Mating competitiveness and fertility of thiotepa-sterilized flies

Summary In the present investigation, an attempt has been made to study the mating competitiveness and fertility of males as well as females ofDacus dorsalis Hendel (Diptera: Tephritidae) treated topically with thiotepa. In the mixed population, treated flies of either sex were found to be sexually more vigorous than untreated flies. However when the mating competitiveness of either sex was determined separately using various methods, treated males were found not to differ significantly in sexual competitiveness from untreated flies. Receptivity of treated and untreated females to males was also studied by the single choice method. Thiotepa-treated and untreated females were found to be equally receptive to males.     

2-Phenylethanol, a presumed sexual stimulant produced by the male cabbage looper moth, Trichoplusia ni.

A sex pheromone produced by male cabbage looper moths, Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone of T. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.     

Regulation of feeding and ovipositional success ofAmblyomma americanum ticks

Summary Duration of the adult femaleAmblyomma americanum feeding period was found to be dependent upon male receptiveness to mating, which was in turn dependent upon when males were placed with females. Prolonging the time to mating by 5 days had no effect on female engorgement weight or length of the preovipositional period, but prolonging mating by 10 days substantially decreased the number of ovipositing females and ablated egg viability. In the absence of males, females were severely stunted in size and had to be forcibly removed from the host.Supported in part by grants from the United States Public Health Service, National Institutes of Health No. AI 17555, RR 05443, and from the Rockefeller Foundation.     

2-Phenylethanol,a presumed sexual stimulant produced by the male cabbage looper moth,Trichoplusia ni

Summary A sex pheromone produced by male cabbage looper moths,Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone ofT. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.Mention of a proprietary product in this paper does not constitute a recommendation or an endorsement of the product by the U. S. Department of Agriculture.     

Hormonal control of pheromone responsiveness in the male black cutwormAgrotis ipsilon

In Lepidoptera, reproduction is linked to chemical communication between conspecific partners. When exposed to the female sex pheromone, males respond by exhibiting typical sexual behaviour which leads to mating. Here we show that presence of the juvenile hormone producing gland (corpora allata) of the male black cutworm,Agrotis ipsilon, is necessary for pheromone responsiveness. Allatectomized males do not show any sexual behaviour, although their antennal olfactory system is functional. Allatectomized males implanted with active corpora allata recover full pheromone receptivity. It is suggested that reproductive processes are synchronized in males and females through endocrine control; timing of the mating activity could serve as an adaptive strategy linked to the migratory behaviour of this species.     

Depth perception by means of ambient sounds in a small mammal

Summary Golden hamsters placed on a jumping stand from which they can descend onto a shallow or deep landing platform prefer to descend on to the shallow platform, even when tested under IR-light without tactile cues. This preference disappears for subjects with plugged ears. The simultaneous recording of the animal's behaviour and possible emission of ultrasound as well as experiments in which the external acoustical conditions or the sound-reflecting properties of the jumping apparatus were altered suggest that the animals use certain parameters of the ambient sound field for depth perception. Acknowledgments. This research was supported by the Fonds National Suisse de la Recherche Scientifique, grant No. 3.349.74.     

Immunosuppressive effect of a mouse placenta fraction on H-2 incompatible split heart allografts

Summary A soluble placenta fraction from mice (A.CA) mated with H-2 histoincompatible males (A/Sn) significantly prolonged the survival of heterotopic A/Sn heart transplants in A.CA recipients. No prolongation of A/Sn heart graft survival was obtained with the corresponding A.CA placenta fraction after A.CA × A.CA mating.The work was supported by the Danish Medical Research Council (Project No. 512-3088).     

Schistosoma mansoni: a chemoattractive factor released by males and its receptor in females

Chemoattraction between developing (23- to 28-day-old) and adult (10- to 12-week-old) Schistosoma mansoni males and females has been described previously. We report here on in vitro attraction of mature worms to released products of worms of the opposite sex. In the absence of a stimulus worms migrated randomly and did not show any preference in their orientation. Males were not significantly attracted to released products of females. Females exhibited greatest attraction to released products of males, and some attraction to the lipid fraction of released products of males. The aqueous fraction of male-released products slightly repelled females. Prior exposure to released products of males rendered females unresponsive to subsequent exposure, suggesting receptor saturation. These findings have important potential implications for the control of schistosomiasis by intercepting attraction and mating between males and females.     

