Extreme Duty Cycles in the Acoustic Signals of Tiger Moths: Sexual and Natural Selection Operating in Parallel.

Sound production in tiger moths (Erebidae: Arctiinae) plays a role in natural selection. Some species use tymbal sounds as jamming signals avoiding bat predation. High duty cycle signals have the greatest efficacy in this regard. Tiger moth sounds can also be used for intraspecific communication. Little is known about the role of sound in the mating behavior of jamming species or the signal preferences underlying mate choice. We recorded sound production during the courtship of two high duty cycle arctiines, Bertholdia trigona and Carales arizonensis. We characterized variation in their acoustic signals, measured female preference for male signals that vary in duty cycle, and performed female choice experiments to determine the effect of male duty cycle on the acceptance of male mates. Although both species produced sound during courtship, the role of acoustic communication appears different between the species. Bertholdia trigona was acoustically active in all intraspecific interactions. Females preferred and ultimately mated with males that produced higher duty cycles. Muted males were never chosen. In C. arizonensis however, sound emissions were limited during courtship and in some successful matings no sound was detected. Muted and clicking males were equally successful in female mate-choice experiments, indicating that acoustic communication is not essential for mating in C. arizonensis. Our results suggest that in B. trigona natural and sexual selection may work in parallel, to favor higher duty cycle clicking.

La producción de sonido en árctidos (Erebidae: Arctiinae) juega un papel fundamental en la selección natural. Algunas especies de polillas utilizan los sonidos producidos por los órganos timbálicos como señales de interferencia para evitar ser depredados por los murciélagos. Llamadas con alto porcentaje de estimulación efectiva suelen ser más eficientes con este fin. Estos sonidos pueden ser utilizados también como forma de comunicación intraespecífica. Poco se sabe acerca de la función del sonido en la conducta de apareamiento de aquellas especies de polillas que utilizan estas señales, además, para interferir el sistema radar de los murciélagos. En este estudio, hemos grabado los sonidos producidos por dos especies de árctidos durante el cortejo, Betholdia trigona y Carales arizonensis. Ambas especies producen llamadas de alto porcentaje de estimulación efectiva como estrategia defensiva contra los murciélagos. Hemos caracterizado la variabilidad en las señales acústicas de ambas especies, se registró la preferencia de las hembras por las llamadas de los machos con diferentes porcentajes de estimulación efectiva y determinamos el efecto de las señales acústicas de los machos en la selección de pareja de las hembras. Aunque ambas especies produjeron sonidos durante el apareamiento, el papel de la comunicación acústica en este contexto difiere entre las especies. Bertholdia trigona produjo emisiones en todas las interacciones intraespecíficas. Las hembras de esta especie prefirieron y seleccionaron machos para aparearse capaces de producir señales con alto porcentaje de estimulación efectiva. Machos incapaces de producir sonido nunca fueron seleccionados para aparearse. En C. arizonensis por el contrario, las emisiones de sonido durante el apareamiento fueron escasas y en algunos casos no se detectó sonido. Las hembras no mostraron preferencia alguna por machos capaces de producir sonido, ni machos mudos, lo cual indica que la comunicación acústica no es esencial para el apareamiento exitoso de C. arizonensis. Nuestros resultados sugieren que en B. trigona, la selección natural y la selección sexual pueden actuar en paralelo para favorecer la producción de sonidos con alto porcentaje de estimulación efectiva.

Tiger moth responses to a simulated bat attack: timing and duty cycle.

Many night-flying insects perform complex, aerobatic escape maneuvers when echolocating bats initiate attack. Tiger moths couple this kinematic defense with an acoustic reply to a bat's biosonar-guided assault. The jamming hypothesis for the function of these moth sounds assumes that tiger moth clicks presented at high densities, temporally locked to the terminal phase of the bat attack will produce the greatest jamming efficacy. Concomitantly, this hypothesis argues that moths warning bats of bad tasting chemicals sequestered in their tissues should call early to give the bat time to process the meaning of the warning signal and that moths calling at low duty cycles are more likely to employ such an aposematic strategy. We report here the first investigation of a tiger moth assemblage's response to playback of a bat echolocation attack sequence. This assemblage of arctiid moths first answered the echolocation attack sequence 960+/-547 ms (mean +/- s.d.) from the end of the bat attack. The assemblage reached a half-maximum response shortly after the first response, at 763+/-479 ms from the end of the terminal buzz. Tiger moth response reached a maximum at 475+/-344 ms from the end of the sequence; during the approach phase, well before the onset of the terminal buzz. In short, much of tiger moth response to bat attack occurs outside of the jamming hypotheses' predictions. Furthermore, no relationship exists between the duty cycle of a tiger moth's call (and thus the call's probability of jamming the bat) and its temporal response to bat attack. These data call into doubt the assumptions behind the jamming hypothesis as currently stated but do not directly test the functionality of arctiid sounds in disrupting echolocation in bat-moth aerial battles.

