Gamma-radiation of Glossina palpalis gambiensis revisited: effect on fertility and mating competitiveness.

African animal trypanosomoses are vector-borne diseases that cause enormous livestock losses in sub-Saharan Africa, with drastic socio-economic impacts. Vector control in the context of an area-wide integrated pest management program with a sterile insect technique component requires the production of high-quality sterile male tsetse flies. In our study, we evaluated the effect of irradiation on the fecundity of Glossina palpalis gambiensis to identify the optimal dose that will induce maximum sterility while maintaining biological performance as much as possible. In addition, male mating performance was evaluated in semi-field cages. The irradiation doses used were 90, 100, 110, 120, 130, 140, and 150 Gy, and untreated males were used as the control. The results showed that pupal production and emergence rates were higher in batches of females that had mated with fertile males than in those that had mated with irradiated males with any experimental dose. A dose of 120 Gy administered to male flies induced 97-99% sterility after mating with virgin females. For the semi-field cage experiments, males irradiated with 120 Gy showed good sexual competitiveness as compared to fertile males and those irradiated with 140 Gy, considering the level of filling of spermatheca and the number of pairs formed. The optimal radiation dose of 120 Gy found in this study is slightly different from the traditional dose of 110 Gy that has been used in several eradication programmes in the past. The potential reasons for this difference are discussed, and an argument is made for the inclusion of reliable dosimetry systems in these types of studies.

Title: Le rayonnement gamma pour Glossina palpalis gambiensis revisité : effet sur la fertilité et la compétitivité sexuelle. Abstract: Les trypanosomoses animales africaines sont des maladies à transmission vectorielle qui causent d'énormes pertes de bétail en Afrique subsaharienne, avec des impacts socio-économiques importants. La lutte antivectorielle dans le cadre d'un programme de lutte intégrée contre les ravageurs à l'échelle d'une zone avec une composante de technique d'insectes stériles nécessite la production de glossines mâles stériles de haute qualité. Dans notre étude, nous avons évalué l'effet de l'irradiation sur la fécondité de Glossina palpalis gambiensis afin d'identifier la dose optimale qui induira une stérilité maximale tout en maintenant au maximum les performances biologiques. De plus, les performances d'accouplement des mâles ont été évaluées en cages de semi-terrain. Les doses d'irradiation utilisées étaient de 90, 100, 110, 120, 130, 140 et 150 Gy, et des mâles non traités ont été utilisés comme contrôle. Les résultats ont montré que les taux de production et d'émergence de pupes étaient plus élevés dans les lots de femelles qui s'étaient accouplées avec des mâles fertiles que dans les lots de celles accouplées avec des mâles irradiés, avec n'importe quelle dose expérimentale. Une dose de 120 Gy administrée à des mouches mâles a induit une stérilité de 97 à 99 % après accouplement avec des femelles vierges. Pour les expériences en cages de semi-terrain, les mâles irradiés à 120 Gy ont montré une bonne compétitivité sexuelle par rapport aux mâles fertiles et à ceux irradiés à 140 Gy, en considérant le niveau de remplissage de leur spermathèque et le nombre de couples formés. La dose de rayonnement optimale de 120 Gy trouvée dans cette étude est légèrement différente de la dose traditionnelle de 110 Gy qui a été utilisée dans plusieurs programmes d'éradication dans le passé. Les raisons potentielles de cette différence sont discutées et un argument est avancé pour l'inclusion de systèmes de dosimétrie fiables dans ce type d'études.

Radiation dose-fractionation in adult Aedes aegypti mosquitoes.

Balancing process efficiency and adult sterile male biological quality is one of the challenges in the success of the sterile insect technique (SIT) against insect pest populations. For the SIT against mosquitoes, many stress factors need to be taken into consideration when producing sterile males that require high biological quality to remain competitive once released in the field. Pressures of mass rearing, sex sorting, irradiation treatments, packing, transport and release including handling procedures for each step, add to the overall stress budget of the sterile male post-release. Optimizing the irradiation step to achieve maximum sterility while keeping off-target somatic damage to a minimum can significantly improve male mating competitiveness. It is therefore worth examining various protocols that have been found to be effective in other insect species, such as dose fractionation. A fully sterilizing dose of 70 Gy was administered to Aedes aegypti males as one acute dose or fractionated into either two equal doses of 35 Gy, or one low dose of 10 Gy followed by a second dose of 60 Gy. The two doses were separated by either 1- or 2-day intervals. Longevity, flight ability, and mating competitiveness tests were performed to identify beneficial effects of the various treatments. Positive effects of fractionating dose were seen in terms of male longevity and mating competitiveness. Although applying split doses generally improved male quality parameters, the benefits may not outweigh the added labor in SIT programmes for the management of mosquito vectors.