The ancient claudin Dni2 facilitates yeast cell fusion by compartmentalizing Dni1 into a membrane subdomain

Dni1 and Dni2 facilitate cell fusion during mating. Here, we show that these proteins are interdependent for their localization in a plasma membrane subdomain, which we have termed the mating fusion domain. Dni1 compartmentation in the domain is required for cell fusion. The contribution of actin, sterol-dependent membrane organization, and Dni2 to this compartmentation was analysed, and the results showed that Dni2 plays the most relevant role in the process. In turn, the Dni2 exit from the endoplasmic reticulum depends on Dni1. These proteins share the presence of a cysteine motif in their first extracellular loop related to the claudin GLWxxC(8–10 aa)C signature motif. Structure–function analyses show that mutating each Dni1 conserved cysteine has mild effects, and that only simultaneous elimination of several cysteines leads to a mating defect. On the contrary, eliminating each single cysteine and the C-terminal tail in Dni2 abrogates Dni1 compartmentation and cell fusion. Sequence alignments show that claudin trans-membrane helixes bear small-XXX-small motifs at conserved positions. The fourth Dni2 trans-membrane helix tends to form homo-oligomers in Escherichia plasma membrane, and two concatenated small-XXX-small motifs are required for efficient oligomerization and for Dni2 export from the yeast endoplasmic reticulum. Together, our results strongly suggest that Dni2 is an ancient claudin that blocks Dni1 diffusion from the intercellular region where two plasma membranes are in close proximity, and that this function is required for Dni1 to facilitate cell fusion.     

The mating behavior of individuals ofDrosophila pseudoobscura from New Zealand

Summary Recently discovered individuals in New Zealand of the North American speciesDrosophila pseudoobscura were analyzed for any divergence in mating behavior. Cultures collected from five localities in North American were mated with a stock from Rotorua, New Zealand. No significant divergence was obtained in any of the within North Americ, and more importantly, between North American and New Zealand mating experiments. Further analyses also showed no development of sterility between recently caught New Zealand and North American flies. We discuss our results in relation to others of this type.Publication No. 5 from the Evolutionary Genetics Laboratory, University of Auckland.Acknowledgements. We thank the University Grants Committee, grant No. 140Z88, for financial assistance. We thank D.G. Futch., L. Barr, A. Beckenach and H. Spencer for their kind assistance in sending us wild caught cultures.     

Sound communication inNezara viridula (L.) (Heteroptera: Pentatomidae): Further evidence that signal transmission is substrate-borne

We investigated the sound communication associated with mating inNezara viridula (L.) to clarify conflicting reports on the medium through which acoustic signals are borne. Recordings made from virgin pairs ofN. viridula during precopulatory and compulatory behaviour have revealed that signals transmitted as vibrations through the substrate are a more likely means of communication than signals transmitted by a radiation of sound pressure waves through the air (at least in Australian populations). We present evidence (additional to that already in the literature) that air-borne acoustics are an unlikely mechanism of sexual communication in this species. Specifically, the recorded pulse train patterns showed no consistency or repeatability in relation to different stages of mating behaviour. In contrast, frequency spectrograms of substrate-borne signals reveal repeatable patterns that do correspond with the stage of mating behaviour.     

Site of sex pheromone biosynthesis in the female housefly,Musca domestica L.

Summary The primary site of sex pheromone biosynthesis in the female housefly is the abdominal integument tissue, whereas the contribution of the legs is relatively minor. A substantial portion of the sex pheromone components are, however, transferred from the abdomen to the legs, probably as a result of grooming.Acknowledgment. This work was supported by the Science and Education Administration of the U.S. Department of Agriculture under grant No. 7801064 from the Competitive Research Grants Office. Contribution of the Nevada Agricultural Experiment Station, Journal Series No 524. Housefly pupae were kindly supplied by Dr Ted Shapas, S.C. Johnson and Son, Inc., Racine, Wisconsin.Author for correspondence.     

Multiple sex-linked reciprocal translocations in a termite from Jamaica

Summary Males of the termiteIncisitermes schwarzi from Jamaica have a diploid chromosome number of 32. In male meiosis there are 7 bivalents, and a ring of 18 chromosomes equivalent to sex chromosomes, 9 X's and 9 Y's. This is the largest reciprocal translocation complex so far described for any plant or animal species.This work was supported by a grant from the National Science Foundation, No. DEB 78-02042.     

