Breaking up the Wall: Metal-Enrichment in Ovipositors,but Not in Mandibles,Co-Varies with Substrate Hardness in Gall-Wasps and Their Associates

The cuticle of certain insect body parts can be hardened by the addition of metals, and because niche separation may require morphological adaptations, inclusion of such metals may be linked to life history traits. Here, we analysed the distribution and enrichment of metals in the mandibles and ovipositors of a large family of gall-inducing wasps (Cynipidae, or Gall-Wasps) (plus one gall-inducing Chalcidoidea), and their associated wasps (gall-parasitoids and gall-inquilines) (Cynipidae, Chalcidoidea and Ichneumonoidea). Both plant types/organs where galls are induced, as well as galls themselves, vary considerably in hardness, thus making this group of wasps an ideal model to test if substrate hardness can predict metal enrichment. Non-galler, parasitic Cynipoidea attacking unconcealed hosts were used as ecological “outgroup”. With varying occurrence and concentration, Zn, Mn and Cu were detected in mandibles and ovipositors of the studied species. Zn tends be exclusively concentrated at the distal parts of the organs, while Mn and Cu showed a linear increase from the proximal to the distal parts of the organs. In general, we found that most of species having metal-enriched ovipositors (independently of metal type and concentration) were gall-invaders. Among gall-inducers, metals in the ovipositors were more likely to be found in species inducing galls in woody plants. Overall, a clear positive effect of substrate hardness on metal concentration was detected for all the three metals. Phylogenetic relationships among species, as suggested by the most recent estimates, seemed to have a weak role in explaining metal variation. On the other hand, no relationships were found between substrate hardness or gall-association type and concentration of metals in mandibles. We suggest that ecological pressures related to oviposition were sufficiently strong to drive changes in ovipositor elemental structure in these gall-associated Hymenoptera.     

Ecological aspects of the external morphology and functionality of the psychomyiid female ovipositor (Insecta,Trichoptera)

Females of most psychomyiid species bear an elongated ovipositor enabling them to oviposit their eggs into grooves and cavities in different kinds of substrates in freshwaters. Although the preference of psychomyiid species for oviposition into distinct substrates and the subsequent larval life performance in aquatic habitats is already known, the mode of oviposition and the functional morphology of the elongated ovipositor have not been described until now. In this study we present SEM photographs of some psychomyiid species with female ovipositors of different lengths and shapes, explaining their preference for oviposition into distinct substrates. Additionally, we discuss some ecological aspects of the ovipositor shapes and the mode of egg laying for psychomyiids. The female ovipositor consists of two body segments, with an elongated IXth and a distinctly shorter Xth segment, which is flexible and can be pushed up dorsally when releasing the eggs. On the basis of SEM photographs, we suppose that the opening of the channel through which the eggs were released is located ventrally near the ovipositor tip. The ovipositor itself is characterised by a ventral cleft reaching from the gonoporus of segment IX to the tip of the last segment X. We stored adult females abdomina overnight in different aqueous dilutions of ethanol leading to different stages of swelling of the ovipositors (grade of swelling in distilled water >30% ethanol >70% ethanol). Some internal membrane-like structures, normally infolded into the ovipositor, became visible by the swelling of the ovipositor. We discuss the possible rearrangement of the organisation of segment IX resulting in the development of an ovipositor on the basis of SEM photographs of the differently swollen ovipositors.     

Calling behaviour in arctiid moths: The effects of temperature and wind speed on the rhythmic exposure of the sex attractant gland

Female arctiid moths rhythmically extrude their ovipositors and thereby rhythmically expose their sex pheromone glands while calling. In Utetheisa ornatrix this behaviour results in concentration-modulated or pulsed pheromone release. The ovipositor protrusion frequencies were determined for 15 arctiid species: U. ornatrix, Haploa clymene, H. colona, H. lecontei, Pyrrarctia isabella, Estigmene acrea, Spilosoma congrua, S. virginica, Ecpantheria scribonia, Phragmatobia fuliginosa, Apantesis nais, A. arge, Pareuchaetes insulata, Cycnia tenera, and Euchaetes egle. Moth species that call early in the scotophase extrude their ovipositors at high frequencies (up to 170.9 ± 24.9 extrusions/min at 25°C) while moth species that call late in scotophase extrude their ovipositors at low frequencies (down to 68.3 ± 5.4 extrusions/min at 25°C). In all species tested, the ovipositor extrusion frequencies were shown to be temperature sensitive with a mean Q₁₀ of 2.0 ± 0.1. In one species, U. ornatrix, the ovipositor extrusion frequency varies with wind speed. In still air the ovipositor extrusion frequency is 70.1 ± 8.4 extrusions/min and at a wind speed of 120 cm/s the ovipositor extrusion frequency is 142.1 ± 8.3 extrusions/min. Suggested functions for rhythmic ovipositor extrusion during calling are discussed.     

Interspecific variation in ovipositor morphology among Manaosbiid and Nomoclastid Harvestmen (Arachnida,Opiliones, Laniatores)

The external anatomy of the ovipositor has generally been overlooked as a source of informative characters in systematic studies of laniatorean harvestmen. In this study, we used scanning electron microscopy to examine the ovipositors of nine species representing the families Manaosbiidae (five species) and Nomoclastidae (four species). Similar to the ovipositor morphology of many gonyleptoidean families, the distal tips of the ovipositors of these harvestmen have four external lobes, with the margins most commonly adorned with 10 large peripheral setae. In manaosbiid and nomoclastid species, these peripheral setae have undivided bases, striated shafts and undivided distal tips. There are typically three setae on each anterior lobe and two setae on each posterior lobe. The medial setae on both anterior and posterior lobes insert into sockets that are slightly more dorsal. We observed small, surface denticles, usually associated with a pore, on the external surface of the lobes. There was interspecific and intraspecific variation in the number and shape of these surface denticles. The association of pores with denticles on the ovipositor appears to be a feature common to not only both families but is also a trait that has not been observed on ovipositors in other families of laniatorean harvestmen.     

