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. 2000 Dec 19;97(26):14406-11.
doi: 10.1073/pnas.260503797.

Chemical Defense: Bestowal of a Nuptial Alkaloidal Garment by a Male Moth on Its Mate

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Chemical Defense: Bestowal of a Nuptial Alkaloidal Garment by a Male Moth on Its Mate

W E Conner et al. Proc Natl Acad Sci U S A. .
Free PMC article

Abstract

Males of the moth Cosmosoma myrodora (Arctiidae) acquire pyrrolizidine alkaloid by feeding on the excrescent fluids of certain plants (for instance, Eupatorium capillifolium). They incorporate the alkaloid systemically and as a result are protected against spiders. The males have a pair of abdominal pouches, densely packed with fine cuticular filaments, which in alkaloid-fed males are alkaloid laden. The males discharge the filaments on the female in bursts during courtship, embellishing her with alkaloid as a result. The topical investiture protects the female against spiders. Alkaloid-free filaments, from alkaloid-deprived males, convey no such protection. The males also transmit alkaloid to the female by seminal infusion. The systemic alkaloid thus received, which itself may contribute to the female's defense against spiders, is bestowed in part by the female on the eggs. 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.

Figures

Figure 1
Figure 1
(A) Cosmosoma myrodora (male) on its larval foodplant (Mikania scandens). (B) Courting Cosmosoma in wind tunnel; the male (Left) has just ejected flocculent, which is visible as a diffuse misty cloud. (C) Ventral view of male; the flap that covers the abdominal pouches is the area between the white markings at base of abdomen. (D) Same, with flocculent being teased out with forceps. (Bar = 1 cm.)
Figure 2
Figure 2
(A) Isolated filaments from flocculent. (B) Portion of antenna of female Cosmosoma, beset with flocculent filaments. (C and D) Enlarged view of filament (stereo pair). (E) Portion of inner lining of abdominal pouch of male, showing the sockets in which the filaments are presumably initially implanted. (Bars = A, 10 μm; B, 100 μm; E, 1 μm.)
Figure 3
Figure 3
Fate of Cosmosoma, offered to N. clavipes spiders. Males: (−) alkaloid free; (+) alkaloid fed. Females: (V) virgin, alkaloid free; (M−) mated with alkaloid-free male; (M+) mated with alkaloid-fed male; (VF−) virgin, festooned with flocculent of alkaloid-free male; (VF+) virgin, festooned with flocculent of alkaloid-fed male. Statistics: *, P < 0.05; **, P < 0.01 (Fisher Exact Probability).

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