Influence of previous mating experience on future mating success in maleLucilia cuprina (Diptera: Calliphoridae)

Receptive and virginL. cuprina females were placed with a virgin male and an experienced male that had mated between one and five times previously. The experienced males secured significantly more matings than virgin males. Males with previous matings also gained experience in competing with males. Males directed mating attempts at each other, seemingly in the context of intrasexual competition. Experienced males directed more mating attempts at virgin males than vice versa. As their number of previous matings increased, experienced males made the first mating attempt at females more often and directed more mating attempts at females compared with virgin males. Females did not actively discriminate against experienced males, even though the proportion of matings secured on the first attempt by experienced males declined with increasing mating experience. Alternative behavioral explanations are discussed.     

The effect of prior housing conditions on the sexual receptivity of females of the blowfly,Lucilia cuprina

Sexual receptivity in sugar-and-water-fed females of the anautogenous blowfly Lucilia cuprinawas low when they had been housed in groups but high when they had been housed singly. Females were completely unreceptive on the second and third days after emergence, irrespective of housing conditions. There after receptivity increased but more rapidly in the singly housed females. Experiments in which females were housed singly for some days and then in groups, or vice versa, showed that receptivity could be influenced by housing conditions experienced both over the first 5 days after emergence and later in life.     

Suppression of populations of Australian sheep blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae), with a novel blowfly trap

The Australian sheep blowfly, Lucilia cuprina , initiates more than 85% of fly strikes on sheep in Australia with an estimated average annual cost of A$280 million to the Australian sheep industry. LuciTrap^® is a commercially available, selective trap for L. cuprina consisting of a plastic bucket with multiple fly entry cones and a synthetic attractant. The impact of LuciTrap on populations of L. cuprina on sheep properties in five Australian states was evaluated by comparing L. cuprina populations on paired properties with and without LuciTraps over seasons when significant fly populations could be expected. Twenty-four comparisons (trials) were conducted over 4 years. During times of 'higher fly density' (when the 48 h geometric mean of trap catches on the control property was greater than five L. cuprina ), the overall geometric mean trap catches for control and trapped properties differed significantly ( P  < 0.001) with mean trap catches of 19.4 and 7.74 L. cuprina , respectively. The selectivity of the LuciTrap was confirmed with 59% of all trapped flies being L. cuprina . Chrysomya spp. and Calliphora spp. constituted 9.3% and 1.1% of the catches with a variety of other flies (mainly Sarcophagidae and Muscidae ) providing the remainder (31%). Lucilia sericata was only trapped in Tasmania and made up 7.7% of the Lucilia spp. catch in that state. Seventy-two per cent of the trapped L. cuprina were female. The deployment of LuciTrap on sheep properties at one trap per 100 sheep from the beginning of the anticipated fly season suppressed the populations of L. cuprina by 60% compared with matched control properties. The LuciTrap is a selective and easy to use fly trap and constitutes an effective, non-insecticidal tool for use in integrated management programs for L. cuprina .     

Sexual receptivity and post-emergence ovarian development in females of Coproica vagans (Diptera: Sphaeroceridae)

Abstract .Males and females of the dung fly species Coproica vagans Haliday 1833 (Diptera: Sphaeroceridae) mate soon after emergence from the puparium. At this time females still have immature ovaries. Therefore, mating precedes vitellogenesis in this species. Data presented here show that mating enhances oogenesis in C. vagans females. Mated females mature their first egg batch sooner and oviposit four days earlier than virgin conspecifics. Mating-related enhancement of oogenesis could be explained either through nutritional benefits to females or male chemical or stimulatory manipulation of the females. Oogenesis was divided into six arbitrary stages, with vitellogenesis beginning in stage 4. Ovarian development beyond stage 4 is rapid compared with pre-vitellogenetic development. Virgin females pause oogenesis in stage 4. The genital opening of mated females is blocked by a mating plug that persists until oviposition begins. The plug seems to ensure the paternity of the last male to mate by preventing females from remating. The operational sex ratio in C. vagans populations is presumed to be strongly male-biased.     

