The lethal and sublethal effects of three pesticides on the striped lynx spider (Oxyopes salticus Hentz)

The striped lynx spider, Oxyopes salticus Hentz, is found in high abundances in agricultural fields where it forages on many agricultural pests. Pesticides are applied to these fields and can therefore impact these natural pest predators. Researchers have examined the effects of a number of pesticides on this spider and other pest predators, but many of these studies only examine how these pesticides affect mortality. More recently, researchers have begun to examine the sublethal effects of these chemicals. We examined both the lethal and sublethal effects of three common pesticides with the active ingredients bifenthrin, carbaryl and malathion. We found that only malathion significantly reduced the post‐exposure lifespan of these spiders; however, each pesticide had sublethal effects on behaviour. Exposure to malathion reduced jumping, likely an important foraging and escape behaviour. Spiders exposed to bifenthrin spent increased time grooming, which can reduce the time spent performing other important behaviours. Finally, spiders that were exposed to carbaryl surprisingly increased their prey capture rate. We show here that pesticides can not only directly affect the lifespan of the striped lynx spider but that each pesticide can cause different sublethal effects that likely impact the survival and ecology of these important pest predators.     

Absence of social facilitation of courtship in the wolf spider, Schizocosa ocreata (Hentz) (Araneae: Lycosidae)

Males of many animal species are reproductively limited by the difficulty and time costs of finding mates. Males of such species should be selected to take advantage of any cues that might reveal the location of prospective mates. Cues to female location are not restricted to those produced by females, but might also include the highly apparent courtship displays of males that have already found a female. By “eavesdropping” on these courting rivals, initiating sexual displays when courting rivals are detected (i.e., social facilitation of displays); males might effectively exploit the mate-searching efforts of their rivals. We tested the possibility that male Schizocosa ocreata wolf spiders exhibit social facilitation of courtship behaviors using a combination of live behavioral trials and video playback with single stimulus presentations. When exposed to visual cues from another male, male S. ocreata can discern the presence of another individual whether that individual is courting or not. However, we found no evidence of social facilitation of courtship or chemoexploratory behaviors in response to seismic or visual cues presented in isolation or combined. While complex, multimodal, male courtship signals are important in mate choice by female S. ocreata, males do not appear to use these cues to socially facilitate their own courtship.     

Male southern water skinks (Eulamprus heatwolei) use both visual and chemical cues to detect female sexual receptivity

A wide range of organisms use chemical and visual cues in mate attraction and courtship; however, chemical discrimination relevant to reproduction and the interplay between these two types of communication are poorly understood in reptiles. We experimentally tested the ability of male Eulamprus heatwolei, a scincoid lizard, to discriminate between sexually receptive and non-receptive females in two ways. First, we conducted 155 staged encounters between males and females over 29 days to determine the start and the duration of the female receptive period based on the date of copulations. These data suggest that the receptive period lasted for approximately 7 days in late October under controlled laboratory conditions. We also recorded 6,330 individual male and female behaviours during these trials to evaluate the frequency of female courtship and rejection behaviours and the intensity of male courtship behaviour. Female courtship increased sharply during the receptive period and then diminished. The disparity between female courtship behaviours and female rejection behaviours was greatest during the receptive period. Male courtship intensity increased sharply prior to the receptive period, peaked during the receptive period and thereafter declined rapidly. To determine if males were using visual cues, chemical cues or both from females, we conducted an experiment during and after the receptive period wherein male lizards were presented with a choice of two retreat sites treated either with the odour of large sexually receptive females, odour of small sexually non-receptive females or no odour (control). Males preferred the scent of females over the odourless control, and analysis using a special form of a generalized linear model, the Bradley–Terry model, showed a clear order of retreat site preferences, with large sexually receptive females favoured over small non-receptive females over the odourless control. We speculate that males use vision to find females and then use their chemosensory ability to chemically evaluate female sexual receptivity once the pair are in close proximity.     

