Neural mechanism for generating and switching motor patterns of rhythmic movements of ovipositor valves in the cricket

In adult female crickets (Gryllus bimaculatus), rhythmic movements of ovipositor valves are produced by contractions of a set of ovipositor muscles that mediate egg-laying behavior. Recordings from implanted wire electrodes in the ovipositor muscles of freely moving crickets revealed sequential changes in the temporal pattern of motor activity that corresponded to shifts between behavioral steps: penetration of the ovipositor into a substrate, deposition of eggs, and withdrawal of the ovipositor from the substrate. We aimed in this study to illustrate the neuronal organization producing these motor patterns and the pattern-switching mechanism during the behavioral sequence. Firstly, we obtained intracellular recordings in tethered preparations, and identified 12 types of interneurons that were involved in the rhythmic activity of the ovipositor muscles. These interneurons fell into two classes: ‘initiator interneurons’ in which excitation preceded the rhythmic contractions of ovipositor muscles, and ‘oscillator interneurons’ in which the rhythmic oscillation and spike bursting occurred in sync with the oviposition motor rhythm. One of the oscillator interneurons exhibited different depolarization patterns in the penetration and deposition motor rhythms. It is likely that some of the oscillator interneurons are involved in producing different oviposition motor patterns. Secondly, we analyzed oviposition motor patterns when the mecahnosensory hairs located on the inside surface of the dorsal ovipositor valves were removed. In deafferented preparations, the sequential change from deposition to withdrawal did not occur. Therefore, the switching from deposition pattern to withdrawal pattern is signaled by the hair sensilla that detect the passage of an egg just before it is expelled.     

Female and male interactions during courtship in Calopteryx maculata and C. dimidiata (Odonata: Calopterygidae): Influence of oviposition behaviour

Calopteryx maculata and C. dimidiata damselfly females respond to male courtship with specific displays which signal differences in their receptivity. These include a rejection (wing spreading) and an invitation (wing-flipping) display, as well as a neutral (sit still) response. There are interspecific differences in the likelihood of each female display and in male responses to these displays. C. maculata males persist in courtship irrespective of female response, while C. dimidiata males generally stop courting when the female's response is rejection or neutrality. I suggest that these differences result from interspecific differences in oviposition behaviour. Female C. maculata oviposit at the water surface, which exposes them to disturbance by males attempting to mate. Females are therefore likely to remate to secure postcopulatory guarding when changing oviposition sites and males are expected to be persistent in courtship. Female C. dimidiata submerge to oviposit, which frees them from male disturbance and means that males have less control over female access to oviposition sites. Males therefore have less influence on mating by females and are expected not to persist in courtship of non-receptive females.     

Female and Male Moths Display Different Reproductive Behavior when Facing New versus Previous Mates

Multiple mating allows females to obtain material (more sperm and nutrient) and/or genetic benefits. The genetic benefit models require sperm from different males to fertilize eggs competitively or the offspring be fathered by multiple males. To maximize genetic benefits from multiple mating, females have evolved strategies to prefer novel versus previous mates in their subsequent matings. However, the reproductive behavior during mate encounter, mate choice and egg laying in relation to discrimination and preference between sexes has been largely neglected. In the present study, we used novel and previous mate treatments and studied male and female behavior and reproductive output in Spodoptera litura. The results of this study do not support the sperm and nutrient replenishment hypotheses because neither the number of mates nor the number of copulations achieved by females significantly increased female fecundity, fertility and longevity. However, females showed different oviposition patterns when facing new versus previous mates by slowing down oviposition, which allows the last male has opportunities to fertilize her eggs and the female to promote offspring diversity. Moreover, females that have novel males present called earlier and more than females that have their previous mates present, whereas no significant differences were found on male courtship between treatments. These results suggest that S. litura females can distinguish novel from previous mates and prefer the former, whereas males generally remate regardless of whether the female is a previous mate or not. In S. litura, eggs are laid in large clusters and offspring competition, inbreeding and disease transfer risks are thus increased. Therefore, offspring diversity should be valuable for S. litura, and genetic benefits should be the main force behind the evolution of female behavioral strategies found in the present study.     

