Egg clutch patterning in Lestes virens (Odonata,Lestidae) with evolutionary emphasis on endophytic oviposition in lestid dragonflies

Egg deposition within plants is one of the most widely distributed and ancient behaviors in Odonata. The resulting clutch consists of eggs placed in peculiar pattern that can be a characteristic for certain groups of Odonata. Despite their importance for paleontological and evolutionary research, data on egg‐clutch positioning are missing or insufficient for most species. Here, patterning of egg clutches in Lestes virens was measured and described in detail for the first time. The female usually produces a linear row of single eggs directed at an angle rightward or leftward to the longitudinal axis of plant substrate. Less often eggs are arranged in egg‐sets consisting of up to 4 eggs. Apparently, the female insect follows the rigid behavior stereotypes during oviposition and is unable to easily switch to the alternate stereotypical behavior of single egg deposition or production of multiegg sets. Based on a literature review and original data, egg clutch patterning of European Lestidae is overlaid on preexisting phylogenies. The resulting evolutionary scenario of egg‐clutch patterning can be considered in the framework of egg‐laying behavior in Lestidae.     

Plasticity and limitations of extended egg retention in oviparous Zootoca vivipara (Reptilia: Lacertidae)

The transition between oviparity and viviparity in reptiles is generally accepted to be a gradual process, the result of selection for increasingly prolonged egg retention within the oviduct. We examined egg retention plasticity in an oviparous strain of the lacertid lizard Zootoca vivipara, a species having both oviparous and viviparous populations. We forced a group of female Z. vivipara to retain their clutch in utero by keeping them in dry substrata, and assessed the effect on embryonic development and hatching success, along with offspring phenotype and locomotor performance. Forced egg retention for one additional week affected the developmental stage of embryos at oviposition, as well as hatchling robustness and locomotor performance. However, embryos from forced clutch retention treatment reached one stage unit more than control embryos at oviposition time. Embryos from control eggs were more developed than embryos from experimental eggs after approximately the same period of external incubation, showing that embryonic development is retarded during the period of extended egg retention, despite the high temperature inside the mother's body. Significant differences in external incubation time were only found in one of the two years of study. Hatching success was much lower in the experimental group with forced egg retention (21.1%) than in the control group (95.4%). Therefore, we conclude that there are limitations that hinder the advance of intrauterine embryonic development beyond the normal time of oviposition, and that extended egg retention does not represent clear advantages in this population of Z. vivipara. Nevertheless, the fact that some eggs are successful after forced egg retention could be advantageous for the females that are able to retain their clutch under unfavourable climatic conditions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 75–82.     

Does the Polyphagous Egg Parasitoid <Emphasis Type="Italic">Trichogramma platneri</Emphasis> Nagarkatti (Hymenoptera: Trichogrammatidae) Display Behavioral Plasticity When Parasitizing Different Hosts?

Trichogramma platneri oviposition behavior on Amorbia cuneana egg masses was investigated under laboratory conditions. No relationship was detected between host surface area, number of edge turning on host eggs, and parasitoid clutch size. It was also observed that females parasitized the egg mass randomly by drilling into the egg mass and parasitizing individual eggs without using stereotypical behaviors to assess individual hosts (i.e. drumming and turning). However, clutch size did change due to ovipositional experience as naïve wasps with little or no ovipositional experience (<6 eggs parasitized), allocated significantly more progeny per host than wasps with longer ovipositional experience (24-h oviposition experience on a single egg mass). Moreover, naïve wasps parasitized significantly more eggs on the outer edge of the egg mass than experienced wasps. We contend that the physical characteristics of A. cuneana eggs and egg masses preclude T. platneri from completely discriminating between individual eggs. However, because T. platneri may be using kairomones from the egg mass, this described oviposition strategy remains effective.     