Mutual mate choice in crayfish: large body size is selected by both sexes, virginity by males only

Mate choice is often assumed to be a prerogative of females because of their putatively larger reproductive investment than males. However, recent evidence suggests that spermatogenesis is far from being limitless and that males show a high selectivity towards their mates, thus maximizing their reproductive success. We investigated mutual mate choice in the crayfish Procambarus clarkii through two experiments. The first experiment explored the effects of body size, chelar size and chelar symmetry and social status of a potential partner. In the second experiment, we asked whether this species can discriminate between partners of the same body size but with different mating status. We used a binary choice test paradigm, in which two 'targets' with opposing characteristics were simultaneously presented to a test animal, the 'chooser'. The results showed that P. clarkii males are more selective than expected. Similar to the other sex, they were significantly attracted by targets with large body sizes, but not by individuals with larger and symmetric chelae or with a dominant status. An inter-sexual difference was found in the second experiment, in which only males seemed to select virgin potential mates. The several adaptive explanations for these preferences, still under debate, are finally discussed.     

Sequential mate encounters: female but not male body size influences female remating behavior

Whether and how individuals choose sequentially among matesis an important but largely neglected aspect in sexual selectionstudies. Here, we explore female remating behavior in the cellarspider Pholcus phalangioides. We focus on body size as one ofthe most important traits involved in mate choice. Large andsmall females (n = 216) were double mated with large or smallmales in all eight possible combinations. All females copulatedwhen virgin, but only 82% accepted a second male. The chanceof a female remating was not significantly predicted by thebody size of the second or first male or by the size differencebetween the two. In contrast, a previous study demonstrateda male size effect in that larger males monopolized femalesuntil egg laying when two males of different sizes were present.We suggest that sequential encounters are more common undernatural conditions than male monopolization of females becauseestimates of concurrent multiple paternity together with observationsin a natural population do not favor mate guarding as the predominantmating strategy in this species. It follows from our study thatthe intensity of sexual selection on male size may be greatlyoverestimated when using a competitive laboratory setting fora species in which females generally encounter mates in a sequentialfashion. Female remating probability was significantly predictedby female size, with large females remating with higher probabilitythan small females. Thus, when mating with large females, malesmay gain higher fertilization success through increased femalefecundity but also face a higher sperm competition risk.     

Effect of body size and larval experience on mate preference in Helicoverpa armigera (Hübner) (Lep., Noctuidae)

Abstract:  We studied the mating selection in the cotton bollworm, Helicoverpa armigera (Hübner), in relation to body size and larval diet in the laboratory. When provided with an artificial diet at larval stage, weight, body and forewing length did not affect the probability of a male/female moth being selected for mating, but the abdominal width of selected female moths was significantly wider than that of non-selected female moths. 30 female moths were dissected and number of eggs was counted after mating, and there was a correlation between the abdominal width and egg number. There was also significant difference of weight loss between selected and non-selected male/female moths after the mating. The effect of operational sex ratio on mating latency and copulation duration were tested, and the result indicated that mating latency of male selection was significantly longer than that of female selection, but the difference of copulation duration was not significant. Cotton, corn and peanut plants were provided to larvae to test the effect of larval host plant experience on mate choice. When cotton- and peanut-fed moth severed as potential partners, both female and male of cotton-fed moths significantly preferred cotton- to peanut-fed moths for mating. The possible reasons for mate preference based on larval host plant experience may account for host plants attributes on sex pheromone variation and sexual maturity. These findings may impact Bacillus thuringiensis resistance management.     