Pheromonal inhibition of male courtship behaviour in the brown tree snake, Boiga irregularis: a mechanism for the rejection of potential mates

Pheromones play a central role in coordinating the events leading up to copulation in snakes. We report here a novel pheromone system in the brown tree snake in which females release a pheromone that inhibits male courtship behaviour. In a previous study, we made observations of female brown tree snakes releasing cloacal secretions (CS) during courtship that appeared to cause courting males to cease courtship. All snakes have glands that release CS through ducts located along the cloacal orifice. Although CS have been studied for many years, their function in the mediation of snake behaviour has not been experimentally well determined. We examined the role of CS in the reproductive behaviour of male and female brown tree snakes. We conducted four experiments to test the effect of both male and female CS on brown tree snake behaviour under two behavioural contexts, courtship and male-male ritualized combat. Within each experiment, we compared the effects of CS to a control. Female CS caused a decrease in the time that males spent courting females and a decrease in the intensity of courtship compared with the control treatment. Male CS did not, however, affect the time that males spent displaying courtship or the intensity of that courtship. Neither male nor female CS had significant effects on male ritualized combat behaviour, including time that males spent in combat or the intensity of combat behaviours displayed. Furthermore, neither female nor male CS had an effect on female courtship versus controls. The inhibition of brown tree snake reproductive behaviours is specific to female CS inhibiting male courtship behaviour. This pheromone acts in concert with the female sex pheromone to regulate the events leading to copulation.Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Alternative reproductive tactics and courtship in the common goby

In the marine common goby Pomatoschistus microps , males either build nests and attract females to spawn or act as sneakers, forcing themselves into other males' nests during mating, to fertilize some of the eggs in the clutch. The reproductive tactics of small males were studied in the presence of surplus nest material and an excess of gravid females, while a larger, nestholding male spawned with a female. Of 24 small males, 13 only attempted to sneak, seven only courted females and/or spawned in their own nest, and four performed both behaviours. The small males who attracted females successfully were significantly larger than the ones who failed to do so. Females had been courting the small male more often when he subsequently spawned in his own nest, than when he did not get a female. The small males did not court the females very frequently, and their courtship rate did not depend on whether or not they attracted females. Instead, female courtship behaviour may be a cue for a male either to spawn as a nest holder or become a sneaker. The study pointed out the importance of female behaviour for male reproductive tactics, which could be more important in fish than is known currently.     

Risky Courtship: Background Contrast,Ornamentation, and Display Behavior of Wolf Spiders Affect Visual Detection by Toad Predators

Males that search widely for females and perform conspicuous courtship displays run a high risk of being detected by their predators. Therefore, gains in reproductive success might be offset by increased mortality due to predation. Male brush‐legged wolf spiders (Schizocosa ocreata) with larger decorative traits (foreleg tufts) are preferred by females as mates, but are more readily detected by predators. However, predation risk may also be influenced by the interaction between components of signals and the environment in which signaling occurs. Courting male spiders were readily accepted as prey by a sympatric predator, the American toad (Anaxyrus americanus). We used video playback to tease apart the interactive effect between visual signals and the signaling environment on the ability of toads to detect courting spiders as a function of distance, background contrast, the presence or absence of male foreleg tufts, and behavioral activity. The response of toads to video sequences of male spiders was similar to their response to live male spiders. Toad response varied over distance toward spiders displayed against high contrast (sunny) vs. low contrast (shaded) backgrounds. Beyond 30 cm, more toads detected courting male spiders against light, ‘sunny’ backgrounds and detected them faster when compared to the same spider stimulus against darker, ‘shady’ backgrounds. In choice tests, toads oriented more often toward courting males with leg tufts than those without. Toad responses also varied with male spider behavior in that only videos of moving males were attacked. Latency to orient and detection by toads was significantly greater for walking males than courting males, and this effect was most evident at distances between 30 cm and 50 cm. Results supported that courting wolf spiders are at significant risk of predation by visually acute predators. Distance, background contrast, and the presence of foreleg decorations influence detection probability. Thus, the same complex visual signals that make males conspicuous and are preferred by females can make males more vulnerable as prey to toads.     

Spiders,microbes and sex: Bacterial exposure on copulatory organs alters mating behaviour in funnel‐web spiders

Environmental microbes have the potential to be involved in nearly all behavioural processes. For example, mating systems where males use intromittent organs to transfer sperm to females represent a means by which environmental microbes collected by males can breach entry into females' body cavities during mating. However, the degree to which the acquisition of environmental microbes onto important sex structures alters courtship behaviours remains unknown. Here, we collected bacteria from the copulatory organs of Agelenopsis pennsylvanica funnel‐weaving spiders in situ to test whether exposure to bacteria on copulatory organs can alter hosts' courtship behaviour, reproductive success and survival. We used a standardized assay to repeatedly measure each spider's aggressiveness, a behavioural component of both male courtship and female sexual receptivity. Then, we experimentally altered the bacteria present on male and female spiders' copulatory organs with an application of either (a) a mixture of bacteria collected from conspecifics to increase bacterial presence, (b) an antibiotic to reduce bacterial presence or (c) a procedural control. Each spider was paired with a size‐matched spider of the opposite sex whose copulatory organs were unaltered, and we measured the latency until the onset and the duration of courtship. Spiders were then isolated, and we measured each individual's time until death and female fecundity over the next 40 days. We found that female exposure to bacteria had multiple effects on mating dynamics. Males took over four times longer to begin courting females that had been exposed to bacteria compared to unexposed and antibiotic‐treated females. Only when courting these bacteria‐exposed females, males began courtship sooner when females were more aggressive. Lastly, females whose mate had been exposed to bacteria experienced reduced survival. These data suggest that bacteria present on animals' copulatory organs can alter courtship behaviours, female survivorship, and may potentially play a role in mating dynamics.     