Chemical odorant of colonial seabird repels mosquitoes.

The crested auklet, Aethia cristatella, emits a class of aldehydes shown to be potent invertebrate repellents when used by heteropterans against their predators. Our aim was to determine the efficacy of these aldehydes against mosquitoes in the laboratory. Synthetic analogues of the auklet odorant were strongly repellent to mosquitoes in controlled laboratory trials. Furthermore, the efficacy was similar to previous reports for commercial mosquito repellents. These results, in combination with a previously published study, show that constituents of the aldehyde odorant are broad spectrum in efficacy against ectoparasitic arthropods of birds. Our report is the first empirical evidence for an endogenous mosquito repellent in birds.

Heteropteran chemical repellents identified in the citrus odor of a seabird (crested auklet: Aethia cristatella): evolutionary convergence in chemical ecology.

The exogenous application of chemical repellents is widespread in birds, but endogenous production is exceedingly rare. We herein report a new class of avian defensive compounds isolated from the feathers and volatile odor of the crested auklet (Aethia cristatella). Mass spectra indicate that n-hexanal, n-octanal, n-decanal, Z-4-decenal and a 12-carbon unsaturated aldehyde comprise the auklet odorant. Octanal and hexanal are also secreted in the repugnant metasternal gland emissions of heteropteran insects and are known to be potent invertebrate repellents. We suggest that the auklet odorant functions as an ectoparasite repellent and a signal of mate quality. This would represent a rare and direct link between vigor, quality and parasite resistance, one of several putative bases for mate selection. This is the first report of defensive compounds produced by a seabird or colonial bird and one of the few examples of chemical defense in a polar or subpolar marine vertebrate.

Chemical defense: bestowal of a nuptial alkaloidal garment by a male moth on its mate.

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.

Chemical egg defense in a green lacewing (Ceraeochrysa smithi)

The green lacewing Ceraeochrysa smithi (Neuroptera, Chrysopidae), like other members of its family, lays its eggs on stalks, but it is unusual in that it coats these stalks with droplets of an oily fluid. The liquid consists of a mixture of fatty acids, an ester, and a series of straight-chain aldehydes. Relative to the eggs of a congeneric chrysopid that lacks stalk fluid, the eggs of C. smithi proved well protected against ants. Components of the fluid, in an assay with a cockroach, proved potently irritant. Following emergence from the egg, C. smithi larvae imbibe the stalk fluid, thereby possibly deriving nutritive benefit, defensive advantage, or both.

Differential mobilization of fatty acids from adipose tissue.

Are the different fatty acids mobilized into plasma in proportion to their concentrations in adipose tissue triglyceride? To answer this question, we fed weaning rabbits a special diet to label the fat stores with a variety of dietary fatty acids. The release of adipose tissue fatty acids into the plasma was then induced by ACTH-stimulated lipolysis. The compositions of the resulting plasma free fatty acids and of the adipose tissue triglyceride were then compared. Plasma free fatty acids increased from 625 mumol/L at baseline to 2938 mumol/L after ACTH and represented fatty acids released from adipose tissue. The relative mobilization of these fatty acids from adipose tissue was defined as the ratio between their percentage in the plasma free fatty acid fraction to their percentage in adipose tissue triglyceride. For the 24 fatty acids examined, the relative mobilization ranged from 0.11 for 22:1 n-11 to 5.06 for 20:5 n-3, a 46-fold difference. Relative mobilization correlated positively with unsaturation and negatively with chain length. The relative mobilization for essential fatty acids was in the order of 20:5 n-3 > 20:4 n-6 > 18:3 n-3 > 22:6 n-3 > 18:2 n-6. Saturated fatty acids, along with oleic acid, were much less well mobilized than the entire group of polyunsaturated fatty acids. Our data indicate that the mobilization of fatty acids into plasma was not proportional to their content in adipose tissue, but rather was influenced by their molecular structure. Eicosapentaenoic acid 20:5 n-3 (EPA), and arachidonic acid 20:4 n-6, precursors of two different prostaglandins, were the fatty acids with the highest mobilization into the plasma.

