The first instar larva of two species of Miltogramminae (Diptera: Sarcophagidae) from the Middle East – examples of peculiar morphology

The first instar larva is described for two species of Miltogramminae flesh flies representing the genera Miltogramma Meigen and Phrosinella Robineau‐Desvoidy. Using a combination of light microscopy and scanning electron microscopy, the habitus is documented along with all important exoskeletal and cephaloskeletal structures. The described first instar larvae show substantial modifications of their morphology in comparison with the saprophagous ground plan defined for calyptrate flies. Miltogramma (Miltogrammidium) efflatouni Rohdendorf possesses the general set of derived character states shared with other species of Miltogramma and shares larval synapomorphies with species representing the subgenera Anacanthothecum Rohdendorf, Cylindrothecum Rohdendorf and Miltogrammidium Rohdendorf. Unique character states of the first instar larva of this species are the spine‐like shape of antennal complex, laterally compressed apical part of mouthhooks and an extreme elongation of the sensilla of the maxillary palpus. Phrosinella (Asiometopa) ujgura (Rohdendorf) possesses a pair of retractable, robust processes on the ventral margin of the first thoracic segment and a very strong, elongated labrum. Both character states are present in other known first instar larvae of genus Phrosinella. A reduction of cuticular ridges on dorsal and lateral surfaces of abdominal segments supports a monophylum consisting of the subgenera Asiometopa Rohdendorf and Caspiomyia Rohdendorf within genus Phrosinella.     

Sprint speed is not reduced by exaggerated male weapons in a flower beetle Dicronocephalus wallichii

Exaggerated sexually selected traits are assumed to decrease the mobility of bearers. However, previous empirical studies have often failed to support this assumption, possibly because locomotor performance represents the integration of numerous morphological, physiological and behavioural traits. Males of a flower beetle Dicronocephalus wallichii Pouillaude 1914 (Coleoptera: Scarabaeidae: Cetoniinae) possess elongated forelegs and a pair of exaggerated horns, which are used as dual weapons in male–male competition for mates. We investigated whether these two sexual traits impede the maximum sprint speed on bamboo branches with different angles and thicknesses under laboratory conditions. Our results suggested that no negative relationship exists between relative foreleg length or horn length and sprint speed. Elongated forelegs and horns may entail negligible locomotor costs. Males with longer horns and forelegs were found to have longer midlegs and hindlegs independent of body size. Thus, elongated midlegs and hindlegs in males may enhance balance, stabilize running on bamboo branches and compensate for the locomotor costs of bearing exaggerated weapons. Furthermore, a positive relationship was found between horn length and sprint speed on a horizontal branch. Males with longer horns probably have more energy and/or invest more heavily in appendage musculature. As is known in other animals, male horns of D. wallichii may act as honest indicators of body condition.     

Comparative morphology of the first instar of three species of Metopia Meigen (Diptera: Sarcophagidae, Miltogramminae)

The first instar larva is described for three species of the kleptoparasitic miltogrammine genus Metopia Meigen: M. campestris (Fallén), M. argentata Macquart and M. argyrocephala (Meigen). Using a combination of light microscopy and scanning electron microscopy, the morphology of the cephaloskeleton as well as the general external morphology are extensively documented, and the phylogenetic implications are discussed. Like other species of Miltogramminae, the first instar of species of Metopia possesses a strong labrum and well‐developed mouth‐hooks. Some other features found in Metopia spp. are rare in the Miltogramminae, such as a serrated ventral surface of the tip of the mouth‐hook and the lack of a posterior spiracular cavity. A few larval features apparently unique for species of Metopia have so far been documented: base of mouth‐hook with a lateral arm‐like extension and abdominal segments with transverse furrow ventrally. The body is equipped with longitudinal cuticular ridges on all segments, which may be a subfamily ground‐plan autapomorphy. Marked morphological and behavioural differences are documented between the first instar of M. argentata and that of M. argyrocephala, the adult females of which are otherwise difficult to separate.     