Title: Fractionnement de la dose d'irradiation chez les moustiques Aedes aegypti adultes. Abstract: Équilibrer l'efficacité du processus et la qualité biologique des mâles adultes stériles est l'un des défis du succès de la technique des insectes stériles (TIS) contre les populations d'insectes nuisibles. Pour la TIS contre les moustiques, de nombreux facteurs de stress sont à prendre en compte lors de la production de mâles stériles qui nécessitent une haute qualité biologique pour rester compétitifs une fois relâchés au champ. Les pressions de l'élevage en masse, du triage par sexe, des traitements d'irradiation, de l'emballage, du transport et de la libération, y compris les procédures de manipulation pour chaque étape, s'ajoutent au budget de stress global du mâle stérile après la libération. L'optimisation de l'étape d'irradiation pour atteindre une stérilité maximale tout en minimisant les dommages somatiques hors cible peut améliorer considérablement la compétitivité de l'accouplement des mâles et il est donc important d'examiner divers protocoles qui se sont révélés efficaces chez d'autres espèces d'insectes, comme le fractionnement de dose. Une dose entièrement stérilisante de 70 Gy a été administrée aux mâles Aedes aegypti en une dose unique ou fractionnée en deux doses égales de 35 Gy, ou une faible dose de 10 Gy suivie d'une seconde dose de 60 Gy. Les deux doses étaient séparées par des intervalles de 1 ou 2 jours. Des tests de longévité, d'aptitude au vol et de compétitivité à l'accouplement ont été réalisés pour identifier les effets bénéfiques des différents traitements. Des effets positifs de la dose de fractionnement ont été observés en termes de longévité des mâles et de compétitivité à l'accouplement. Bien que l'application de doses fractionnées améliore généralement les paramètres de qualité des mâles, les avantages peuvent ne pas compenser le travail supplémentaire dans les programmes TIS pour la gestion des moustiques vecteurs.

Impacts of ionization radiation on the cuticular hydrocarbon profile and mating success of male house crickets (Acheta domesticus).

PURPOSE: Ionizing radiation is well known to have drastic impacts on major life history features including survivorship, growth, fertility, and longevity. What is much less appreciated is how radiation stress can cause changes to more subtle traits, such as those associated with sexual signaling, an underappreciated but vital aspect of insect reproduction. In the House Cricket (Acheta domesticus) cuticular hydrocarbons are vital for sex and species recognition, as well as a possible indicator of stress, making them crucial for successful mating and reproduction. MATERIALS AND METHODS: Here, we analyze the impacts of ionizing radiation on the cuticular hydrocarbons of male crickets and its subsequent impacts on mating success. We exposed juvenile (14-day, 4th instar) male crickets to a broad range of radiation doses (2 Gy - 2 Gy). RESULTS: We detected significant changes in individual cuticular hydrocarbons across a broad range of doses in mature male crickets using gas-liquid chromatography. Specifically, dose was identified as a significant contributing factor to hydrocarbon increases p < .0001. Mating success was significantly reduced in 12 Gy (p < .0001), 10 Gy (0.0001), and 7 Gy (0.0060) groups compared to non-irradiated controls. CONCLUSION: Insect chemical communication can be species specific, and functionally specialized. Here, we show that radiation can alter the chemical signals used to attract mates in a large bodied insect and this may be a contributing factor to the described reduction in male mating success. Further research should be conducted to further analyze the various modes of communication employed by male crickets to attract mates i.e. acoustic signaling, and how this may also contribute to the reduction in mating success seen in irradiated males.

A rapid quality control test to foster the development of the sterile insect technique against Anopheles arabiensis.

