Biosynthesis of Quinoline by a Stick Insect.

The Peruvian stick insect Oreophoetes peruana is the only known animal source for unsubstituted quinoline in nature. When disturbed, these insects discharge a defensive secretion containing quinoline. Analysis of samples obtained from l-[2',4',5',6,'7'-2H5]tryptophan-fed stick insects demonstrated that the insects convert it to [5,6,7,8-2H4]quinoline by removing the 2'-CH moiety in the indole ring of tryptophan. Analogous experiments using l-[1'-15N]tryptophan and l-[1'-15N,15NH2]tryptophan showed that the indole-N atom is retained while the α-amino group is eliminated during the biosynthesis. Mass spectra recorded from quinoline derived from [2-13C1]tryptophan-fed insects indicated that the α-carbon atom of tryptophan is incorporated as the C-2 atom of the quinoline ring.

Big wigs and small wigs: Time, sex, size and shelter affect cohabitation in the maritime earwig (Anisolabis maritima).

Animal aggregations can occur for a variety of abiotic factors, such as resource limitation, or biotic factors, including group foraging and protection from predators. In our study, we examined whether time, sex, body size or shelter availability affected aggregation behavior of the maritime earwig, Anisolabis maritima (Order Dermaptera), an insect found globally at high densities under driftwood. Specifically, we monitored the distribution of two individuals in arenas with either two shelters (no habitat limitation) or one shelter (habitat limitation) to determine their propensity for cohabitation at times of peak activity and times of quiescence. Females, whose high levels of aggression are often associated with maternal care, were particularly averse to cohabitation, whereas males were generally more tolerant of other earwigs. Females initially preferred not to cohabitate when placed with a male, but were more tolerant of cohabitation later, regardless of the number of shelters. Same-sex pairs, on the other hand, were less likely to cohabitate with only one shelter present, but males were again more tolerant of conspecifics than females regardless of habitat limitation. When competition for one shelter did not lead to cohabitation, the lone occupant was more likely to be the larger individual in same-sex trials and females in mixed-sex trials. Understanding the tolerance for close proximity under these varying conditions may provide insight into aggregative behavior and spatial distribution patterns in the maritime earwig.

Polyandrous females provide sons with more competitive sperm: Support for the sexy-sperm hypothesis in the rattlebox moth (Utetheisa ornatrix).

Given the costs of multiple mating, why has female polyandry evolved? Utetheisa ornatrix moths are well suited for studying multiple mating in females because females are highly polyandrous over their life span, with each male mate transferring a substantial spermatophore with both genetic and nongenetic material. The accumulation of resources might explain the prevalence of polyandry in this species, but another, not mutually exclusive, possibility is that females mate multiply to increase the probability that their sons will inherit more-competitive sperm. This latter "sexy-sperm" hypothesis posits that female multiple mating and male sperm competitiveness coevolve via a Fisherian runaway process. We tested the sexy-sperm hypothesis by using competitive double matings to compare the sperm competition success of sons of polyandrous versus monandrous females. In accordance with sexy-sperm theory, we found that in 511 offspring across 17 families, the male whose polyandrous mother mated once with each of three different males sired significantly more of all total offspring (81%) than did the male whose monandrous mother was mated thrice to a single male. Interestingly, sons of polyandrous mothers had a significantly biased sex ratio of their brood toward sons, also in support of the hypothesis.

Z linkage of female promiscuity genes in the moth Utetheisa ornatrix: support for the sexy-sperm hypothesis?

Female preference genes for large males in the highly promiscuous moth Utetheisa ornatrix (Lepidoptera: Arctiidae) have previously been shown to be mostly Z-linked, in accordance with the hypothesis that ZZ-ZW sex chromosome systems should facilitate Fisherian sexual selection. We determined the heritability of both female and male promiscuity in the highly promiscuous moth U. ornatrix (Lepidoptera: Arctiidae) through parent-offspring and grandparent-offspring regression analyses. Our data show that male promiscuity is not sex-limited and either autosomal or sex-linked whereas female promiscuity is primarily determined by sex-limited, Z-linked genes. These data are consistent with the "sexy-sperm hypothesis," which posits that multiple-mating and sperm competitiveness coevolve through a Fisherian-like process in which female promiscuity is a kind of mate choice in which sperm-competitiveness is the trait favored in males. Such a Fisherian process should also be more potent when female preferences are Z-linked and sex-limited than when autosomal or not limited.

Paternal inheritance of a female moth's mating preference.

Females of the arctiid moth Utetheisa ornatrix mate preferentially with larger males, receiving both direct phenotypic and indirect genetic benefits. Here we demonstrate that the female's mating preference is inherited through the father rather than the mother, indicating that the preference gene or genes lie mostly or exclusively on the Z sex chromosome, which is strictly paternally inherited by daughters. Furthermore, we show that the preferred male trait and the female preference for that trait are correlated, as females with larger fathers have a stronger preference for larger males. These findings are predicted by the protected invasion theory, which asserts that male homogametic sex chromosome systems (ZZ/ZW) found in lepidopterans and birds promote the evolution of exaggerated male traits through sexual selection. Specifically, the theory predicts that, because female preference alleles arising on the Z chromosome are transmitted to all sons that have the father's attractive trait rather than to only a fraction of the sons, such alleles will experience stronger positive selection and be less vulnerable to chance loss than would autosomal alleles.