Host-handling behavior of the parasitoid,Diglyphus minoeus [Hym.: Eulophidae], parasitizing the honeysuckle leaf-miner,Phytomyza lonicerae [Dipt.: Agromyzidae]

The host-handling behavior of individual female waspsDiglyphys minoeus which attack the larvae of the honeysuckle leaf-miner,Phytomyza lonicerae, include 4 types of behavior: probing, ovipositor insertion, host-feeding, and resting. Ovipositor insertion may either be injection of venom, probing of the host by the sensilla on the ovipositor's tip or egg laying. Three types of attacks were distinguished: oviposition attack for unparasitized larvae, host-feeding attack for unparasitized host larvae and host rejection for previously parasitized host larvae. Oviposition attack was characterized by frequent alternation between probing and ovipositor insertion, long duration of ovipositor insertion and resting, and the long duration of host-handling. Resting behavior is thought to protect the progeny against superparasitism, host-feeding by other wasps or hosts' recovery from paralysis. Host-feeding attack was characterized by frequent alternation between host-feeding and ovipositor insertion and long duration of host-feeding. Host rejection was composed mainly of probing and ovipositor insertion and short handling time.      

Intra-specific Variation in the Effect of Male Seminal Substances on Female Oviposition and Longevity in Callosobruchus chinensis

Male seminal substances have been shown to induce oviposition and reduce female longevity in a number of species including the adzuki bean beetle Callosobruchus chinensis. Here the micro-injection of extracts of male reproductive tissues is used to determine the effect of male and female strain on female fecundity and longevity. Four strains of C. chinensis, known to differ in their propensity to remate were assayed. The results indicate that male and female strain both influence female fecundity and longevity. However, consistent patterns of response were not observed as revealed by a significant interaction between male and female strains. The evolutionary implications of these results are discussed.     

玉米螟赤眼蜂（Trichogramma ostriniae）寄主标记信息素和学习经历对产卵行为的影响

报道了标记信息素和雌蜂经历对玉米螟赤眼蜂Trichogramma ostriniae产卵行为的影响。研究结果表明,玉米螟赤眼蜂的寄主标记信息素是在其产卵过程中的收场阶段由产卵器产生的,并且标记在寄主卵表的化学物质;玉米螟赤眼蜂对标记信息素的识别不具有先天性,其必须先用产卵器插入寄生卵来检测是否被寄生,然后其触角不停地敲击,通过学习获得对标记信息素的识别能力,从而放弃了对寄生卵的选择,学习对初始放弃时间有着重要影响,改善了其对寄主搜索效率,这种学习行为是与寄主联系在一起学习的,它能根据寄主被寄生与否而对标记信息素作出反应与不反应。该研究丰富了生态学理论,为其在生防中更好的应用提供了科学依据。     

Isolation of the abdomen releases oviposition behaviour in females of the cricket, Acheta domesticus

Upon isolation, abdomens of adult female house crickets (Acheta domesticus) produced abdominal and ovipositor movements characteristic of normal oviposition. Oviposition behaviour was thus released even in reproductively mature or immature virgins where under normal conditions it was never observed. Decapitation was not sufficient to release oviposition behaviour but transection of the ventral nerve cord between the thorax and the abdomen of immobilized females evoked the response. These observations indicate that the motor programmes for certain components of the oviposition sequence reside in the abdominal ganglia. Moreover, the prerequisite circuitry for ovipositional posturing of the abdomen and ovipositor appears to be functional prior to sexual maturity and insemination, primed by mating, and subject to inhibition by the thoracic ganglia.     

