Toxicity of Fipronil to the Predatory Lacewing Chrysoperla carnea (Neuroptera: Chrysopidae)

All the developmental stages of Chrysoperla carnea (Stephens) were treated with fipronil using different modes of exposure under laboratory conditions. Eggs were dipped in an aqueous range of concentrations and no effects were recorded, except at the highest concentration. Pupae treated topically on the silk cocoon moulted to healthy adults, without any deleterious effects on their reproduction. In contrast, larvae and adults were killed by the compound, irrespective of the mode of treatment, even at rates below the maximum field recommended rate in Spain (30 g c.p./ha). Sublethal concentrations of fipronil did not affect the fecundity or fertility of survivors. We conclude that fipronil is very toxic under laboratory conditions to this predatory lacewing.     

Predatory behaviour of lutzia on Culex fatigans

The carnivorous mosquito Lutzia (= Culex) raptor devours 20 to 50 larvae (third instar) of Culex fatigans in a day. The predatory capacity of L. raptor is not influenced by changes in volume of water, but significantly influenced by changes in prey density. With increasing prey density, the percentage of prey killed and left unconsumed increases. The duration required to subdue and consume a single larva is 15 min for L. raptor previously deprived of food for 3 to 24 hrs; the handling duration of prey increases to 20 min for the predator previously deprived food for 1 hr. The duration increases with increasing prey size; L. raptor requires 1, 6, 62 or 113 min to handle a single II, III, IV or mini pupa of Culex fatigans weighing 0.2,1.2,4.2 and 4.0 mg respectively.     

Novel protein from larval sponge cells,ilborin, is related to energy turnover and calcium binding and is conserved among marine invertebrates

Sponges (phylum Porifera) are early-branching animals, whose outwardly simple body plan is underlain by a complex genetic repertoire. The transition from a mobile larva to an attached filter-feeding organism occurs by metamorphosis, a process accompanied by a radical change of the body plan and cell transdifferentiation. The continuity between larval cells and adult tissues is still obscure. In a previous study, we have produced polyclonal antibodies against the major protein of the flagellated cells covering the larva of the sponge Halisarca dujardini, used them to trace the fate of these cells and shown that the larval flagellated cells transdifferentiate into the choanocytes. In the present work, we identified the sequence of this novel protein, which we named ilborin. A search in the open databases showed that multiple orthologues of the newly identified protein are present in sponges, cnidarians, flatworms, ctenophores and echinoderms, but none of them has been described yet. Ilborin has two conserved domains: triosephosphate isomerase-barrel, which has enzymatic activity against macroergic compounds, and canonical EF-hand, which binds calcium. mRNA of ilborin is expressed in the larval flagellated cells. We suggest that the new protein is involved in the calcium-mediated regulation of energy metabolism, whose activation precedes metamorphosis.     

A Revision of South American Austroperlidae (Plecoptera)

The South American Austroperlidae are revised. Klapopteryx kuscheli and Penturoperla barbata are redescribed. The male and nymph of K. armillata are described and figured for the first time and the female genitalia redescribed. K. costalis is declared a junior synonym of K. armillata. K. barilochensis is transferred to Andesobius new genus and redescribed. New family and generic diagnoses and keys to genera and species are given.     

Thyroxine as a Mediator of Metamorphosis of Atlantic Halibut, Hippoglossus Hippoglossus

The response of morphological, histological and endocrinological development to exogenous 1-thyroxine (T₄) and to water depth during metamorphosis in Atlantic halibut, Hippoglossus hippoglossus, was investigated. Exogenous T₄ was given in daily doses of 0.1, 0.05 ppm or a control treatment to halibut larvae at 550 daydegrees (posthatch, premetamorphic) for 14 days. Water depths of 40 cm, 10 cm or 1.5 cm were used to rear halibut larvae from 590 daydegrees for 21 days. Halibut larvae given exogenous T₄ at 0.1 ppm had accelerated eye migration relative to MH in fish given 0.05 ppm and in control fish. Pigmentation was correlated with dosage after 14 days. The volume of thyroid tissue was expressed in a dose-dependent manner and exhibited a size-dependency within each treatment. However, the follicles were atypical with reduced colloid, increased lumen and low epithelial cells even in the control group. The results indicate that T₄ is a mediator in halibut metamorphosis. In the water depth experiment, only cortisol levels of larvae reared in 1.5 cm water were significantly affected after 21 days, but this was not correlated with metamorphic rate. Hormone profiles, morphological changes and size suggest the existence of a window of opportunity for metamorphosis in halibut extending from about 16 mm and tapering off about 21 mm SL. The pooled hormone profiles indicate the commencement of a hormonal cascade similar to that of other flatfishes during metamorphosis. The results indicate that growth, neural and skeletal transformation, and pigmentation are biochemically separate processes in the metamorphosis of Atlantic halibut.     

