The larva of the green lacewing (Ceraeochrysa cubana) (Neuroptera, Chrysopidae) is a natural predator of eggs of Utetheisa ornatrix (Lepidoptera, Arctiidae), a moth that sequesters pyrrolizidine alkaloids from its larval foodplant (Fabaceae, Crotalaria spp.). Utetheisa eggs are ordinarily endowed with the alkaloid. Alkaloidfree Utetheisa eggs, produced experimentally, are pierced by the larva with its sharp tubular jaws and sucked out. Alkaloid-laden eggs, in contrast, are rejected. When attacking an Utetheisa egg cluster (numbering on average 20 eggs), the larva subjects it to an inspection process. It prods and͞or pierces a small number of eggs (on average two to three) and, if these contain alkaloid, it passes ''negative judgement'' on the remainder of the cluster and turns away. Such generalization on the part of the larva makes sense, because the eggs within clusters differ little in alkaloid content. There is, however, considerable between-cluster variation in egg alkaloid content, so clusters in nature can be expected to range widely in palatability. To check each cluster for acceptability must therefore be adaptive for the larva, just as it must be adaptive for Utetheisa to lay its eggs in large clusters and to apportion alkaloid evenly among eggs of a cluster.Ceraeochrysa cubana ͉ Chrysopidae ͉ Utetheisa ornatrix ͉ Arctiidae ͉ pyrrolizidine alkaloid T he moth Utetheisa ornatrix (family Arctiidae) (henceforth called Utetheisa) endows its eggs with pyrrolizidine alkaloids [henceforth called alkaloid(s)]. It sequesters the chemicals as a larva from its foodplants, legumes of the genus Crotalaria (family Fabaceae), and retains them through metamorphosis into the adult stage. Both parents contribute to the egg endowment. The male transmits alkaloid to the female with the sperm package at mating, and the female allocates a portion of this gift, together with a share of her own alkaloid, to the eggs (1).Here we present evidence that the alkaloids protect the eggs against a natural enemy, the larva of the green lacewing, Ceraeochrysa cubana (family Chrysopidae) ( Fig. 1 A and B). Specifically, we demonstrate that (i) the larva, in laboratory tests, rejects alkaloid-containing Utetheisa eggs, while avidly consuming alkaloid-free eggs offered as controls; (ii) the larva exercises this discrimination in the field as well; (iii) the larva is more strongly deterred by the N-oxide form of the alkaloid than the free base form; (iv) the alkaloid in Utetheisa eggs occurs mainly in the N-oxide form; (v) the eggs in a given cluster are equally endowed with alkaloid; and (vi) the larva seems to act on this information: it abandons a cluster, no matter what the cluster size, if the first few eggs it samples are distasteful. Materials and MethodsThis study was done at our Cornell laboratories and at the Archbold Biological Station, Lake Placid, Highlands County, FL.Experimental Animals. Utetheisa occur at the Archbold Station, often in abundance, in association with stands of Crotalaria mucronata, the major local foodplant. ...
Hydroxydanaidal, the corematal courtship pheromone of maleUtetheisa ornatrix, shows pronounced quantitative variation in natural populations of the moth. Males that, as larvae, fed on seed-bearing rather than immature food plants (Crotalaria spectabilis orC. mucronata) produce higher levels of hydroxydanaidal. Such males also have higher systemic loads of pyrrolizidine alkaloid, the known metabolic precursor of hydroxydanaidal, whichUtetheisa sequester from their larval diet and which is concentrated in the seeds ofCrotalaria. Males raised on seed-bearing plants also achieve higher adult weight. In the context of sexual selection, therefore, femaleUtetheisa could, through assessment of male hydroxydanaidal levels, gauge both the alkaloid content and body weight of their suitors.
The amount of cantharidin (Spanish fly) that the Neopyrochroaflabellata male presents to the female as a glandular offering during courtship represents only a small fraction of the total cantharidin the male accumulates systemically following ingestion of the compound. A major fraction of the acquired cantharidin is stored by the male in the large accessory glands of the reproductive system. At mating, the male transfers this supply, presumably as part of the sperm package, to the spermatheca of the female. The female in turn allocates the gift to the eggs. Eggs endowed with cantharidin proved relatively invulnerable to attack by a predaceous beetle larva (Coleomegilla maculata).We demonstrate here that the cantharidin ingested by male Neopyrochroa flabellata (1) is transferred in large measure to the female at mating, and by the female, for protective purposes, to the eggs. Specifically, we demonstrate that (i) cantharidin (Spanish fly), ingested by the male, accumulates primarily in the large accessory glands of the reproductive system; (ii) mating leads to appearance of cantharidin in the sperm receptacle (spermatheca) of the female; (iii) eggs sired by cantharidin-fed males contain cantharidin; and (iv) cantharidin-laden eggs, unlike cantharidin-free eggs, are protected against predation. Preliminary aspects of this study were reported earlier (2). MATERIALS AND METHODSSource and maintenance of beetles, chemical analyses for cantharidin content, and statistical analyses were as described (1). Values (including those in the figures) are given as mean ± SEM.Cantharidin Feeding. Males designated as cantharidin-fed (n = 58) were offered crystalline cantharidin as described (1). Total cantharidin offered to individuals ranged from 5 to 3050 ,ug, given over a span of 1-31 days. Mean quantity per beetle was 766 ± 83 ,ug, given over a period of 8.4 ± 0.9 days.Males designated as cantharidin-unfed (n = 34) were kept unexposed to cantharidin.Dissection. Beetles were killed by freezing and dissected under saline solution. Components of the male reproductive system that were analyzed for cantharidin content were (see Fig. 1A) as follows: testes, including the ducts leading to the seminal vesicles; seminal vesicles; large accessory glands; small accessory glands; and ejaculatory duct. Components of the female reproductive system that were analyzed were (see Fig. 1C) as follows: ovaries, spermatheca, and median oviduct. For both males and females, heads were also analyzed, as well as the alimentary canal, and a sample, designated as remains, consisting of all body parts, minus head, reproductive system, and gut. All samples were weighed immediately after dissection. A small fraction of samples was lost in the course of the analyses (sample sizes for component parts were therefore sometimes variable).Dissection of mated males (n = 7) and mated females (n = 9) was performed, respectively, within 1.0-3.5 h (2.6 ± 0.4 h) and 0.1-2.7 h (1.2 ± 0.3 h) after mating.Matings. These were staged in Petri dishes, as in the co...
Male Neopyrochroa flabellata have a natural affinity for cantharidin (Spanish fly). They are attracted to cantharidin baits in the field and feed on the compound if it is offered to them in the laboratory. Males that ingest cantharidin secrete cantharidin from a cephalic gland. Females sample secretion from this gland during courtship and mate preferentially with males that had fed on cantharidin. Cantharidin-unfed males can be rendered acceptable to females if cantharidin is added to their cephalic gland.
Abstract--Two quinones (2,3-dimethyl-l,4-benzoquinone and 2,3,5-trimethyl-l,4-benzoquinone) and three phenols (2,3-dimethylphenol, 2-methyl-5-ethylphenol, and 2,3,4-trimethylphenol) were isolated from the defensive secretions of opilionids (Laniatores) from the Panama Canal Zone. The trimethylphenol was not previously reported as a natural product.
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