Modification of female onion fly,Delia antiqua (Meigen), reproductive behavior by male paragonial gland extracts (Diptera: Anthomyiidae)

Egg depositional rates of onion flies, Delia antiqua(Meigen), injected thoracically with extracts of male paragonial glands were identical (14.5 eggs/female/ day) to those of normally mated females. Moreover, when continuously exposed to males, extract-injected females refused to mate and produced unfertilized eggs for the duration of the > 15- day experiment. For this normally monocoitic dipteran, <1 male equiv of paragonial secretion completely reproduced the ovipositional responses characteristic of normal mating, and this effect required no involvement of the genitalia or genital chamber. We suggest that the receptor for the active chemical (s) (sex peptide?) would be an excellent target for biorational insect control by sterilization. Moreover, these primer sex pheromones might play an important role in insect reproductive isolation and evolution.     

Genetics of the hemolymph esterases ofLucilia cuprina (Diptera: Calliphoridae)

When hemolymph from adults ofLucilia cuprina was partitioned on native polyacrylamide gels, nonspecific esterase staining demonstrated 10 bands with up to six bands in an individual. The bands derive from alleles at two loci,E _HA (five alleles) andE _HB (four alleles).E _HA is located on chromosome 4, 16.3 map units fromsv (singed vibrissae) and 22.1 map units fromra (radial vein gaps).E _HB is located on chromosome 5, 34.0 map units fromto ² (topaz² eyes) and 7.2 map units frommv (M1-veinless).     

No reduction of female sexual receptivity following mating in a stalk‐eyed fly,Cyrtodiopsis dalmanni (Diptera: Diopsidae)

The level of female sexual receptivity is an important component of male and female reproductive success. In many insects, mating itself causes a sharp decline in female receptivity. This can be a direct result of the physical act of mating, or because of actions of sperm or seminal fluid proteins. The degree to which males can decrease female receptivity will directly affect their reproductive success, by altering the chance that their sperm will be used in fertilizations in the interval before the female mates again. In this study, we investigated the effect of mating on female receptivity in the sexually dimorphic stalk‐eyed fly, Cyrtodiopsis dalmanni. Our results showed no evidence for mating‐induced reductions in female receptivity. In addition, we found that matings with males that differed in eyespan did not cause differences in the level of female receptivity. There was also no evidence that females remated sooner when presented with large eyespan males. These results are surprising, given the indirect benefits that females gain from matings with large eyespan males. Finally we demonstrate that males do not appear to discriminate between females on the basis of female mating status.     

Effect of male body size on sperm precedence in the polyandrous butterfly Pieris napi L. (Lepidoptera: Pieridae)

Male Lepidoptera produce an ejaculate during copulation thatcontains both sperm and accessory gland nutrients and may functionas paternal investment and/or male mating effort Several studieshave examined how ejaculates function as paternal investment,but few have determined the influence of sperm competition onmale investment This study examines the effect of male bodysize on sperm precedence in the polyandrous butterfly Pierisnapi L. We used male body mass as an indicator of the size ofejaculate transferred and found that relative male size hada significant effect on paternity. The offspring of twice-matedfemales showed a low incidence of mixed paternity. Larger malesobtained the majority of fertilizations, and the degree of second-malesperm precedence was influenced by relative body size of matingmales. In general, second mates obtained fewer fertilizationsthe larger the size of the first mate. The interval betweenthe first and second mating was influenced by the size of thefirst male mate Females first mated to small males remated soonerthan females first mated to larger males Our results suggestthat large males may have a selective advantage over small maleswhen both a male's fertilization success and a female's refractoryperiod are influenced by the size of ejaculate transferred.Furthermore, the effect of male body size on the proportionof offspring sired lends support to the hypothesis that spermcompetition has played a major role in the evolution of ejaculatesize.     

The effects of body size on mating and reproduction in Brachinus lateralis (Coleoptera: Carabidae)

Abstract. 1. The causes and reproductive consequences of body size variation of Brachinus lateralis Dejean, a parasitic carabid beetle, were investigated.
2. Body size variation occurs within and between sites. Host size has a major influence on body size of the adult.
3. Fecundity is positively correlated with body size. Egg size is not correlated with body size.
4. Mating males tend to be larger than non-mating males. There is a positive correlation of body sizes in mating pairs.
5. Limited opportunity for host choice may maintain size variation despite the advantages of large size.
6. The non-random patterns of mating for a species without obvious intrasexual aggression suggest that subtle means of male-male competition or female choice may be important.     