Oviposition behavior and progeny allocation of the polyembryonic waspCopidosoma floridanum (Hymenoptera: Encyrtidae)

Oviposition behavior was used to determine the primary clutch size and sex ratio of the polyembryonic wasp Copidosoma floridanumAshmead (Hymenoptera: Encyrtidae) parasitizing Pseudoplusia includens(Walker) (Lepidoptera: Noctuidae). The laying of a female egg was associated with a pause in abdominal contractions during oviposition, while the laying of a male egg was associated with uninterrupted abdominal contractions. Although unmated females produced only male broods, they also displayed male and female egg oviposition movements. Wasps always laid a primary clutch of one or two eggs. For mated females if only one egg was laid, the emerging secondary clutch was all male or female, but if two eggs were laid a mixed brood of males and females was almost always produced. The secondary clutch of single sex broods was usually between 1000 and 1200 individuals, but the secondary clutch of mixed broods averaged 1143 females and 49 males. Thus, the primary sex ratio for mixed broods was 0.5 (frequency males), but the secondary sex ratio was 0.042. Manipulation of the sequence of male and female egg oviposition or of the primary clutch did not produce major alterations in the secondary clutch size or sex ratio.     

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.     

Count Your Eggs Before They Invade: Identifying and Quantifying Egg Clutches of Two Invasive Apple Snail Species (Pomacea)

Winning the war against invasive species requires early detection of invasions. Compared to terrestrial invaders, aquatic species often thrive undetected under water and do not garner notice until too late for early action. However, fortunately for managers, apple snails (Family Ampullariidae, Genus Pomacea) provide their own conspicuous sign of invasion in the form of vibrantly colored egg clutches. Managers can potentially use egg clutches laid in the riparian zone as a means of early detection and species identification. To facilitate such efforts, we quantified differences in characteristics (length, width, depth, mass, egg number) of field-laid clutches for the two most common invasive species of apple snail, P. canaliculata and P. maculata, in native and non-native populations. Pomacea canaliculata native and non-native populations differed noticeably only in width. Native P. maculata clutches possessed significantly greater width, mass and eggs numbers compared with native P. canaliculata. Non-native P. maculata clutches significantly exceeded all other populations in all measured characteristics. Consequently, these traits may successfully distinguish between species. Fecundity data also allowed us to develop models that accurately estimated the number of eggs per clutch for each species based on clutch dimensions. We tested one, two and three dimensional models of clutches, including rendering a clutch as either a complete ellipsoid or an ellipsoid intersected by a cylinder to represent the oviposition site. Model comparisons found the product of length and depth, with a different function for each population, best predicted egg number for both species. Comparisons of egg number to clutch volume and mass implied non-native P. canaliculata may be food limited, while non-native P. maculata appeared to produce such enormous clutches by having access to greater nutrients than the native population. With these new tools, researchers and managers can quickly identify, quantify and begin eradication of new non-native apple snail populations.     

Bemerkungen zur Biologie sowie Haltung und Vermehrung des Sokotra-Riesengeckos, Haemodracon riebeckii (Peters, 1882)

The Socotra Giant Gecko, Haemodracon riebeckii, is the largest species of lizard on Socotra Island. The nocturnal, arboreal and rupiculous living geckos are omnivorous. Two pairs were kept in terrariums and were fed with various insects (crickets, locusts, cockroaches), sweet fruits and other feeding stuff (such as meat, fish). Temporarily H. riebeckii was kept together with other lizards (Eublepharis macularius, Trachylepis socotrana), without any signs of aggressive behaviour. Juveniles and adults of both sexes are able to produce a sound. These acoustic signals seem to be related to predators, because never any intraspecific function could be observed. Within seven years of captive breeding two females produced 253 eggs. Usually two white and sticky soft-shelled eggs were laid within one clutch, more rarely a single egg was laid. The two eggs of a clutch were always laid on the same day. H. riebeckii belongs to the geckos that bury their eggs and practice some brood care, but no special parental care. The female is able to proof with her hind legs the deep and shape of a hollow in the substrate to bury the eggs, which were buried in a sticky and soft-shelled condition. They are oval in shape (egg length 16.4-19.8 mm, egg width 12.4-17.8 mm, quotient EL:EW 1.22±0.05) and have in the beginning a weight ranging from 1.7100 to 2.5201 g. As typical for geckos with hard-shelled eggs the egg weight decreases during the incubation period. The loss can be between 5.59 to 30.29%. The development of eggs up to hatching of young depends upon temperature and the germinal stage in the laid egg. The time difference between the hatching of the young within one clutch of two eggs was usually 1 to 5 days. In some cases there were, however, longer differences (up to 61 days), which are probably caused by different developmental stages of the embryos during the time of egg laying. The shortest incubation period recorded during our investigations was 83 days for eggs incubated at constant temperature of 28 to 29.5 °C and the longest 359 days at 26 to 26.5 °C. Constant high incubation temperatures caused a premature hatching of young. In normal hatched young were the yolk sac retracted and the navel closed. In premature hatched young were the yolk not resorbed and the mortality within the first three month comparatively high. The snout-vent length (SVL) of newly hatched young is from 27 to 39 mm and the tail length (TL) from 25 to 38 mm (SVL:TL index 0.90-1.27), the weight is from 0.7688 to 1.5366 g. Young specimens are distinguished from adults by the brown/white striped lower jaw and the white-banded tail. Young which hatched in the terrarium were eaten by the adults. A loss of young can be avoided if they are raised individually.     