Male irradiation affects female remating behavior in Anastrepha serpentina (Diptera: Tephritidae)

Female remating in target pest species can affect the efficacy of control methods such as the Sterile Insect Technique (SIT) but very little is known about the postcopulatory mating behavior of these pests. In this study, we investigated the remating behavior of female Anastrepha serpentina (Diptera: Tephritidae), an oligophagous pest of Sapotaceae. First, we tested how long the sexual refractory period of females lasted after an initial mating. Second, we tested the effect of male and female sterility, female ovipositing opportunities and male density on female propensity to remate. Lastly, we tested if the amount of sperm stored by females was correlated to the likelihood of females to remate. We found that receptivity of mass-reared A. serpentina females had a bimodal response, with up to 16% of mass-reared A. serpentina females remating five days after the initial copulation, decreasing to 2% at 10 and 15 days and increasing to 13% after 20 days. Compared to fertile males, sterile males were less likely to mate and less likely to inhibit females from remating. Copula duration of sterile males was shorter compared to fertile males. Remating females were less likely to mate with a sterile male as a second mate. Sterile females were less likely to mate or remate compared to fertile females. Opportunity to oviposit and male density had no effect on female remating probability. Sperm numbers were not correlated with female likelihood to remate. Information on the post-copulatory behavior of mass-reared A. serpentina will aid fruit fly managers in improving the quality of sterile males. We discuss our results in terms of the differences this species presents in female remating behavior compared to other tephritids.     

Oviposition Behaviour of Lygus rugulipennis and its Preferences for Plant Wounds

Little information is available on the oviposition behaviour and strategies of Lygus bugs, and these topics are unknown for most Miridae. Lygus rugulipennis, a widespread polyphagous species in the Palaearctic Region, is a serious pest of both herbaceous crops and fruit trees. Here we report on the L. rugulipennis oviposition behaviour and preferences. Experiments were carried out utilizing fresh green beans, and data were recorded using a computerized system for behavioural acquisitions. The L. rugulipennis female examines the plant substrate by means of the labial tip and then probes into the tissue using her stylets. Once the substrate is suitable, the female inserts her ovipositor precisely in the point previously probed and lays an egg. To investigate females’ oviposition preferences, their behaviour was compared on healthy green beans vs. artificially wounded green beans, with different types of wounds and at different time intervals (1?h, 6?h, 12?h, 24?h and 48?h) after wounding. Through labial and stylet examination, females distinguished healthy and wounded tissues and significantly preferred to oviposit in the latter, with different egg densities depending on the type of wound. Such preference changed at different time intervals after wounding. The lower resistance of the wounded substrate to ovipositor insertion, compared with the healthy substrate, was confirmed through a penetrometer test. Lygus preference for damaged tissues is discussed in terms of oviposition strategies in the insect-plant interaction context and strategies to escape natural enemies.     

Initial preference for plant species and state during oviposition site selection by an odonate

Endophytic egg‐laying odonates use an ovipositor to insert their eggs inside plant tissues. Before egg deposition, oviposition site selection consists of two crucial steps: (i) the initial choice, typically decided in species that oviposit in tandem within vertical substrates by the male when landing and then by the female by staying on the substrate or flying to another; and (ii) the insertion site choice, made by the female who uses her ovipositor to palpate the substrate. Some odonates prefer to deposit their eggs within specific plant species. Some are able to discriminate between living and dead substrates during the initial choice. However, the extent to which odonates discriminate among distinct plant species during the initial choice is unknown. We studied the initial site preference in Lestes macrostigma (Odonata: Lestidae) to determine whether the males and/or females show a distinct preference among five types of shoots when landing on or when palpating the substrate, respectively. Male L. macrostigma preferred to land on Bolboschoenus maritimus and dead Juncus spp. When focusing on J. maritimus, females preferentially palpated the substrate when the male landed on dead shoots. We suggest that the male preference for these substrates is consistent with that of the female during insertion site choice but also during egg deposition. Such behavior should reduce the duration of oviposition, with benefits of reducing the predation risk and increasing available time for foraging. The advantage in preferring these substrates should be linked to a selection pressure acting on egg development and/or survival.     