A dipteran from south of the Antarctic Circle: Belgica antarctica (Chironomidae) with a description of its larva

Belgica antarctica Jacobs is recorded for the first time from two localities south of the Antarctic circle: Orford Cliff (66°55'S) on the Continental mainland and the Refuge Islands (68°21'S). The larva is described, and measurements of head capsule lengths indicate four instars. The larvae south of the Antarctic circle appear to be slightly smaller than those from within the main distributional range. Belgica antarctica is certainly the earth's southernmost free-living holometabolous insect, but the flea Glaciopsyllus antarcticus has been recorded 14 minutes of latitude farther south than the southernmost records of B. antarctica.     

Photoreceptive organs in larvae of Spionidae (Annelida) and Sipuncula

A pair of spherical unpigmented ocelli in addition to pigmented eyes have been observed in the anterior part of the prostomium in larvae of more than 40 species of Spionidae examined alive with light microscopy. Ocelli become visible in larvae at the one- to three-segment stage, increase in size as growth proceeds, and probably disintegrate in the course of metamorphosis because they were not observed in adults and settled juveniles. One pair of transparent, spherical bodies is also found in the anterior part of the head of planktotrophic pelagosphera larvae of Sipuncula. These bodies are in a similar position and have a similar appearance and size to unpigmented ocelli in Spionidae larvae. A pair of epidermal invaginations, densely covered with short cilia, is also observed antero-laterally in the head in pelagospheras of one species. These invaginations appear similar to the nuchal organs present in many polychaete larvae. Photoreceptive organs so far reported for sipunculan larvae comprise only pigmented eyes. Unpigmented ocelli and nuchal organs have never been reported in pelagospheras. Further ultrastructural investigations on sipunculan larvae are encouraged to clarify the composition, function and morphogenesis of transparent, spherical bodies and ciliated invaginations in the anterior part of the head. Such investigations may help to better understand the nature of photoreceptive structures and nuchal organs in Sipuncula, and also contribute to phylogenetic hypotheses regarding relationships of the Sipuncula and Annelida.     

The life cycle of Anguina agrostis: Development in host plant

Bird A.F. and Stynes B.A. 1981. The life cycle of Anguina agrostis: Development in the host plant. Internationaljournal for Parasitology11: 431–440. The growth and development of the infective second stage “dauer” larvae (DL₂) of Anguina agrostis into adults have been followed under field conditions in rye grass (Lolium rigidum). Three moults were observed to occur during the parasitic phase of development. From the third (second parasitic) moult onwards, there was much more variability in the size of the female nematodes than in the males and sexual dimorphism became very pronounced. The transition from the DL₂ to the second stage parasitic larva (PL₂) is marked by the disappearance of the numerous lipid storage granules which are characteristic of the DL₂, and the development in the PL₂ of an intestine which becomes more pronounced in each succeeding stage, particularly in the adult female. Anguina agrostis is unusual among parasitic nematodes in that the DL₂ has the thickest cuticle of all stages, including adults. The L₄ and adult males have thicker cuticles than the females at the same stages of development. Moulting appears to involve resorption of the innermost basal zone of the shed cuticle as well as morphological and chemical changes to the epicuticle.     

The life history of Labiostrongylus eugenii, a nematode parasite of the Kangaroo Island wallaby (Macropus eugenii): development and hatching of the egg and the freeliving stages

Smales L. R. The life history of Labiostrongylus eugenii, a nematode parasite of the Kangaroo Island Wallaby (Macropus eugenii): development and hatching of the egg and the free living stages. International Journal for Parasitology7: 449–456. Labiostrongylus eugenii (Trichonematidae) occurs in the stomach of the Kangaroo Island Wallaby. Egg morphology is similar to that of other strongyloids. When incubated at 25°C embryogenesis is completed in about 30 h. An incomplete moult occurs within the egg, and larvae hatch at a sheathed second-stage $\text{43}\text{1}\text{2}\text{–83}\text{1}\text{2}$ h later. Development occurred at all temperatures between 2° and 37°C with an optimum about 25°C and an upper limit near 37°C. The hatching process is very rapid, taking about 2 min. It is signalled by increased larval activity followed by a change in shell permeability. The larva hatches at that pole of the shell which has become plastic.The sheathed second-stage larva measures 659.50 ± 22.54 μm by 27.98 ± 1.22 μm. Its internal structures are concealed by a mass of opaque granules which were demonstrated as neutral lipid by oil red O staining. A second incomplete moult at 3–4 days results in a doubly sheathed infective larva from which the lipid gradually disappears. The mouth never appears patent and the larvae neither feed nor grow but rather decrease in size with age. Optimal temperatures for larvae range between 15°–25°C with 37°C about the upper limit. The significance of this developmental pattern is discussed.