Oviposition Behavior of the Predatory Midge Aphidoletes aphidimyza in Response to Aphid Patch Quality

Female Aphidoletes aphidimyza confronts serious challenges from both aphid prey and conspecifics. These challenges constitute strong selective pressures on the predatory midge to have an adaptive oviposition strategy. We did laboratory experiments to investigate clutch size of A. aphidimyza in response to the aphid Rhopalosiphum padi (density and age) and the presence of conspecific eggs (density) and larvae (age) in aphid colonies. The results of our study show that A. aphidimyza female adjusts its foraging effort by assessing the quality of prey patches. The number of eggs laid increased in response to aphid density. However, patches consisting of older aphids received fewer eggs. The number of eggs laid decreased in response to the presence of conspecific eggs, and in response to the presence of 2-day old conspecific larvae. Our study reveals deterrent effects on A. aphidimyza oviposition decisions on clutch size in response to older aphids and the presence of more conspecific eggs and older larvae.     

Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

相似文献   

On oviposition in weevils of the genus <Emphasis Type="Italic">Larinus</Emphasis> Dej. (Coleoptera,Curculionidae)

The following actions performed by females of several Larinus Dej. species during egg laying are described: search of an appropriate place on the plant, making the hole for the egg, oviposition proper, and sealing the hole. The hole preparation takes the longest time and the greatest effort. Only one individual usually completes development in one flower head. Females of Larinus vulpes Ol. prefer larger flower heads for oviposition and occasionally lay eggs into stems. The ability of females to distinguish the flower heads with already laid eggs is discussed. Species of Larinus may be divided into two groups with “early” and “late” oviposition. The evolution of egg laying in the genus Larinus is discussed.     

Suitability of non-fertilized eggs of Homalodisca vitripennis for the egg parasitoid Gonatocerus morrilli

Gonatocerus morrilli (Howard) (Hymenoptera: Mymaridae) is an egg parasitoid used in California, USA to control glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae). Virgin GWSS females deposit non-fertilized eggs and mated females can exhaust sperm reserves for egg fertilization. However, nothing is known about Gonatocerus spp. performance when using non-fertilized GWSS eggs as hosts. Host age preference for oviposition and suitability of non-fertilized GWSS eggs as hosts for G. morrilli reproduction were investigated to determine whether non-fertilized eggs on sentinel plants could be used to monitor egg parasitoid populations. Gonatocerus morrilli parasitized all ages of GWSS eggs (1–8 days old) regardless if the host egg was fertilized or not. In choice tests (fertilized versus non-fertilized eggs), parasitoids failed to emerge as adults from non-fertilized eggs more often than from fertilized eggs. The results indicate that non-fertilized eggs were accepted by G. morrilli as suitable hosts for oviposition, but were less suitable for immature development compared to fertilized eggs.     

Use of statistical models based on radiographic measurements to predict oviposition date and clutch size in rock iguanas (Cyclura nubila)

The ability to noninvasively estimate clutch size and predict oviposition date in reptiles can be useful not only to veterinary clinicians but also to managers of captive collections and field researchers. Measurements of egg size and shape, as well as position of the clutch within the coelomic cavity, were taken from diagnostic radiographs of 20 female Cuban rock iguanas, Cyclura nubila, 81 to 18 days prior to laying. Combined with data on maternal body size, these variables were entered into multiple regression models to predict clutch size and timing of egg laying. The model for clutch size was accurate to 0.53 ± 0.08 eggs, while the model for oviposition date was accurate to 6.22 ± 0.81 days. Equations were generated that should be applicable to this and other large Cyclura species. © 1995 Wiley-Liss, Inc.     