The male and female first instar larvae of Anaphes victus and A. listronoti (Hymenoptera, Mymaridae)

 Anaphes victus and A. listronoti are two closely related species, respectively solitary and gregarious parasitoids of eggs of the carrot weevil Listronotus oregonensis (Coleoptera, Curculionidae). Both species are sympatric, and the regulation of super- and multiparasitism that occurs regularly in this host is done by larval fights between the mymariform first instar larvae. The morphology of both male and female first instar larvae of A. victus and A. listronoti is described using scanning electron microscopy. Both species have first instar larvae of the mymariform type and present sexual dimorphism. The main difference between the two species is that larvae of A. victus are clearly segmented while larvae of A. listronoti show no visible segmentation. Male larvae of both species have two types of perioral hooks, longer and less dense dorsal setae than females and developed undertail spines. Female larvae of both species have short abdominal setae. These morphological differences are discussed in the context of intra- and interspecific larval competition. Accepted: 25 May 1997     

Larvae of scarab beetles of the subfamily Trichiinae (Coleoptera,Scarabaeidae) from the Russian Far East

Previously unknown larvae of three species (Osmoderma davidis Fairmaire, Gnorimus subopacus Motschulsky, and Lasiotrichius succinctus (Pallas)) of the subfamily Trichiinae are described and illustrated. Original keys to larvae of the subfamilies Trichiinae, Cetoniinae, and Valgiinae and to the genera of the subfamily Trichiinae of the Russian fauna are compiled. The larva of Osmoderma davidis differs from that of O. barnabita Motschulsky in the shape of the frontal sutures and chaetotaxy of the frontal triangle and clypeus. The larvae of Gnorimus subopacus differ from those of G. nobilis (L.) and G. octopunctatus (F.) in the position of symmetrical rows of setae on the anal sternite. The larvae of representatives of the genus Lasiotrichius Reitter, described for the first time, differ from those of all the other genera of the subfamily Trichiinae in the smooth head capsule and in the absence of tubercles on the labrum. These larvae differ from those of the genus Trichius in the completely pale brown basal membrane at the antennae (the membrane of Trichius bears black stripe).     

外寄生性花绒寄甲的寄生选择及其发育表现

"选择-表现"假说认为,成虫应该选择有利于子代发育的高品质寄主,但在寄主选择中,除了寄主品质外,其他因素也可能影响寄主选择决策。寄主选择研究通常以成虫为对象,而对那些初龄幼虫选择寄主的寄生性昆虫很少关注。以1龄幼虫积极搜寻寄主的寄生性花绒寄甲为模式生物,采用双选试验设计,观察了花绒寄甲初孵幼虫在不同体重青杨天牛幼虫之间、在已被寄生与健康的黄粉虫蛹之间的寄生选择性;然后采用回归设计,观察了花绒寄甲寄生若干不同体重的青杨天牛幼虫后的发育表现。研究结果表明,花绒寄甲1龄幼虫对体型较大的青杨天牛幼虫的选择偏好显著大于对体型较小的寄主幼虫的选择,选择大体型幼虫的比值比是选择小体型幼虫的4.55倍;对已被寄生的寄主黄粉虫蛹的选择偏好显著大于对健康寄主蛹的选择,选择已被寄生寄主的比值比是选择健康寄主的12.57倍。寄生青杨天牛幼虫的花绒寄甲幼虫发育历期平均为11.49 d、蛹历期为26.67 d、幼虫发育至成虫的羽化率50%,这些发育表现与寄生时青杨天牛幼虫的体重没有显著关系。但刚羽化寄甲成虫体重与寄生时寄主的体重存在显著的正直线关系:寄生时的寄主体重每增大0.01 g,羽化出的寄甲成虫体重增大近0.08%;方差分析寄甲成虫体重在不同寄主体重水平之间的差异表明,从体型较大寄主中羽化的寄甲成虫体重显著大于从体型较小寄主中羽化的成虫。研究结果说明,花绒寄甲初孵幼虫在寄主选择决策时,在寄主体型大小与被寄生状态之间可能采取折衷对策,而且对体型大小不同的寄主选择与子代发育适合度表现存在一致性,从而支持"选择-表现"假说。     