Circular stapled rectal stricturoplasty with the Proximate intraluminal stapler.

PURPOSE: Benign rectal strictures arise from a variety of causes, and numerous techniques have been developed to deal with them. When even the most innovative methods of stricture treatment fail, major resection may be required. An alternative to resection is desirable. METHODS: A case is presented in which the Proximate curved intraluminal stapler was used to perform successful stricturoplasty of a low rectal stricture when other methods failed. RESULTS: Circular stapled rectal stricturoplasty provided a wide lumen, minimized perforation risk, and preserved continence. CONCLUSION: Circular stapled rectal stricturoplasty is an option to consider when other treatments for rectal stricture fail.

Effects of dietary fat content, saturated fatty acids, and fish oil on eicosanoid production and hemostatic parameters in normal men.

Populations that consume a diet rich in marine lipids have been reported to have a lower risk of coronary heart disease. However, some Western population groups with a high fish consumption continue to suffer elevated rates of coronary heart disease. Many of these individuals consume a diet rich in saturated fats in addition to the fish. To examine these possible dietary interactions we fed six healthy men diets that contained two levels of saturated fat (5% and 19% of energy). During 3-week periods the study subjects were given diets with a low-(25% of energy) and high-(39% of energy) fat content with and without inclusion of n-3 polyunsaturated or monounsaturated fatty acids (2% of energy). The effects of the n-3 fatty acids on the principal plasma lipid fractions were similar regardless of the saturated fat intake. Platelet function, as measured by the skin bleeding time, was inhibited when n-3 fatty acids were added to the low saturated-fat diet. In vivo thromboxane A2 production as assessed by urinary metabolites also declined (p < 0.01) during supplementation with n-3 fatty acids to a low-fat diet. Prostacyclin production were reduced on a low-fat diet compared to a high-fat diet regardless of supplementation with n-3 fatty acids. N-3 fatty acids stimulated the synthesis of modest amounts of thromboxane A3 and prostacyclin I3, on both the low and high saturated-fat diets. These studies showed that the effects of eicosapentaenoic and docosahexaenoic acids on platelet and vascular function and eicosanoid production are modulated by the content of saturated fatty acids in the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular risk factor levels in ethnic Hawaiians.

We report a cardiovascular risk factor survey of "native" Hawaiians 20-59 years old (70 percent, or 257), living on the Hawaiian Homestead lands on the island of Molokai, Hawaii. More than 60 percent of both sexes were overweight. Among males, 42 percent were smokers. The percent of the population with systolic blood pressure greater than 140 mm Hg or a diastolic pressure greater than 90 mm Hg or taking hypertensive medications was 14 percent of those ages 20-39 and 36 percent of those ages 40-59. The percent with serum cholesterol greater than or equal to 6.2 mmol/L ranged from 8 percent of those 20-29 years old to 46 percent in those 50-59 years old. Two percent of those ages 20-29 had a history of diabetes, or 2 + or greater glycosuria by dipstick, as did 23 percent of those ages 50-59. The majority of the known diabetics exhibited glycosuria and elevated glycohemoglobin levels, indicating poor control. Hypertension, although usually known to the participant, was frequently uncontrolled. From these data, it appears that among this group of Hawaiians major risk factors for cardiovascular disease were frequent, while at the same time the levels of awareness and/or control for most of these factors were low.

Are the n-3 fatty acids from dietary fish oil deposited in the triglyceride stores of adipose tissue?

