Firefly "Femmes Fatales" Acquire Defensive Steroids (Lucibufagins) from theirFirefly PreyThomas Eisner; Michael A. Goetz; David E. Hill; Scott R. Smedley; Jerrold MeinwaldProceedings of the National Academy of Sciences of the United States of America, Vol. 94, No.18. (Sep. 2, 1997), pp. 9723-9728.Stable URL:http://links.jstor.org/sici?sici=0027-8424%2819970902%2994%3A18%3C9723%3AF%22FADS%3E2.0.CO%3B2-TProceedings of the National Academy of Sciences of the United States of America is currently published by National Academyof Sciences.Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/nas.html.Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academicjournals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers,and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community takeadvantage of advances in technology. For more information regarding JSTOR, please contact [email protected]://www.jstor.orgWed Jan 16 15:41:55 2008/'roc. Natl. Acad. Sci. USA Vol. 94. pp. 9723-0728, September LO07 Ecology Firefly "femmes fatales" acquire defensive steroids (lucibufagins) from their firefly prey (steroidal pyrones/Coleoptera: I,ampyridae/Photuris/Photinus/Phidippus) Section of Neul-obiology and Ue11avio1-. tl)ep;~rtment of Chemistry, Corncll University, Ithaca. NY 14853 C'ontr?h~ttc,dI>y 7'lzornas Eztnc~r, June 25, 1997 ABSTRACT Female fireflies of the genus Photuris, the so-called firefly "femmes fatales," prey on male fireflies of the genus Photinus. The females are able to entrap the males by faking the flash signal characteristics of the Photinus female. We found that by feeding on Photinus males, Photuris females gain more than nutrients. They also acquire defensive steroidal pyrones called lucibufagins, which are contained in Photinus but which Photuris fireflies are unable to produce on their own. Photuris females that eat Photinus males or lucibufagin are rejected by Phidippus jumping spiders. Lucibufagin itselfproved to be a deterrent to such s~iders. Field-collected Photuris females contain lucibufagin in varying amounts. The more lucibufagin they contain the more unacceptable they are to Phidippus. Fireflies, thc Pamiliar luminescent bectles of the family Lampy- ridae, arc protected against predation. They arc known to he unacceptable to a number ol'vertebratcs (1-3), and wc showcd that species of thc gcnus Photinus arc unpalatable to thrushcs (4). Novel steroidal pyrones arc thc basis of this unpalatability, and wc found thcse pyrones systemically in all spccics of Photir~us that wc investigatcd (P. i,ynitus, P. mmagb~ellus, and P. pymlis; refs. 4-7). Rccause of thcir close structural relationship to the cardiotonic steroids (e.g., bul'alin) found in the venom of Chincsc toads (BLL~~ spp.) (8, 9), we callcd thc compounds lucibul'agins (LRG; for instance, 1) (4). Hccausc LRG are of intrinsic chemical intcrcst, we broad- cncd our study to include othcr l'irel'lics to sec whether they might producc variants of thesc steroids. Wc found Grcl'lics of another genus, f'/zzoturis, also to contain LRG. Howcvcr, we lcarned that thesc spccics do not producc LBG themselves, acquiring thcm instead by prcying on Plzotinus. Ncrein wc dctail thc particulars of this chcmical usurpation strategy. We knew that Pl~otui-is fcmalcs hunt species ol' Pllotirzus. Femalc Plloturis, appropriatcly callcd l'ircl'ly "femmcs latales," lure male P1zotir1u.s by masqucrading as females of the lattcr (10, 11). In l'irel'ly courtship, males fly about at night, flashing thcir light organs in a characteristic, species-specil'ic pattern. Females answer their respective males from their perchcs, usually with single Slashes, timed to l'ollow the male "calls" with a spccics-specific dclay. P/zoturis females lurc P1lotinu.s malcs by flashing with a dclay imitativc of that ol'thc Pllotinus l'cmalc. Thc P/zotirzus malcs arc thcrcby drawn to thc femmcs fatalcs, only to hc caught and caten (12-15). Thc femmcs fatalcs, in turn, arc enrichcd with LBG. Thc data wc prescnt herc dcmonstrate that (i) fcmalc PI~otui,is, in thc field, contain LBG, as do Plzotinus; (ii) fcmale PI~otui,is, at adult emergcncc, are LBG-frce, hut bccome LBG-laden if fcd on Photinus males or on purc LBG; (iii) l'cmale Plzoturis, fcd on malc Plzotinus or LBG, arc lcss vulnerable to predation by Plzidippus spiders than unfed con- trols; and (A!) the degree ol' protection ol' Geld-collected P/zzoturis females against Phidippus is a f~~nctionof the l'cmale's LRG content. MATERIALS AND METHODS Statistics and Conventions. Statistical analyses (cxccpt of l'requcncy data) werc pcrl'ormcd by using susr~r(I6). All t tests compared mcans of indcpcndcnt samplcs. Following ANOVAs that indicatcd significant dil'l'crcncc (P < 0.05), multiple comparison tcsts werc conductcd (Tukcy-Kramcr, expcrimcnt widc cx = 0.05). Contingcncy tcsts of frequency data cmploycd thc G-statistic (with Williams correction) (17). All valucs arc givcn as mcan -+ SE. Thc onc LBG available to us for tcsting in pure form, 12-oxo-2P,3P-di-O-acctyl-2P,5P-I la-trihydroxyhul'alin (I), thc principal LBG from P. pym1i.s (S), is abbreviated as LRG-I throughout thc paper. Fireflies (Photinus and Photuris). Thc P1lotirzu.s wcrc of two spccies, P. ig11itu.s and P. rnagirzellus (Fig. 1 B and C). They wcre collected as adults at night in mcadows in the vicinity ol' Ithaca, l'ompkins County, Ncw York. Most werc taken in flight, dctectcd by thcir flashes. Most of the PI~otui,is also camc from Ithaca. Field-collcctcd adults (Fig. I A)