Migrant selection in a natural population ofDrosophila

Summary Migrant flies ofDrosophila nigrospiracula, a desert species, showed a higher rate of mating than non migrant flies. Increase of mating ability may be favoured by low migration rate, but its causes are not yet well understood. This is the first time that migrant selection is documented from nature.We gratefully acknowledge the field assistance of Robert Mangan, Margaret Jefferson, Don Vacek and Dorthe Jurgenson.     

Photoperiodic regulation of mating behaviour in the linden bug,Pyrrhocoris apterus,is mediated by a brain inhibitory factor

Active inhibition of mating behaviour in a male insect is reported here for the first time. InPyrrhocoris apterus L. (Heteroptera), the most important inhibitory pathway runs from the pars intercerebralis (PI) of the brain and does not pass through the corpora allata. The inhibitory activity of the PI is promoted by short day conditions and suppressed by long days. As the effect of photoperiod is delayed, transfer procedures enabled us to record daily rhythms in mating behaviour during short days. While the extirpation of the PI results in a discrete phase shift of the long day rhythm, there is a much less significant phase shift after this operation during short days. Thus the PI has been shown to mediate the effect of photoperiod on both the inhibition and the rhythm of mating behaviour.     

A sex pheromone from the mandibular glands in bumblebee queens

Summary In this paper it is shown that the mandibular glands of young bumblebee queens produce a species-specific sex pheromone. From our results it becomes obvious that the pheromone is a releaser for the mating attempts made by the conspecific males.Supported by The Netherlands Organisation for the advancement of Pure Research ZWO.     

Schistosoma mansoni: A chemoattractive factor released by males and its receptor in females

Chemoattraction between developing (23- to 28-day-old) and adult (10- to 12-week-old)Schistosoma mansoni males and females has been described previously. We report here on in vitro attraction of mature worms to released products of worms of the opposite sex. In the absence of a stimulus worms migrated randomly and did not show any preference in their orientation. Males were not significantly attracted to released products of females. Females exhibited greatest attraction to released products of males, and some attraction to the lipid fraction of released products of males. The aqueous fraction of male-released products slightly repelled females. Prior exposure to released products of males rendered females unresponsive to subsequent exposure, suggesting receptor saturation. These findings have important potential implicatons for the control of schistosomiasis by intercepting attraction and mating between males and females.     

The transfer of juvenile hormone from male to female during mating in the Cecropia silkmoth

Summary The juvenile hormone (JH) stored in the accessory sex glands (ASG) of adult maleHyalophora cecropia (L.) originates both from sequestration of circulating hormone and from JH synthesized de novo in the ASG from JH acid taken up from the hemolymph. The secretions present in the lumina of the ASG contain most of the accumulated JH. During mating, endogenous JH, labeled biosynthetically via injected [³H-methyl]-methionine, is transferred along with the other seminal material to the bursa copulatrix of the female. The physiological significance of the JH transfer remains unknown.Research was supported by a grant from the National Science Foundation (PCM72-01892) and Organized Research Funds from Texas A&M University.This work was done as partial fulfillment for the degree of Doctor of Philosophy.     

Sex determining mechanisms: an evolutionary perspective

Theories on the evolution of sex determining mechanisms are reviewed for male and female heterogamety, environmental sex determination, and briefly, haplo-diploidy and hermaphroditism. Because of their discrete and well-defined nature, sex determining mechanisms lend themselves to three types of evolutionary questions: what variety occurs and might be expected but does not occur, how do changes occur from one mechanism to another, and why do certain changes occur? All three approaches were illustrated for these different sex determining mechanisms. A generality emerging from these studies is that, at the level of selection of the sex ratio, there are no intrinsic problems in evolving from one sex determining mechanism to another: straightforward transitions between different mechanisms exist under various conditions.     

Mating attempts between the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L. (Lepidoptera: Arctiidae), involve a common sex pheromone composition

It has been suggested that a common sex pheromone composition may account for interspecific sexual interactions observed with certain moths in the Arctiidae. In this study, it is demonstrated that the sex pheromones released by females of the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L., have similar activities and elute at the same retention time on analysis by coupled gas chromatography (GC)-electrophysiology with males from each species. Peak enhancement on GC, chiral GC and coupled GC-mass spectrometry using authentic compounds show that the sex pheromone for bothC. dominula andT. jacobaeae is (3Z,6Z,9S,10R)-9,10-epoxyheneicosa-3,6-diene.