Effect of the rhg1 Gene on Population Development of Heterodera glycines

The effect of the rhg1 gene on equilibrium population densities (E) and reproduction factors (Rf) of Heterodera glycines was studied by comparing the nematode population development on two near-isogenic soybean lines (NIL), differing at the rhg1 locus. The NIL were inoculated with a series of initial egg densities (Pi) in the greenhouse. The relationships between final population densities (Pf = females per plant or eggs per plant) or Rf (final egg density/Pi) on both NIL and Pi were adequately described by quadratic models. The rhg1 gene suppressed Pf and Rf at all Pi of a population of H. glycines race 3 (HG Type 0-); E and maximum Rf were higher on the NIL-S line than on the NIL-R line. After two generations of culture of the race 3 population on the NIL-R line, the population selected by the rhg1 gene (R-eggs) had higher Pf and Rf on the NIL-R line than the population cultured on the NIL-S line (S-eggs) at all Pi. Both R-eggs and S-eggs produced similar egg numbers on the NIL-S line, which was higher than the egg number of either population on the NIL-R line at all Pi. The ratio of E in female numbers on the NIL-R line to E on the NIL-S line increased from 29% for the original race 3 population (S-eggs) to 46% for the rhg1-selected population (R-eggs). Regardless of different egg sources, a trend of increase in the number of eggs per female with the rise of Pi was observed on the NIL-S line. In contrast, female fecundity of both populations declined with the increase of Pi on the NIL-R line. At most inoculum densities, the highest number of eggs per female was observed on the NIL-S line inoculated with the R-eggs, whereas the lowest number of eggs per female was detected on the NIL-R line inoculated with the S-eggs. This study demonstrated that the E and maximum Rf determined by the quadratic models are useful measurements of plant resistance to nematodes.     

Effects of predation on clutch size and egg dispersion in the codling moth Laspeyresia pomonella

ABSTRACT.

• 1 The effects of predation on clutch size and egg dispersion in the codling moth Laspeyresia pomonella (L.) were experimentally studied in an orchard by recording survival of eggs glued onto different substrates.
• 2 Egg mortality due to sucking insects was readily distinguishable from that due to chewing insects.
• 3 In both the field and laboratory, females preferred to deposit eggs singly on the uppersides of leaves.
• 4 Eggs on the uppersides of leaves and on fruit survived significantly better than did those on the undersides of leaves or on twigs.
• 5 Egg losses were highest during the early part of the flight season.
• 6 The smallest (one egg) and largest (nine eggs) clutches, associated with one egg-bearing leaf per twig, both suffered the lowest rates of predation. Factors selecting against oviposition on fruits and production of large clutch sizes are presented and discussed.

     

The influence of maternal thermal environments on reproductive traits and hatchling traits in a Lacertid lizard,Takydromus septentrionalis

The thermal environment can induce substantial variation in important life-history traits. Experimental manipulation of the thermal environment can help researchers determine the contribution of this factor to phenotypic variation in life-history traits. During the reproductive season, we kept female northern grass lizards, Takydromus septentrionalis (Lacertidae), in three temperature-controlled rooms (25, 28 and 32 °C) to measure the effect of the maternal thermal environment on reproductive traits. Maternal thermal environment remarkably affected reproductive frequency and thereby seasonal reproductive output, but had little effect on reproductive traits per clutch or hatchling traits. Females kept at 32 °C produced more clutches and thus had shorter clutch intervals than females from 28 to 25 °C. Clutch size, clutch mass, relative clutch mass, egg size and hatchling traits did not vary among the three treatments. The eggs produced by the females were incubated at 27 °C and the traits of hatchlings were measured. The result that egg (offspring) size was independent of maternal thermal environments is consistent with the prediction of the optimal egg size (offspring) theory. The eggs produced by low temperature females (28 and 25 °C) took longer time to complete their post-oviposition development than did eggs produced by high temperature females (32 °C). This suggests that the eggs from low temperatures might have been laid when the embryos were at relatively early stages. Therefore, maternal thermal environment prior to oviposition could affect post-oviposition development in T. septentrionalis.     

Is juvenile hormone involved in the maternal regulation of egg size and progeny characteristics in the desert locust?