Influence of male aggregation size on female visitation in Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

Abstract  The importance of male aggregation size for female visitation and initiation of male pheromone-calling was investigated in Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) using artificial male aggregations in large laboratory cages. Female B. tryoni visited the largest aggregation more frequently than single males in association with a higher proportion of calling males, but there was no correlation between aggregation size and female visitation. Female B. tryoni had a limited capacity to perceive a difference between the number of calling males. Calling propensity of male B. tryoni was increased by the presence of conspecific males. Increased calling propensity in larger groups of male B. tryoni may be due to social facilitation of male calling behaviour. Female visitation at aggregations was only weakly associated with male calling, suggesting that aggregation size and the number of pheromone-calling males are not the only factors important in locating mates in B. tryoni , and it is possible that low-density populations could persist so long as females can encounter single males.     

Cytogenetic mapping of the male-determining region of Lucilia cuprina (Diptera: Calliphoridae)

The Y chromosome of Lucilia cuprina was cytogenetically dissected by recovering adjacent segregation products from crosses with appropriate autosomal and Y-autosome translocations. By these means Y chromosomes lacking most of the short, long, or both arms were isolated. Only the centromeric portion of the Y chromosome was necessary for male determination and fertility, the bulk of the short and long arms having no role in sex determination. Additionally, it was shown that most of the short arm can be passed into the female line with no marked effect. These results, together with evidence from other studies, indicate that male determination in L. cuprina is centred in a discrete region near the Y chromosome centromere.     

What is driving male mate preference evolution in Jamaican field crickets?

Male mating preferences are often a neglected aspect of studies on sexual selection. Male mating preferences may evolve if they provide males with direct‐fitness benefits such as increased opportunity to fertilize more eggs or indirect‐fitness benefits such as enhanced offspring survival. We tested these ideas using Jamaican field crickets, Gryllus assimilis, previously shown to exhibit male mating preferences. We randomly mated males to either their preferred or non‐preferred potential mates and then asked whether mating treatment influenced egg oviposition or offspring viability. Preferred females were not significantly more fecund and did not produce more viable eggs or offspring than non‐preferred females. Male mate preferences were therefore inconsistent with both the direct‐ and indirect‐fitness benefits hypotheses under the conditions of our experiment. Our null results leave us with an open question about what is driving the evolution of mating preferences in male crickets. Future research should explore the whether the offspring of preferred females are more attractive, have stronger immune systems, and/or experience higher adult longevity.     

Waning of repetitive hopping in the blowfly Phormia regina Meigen (Diptera: Calliphoridae)

Wingless blowflies (Phormia reginaMeigen)released on a flat uniform substrate hop repeatedly. The rate of hopping decreases with time. Decremental responsiveness resembles behavioral habituation. It can be reestablished by tactile stimulation and is due neither to muscle fatigue nor to sensory receptor adaptation. No effects of age or circadian rhythms were observed. The initial rate of hopping increases with increasing food deprivation, as does the time for waning to be completed. Decapitated flies and isolated wingless thoraxes hop almost as well as control flies and wane at the same rates.     

Factors Influencing the Choice of Female Mate Rejection Strategies in the Seaweed Fly Coelopa nebularum (Diptera: Coelopidae)

Female Coelopa nebularum attempt to avoid mating with males by adopting up to three behavioral responses. Kicking and shaking are designed to dislodge mounted males, whereas downward abdominal curling prevents engagement of genitalia. We find that some females are more willing to mate than others, but their choice of rejection strategy is inconsistent. Mating does not affect behavior in immediately subsequent encounters. Male size influences the choice of rejection strategy and is positively associated with mating success. Different strategies have similar success rates. The response to a mount is not influenced by the size of a male encountered immediately beforehand. We propose that these results are inconsistent with adaptive mate choice or mate assessment and suggest that females are simply attempting to avoid the costs of mating with all males.