The Immature Stages of Ptilocolepus extensus McLachlan, 1884 (Trichoptera: Hydroptilidae: Ptilocolepinae) with Notes on Biology

The last instar larva and the pupa of Ptilocolepus extensus McLachlan, 1884, an endemic of the Iberian Peninsula, are described for the first time. The final instar larva of Pt. extensus bears close resemblance to those of Ptilocolepus granulatus (Pictet, 1834), but the abdomen has a well-developed dorsal sclerotized plate on segment VIII; this is a morphological feature which has not been observed in any other Ptilocolepinae. Final instar larvae make dorsoventrally flattened, elongate-oval cases of leaf pieces from several moss and liverwort species; such cases are characteristic of the Ptilocolepinae. Some additional data on biology and geographical distribution are given.     

A description of larval and early juvenile development in Paralomis spinosissima (Decapoda: Anomura: Paguroidea: Lithodidae) from South Georgia waters (Southern Ocean)

The early ontogenetic stages of Paralomis spinosissima Birstein and Vinogradow, 1972, are described in detail and illustrated, with notes on morphological variability observed. Larval and early juvenile development was described to the crab I instar reared under controlled conditions of temperature and food supply. The abbreviated larval development invariably passed through two zoeal stages and the benthic megalopa stage. The larval development was completed without food supply, and food Artemia nauplii were first given after moult to the crab-I stage. Simplification and retarded development of the mouthparts are discussed as a function of lecithotrophy of these larvae and based on morphology no facultative feeding mode is suggested. Lecithotrophy in the Southern Ocean Lithodidae is discussed to be an adaptation allowing independence from seasonal food availability at high latitudes.     

Changes in oxygen uptake and respiratory quotient during post-embryonic development of the leaf-insect Phyllium crurifolium Serville (Phasmida: Phylliidae)

Respiratory changes in laboratory stocks of Phyllium crurifolium, from hatching to instar VI, are described. The significance of these changes is discussed.     

The ontogeny of appendages and carapace of Neonesidea schulzi (Ostracoda: Bairdiidae) from the Red Sea coast,Egypt

The ostracod genus Neonesidea is broadly distributed in shallow marine waters. The ontogeny of the N. schulzi (Bairdiidae) is described in detail by studying the development of the appendages and variations in carapace form, size and structure. Neonesidea schulzi has eight post-embryonic instars, and a gap in its ontogenetic development during instar A-6, where no new Anlage is added. The Anlagen of the copulatory organs and the forked terminal claw of second antenna appear in the seventh (A-1) instar, and the first thoracic legs of podocopid ostracods are shown to descend from the thoracic region. For the first time in ostracods, observations of moulting from sixth and seventh instars are presented.     

Chaoborus crystallinus predation on Daphnia pulex: can induced morphological changes balance effects of body size on vulnerability?

Juvenile Daphnia pulex form neckteeth in reponse to chemicals released by predatory Chaoborus crystallinus larvae. Formation of neckteeth is strongest in the second instar followed by the third instar, whereas only small neckteeth are found in the first and fourth instar of experimental clones. Predation experiments showed that body-size-dependent vulnerability of animals without neckteeth to fourth instar C. crystallinus larvae matched the pattern of neckteeth formation over the four juvenile instars. Predation experiments on D. pulex of the same clone with neckteeth showed that vulnerability to C. crystallinus predation is reduced, and that the induced protection is correlated with the degree of neckteeth formation. The pattern of neckteeth formation in successive instars is probably adaptive, and it can be concluded that neckteeth are formed to different degrees in successive instars as an evolutionary compromise to balance prediation risk and protective costs.     