Behaviour of Arctic charr Salvelinus alpinus during an induced mating season in captivity: how male relative size influences male behavioural investment and female preference over time

The behaviour of sexually mature Arctic charr Salvelinus alpinus specimens (fifth farm generation) was observed in captivity for four consecutive days. Only agonistic interactions between males of different size were facilitated on the first 2 days, while both agonistic and courtship interactions were possible from the third day up to the end of the experiment. The reliability of behavioural analysis was assessed in order to reduce the possibility of observer errors within the generated datasets. The behavioural investment of big males, small males and females was analysed using general linear models (two‐way repeated measures ANOVAs with time and male size as factors). A peak in the agonistic interactions between males occurred during the first day of interactions, where the agonistic investment of big males was significantly higher than that of small males. This resulted in an increased investment in submissive behaviour by the small males, who consistently performed submissive behaviours from the second day of interactions up to the end of the trial. Big males were found to invest significantly more than small males in courtship behaviours for the duration of the trial. Even though females performed inter‐sexual behaviours towards both big and small males for the entire observation period, female interaction rate towards big males was higher than towards small males. This study suggests that both male investment in mating behaviour and female preference might be related to male characteristics such as body length and that S. alpinus behavioural patterns and mate choice cues might be strongly context‐related and characterized by high levels of behavioural plasticity (i.e. presence–absence of certain behavioural units or potential reversal of a mate choice cue) within the same species. Finally, in light of this, some conservation measures are discussed. In particular, effective management plans should take into account the high level of behavioural plasticity likely to be occurring in this species.     

Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin (Corynopoma riisei)

Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C. riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone‐treated females showed lower stress levels compared to the control group. Furthermore, pheromone‐treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.     

Competition-induced switch in young of the year perch,Perca fluviatilis: an experimental test of resource limitation

Synopis Reproductively developed male fathead minnows, Pimephales promelas, exhibited courtship behaviour in the presence of female conspecifies under laboratory conditions. Male courtship consisted of several distinctive and visually conspicuous behaviours directed toward females, including approach, display, and two contact behaviours, as well as leading behaviour from the female to a suitable spawning site. An ovulated condition in females was not necessary to generate male courtship behaviour; in fact, the amount of courtship exhibited by males may depend inversely on the readiness of females to spawn.     

Male swordtails court with an audience in mind

Females are usually considered to be the target of male courtship behaviour. In nature, however, social interactions rarely occur without other observers; thus, it is conceivable that some male courtship behaviours are directed not towards females, but rather towards male rivals. The northern swordtail, Xiphophorus birchmanni, is a freshwater fish found in high densities in natural streams. Males court by swimming close to and in parallel with the female, raising their large sail-like dorsal fin, and quivering briefly. Here, we show that females prefer males that display small dorsal fins to those with large ones, and that males are less aggressive to other males with large dorsal fins. Male swordtails also raise their dorsal fins more frequently when courting in the presence of other males. These results suggest that, despite female avoidance of large dorsal fins, males that raise their fin during courtship benefit by intimidating potential competitors; the intended receivers of this signal are thus males, not females. Intrasexual selection can therefore offset the forces of intersexual selection, even in a courtship display.     

Mating with sperm-depleted males does not increase female mating frequency in the parasitoid Lariophagus distinguendus

