Scarlet-bodied Wasp Moth (Cosmosoma myrodora) - way cool biology!

Gary Anweiler gganweiler at
Wed Nov 1 23:41:29 EST 2006

Mike - if this is the butterfly laying those wonderful eggs, how should I put it .........this ain't no butterfly!!

  ----- Original Message ----- 
  From: Mike Quinn 
  To: Leps-L 
  Sent: Wednesday, November 01, 2006 1:49 PM
  Subject: Scarlet-bodied Wasp Moth (Cosmosoma myrodora) - way cool biology!

  Scarlet-bodied Wasp Moth (Cosmosoma myrodora) - NABA-SoTX
  TX: Calhoun Co
  Port O'Connor
  25 - X - 2006
  Petra Hockey

  This insect's biology is as fascinating as the adults are beautiful... 

  Conner, W.E , R. Boada, F.C. Schroeder., A. Gonzàlez, J. Meinwald, & T. Eisner. 2001. Chemical defense: bestowal of a nuptial alkaloidal garment by a male moth upon its mate. Proceedings of the National Academy of Sciences 97(26):14406-14411.




  Moth Photographers Group



  The moth occurs along the southeastern U.S. coast from Texas to Florida. 

  NBII (formerly USGS) photo and (incomplete) range map:

  Climbing Hempweed, the caterpillar food plant, is wide ranging primarily from central Texas eastward. Dogfennel Eupatorium, an important adult food plant, is more narrowly dispersed and may account for the narrow distribution of the moth in Texas. 


  Climbing Hempweed (Mikania scandens) - pix, TX range by region

  Dogfennel Eupatorium (Eupatorium capillifolium) - pix, TX range by region



  These moths display warning coloration, yet the caterpillars host on non-toxic Climbing Hempweed, Mikania scandens, (family Asteraceae), a weedy vine at field margins and roadsides that can completely obscure bushes and small trees. The male moth extracts toxins known as "Pyrrolizidine alkaloids" (or PAs) from Dogfennel Eupatorium (Eupatorium capillifolium) and showers these toxins (Fig. 1B) over the female on filaments (Fig. 2) prior to mating and also passes more alkaloids to the female during insemination. The female in turn transfers some of the alkaloids to the eggs during laying. 

  Fig. 1, B: the male (Left) has just ejected PAs, which are visible as a diffuse misty cloud.

  Fig. 2, SEM of filaments laden with PAs.

  Conner et al. (2001) report that, "Although paternal contribution to egg defense had previously been demonstrated for several arctiid moths, protective nuptial festooning of a female by its mate, such as is practiced by C. myrodora, appears to be without parallel among insects." 



  The filaments are termed flocculent:

  The Flocculent. When we prodded open the ventral pouches of a male, the flocculent, which is ordinarily densely packed within, tended to bulge out. Further prodding may cause clusters of filaments to break loose and to float away on air. The filaments tend to stick to foreign objects, but they readily separate from one another. To effect their mass expulsion, the male presumably needs do no more than partially evert the pouches by compressing them from within. 

  Anatomically, the filaments may represent modified scales. Indeed, the cuticular membrane lining the pouches bears pores (Fig. 2E) that may be the openings of the sockets in which the filaments were originally implanted. 

  The filaments are elaborately structured (Fig. 2 A-D). Flattened rather than cylindrical, and highly sculpted, they seem to be built for lightness, flexibility, and strength. The sculpting also ensures that a vast surface is provided for dissemination of the alkaloid. 



  "Field-collected moths were obtained at the Archbold Station [FL] by baiting with air-dried roots of Eupatorium capillifolium (Asteraceae), a plant that we found to contain pyrrolizidine alkaloids. We had previously noted Cosmosoma to be attracted to such bait. The roots were hung in clusters, about 1.5 m above the ground, and were kept moistened. They were inspected intermittently throughout the night for visiting Cosmosoma that had alighted on them."


  Cosmosoma is not alone among Arctiidae in possessing male abdominal pouches laden with flocculent. Such structures have been noted in a number of species of Cosmosoma, all members of the tribe Euchromiini, in which the pouches may even have evolved more than once (17). No function has been demonstrated for the pouches, although an interesting observation suggests they may at times be used for defense. Even slight manual disturbance is said to result in forceful expulsion of flocculent in some species (18). We never noted our Cosmosoma to respond in such fashion. 

  Nor is Cosmosoma alone among arctiids in being attracted to pyrrolizidine alkaloids or pyrrolizidine alkaloid-containing plants (19, 20). Alkaloid sequestration, for protective purposes as in Cosmosoma, is therefore likely to occur in other species as well. 


  Cosmosoma festivum - recorded 1x s. TX, s. FL

  C. festivum - photo

  Other species of Cosmosoma south of the border: 

  A different arctiid (Cisseps fulvicollis) on Eupatorium, no doubt also collecting PAs...


  Conner et al. (2001) briefly mention that Danaus gilippus also use PAs.

  Queens (Danaus gilippus) require PAs for courtship as well, but in this case the PAs are converted to pheromones rather than protective chemicals. (If I had known there was this fascinating world of plant-insect interaction chemistry, I might have paid more attention during Organic Chemistry...) 

  Multiple male Queens on withered Eupatorium greggii

  Boppré (1979) apparently found that withered or damaged plants in the tribes Senecioneae and Eupatorieae of the Asteraceae, as well as plants in the Boraginaceae and Fabaceae were particularly attractive to male danaids. 

  Boppré, M. 1979. Lepidoptera and withered plants. Antenna (Bulletin of the Royal Entomological Society of London 3: 7-9.

  Multiple male Queens on Senecio riddelli 

  Multiple male Queens on Senecio confusis

  Male Queen shown with extruded hairpencils releasing pheromones in front of a female Queen:

  Mike Quinn, Austin
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