BACKGROUND: With the fight against malaria reportedly stalling there is an urgent demand for alternative and sustainable control measures. As the sterile insect technique (SIT) edges closer to becoming a viable complementary tool in mosquito control, it will be necessary to find standardized techniques of assessing male quality throughout the production system and post-irradiation handling. Flight ability is known to be a direct marker of insect quality. A new version of the reference International Atomic Energy Agency/Food and Agricultural Organization (IAEA/FAO) flight test device (FTD), modified to measure the flight ability and in turn quality of male Anopheles arabiensis within a 2-h period via a series of verification experiments is presented. METHODS: Anopheles arabiensis juveniles were mass reared in a rack and tray system. 7500 male pupae were sexed under a stereomicroscope (2500 per treatment). Stress treatments included irradiation (with 50, 90, 120 or 160 Gy, using a Gammacell 220), chilling (at 0, 4, 8 and 10 °C) and compaction weight (5, 15, 25, and 50 g). Controls did not undergo any stress treatment. Three days post-emergence, adult males were subjected to either chilling or compaction (or were previously irradiated at pupal stage), after which two repeats (100 males) from each treatment and control group were placed in a FTD to measure flight ability. Additionally, one male was caged with 10 virgin females for 4 days to assess mating capacity (five repeats). Survival was monitored daily for a period of 15 days on remaining adults (two repeats). RESULTS: Flight ability results accurately predicted male quality following irradiation, with the first significant difference occurring at an irradiation dose of 90 Gy, a result which was reflected in both survival and insemination rates. A weight of 5 g or more significantly reduced flight ability and insemination rate, with survival appearing less sensitive and not significantly impacted until a weight of 15 g was imposed. Flight ability was significantly reduced after treatments at 4 °C with the insemination rate more sensitive to chilling with survival again less sensitive (8 and 0 °C, respectively). CONCLUSIONS: The reported results conclude that the output of a short flight ability test, adapted from the previously tested Aedes FTD, is an accurate indicator of male mosquito quality and could be a useful tool for the development of the SIT against An. arabiensis.

Optimization of irradiation dose to Aedes aegypti and Ae. albopictus in a sterile insect technique program.

The sterile insect technique (SIT) may offer a means to control the transmission of mosquito borne diseases. SIT involves the release of male insects that have been sterilized by exposure to ionizing radiation. We determined the effects of different doses of radiation on the survival and reproductive capacity of local strains of Aedes aegypti and Ae. albopictus in southern Mexico. The survival of irradiated pupae was invariably greater than 90% and did not differ significantly in either sex for either species. Irradiation had no significant adverse effects on the flight ability (capacity to fly out of a test device) of male mosquitoes, which consistently exceeded 91% in Ae. aegypti and 96% in Ae. albopictus. The average number of eggs laid per female was significantly reduced in Ae. aegypti at doses of 15 and 30 Gy and no eggs were laid by females that had been exposed to 50 Gy. Similarly, in Ae. albopictus, egg production was reduced at doses of 15 and 25 Gy and was eliminated at 35 Gy. In Ae. aegypti, fertility in males was eliminated at 70 Gy and was eliminated at 30 Gy in females, whereas in Ae. albopictus, the fertility of males that mated with untreated females was almost zero (0.1%) in the 50 Gy treatment and female fertility was eliminated at 35 Gy. Irradiation treatments resulted in reduced ovary length and fewer follicles in both species. The adult median survival time of both species was reduced by irradiation in a dose-dependent manner. However, sterilizing doses of 35 Gy and 50 Gy resulted in little reduction in survival times of males of Ae. albopictus and Ae. aegypti, respectively, indicating that these doses should be suitable for future evaluations of SIT-based control of these species. The results of the present study will be applied to studies of male sexual competitiveness and to stepwise evaluations of the sterile insect technique for population suppression of these vectors in Mexico.

The reproductive response to the male effect of 7- or 10-month-old female goats is improved when photostimulated males are used.