Sexual conflicts due to divergent male and female interests in reproduction are common in parasitic Hymenoptera. The majority of parasitoid females are monandrous, whereas males are able to mate repeatedly. Thus, accepting only a single mate might be costly when females mate with a sperm‐depleted male, which may not transfer a sufficient amount of sperm. In the present study, we investigated the reproductive performance in the parasitoid Lariophagus distinguendus Först. (Hymenoptera: Pteromalidae) and studied whether mating with experimentally sperm‐depleted males increases the tendency of females to remate. Males were able to mate with up to 17 females offered in rapid succession within a 10‐h test period. The resulting female offspring, as an indirect measure of sperm transfer, remained constant during the first six matings and then decreased successively with increasing number of copulations by the males. Experimentally sperm‐depleted males continued to mate even if they transferred only small amounts or no sperm at all. Unlike males, the majority of females mated only once during a 192‐h test period. A second copulation was observed only in a few cases (maximum 16%). The frequency of remating was not influenced by the mating status of the first male the females had copulated with, suggesting that these events are not controlled by sperm deficiency of the females. Furthermore, we investigated male courtship behaviour towards mated females. Male courtship intensity towards mated females decreased with increasing time. However, females that had mated with an experimentally sperm‐depleted male did not elicit stronger or longer‐lasting behavioural responses in courting males than those that had mated with a virgin male. As the observed behaviours in L. distinguendus are known to be elicited by a courtship pheromone, these results suggest that females no longer invest in pheromone biosynthesis after mating (as indicated by ceasing behavioural responses of courting males), irrespective of whether they have received a sufficient amount of sperm or not. We discuss the results with respect to a possible mating strategy of sperm‐depleted males.     

Eavesdropping and signal matching in visual courtship displays of spiders

Eavesdropping on communication is widespread among animals, e.g. bystanders observing male-male contests, female mate choice copying and predator detection of prey cues. Some animals also exhibit signal matching, e.g. overlapping of competitors' acoustic signals in aggressive interactions. Fewer studies have examined male eavesdropping on conspecific courtship, although males could increase mating success by attending to others' behaviour and displaying whenever courtship is detected. In this study, we show that field-experienced male Schizocosa ocreata wolf spiders exhibit eavesdropping and signal matching when exposed to video playback of courting male conspecifics. Male spiders had longer bouts of interaction with a courting male stimulus, and more bouts of courtship signalling during and after the presence of a male on the video screen. Rates of courtship (leg tapping) displayed by individual focal males were correlated with the rates of the video exemplar to which they were exposed. These findings suggest male wolf spiders might gain information by eavesdropping on conspecific courtship and adjust performance to match that of rivals. This represents a novel finding, as these behaviours have previously been seen primarily among vertebrates.     

The mating behaviour of the egyptian cotton leafworm moth, spodoptera littoralis (Boisd.)

A detailed study of courtship in Spodoptera littoralis showed that there were four significant behaviour patterns. The male flew to a calling female and hovered above her with his brushes fully extended. In response, the female lifted her wings, curved her abdomen and withdrew her pheromone gland. The male settled beside the female to pair and then moved to hang head downwards during copulation. Thirty percent of successful courtships lacked one of the main behaviour patterns. Nearly half the courtships observed did not end in copulation: none of these included all of four major behaviour patterns and the majority lacked two or three. Females often rejected males with a rapid flick of the wings. Antennaless males did not mate or extend the brushes in response to a calling female. Just over half of the antennaless females observed during 135-min tests mated with normal males, but courtship was abnormal. Olfactory cues appeared to be important to females in recognizing the courting male, since antennaless females did not wing flick, were significantly more likely to take to flight as the result of the male brush display and frequently failed to retract the pheromone gland during the latter states of courtship. The courtship behaviour of S. littoralis is compared with published accounts for other Noctuids.     

Hunger‐dependent and sex‐specific antipredator behaviour of larvae of a size‐dimorphic mosquito

1. Modification of behaviours in the presence of predators or predation cues is widespread among animals. The costs of a behavioural change in the presence of predators or predation cues depend on fitness effects of lost feeding opportunities and, especially when organisms are sexually dimorphic in size or timing of maturation, these costs are expected to differ between the sexes. 2. Larval Aedes triseriatus (Say) (Diptera: Culicidae) were used to test the hypothesis that behavioural responses of the sexes to predation cues have been selected differently due to different energy demands. 3. Even in the absence of water‐borne predation cues, hungry females (the larger sex) spent more time browsing than did males, indicating a difference in energy needs. 4. In the presence of predation cues, well‐fed larvae of both sexes reduced their activity more than did hungry larvae, and males shifted away from high‐risk behaviours to a greater degree than did females, providing the first evidence of sex‐specific antipredator behaviour in foraging mosquito larvae. 5. Because sexual size dimorphism is common across taxa, and energetic demands are probably correlated with size dimorphism, this research demonstrates the importance of investigating sex‐specific behaviour and behavioural responses to enemies, and cautions against generalising results between sexes.     

<Emphasis Type="Italic">fruitless</Emphasis> alternative splicing and sex behaviour in insects: an ancient and unforgettable love story?