Courtship in Drosophila quadrilineata with a unique male behavioral element, abdomen bending

This paper describes courtship of Drosophila quadrilineata of the immigrans group and reports a species-specific element, abdomen bending, that has not been described in Drosophila. The male bends his abdomen right and left as a display to the female. During courtship the male circles around the female, bends his abdomen, and taps her. The male licks the female ovipositor repeatedly, often after the females extrusion. Although the females ovipositor extrusion is thought to indicate rejection of a courting male in many species, the male of D. quadrilineata continues courtship. It is possible that the extrusion is a females mating signal to the courting male. The male of D. quadrilineata mounts the female in a rearward position and the genitalia of both sexes couple after mounting. This mounting position is shared by the species belonging to the immigrans group. We never observed behavior in which it appeared as if the male displayed the black stripes to the female. Males court one another and a courtship chain is frequently formed even in the absence of females. The males abdomen bending and the females extrusion followed by the males licking are discussed.     

Quantitative genetics of oviposition behaviour and interactions among oviposition traits in the sand cricket

We performed a quantitative genetic study of oviposition behaviours and oviposition traits in the sand cricket Gryllus firmus. Egg survival in crickets depends on the depth at which they are inserted into the soil with the ovipositor. We examined whether egg depth depends on ovipositor length alone, or on both morphological and behavioural traits associated with oviposition. Heritability estimates were high (h² >0.5) for ovipositor length and small (h²=0.2) for oviposition behaviours. Negative genetic correlations between ovipositor length and some behavioural traits (digging depth and the behavioural component of egg depth) indicated compensation between oviposition traits on egg depth. Because of behavioural compensation, females with different ovipositor lengths subject to stabilizing selection on egg depth could have equal fitnesses. Females laid their eggs deeper, and their eggs were marginally more evenly distributed in dry than in wet sand. This suggests adaptive phenotypic plasticity in laying behaviour, but may also result from physical constraints of the substrate on the insertion of the ovipositor. The absence of significant between-family variation in oviposition traits in response to sand moisture indicates low evolutionary potential for phenotypic plasticity in oviposition traits according to soil moisture. In highly unpredictable environments, females could spread the risk of desiccation by laying eggs at different depths independently of environmental conditions (bet hedging). Our results show significant additive genetic influences on the ability of a female to spread risks as measured by genetic variation in egg distribution, suggesting that a bet-hedging strategy of egg laying has the potential to evolve in this population. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

An algal cyclostat with computer-controlled dynamic light regime

Platycnemis pennipes deposits eggs into plant tissue at or just below the water surface. On a number of different plant species egg deposition rate was found to be similar, while oviposition duration varied. Eggs were not always to be found in the substrate after a female had probed the substrate with her ovipositor. Actual oviposition took place only during longer stays.     

Comparison of oviposition behavior of a solitary and a gregarious parasitoid (Hymenoptera: Mymaridae)

Anaphes victus Huber andAnaphes listronoti Huber (Hymenoptera: Mymaridae) are respectively solitary and gregarious egg parasitoids of the carrot weevil,Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae). We made detailed ethograms of the oviposition behavior on unparasitized and parasitized hosts for the two species. We then compared the behavior of virgin and mated females for the oviposition of male and female progenies. The two species did not always oviposit after insertion of the ovipositor, but these punctures without oviposition could be readily differentiated from oviposition.A. victus oviposited only once by puncture, whileA. listronoti deposited one to three eggs during the same sequence. The variability of the duration of the various components was generally lower for a given female than between females. Two components, the abdominal vibrations and the pause, were significantly shorter in ovipositions that resulted in male progency for the two species. However, an important overlap in duration prevents using these differences to sex the progeny at oviposition. Virgin females of both species, although capable of producing only males, exhibited both behaviors. Parasitized hosts were recognized through internal and external markings that were used in host discrimination.     