The exposure of adult, female, Mediterranean goats during anoestrus to males with induced sexual activity via photostimulation, induces a very high percentage of ovulations. The present work examines the ability of photostimulated bucks to improve the male effect-induced reproductive response of young does over that induced by non-stimulated bucks. A 2×2 factorial experiment was designed, consisting of doe age and buck photoperiod treatments. During seasonal anoestrus, 41 does aged 7 (n=19) or 10 (n=22) months were subjected to the male effect on 10 April; half of each group was exposed to males rendered sexually active by prior exposure to 3 months of long days (16 h of light/day) from 31 October (PHOTO bucks), and half to males maintained under the natural photoperiod (CONTROL bucks). Oestrous activity was recorded daily by direct visual observation of the marks left by male-worn marking harnesses over the 32 days following the bringing of the sexes together (introduction). Doe body weight and body condition were determined weekly. Ovulation was detected by measuring plasma progesterone concentrations twice per week over the 3 weeks after introduction. The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. The interaction doe age × buck photoperiod treatment had no effect on any outcome. The percentage of females showing ovulation or oestrus was higher in the does exposed to PHOTO bucks (85% v. 43% for those exposed to CONTROL bucks) they also showed higher fertility (75% v. 43%) and productivity (1.05±0.17 v. 0.57±0.16 kids born per doe serviced) (all P values at least P<0.05). The 10-month-old group showed higher percentage of females showing ovulation, oestrus, fertility and productivity than the 7-month-old does after the male effect (females showing ovulation: 82% v. 42%; showing oestrus: 73% v. 42%; fertility: 73% v. 42% and productivity: 1.09±0.17 v. 0.47±0.14 goat kids born per doe serviced; respectively, all P values at least P<0.05). The present results show that the use of photostimulated males improves the reproductive performance of 7- and 10-month-old does, and may contribute towards increasing their productivity and lifetime reproductive performance.

Effects of radiofrequency electromagnetic radiation (RF-EMF) on honey bee queen development and mating success.

Mobile phones can be found almost everywhere across the globe, upholding a direct point-to-point connection between the device and the broadcast tower. The emission of radiofrequency electromagnetic fields (RF-EMF) puts the surrounding environment inevitably into contact with this radiation. We have therefore exposed honey bee queen larvae to the radiation of a common mobile phone device (GSM band at 900 MHz) during all stages of their pre-adult development including pupation. After 14 days of exposure, hatching of adult queens was assessed and mating success after further 11 days, respectively. Moreover, full colonies were established of five of the untreated and four of the treated queens to contrast population dynamics. We found that mobile phone radiation had significantly reduced the hatching ratio but not the mating success. If treated queens had successfully mated, colony development was not adversely affected. We provide evidence that mobile phone radiation may alter pupal development, once succeeded this point, no further impairment has manifested in adulthood. Our results are discussed against the background of long-lasting consequences for colony performance and the possible implication on periodic colony losses.

Feasibility of using the radiation-based sterile insect technique (SIT) to control the olive fruit fly, Bactrocera oleae Gmelin (Diptera: Tephritidae) in Iran.

Bactrocera oleae is one of the most hazardous pests threatening olive orchards in Iran. SIT is an environment-friendly system of pest control based on releasing sterile males able to compete with wild males to mate with wild females. To determine sterile doses of radiation, pupae were irradiated to the doses of 0-160 Gy. Doses of 90-100 Gy were found optimal providing the necessary sterilization without severely impairing the competitiveness of the irradiated males in mating.

Male mice ultrasonic vocalizations enhance female sexual approach and hypothalamic kisspeptin neuron activity.

Vocal communication in animals is important for ensuring reproductive success. Male mice emit song-like "ultrasonic vocalizations (USVs)" when they encounter female mice, and females show approach to the USVs. However, it is unclear whether USVs of male mice trigger female behavioral and endocrine responses in reproduction. In this study, we first investigated the relationship between the number of deliveries in breeding pairs for 4months and USVs syllables emitted from those paired males during 3min of sexual encounter with unfamiliar female mice. There was a positive correlation between these two indices, which suggests that breeding pairs in which males could emit USVs more frequently had more offspring. Further, we examined the effect of USVs of male mice on female sexual behavior. Female mice showed more approach behavior towards vocalizing males than devocalized males. Finally, to determine whether USVs of male mice could activate the neural system governing reproductive function in female mice, the activation of kisspeptin neurons, key neurons to drive gonadotropin-releasing hormone neurons in the hypothalamus, was examined using dual-label immunocytochemistry with cAMP response element-binding protein phosphorylation (pCREB). In the arcuate nucleus (Arc), the number of kisspeptin neurons expressing pCREB significantly increased after exposure to USVs of male as compared with noise exposure group. In conclusion, our results suggest that USVs of male mice promote fertility in female mice by activating both their approaching behavior and central kisspeptin neurons.

Effect of ionising (gamma) radiation on female Anopheles arabiensis.

