saturniidae), Attacinae. Edition C. Lemaire, 42, boulevard Victor Hug --F. 92200 Neuilly-sur-Seine, France, 238 pp. + 49 pis, Marsh, F. L. 1941. A few life-history details of Sanlia cecropia within the southwestern limits of Chicago. Ecology 22:331-337. Rau, P. and N. Rau. 1912, Longevity in saturniid moths: an experimental study. 1. BioI. 12:179-204, Figs. 1-5. __, 1914. Longevity in saturniid moths and its relation to the function of reproduction. Trans. Aca , Sci. St. Loui  23:1-77. Sternburg, J, G. and G. P. Waldbauer. 1969. Bimodal emergencc of adult cecropia moths under natural conditions. Ann. Entomol. Soc. Amer. 62:1422-1429. Sternburg, J. G., G. P. Waldbauer, and A. G. Scarbrougb. 1981. Distribution of cecropia moth (Saturniidae) in central Illinois: a study in urban ecology. J. Lepid, Soc. 35:304-320. Waldbauer, G. P. and J. G. Sternburg, 1973. Polymorphic termination of diapause by cecropia: genetic and geographical aspects. BioI. Bull. 145:627-641. __, 1979, Inbreeding depression and a behavioral mechanism for its avoidance in Hyalophora cecropia. Amer. Midland Nat. 102:204--208. Wilson, E. O. and W. H. Bossert. 1963. Chemical communication among animals. Recent Prog, Hormone Res. 19:673-716. 6The Great Lakes Entomologist, Vol. 18, No. 4 [1985], Art. 1https://scholar.valpo.edu/tgle/vol18/iss4/1

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Longevity and Weight Loss of Free-flying Male Cecropia Moths, \u3ci\u3eHyalophora Cecropia\u3c/i\u3e (Lepidoptera: Saturniidae)

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