The role of juvenile hormone (JH) in the maternal regulation of progeny characteristics was examined in the desert locust, Schistocerca gregaria. Female adults of this species are known to produce smaller but more eggs when reared in isolation than do those reared in a group. Eggs laid by isolated females develop green hatchlings typical of solitarious forms, whereas those laid by the latter produce black hatchlings typical of gregarious forms. Topical application of a juvenile hormone analog (JHA), fenoxycarb, or implantation of corpora allata (CA) taken from the migratory locust, Locusta migratoria, caused crowded S. gregaria females to deposit smaller eggs, but did not have a significant effect on the number of eggs per egg pod except at high doses of JHA. The production of smaller eggs by treated and untreated crowded females was closely associated with earlier deposition of the egg pods and shorter oviposition intervals. However, neither JHA application nor CA implantation influenced the progeny characteristics in actively reproducing aged females under crowded conditions, while untreated control females started producing smaller and more eggs upon transfer to isolated conditions. These results may suggest that JH is not directly involved in the maternal regulation of phase-dependent progeny characteristics.     

A quantified ethogram for oviposition behavior and oviposition preference in the hemipterophagous butterfly Spalgis epius (Westwood) (Lepidoptera: Lycaenidae)

In this study, we examined the oviposition behavior and preference of Spalgis epius, a potential predator of mealybug crop pests. An ethogram of oviposition behavior was constructed based on observations made in an oviposition cage. Ovipositional behavioral acts were catalogued and separated into two behavioral repertoires: searching and egg laying. Gravid females of S. epius oviposited similar numbers of eggs on three mealybug species. Females preferred eggs and adults to nymphs of mealybugs for oviposition. Among three species of mealybugs attended by ants, females laid fewer eggs in the mealybug mass attended by Oecophylla smaragdina than on mealybugs attended by Tapinoma melanocephalum and Camponotus variegatus. Females preferred mealybug masses already containing conspecific eggs to mealybug masses containing conspecific larvae or Cryptolaemus montrouzieri larvae for egg deposition. Gravid females laid larger numbers of eggs under bright sunlight than in diffused sunlight or shade. The results of this study showed that S. epius can effectively attack any species of mealybugs, avoid intra- and interspecific competition, and co-exist with some species of ants attending mealybugs. With the knowledge of these behaviors, this predator can be effectively utilized as a major biological control agent of mealybugs.     

On the reproductive biology of the herbivorous spiny-tailed agamid Uromastyx philbyi in western Saudi Arabia

Abstract

The reproductive biology of the Spiny-tailed Agamid Uromastyx philbyi, a herbivorous desert lizard, was studied in western Saudi Arabia. Reproduction is seasonal, with mating in early spring (March), oviposition in late spring (May–June), and hatching in summer (July). The mean clutch size was 6.67 eggs. Eggs are large (mean mass = 7.48 g) and relative clutch mass (RCM) averaged 0.49. Clutch mass and RCM increased with increasing egg mass. Clutch size, egg size, clutch mass, and RCM were significantly correlated with maternal body size.     

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.     

Influence of egg size differences within egg clutches on larval parameters in nine libellulid species (Odonata)

Abstract.  1. In libellulids, egg size differs between species and populations. There are also size differences within egg clutches of individual females.
2. Past experiments suggest that there are two different types of egg clutches in libellulids. Egg size decreases significantly during oviposition in species that perform non-contact guarding during oviposition. In contrast, in species ovipositing in tandem, egg size is randomly distributed.
3. This study deals with the possible consequences of egg size variation within the different egg clutch types. The study examined whether there is a correlation between egg development time, offspring sex or larval size and egg size.
4. The current experiments were conducted in Namibia and Germany. Five non-contact guarding and four tandem guarding libellulid species were used.
5. In some species larger eggs needed more time to develop, in some species no correlation between egg size and egg development time could be found, whereas in other species larger eggs developed faster.
6. The sex ratio was biased towards females in Leucorrhinia dubia and in Sympetrum striolatum and egg size was not associated with gender.
7. In both egg clutch types larger eggs resulted in larger larvae. In this study, evidence was found that the effects of egg size diminished with progressing larval development under good conditions. However, it is possible that the effects may have a greater influence under harsh circumstances.