Background: In a mosquito sterile insect technique programme the ideal scenario is to release male mosquitoes only. However, because there are currently no sex separation strategies which guarantee total female elimination, this study investigated the effect of irradiation on physiological and reproductive fitness of females of an Anopheles arabiensis genetic sexing strain. Methods: Female pupae were irradiated at 70 Gy and the effects of irradiation on adult emergence, longevity, blood-feeding capability, mating ability, fecundity and fertility were assessed. Results and conclusion: Irradiation reduced adult emergence and fecundity but did not affect adult survivorship, mating and blood feeding ability, which suggests that irradiated female mosquitoes can transmit disease pathogens.

Effects of radiation on inherited sterility in the European grapevine moth (Lobesia botrana).

BACKGROUND: The sterile insect technique (SIT) is an alternative, environmentally friendly method for controlling insect pests. In the Lepidoptera, a low dose of gamma irradiation causes inherited sterility (SIT-IS), leading to full sterility in females but only partial sterility in males, which successfully compete with wild males for mates. This study examined the effect of a low radiation dose (150 Gy) on the fitness parameters of male and female Lobesia botrana, a polyphagous and major pest of vineyards found in the Middle East, Europe and the Americas. RESULTS: Irradiation of the pupae did not affect their emergence rate, flight ability out of a cylinder, male response to sex pheromone in a field cage or male or female mating success. A major effect of irradiation was observed in the significantly reduced number of irradiated females' offspring reaching pupation, and as a consequence a limited number of F2 offspring. The effect of irradiation on male partial sterility (also called inherited sterility) was reflected in the male-biased sex ratio of F1 offspring of irradiated males, the reduced number of F1 offspring and the very low number of F2 descendants. CONCLUSION: This study demonstrates the feasibility of controlling L. botrana using SIT-IS. Adding this method to the arsenal of environmentally friendly tools to control this pest may assist in further reducing the use of insecticides on edible crops.

Mating competitiveness of Aedes albopictus radio-sterilized males in large enclosures exposed to natural conditions.

Mating competitiveness trials have been conducted in large net-screened enclosures (8 by 5 by 2.8 m) built in a natural shaded environment, in the summers of 2006, 2007, 2008, and 2009 in northern Italy. Aedes albopictus (Skuse) males were radio-sterilized by applying gamma radiations at doses in the range 30-60 Gy. Gamma radiation was administered to aged pupae at the rate of 2.3 Gy/min. Reared radiated males (originally collected in Rimini, Forli, Bologna, Matera, Pinerolo) and hybrid radiated males were tested against wild fertile males (originated from eggs collected in Rimini and Cesena) and reared fertile males, in multiple comparisons for mating competitiveness with reared or wild females. The ratio was kept constant at 100-100_100 (fertile males-radiated males_virgin females). Mating competitiveness was estimated through the calculation of the hatching rate of the eggs laid in oviposition traps positioned inside enclosures. No clear effect of the strains tested (reared, wild, or hybrid) was found. Results demonstrated that reducing the radiation dose from 60 to 30 Gy increases males' competitiveness. Laboratory investigations conducted after controversial results in the 2006 preliminary trials, showed that radiation induces precociousness in adult male emergence.

The effect of Laminaria japonica polysaccharides on the recovery of the male rat reproductive system and mating function damaged by multiple mini-doses of ionizing radiations.

To evaluate the radiation-protect effects of Laminaria japonica polysaccharides (LJP) on male reproductive system damage and mating dysfunction induced by multiple mini-dose ionizing radiations, male rats were administrated with radiation and/or LJP. Results showed that mating function (such as erection, mount and ejaculation), sperm count and survival rate in LJP group were significantly better than the corresponding model group after the radiation. The testis organ coefficient, GSH (glutathione) content, serum sex hormones (luteinizing hormone, follicle-stimulating hormone, testosterone and estradiol) levels improved while MDA (malondialdehyde) content decreased. In addition, SOD (superoxide dismutase), GSH-PX (glutathione peroxidase), LDH (lactate dehydrogenase) activities were enhanced while testicular tissue damage was reduced, 14 days after the cessation of radiation; all indicators in the LJP group were similar to the control group. Our results suggest that, LJP has some promoting effects on the recovery of the reproductive system and mating dysfunction induced by radiation.

Radiation biology of mosquitoes.