Courtship behaviours are common features of animal species that reproduce sexually. Typically, males are involved in courting females. Insects display an astonishing variety of courtship strategies primarily based on innate stereotyped responses to various external stimuli. In Drosophila melanogaster, male courtship requires proteins encoded by the fruitless (fru) gene that are produced in different sex-specific isoforms via alternative splicing. Drosophila mutant flies with loss-of-function alleles of the fru gene exhibit blocked male courtship behaviour. However, various individual steps in the courtship ritual are disrupted in fly strains carrying different fru alleles. These findings suggest that fru is required for specific steps in courtship. In distantly related insect species, various fru paralogues were isolated, which shows conservation of sex-specific alternative splicing and protein expression in neural tissues and suggests an evolutionary functional conservation of fru in the control of male-specific-courtship behaviour. In this review, we report the seminal findings regarding the fru gene, its splicing regulation and evolution in insects.     

Reproductive Behaviour of the Annona Fruit Borer, Cerconota anonella

The Annona fruit borer, Cerconota anonella, causes significant damage to the fruits of Annona squamosa (custard apple) and A. muricata (soursop). The methods currently available for the control of this pest are costly and new techniques, possibly involving the use of pheromones for trapping or disrupting the mating cycle of the insect are required. In order to provide the basic information required for the development of new control systems, the reproductive behaviour of the moth was observed under laboratory conditions. The calling and courtship behaviours exhibited by virgin females and males of C. anonella commenced at the eighth hour of the scotophase and continued for a 3.5‐h period. Males were attracted by conspecific females as young as 1 d old, and showed a courtship behaviour composed of three steps: antennation, wing fanning and short flights. Mating mainly occurred when both males and females were between 2 and 5 d old, but maximum activity was observed on the third day after emergence. Receptive females elevated their wings, showing their abdomens where the abdominal hairpencils were already exposed. As part of the courtship repertoire and immediately prior to copula, males performed pronounced sideways movements of their abdomens, a behaviour that appears to be exclusive to C. anonella.     

Photoperiod influences the development and the expression of personality traits and social behaviour in wild cavies (Cavia aperea)

Seasonality influences behaviour, physiology and life history of organisms, and photoperiod is a reliable and influential cue gearing individual adaptation to seasonal changes in the environment. Plastic phenotypic adjustments according to the prevailing season are a widespread, well-studied phenomenon. Less well known are effects on developmental trajectories of animals born into different seasons. By manipulating the photoperiod during pregnancy and lactation independent of food availability and temperature, we studied if maternal behaviour in the precocial wild cavy (Cavia aperea) responds to this seasonal cue and if maternal behaviour and photoperiod shape offspring development and behaviour. We repeatedly observed mothers before and after birth. We investigated if pups differ in risk-taking behaviours directly after birth (indicating direct prenatal effects) or only after gaining independence of the mother (indicating delayed prenatal or postnatal effects due to own cue sampling). Furthermore, we tested if different simulated seasons of birth affect social and aggressive behaviour of adult animals. While theoretical predictions according to risk-taking are quite clear, they are contradictory for social behaviours that are much less well studied. We predicted that animals born into spring photoperiods would be aggressive because of a need to gather enough resources for early reproduction and successfully establishing a territory at least in males. Spring-born males were more aggressive than autumn-borns, while females did not differ with respect to season. Spring-born females, however, lost more body mass when they had to integrate into an established group and autumn-born females initiated more aggressive interactions. Our data demonstrate flexible and long-term stable seasonal effects on behaviours that likely affect fitness outcomes under natural conditions.     

Multiple male traits interact: attractive bower decorations facilitate attractive behavioural displays in satin bowerbirds

Sexually selected male courtship displays often involve multiple behavioural and physical traits, but little is known about the function of different traits in mate choice. Here, we examine female courtship behaviours to learn how male traits interact to influence female mating decisions. In satin bowerbirds (Ptilonorhynchus violaceus), successful males give highly aggressive, intense behavioural displays without startling females. Males do this by modulating their displays in response to female crouching, which signals the display intensity that females will tolerate without being startled. Females typically visit multiple males for multiple courtships before choosing a mate, and females show differing tolerance for intense displays during their first courtship with each male. We test three hypotheses that may explain this: (i) familiarity with the courting male; (ii) the order of the courtship in mate-searching; and (iii) the attractiveness of the courting male. We found that females are more tolerant of intense displays during first courtships with attractive males; this increased female tolerance may allow attractive males to give higher intensity courtship displays that further enhance their attractiveness. We then examined why this is so, finding evidence that females are less likely to be startled by males with better physical displays (bower decorations), and this reduced startling then contributes to male courtship success. This role of physical displays in facilitating behavioural displays suggests a novel mechanism by which multiple physical and behavioural traits may influence female choice.