Calling Behavior in the Primitive Longhorned Beetle Prionus californicus Mots.

Many prionine species share morphological and behavioral traits commonly associated with production of volatile pheromones by females. Adults Prionus californicus Mots. are sexually dimorphic, males being smaller and having antennae that are much more strongly serrate than those of females. Females of this species produce a volatile pheromone that attracts males. We conducted studies characterizing calling behavior of P. californicus females. In these studies females typically lowered their heads and raised their abdomens while extending their ovipositors. The extended ovipositor was often flexed and the abdomen rhythmically contracted during these bouts which lasted up to 10 min. In some cases females everted a membranous, cylindrical sac from the dorsal surface of the ovipositor which was retracted before the ovipositor was withdrawn. This eversible sac has not reported for a cerambycid species, and is likely to be involved in production and/or release of pheromone.     

寄生垂叶榕的两种非传粉榕小蜂的产卵行为

通过对两种果外产卵非传粉榕小蜂Philotrypesissp.和Sycoscaptersp.产卵行为的详细观察,发现两种小蜂产卵期都集中在榕果发育的间花期,并且只在进过传粉榕小蜂的榕果内产卵。这两种小蜂的产卵行为基本都可以分为寻找产卵位点、刺壁、产卵和回收产卵器等步骤。落在果面上的两种小蜂的繁殖雌蜂都通过触角敲击果面寻找产卵位点。产卵结束后,Philotrypesissp.大多数情况在原位收回产卵针,而Sycoscaptersp.必须向前爬行才能将产卵针从果内收回。为了争夺产卵位点,在同一榕果产卵的Philotrypesissp.繁殖雌蜂之间会进行打斗。而Sycoscaptersp.繁殖雌蜂之间未观察到打斗行为。两种小蜂产卵器长度虽显著长于各自产卵时榕果果壁厚度,但却显著短于其产卵时榕果果壁和子房层的总厚度,说明这两种小蜂采用产卵针直接刺穿小花子房的产卵模式。     

Nature's Swiss Army knives: ovipositor structure mirrors ecology in a multitrophic fig wasp community

Background

Resource partitioning is facilitated by adaptations along niche dimensions that range from morphology to behaviour. The exploitation of hidden resources may require specially adapted morphological or sensory tools for resource location and utilisation. Differences in tool diversity and complexity can determine not only how many species can utilize these hidden resources but also how they do so.

Methodology and Principal Findings

The sclerotisation, gross morphology and ultrastructure of the ovipositors of a seven-member community of parasitic wasps comprising of gallers and parasitoids developing within the globular syconia (closed inflorescences) of Ficus racemosa (Moraceae) was investigated. These wasps also differ in their parasitism mode (external versus internal oviposition) and their timing of oviposition into the expanding syconium during its development. The number and diversity of sensilla, as well as ovipositor teeth, increased from internally ovipositing to externally ovipositing species and from gallers to parasitoids. The extent of sclerotisation of the ovipositor tip matched the force required to penetrate the syconium at the time of oviposition of each species. The internally ovipositing pollinator had only one type of sensillum and a single notch on the ovipositor tip. Externally ovipositing species had multiple sensilla types and teeth on their ovipositors. Chemosensilla were most concentrated at ovipositor tips while mechanoreceptors were more widely distributed, facilitating the precise location of hidden hosts in these wasps which lack larval host-seeking behaviour. Ovipositor traits of one parasitoid differed from those of its syntopic galler congeners and clustered with those of parasitoids within a different wasp subfamily. Thus ovipositor tools can show lability based on adaptive necessity, and are not constrained by phylogeny.

Conclusions/Significance

Ovipositor structure mirrored the increasingly complex trophic ecology and requirements for host accessibility in this parasite community. Ovipositor structure could be a useful surrogate for predicting the biology of parasites in other communities.     

Morphology of ovipositors in oribatid mites of the superfamily Crotonioidea (Acari,Oribatida)

The structure of ovipositors in 16 species of oribatid mites from the superfamily Crotonioidea (Acari, Oribatida) was studied. Similarities and differences in the ovipositor morphology are revealed. A brief comparative analysis of the structure of ovipositors in Macropylina (Crotonioidea) and Brachypylina oribatid mites was performed.     

Flexible ovipositor sheaths in parasitoid Hymenoptera (Insecta)

The structure of the ovipositor sheaths is examined in a number of parasitic wasps as well as a few non-parasitic taxa. Parasitic wasps in the families Aulacidae, Braconidae, Ichneumonidae, Megalyridae, and Stephanidae with a very elongate, external ovipositor have the lateral wall of the sheath finely transversely subdivided by narrow furrows. This makes the sheath highly flexible, allowing it to support the ovipositor proper during ovipositing. The taxa having such a flexible sheath all drill into wood to lay their eggs. Support at the tip of the ovipositor is crucial in the initial stages of oviposition. The flexible ovipositor sheath is possibly a very ancient trait, arising prior to the radiation of extant Apocrita. This is corroborated by their presence in fossil Hymenoptera from the Upper Jurassic. The occurrence of short and/or concealed ovipositors with rigid sheaths in many extant apocritan taxa must therefore be assumed to be the result of multiple reversals.