Adipose tissue is the chief reservoir of the essential fatty acids (n-3 and n-6). To study the incorporation of the dietary n-3 fatty acids eicosapentaenoic acid (EPA) (20:5) and docosahexaenoic acid (DHA) (22:6), and a unique monounsaturated fatty acid, cetoleic acid (22:1n-11), into adipose tissue, rabbits were fed two different processed fish oils: MaxEPA (high in EPA and DHA; Seven Sea Ltd, Hull, UK) and herring oil (high in cetoleic acid). EPA and DHA increased from 0% of total adipose tissue fatty acid, in the adipose tissue of control rabbits to 2.2% and 4.9%, respectively, in MaxEPA-fed rabbits. The DHA-to-EPA ratio in the adipose tissue was higher than that in the diet, indicating alternative metabolic pathways for EPA. In the adipose tissue of herring-oil-fed rabbits, cetoleic acid increased from 0% to 7.9% of total fatty acids. The deposition of EPA and DHA was 1.8% and 2.8%, respectively. Our data indicated that these unique long-chain unsaturated fatty acids from dietary fish oils were readily incorporated into the fat stores from whence they could be mobilized.

Courtship pheromone production and body size as correlates of larval diet in males of the arctiid moth,Utetheisa ornatrix.

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.

Magnetic resonance microscopy: in vivo sectioning of a developing insect.

The utility of magnetic resonance imaging vis-a-vis insect morphology and development was investigated. MRI is a noninvasive technique that distinguishes between tissues based on proton content and proton 'environment'. At present a resolution of 100 micron is achievable. The technique avoids fixation artifacts and allows the detection of motion within the organism.

Sphenoethmoidal mucoceles with intracranial extension.

Mucoceles of the paranasal sinuses are benign, expansile, locally destructive lesions that are thought to occur secondary to obstruction of the sinus ostia. Nasal and/or ocular signs and symptoms are the usual clinical manifestations of mucoceles arising in the ethmoid and sphenoid sinuses, and intracranial extension is rare. We describe three cases of widely destructive sphenoethmoidal mucoceles extending intracranially, with bone erosion and dural exposure in all cases and brain necrosis in one case.

Stink of Stinkpot Turtle Identified: ohgr-Phenylalkanoic Acids.

The exocrine secretion of the "stinkpot turtle," Sternotherus odoratus, discharged by the animals in response to disturbance, contains four omega-phenylalkanoic acids (phenylacetic, 3-phenylpropionic, 5-phenylpentanoic, and 7-phenylheptanoic). The last two of these are new natural products. The first two are powerfully malodorous and responsible for the stench of the fluid. Lesser components, including several aliphatic acids, are also present. Only a few milligrams of secretion are discharged by a turtle at any one time. Although bioassays with fish suggest that the secretion has the potential to serve as a feeding deterrent to predators, it is argued that Sternotherus does not ordinarily discharge enough fluid to effect this action and may employ its secretion only as an aposematic signal that warns predators of its more generalized undesirability.

Benzoyl cyanide in the defensive secretion of polydesmoid millipeds.

A novel cyanogenetic compound benzoyl cyanide, was isolated from the defensive secretion of 3 polydesmoid millipeds (Pseudopolydesmus seratus, Apheloria corrugata and A. trimaculata). The secretion of the 3 species also contains mandelonitrile and benzaldehyde, and that of P. serratus contains mandelonitrile benzoate, benzoic acid, isovaleric acid, myristic acid and stearic acid.

The transport of esterified cholesterol in plasma high density lipoproteins of human subjects: a mathematical model.

The pattern of labeling of free and esterified cholesterol in the plasma high-density lipoproteins after an intravenous injection of [3H]-mevalonic acid has been examined in six human subjects with a variety of plasma lipoprotein phenotypes. Attempts have been made to fit these data to theoretical models of high-density lipoprotein esterified cholesterol transport constructed on the basis of previous experimental observation. The first model, which assumed that the high-density lipoprotein esterified cholesterol transport constructed on the basis of previous experimental observation. The first model, which assumed that the high-density lipoprotein esterified cholesterol comprised a single homogeneous pool, was incompatible with the observed data. The second model assumed a two-pool model in which all of the plasma esterified cholesterol was produced in a small, rapidly turning over subfraction of the high-density lipoproteins. From this pool it was assumed that esterified cholesterol was transferred to other lipoprotein fractions, including transfer to a larger and much more slowly turning over subfraction of the high density lipoproteins. The second model was quite compatible with the observed data. Furthermore, the calculated net transport of esterified cholesterol through the fast turning over pool was in a range similar to that reported elsewhere for whole plasma. It has been concluded that the two-pool model not only fits the experimental data, but also accords well with previously documented observations of plasma esterified cholesterol transport.