Drosophila Pheromone-Sensing Neurons Expressing the ppk25 Ion Channel Subunit Stimulate Male Courtship and Female Receptivity

As in many species, gustatory pheromones regulate the mating behavior of Drosophila. Recently, several ppk genes, encoding ion channel subunits of the DEG/ENaC family, have been implicated in this process, leading to the identification of gustatory neurons that detect specific pheromones. In a subset of taste hairs on the legs of Drosophila, there are two ppk23-expressing, pheromone-sensing neurons with complementary response profiles; one neuron detects female pheromones that stimulate male courtship, the other detects male pheromones that inhibit male-male courtship. In contrast to ppk23, ppk25, is only expressed in a single gustatory neuron per taste hair, and males with impaired ppk25 function court females at reduced rates but do not display abnormal courtship of other males. These findings raised the possibility that ppk25 expression defines a subset of pheromone-sensing neurons. Here we show that ppk25 is expressed and functions in neurons that detect female-specific pheromones and mediates their stimulatory effect on male courtship. Furthermore, the role of ppk25 and ppk25-expressing neurons is not restricted to responses to female-specific pheromones. ppk25 is also required in the same subset of neurons for stimulation of male courtship by young males, males of the Tai2 strain, and by synthetic 7-pentacosene (7-P), a hydrocarbon normally found at low levels in both males and females. Finally, we unexpectedly find that, in females, ppk25 and ppk25-expressing cells regulate receptivity to mating. In the absence of the third antennal segment, which has both olfactory and auditory functions, mutations in ppk25 or silencing of ppk25-expressing neurons block female receptivity to males. Together these results indicate that ppk25 identifies a functionally specialized subset of pheromone-sensing neurons. While ppk25 neurons are required for the responses to multiple pheromones, in both males and females these neurons are specifically involved in stimulating courtship and mating.     

Structure and function of the ovipositor and associated sensilla of the apple maggot,Rhagoletis pomonella (Walsh) (Diptera : Tephritidae)

The ovipositor of Rhagoletis pomonella (Walsh) (Diptera : Tephritidae) has a dorsal process which terminates distally in a slightly upcurved tip and 2 ventral processes that are joined throughout their length by a membrane up to the region of the cloaca, where the ventral processes are not attached. The surface of the ovipositor contains both hair-like and campaniform mechanosensilla capable of monitoring both cuticular stress and mechanical contact of the ovipositor from the initial through the final steps of penetration of the fruit, egg-laying, copulation, and possibly dragging the ovipositor during deposition of the oviposition deterrent pheromone. Near the tip of the ovipositor are 2 longitudinally aligned grooves, each containing 3 pairs of chemosensilla. In addition, 1 pair of shorter chemosensilla are just distal to and outside the groove. All chemosensilla contain 3 or 4 chemosensitive neurons. During fruit penetration and egg-laying, the ovipositor is protracted, thus placing the chemosensilla in contact with various fruit chemicals. These chemosensilla are responsive to naturally occurring fruit chemicals. The possible role of the ovipositor chemosensilla in monitoring fruit quality, the deposition of the oviposition deterrent pheromone, the presence of chemical contaminants on the ovipositor, and the female's own accessory reproductive gland secretions remains to be established.     