There is currently renewed interest in assessing the feasibility of the sterile insect technique (SIT) to control African malaria vectors in designated areas. The SIT relies on the sterilization of males before mass release, with sterilization currently being achieved through the use of ionizing radiation. This paper reviews previous work on radiation sterilization of Anopheles mosquitoes. In general, the pupal stage was irradiated due to ease of handling compared to the adult stage. The dose-response curve between the induced sterility and log (dose) was shown to be sigmoid, and there was a marked species difference in radiation sensitivity. Mating competitiveness studies have generally been performed under laboratory conditions. The competitiveness of males irradiated at high doses was relatively poor, but with increasing ratios of sterile males, egg hatch could be lowered effectively. Males irradiated as pupae had a lower competitiveness compared to males irradiated as adults, but the use of partially-sterilizing doses has not been studied extensively. Methods to reduce somatic damage during the irradiation process as well as the use of other agents or techniques to induce sterility are discussed. It is concluded that the optimal radiation dose chosen for insects that are to be released during an SIT programme should ensure a balance between induced sterility of males and their field competitiveness, with competitiveness being determined under (semi-) field conditions. Self-contained 60Co research irradiators remain the most practical irradiators but these are likely to be replaced in the future by a new generation of high output X ray irradiators.

Influence of radar radiation on breeding biology of tits (Parus sp.).

The aim of the present study is to observe the influence of long-term exposure to radar radiation on breeding biology of tits (Parus sp.), living and building nests around a military radar station, emitting pulse-modulated microwave radiation of 1,200-3,000 MHz. Two series of 36 nest-boxes each were located on the radar station area. Measurements of exposure were performed separately for each nest-box. Average power density (P(av), W/m(2)) and dose of exposure (W/m(2) x h) were recorded for each nest-box during 45 days. Control nest-boxes (N = 42) were located in other part of the same forests, free from radar radiation. The assessment of effects of radar exposure on breeding biology of tits included number of inhabited nest-boxes, number of eggs, and nestlings in the nest (Why not chick mortality?). Experimental nest-boxes were either exposed to relatively high levels of radiation (2.0-5.0 W/m(2), mean 3.41 +/- 1.38 W/m(2)) or an intermediate level of radiation that ranged from 0.1-2.0 W/m(2) (mean 1.12 +/- 0.84 W/m(2)). For control nest-boxes the exposure ranged from 0.001-0.01 W/m(2) (mean 0.0062 +/- 0.0007 W/m(2)). Only blue or great tits occupied all nest-boxes, used in the experiment. The number of nesting blue tits was higher in nest-boxes located on the radar station area than in the control boxes. In contrast, control nest-boxes were inhabited mainly by great tits. On the radar station area, blue tits nested in high exposed nest-boxes (67,0%) and great tit occupied mainly these boxes, which were exposed to low-level radiation (62,5%), the difference being statistically significant (p < 0.01). No statistically significant differences in other parameters of breeding biology (number of eggs per box, number of nestling per box) were observed between tits occupying exposed and control nest boxes. Results of the present study show that radar radiation generally does not lead to decrease of number of nesting tits, but may cause shifts in tits species living around the radar station. (But is the microhabitat, apart from the radiation level, around each nest box more likely to attract one species of tit or another?).

[Influence of ionizing radiation on the attractiveness of male mice to chemosignals of intact individuals].

Within short-terms after exposure to ionizing radiation, CBA and C57Bl/6 male mice were found not only to retain but also to enhance their attractiveness to chemosignals of intact males of the same genotype (syngenic). It was shown that the time period of higher attractiveness increased with the absorbed dose (from 1 to 6 Gy). Within several days after exposure to 6-Gy irradiation, male mice were temporarily unable to discriminate between chemosignals of syngenic and allogenic (alien genotype) individuals. Unlike male mice of the CBA strain, male mice of the C57Bl/6 strain displayed no changes after exposure to 1-Gy irradiation, but the effect of 2-6 Gy was more persistent. These phenomena can be explained by the lower olfactory reactivity combined with higher radiosensitivity of C57Bl/6 mice. Irradiated male mice temporarily lost their olfactory ability to discriminate the genotype of females' volatile secretions and to distinguish between females' and males' volatile secretions.

"Some guys have all the luck": mate preference influences paced-mating behavior in female rats.