Hatchling Size and Aspects of Biology in the Deep-Sea Amphipod Genus Eurythenes (Crustacea: Amphipoda)

Records attributed to Eurythenes gryllus are discussed in the light of described morphological variation, and the existence of a third species in the genus is postulated. The presence of five pairs of oostegites in E. gryllus, a character almost unique among the Amphipoda, is confirmed. Brooding females of E. gryllus and E. obesus, captured in deep midwater hauls in the eastern North Atlantic Ocean, are reported for the first time. The 120 mm E. gryllus female carried 237 hatchlings (mean length 11.13 mm) and the 48 mm E. obesus female 47 hatchlings (mean length 7.99 mm). Hatchlings showed variability in size and bodily proportion, and measurements of individual body segments could not be used to predict overall length. Despite this variability, no evidence for more than one instar was found. The hatchlings of E. gryllus are established as a hitherto unrecognized instar in this species. Egg size for E. gryllus and E. obesus is predicted. The biological consequences of the absolute and relative size of hatchling in the two species, and the depths of capture of the E. gryllus female, are discussed.     

Postembryonic development of the female reproductive system in the pycnogonid Propallene longiceps (Pycnogonida,Callipallenidae)

The postembryonic development of the female reproductive system in the pycnogonid Propallene longiceps is examined. The germ cells can be detected first in the later stage of the 3rd instar and become a paired gonad covered with gonadal epithelium in the next instar. The larval gonad changes its shape: paired at the 4th instar, reversed U-shaped at the fifth, unpaired at the sixth, and paired again at the seventh. Oocytes can be distinguished, and the extension of the ovary into the walking legs begins at the 7th instar. Growing oocytes protrude outward from the ovary on cellular stalks in the pedal part. The trunk ovary becomes U-shaped, and the oviducts and genital pores start forming at the 8th instar. The disappearance of trunk ovary begins at the 9th instar, and is complete at the next adult stage. The connection between the pedal ovarian lumen and the genital pores via the oviducts is complete in the adult, and the female reproductive system becomes segmentally arranged. This study confirms that the segmental arrangement of adult female reproductive system in P. longiceps, which is unique among recently described arthropods, is a secondary state in pycnogonids attained by reducing the trunk part of ovary.     

Larval morphology of Agabus clypealis (Thomson, 1867) and A. pseudoclypealis Scholz, 1933 and notes on their distribution (Coleoptera: Dytiscidae)

The third instar larvae of Agabus clypealis (Thomson, 1867) and A. pseudoclypealis Scholz, 1933 are described. Important morphological structures (head, legs, and abdominal segment 8 with urogomphi) are illustrated. Both species share a completely sclerotized abdominal segment 6 with A. setulosus (J. Sahlberg, 1895). Morphological characters and species phenology are discussed in relation to the A. confinis-species group. All available literature records and some new and additional data on distribution of the two species are provided. Agabus clypealis is recorded for the first time from Estonia, and there is no reason to doubt the records of A. pseudoclypealis from Kazakhstan.     

Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Helicoverpa armigera (Lepidoptera: Noctuidae): Effect of prey and predator stages

Abstract Understanding predator–prey interactions has a pivotal role in biological control programs. This study evaluated the functional response of three larval instars of the green lacewing, Chrysoperla carnea (Stephens), preying upon eggs and first instar larvae of the cotton bollworm, Helicoverpa armigera Hübner. The first and second instar larvae of C. carnea exhibited type II functional responses against both prey stages. However, the third instar larvae of C. carnea showed a type II functional response to the first instar larvae of H. armigera, but a type III functional response to the eggs. For the first instar larvae of C. carnea, the attack rate on H. armigera eggs was significantly higher than that on the larvae, whereas the attack rate of the second instar C. carnea on H. armigera larvae was significantly higher than that on the eggs. For the third instar larvae of C. carnea, the attack rate on the larvae was 1.015 ± 0.278/h, and the attack coefficient on the eggs was 0.036 ± 0.005. The handling times of the third instar larvae on larvae and eggs were 0.087 ± 0.009 and 0.071 ± 0.001 h, respectively. The highest predation rate was found for the third instar larvae of C. carnea on H. armigera eggs. Results of this study revealed that the larvae of C. carnea, especially the third instar, had a good predation potential in controlling H. armigera eggs and larvae. However, for a comprehensive estimation of the bio‐control abilities of C. carnea toward H. armigera, further field‐based studies are needed.