Aquatic eggs are fertilised by multiple males not engaged in amplexus in a stream-breeding frog

In anuran amphibians, multiple males amplexing a single female to fertilise her eggs has been found for less than 25 species, whereas matings without amplexus are known for less than five species. Here we provide a new example of simultaneous polyandry with multiple males not engaged in amplexus, in Feirana taihangnicus, a stream-dwelling, explosive breeder endemic to central China. Laboratory experiments showed that when one female was kept with one male in a vessel with elevated, flat stones, the female stood on her head with her swollen cloaca against the undersurface of the stone substrate to lay eggs (clutch size ranged from 371 to 533, n = 7 females). Then, 10–102 min after oviposition began, the male stood on his head and released sperm over the eggs distributed as a single layer on the stone surfaces. It took about 3 h for the female to finish oviposition and for the male to finish fertilisation. On average, 96% of eggs were fertilised. In natural oviposition habitats, stream sections with slow flowing, we observed that 1 up to 15 males (8.7 ± 6.6, n = 6 cases), none in amplexus, participated in fertilising the eggs deposited by a single female. Evolutionary implications of this unusual reproductive strategy remain to be explored.     

PHYLOGENETIC RELATIONSHIPS OF SCOTUSSA AND LEIOTETTIX (ORTHOPTERA: ACRIDIDAE)

Abstract— A cladistic analysis of the South American grasshopper genera Scotussa and Leiotettix was performed in order to test the monophyly of these genera. Eurotettix, Chlorus and the Dichroplus bergi species group were included as terminal taxa. The genus Atrachelacris was used to root the tree. Twenty-nine characters from external morphology, male genitalia and female ovipositor were used in the analysis. In order to test for association between the structural change that occurred in the ovipositor valves of Scotussa and the functional change of the oviposition habits, the data matrix was partitioned and two analyses were performed. Characters from the female ovipositor were excluded from the data set used in the first analysis and another analysis was performed where all the characters were included in the analysis. Information on oviposition habits was then mapped on the cladogram, to determine the transformation for performance. Both analyses yielded only one most parsimonious tree and produced congruent results, confirming the monophyly of Leiotettix and Scotussa and corroborating their close relationship. Characters from the female ovipositor valves were informative not only at the species level but also at higher levels in the cladogram. The results also support the hypothesis of association between the structural change that occurred in the ovipositor valves of Scotussa with the functional change in the oviposition habits. However, this association did not seem to be correlated with the adaptive radiation in the genus.     

The role of cercal sensory feedback during spermatophore transfer in the cricket, Acheta domesticus

The role of the cerci in the spermatophore transfer behavior of the cricket Acheta domesticus was examined. During transfer, the male cerci were held close to the female abdomen where they produced small flicking movements. Male cercal ablation significantly decreased mating success by reducing both the ability of the male to hook the epiphallus on to the female subgenital plate and to transfer the spermatophore. During spermatophore transfer, the male must thread the spermatophore tube into the female genital papilla and attach the spermatophore, via its attachment plate, to the base of the ovipositor. Extracellular recordings from the male genital nerve revealed that a centrally driven, rhythmic bursting activity of genital efferents produced the rhythmic contractions of the five pairs of genital muscles responsible for spermatophore threading. Tactile stimulation of campaniform sensilla on the medial aspect of each cercus inhibited the activity of those motor units responsible for advancing the spermatophore tube during threading, while simultaneously activating the motor units responsible for adjusting the position of the epiphallus. We conclude that mechanosensory neurons on the cerci of the male cricket supply important information on female position to the motor program responsible for spermatophore threading and transfer.     

Host Handling Time in a Polyembryonic Wasp is Affected both by Previous Experience and by Host State (Parasitized or Not)

Foraging behavior for hosts in parasitoids resembles that of predators with respect to finding, evaluating and manipulating of the prey. Host handling time may depend on the life history of the parasitoid and can be affected by oviposition experience. Additionally, handling time can be affected by host aggregation, species, size and state (parasitized or not). We studied handling times in the egg-larval parasitoid wasp Copidosoma koehleri. We allowed naïve female wasps to oviposit into three consecutive unparasitized hosts, and measured time until oviposition, and the duration of ovipositor insertion. We recorded the same data for naïve females ovipositing into already parasitized hosts. We found that both previous experience by females and previous parasitism of hosts reduced handling time. The results suggest that host handling durations reflect the interplay between host state and parasitoid internal state.