In the present study, mating behavior was observed in female rats that were given the opportunity to mate with two males simultaneously. Three groups of females were tested: 1) sexually naïve, naturally cycling rats in proestrous; 2) sexually naïve, hormone-primed, ovariectomized (OVX) rats; and 3) hormone-primed, OVX rats tested 1 week after sexual receptivity testing. One male rat was determined to be the preferred male for each female, if she spent more time with him during a mating test. Independent of sexual experience, female rats were less likely to leave their preferred male than their non-preferred male following intromissions. However, when they left their preferred male, they returned to him faster than to their non-preferred male. This effect of preference was slightly more robust in the OVX rats. When female rats from Group 2 were tested with the same pair of males for 3 additional tests, each female's preference for a particular male was stable. That is, a female rat preferred the same male in approximately 3 out of the 4 tests, which is more likely than would be expected by chance. In a final experiment, pairs of male rats were tested with different females once weekly to determine if different females would prefer particular males consistently. Although no male rat was preferred by all females, females consistently preferred the same male from each pair during approximately 70% of the tests. In conclusion, female mate preference may have adaptive significance for the reproductive success of rats.

CaM kinase II and visual input modulate memory formation in the neuronal circuit controlling courtship conditioning.

In Drosophila, calcium/calmodulin-dependent protein kinase II (CaM kinase) has been shown to be important in the expression of both learning and memory for the associative behavior courtship conditioning. In this study we examine the role of visual input in producing this behavior and the effects of modifying visual input on CaM kinase-dependent memory formation. Inhibition of CaM kinase blocked apparent learning regardless of visual input. Visual input selectively affected the memory phase of courtship conditioning: normal visual input masked the memory effects of inhibition of CaM kinase resulting in generation of memory without apparent learning, whereas disruption of visual input revealed the CaM kinase-dependence of memory. Visual input was found to be important only during the training period, which implies that vision and CaM kinase are interacting in the formation rather than the retrieval of memory. Our results suggest a model for courtship conditioning in which multiple sensory inputs are integrated at a CaM-kinase-dependent neuronal switch to modulate courtship behavior.

Photoperiodic regulation of substance P immunoreactivity in the mating behavior pathway of the male golden hamster.

Mating behavior in the male golden hamster is regulated by both gonadal steroids and photoperiod. Gonadal steroids may regulate mating behavior by actions on the medial nucleus of the amygdala, bed nucleus of the stria terminalis, and medial preoptic area. Neurons in these areas actively accumulate gonadal steroids and lesions of these nuclei disrupt mating behavior in male hamsters. Photoperiodic regulation of mating behavior is regulated, at least in part, by decreased responsiveness to gonadal steroids. Therefore, we sought to determine if the changes induced by changes in gonadal steroids would mimic those induced by changes in photoperiod. The number of substance P-containing neurons in these areas decrease following castration and are restored with testosterone treatment suggesting that this peptide may mediate steroidal regulation of male mating behavior. To determine the effect of photoperiod on substance P, peptide containing neurons were counted in (1) enucleates (n = 6), (2) enucleated castrates treated with testosterone (n = 6), (3) castrates treated with testosterone (n = 4), and (4) intact controls (n = 6). Bilateral enucleation caused a decrease in the number of substance P neurons in the medial nucleus, bed nucleus of the stria terminalis, and medial preoptic area (P less than 0.05). Testosterone treatment prevented this decrease (P less than 0.05). Thus, a decrease in daylength causes a decrease in substance P in the medial nucleus of the amygdala, the medial bed nucleus of the stria terminalis and the medial preoptic area that is mediated by changes in testosterone levels.

Effects of gamma radiation on development, sterility, fecundity, and sex ratio of Dermanyssus gallinae (DeGeer) (Acari: Dermanyssidae).

Protonymphal Dermanyssus gallinae were irradiated with 0.50, 0.75, 1.0, 3.0, and 6.0 krad of gamma radiation and subsequently monitored regarding their developmental, feeding, and mating success. Also, sex ratios of adults treated as protonymphs were recorded as were sex ratios of embryos and F1 adults produced by these adults. Doses up to 1.0 krad did not prevent development of treated protonymphs to the adult stage or stop mating. Three krad reduced the number of treated protonymphs attaining adulthood and 6.0-krad treatment prevented all mites from developing to the adult stage. Egg (embryo) production was normal for mites treated with 0.50 krad, but significantly curtailed by doses of 0.75 krad and greater. Radiation doses used in this study did not appear to affect the normal variable sex ratios observed in untreated mites.