Postembryonic development of Nymphon unguiculatum Hodgson 1915 (Pycnogonida, Nymphonidae) from the South Shetland Islands (Antarctica)

Male specimens of the sea spider species Nymphon unguiculatum, carrying eggs, larvae and postlarvae in various stages of development, were collected off the South Shetland Island at water depths between 112 and 472 m in austral summer 2006/2007. Here, we describe the external morphology of four postembryonic stages (protonymphon, instar 1, instar 2, and instar 3) carried by these specimens. We found that (1) protonymphon larvae hatch from the eggs; (2) larvae and postlarval stages have yolk reserves and are characterized by a relatively large size (average body lengths of 0.46, 0.55, 0.65 and 0.73 mm in the successive stages); (3) postlarvae remain on the ovigerous legs of males during several moults; (4) a spinning apparatus is present; (5) the development of walking legs is sequential. The larval and postlarval development of N. unguiculatum is compared with that known from other pycnogonid species.     

Two new species of Ammothea (Pycnogonida, Ammotheidae) from Antarctic waters

Two new species of the genus Ammothea are described from Elephant Island and the South Shetlands Islands, Antarctica. The material was captured during the Polarstern cruise XXIII/8 to the Antarctic Peninsula area. The main features of Ammothea pseudospinosa n. sp. are a proboscis distinctly trilobulated distally with a constriction at 2/3 of its length and dimorphism between the propodi of the anterior (first and second) and posterior (third and fourth) legs, and a trunk: proboscis length ratio of about 1.5. The main features of Ammothea childi n. sp. are a cylindrical proboscis, longer than trunk length, and adults with functional chelifores. These species are compared with their closest congeners from the Southern Ocean: A. pseudospinosa n. sp. with Ammothea spinosa and Ammothea allopodes; A. childi n. sp. with Ammothea gigantea, Ammothea bicorniculata and Ammothea hesperidensis.     

Postembryonic development of the sea spider Ammothella biunguiculata (Pycnogonida,Ammotheidae) endoparasitic to an actinian Entacmaea quadricolor (Anthozoa,Stichodactylidae) in Izu Peninsula,Japan

Postembryonic developmental stages of an endoparasitic pycnogonid, Ammothella biunguiculata in Izu Peninsula, Japan are described. Eleven stages were identified beginning with a protonymphon larva attached to the male oviger. We found endoparasitic individuals in the host actinian from the second to tenth instar, and forms in the ninth stage to adult were found free-living. This indicates a transition from being endoparasitic to free-living during the ninth to tenth instar stages. The first instar protonymphon attached to the adult male oviger has a gland duct on the anterior margin of each chelifore scape which completely disappears with the second instar. The disappearance of the chelifore gland duct coincides with the beginning of an endoparasitic stage in the development of this species. Although the larval morphology and the postembryonic development of pycnogonids have been summarized by several authors, the present study concludes that much remains to be learnt.     

Postembryonic development of Tanystylum bealensis (Pycnogonida, Ammotheidae) from Barkley Sound, British Columbia, Canada

All developmental stages of Tanystylum bealensis are described. This is the first complete developmental series of a pycnogonid species collected from a natural, rather than a laboratory-reared population. Development proceeds through a series of nine instars from egg to adult, with major defining characteristics of the instars being the addition of walking legs, loss of chelifores, and modification of larval appendages into adult palps and ovigers. All stages are free-living on the hydroid Plumularia setacea, except for the first instar (protonymphon), which remains on the ovigers of the adult male for a short time after hatching. Development in T. bealensis is compared to development in both the closely related species T. orbiculare and to the more distantly related Achelia alaskensis.     

Comparative toxicity,growth inhibitory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis (Boisd.)

Eleven monoterpenes, phenylpropenes and sesquiterpenes were evaluated for their insecticidal and growth inhibitory activities against the second and fourth larval instars of Spodoptera littoralis. Among the tested compounds, 1,8-cineole revealed the highest fumigant toxicity against the 2nd and 4th larval instars with LC₅₀ values of 2.32 and 3.13 mg/L air, respectively. The monoterpenes, p-cymene, α-terpinene, (−)α-pinene and (−)-carvone were highly toxic to both larval stages as their LC₅₀ values ranged between 7.35 and 13.79 mg/L air against 2nd larval instar and between 14.66 and 32.02 mg/L air against 4th larval instar. In topical application assay against the 4th larval instar, (−)-carvone (LD₅₀ = 0.15 mg/larva) and cuminaldehyde (LD₅₀ = 0.27 mg/larva) were the most potent contact toxicants. In residual film assay, trans-cinnamaldehyde, (−)-citronellal and p-cymene showed the highest insecticidal activity against the 2nd larval instar, while α-terpinene and (−)-carvone were most effective compounds against the 4th larval instar. Moreover, the tested compounds caused strong growth reduction of both larval stages with growth inhibition higher than 80% in the 2nd larval instar and higher than 70% in the 4th larval instar. On the other hand, (−)-carvone, cuminaldehyde and (Z,E)-nerolidol showed pronounced inhibitory effects on acetylcholinesterase (AChE) and adenosine triphosphatases (ATPases) activity of S. littoralis larvae. Cuminaldehyde (IC₅₀ = 1.04 mM) and (Z,E)-nerolidol (IC₅₀ = 0.02 mM) caused the highest inhibition of AChE and ATPases, respectively. Taken together, the results indicate that monoterpenes, phenylpropenes and phenylpropenes could be used to develop new botanical insecticides for S. littoralis management.     

Host suitability and fitness-related parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae) as a parasitoid of the cabbage looper,Trichoplusia ni (Lepidoptera: Noctuidae)

The seven age-classes of Trichoplusia ni (Hübner) larvae evaluated in this study as hosts of Campoletis sonorensis indicates that early 2nd larval instar (3–5 day-old larvae) of T. ni represents the most suitable host stage for the development of the larval endoparasitoid C. sonorensis. The higher suitability of early 2nd larval instar of T. ni resulted in more parasitised larvae, a higher rate of successful parasitoid emergence, a higher rate of female progeny, and a lower rate of immature parasitoid mortality. The fitness gain of C. sonorensis on late 1st larval instar (2 day-old larvae) and late 2nd larval instar –early 3rd instars (6–8 day-old larvae) stages of T. ni is negatively affected by the trade-offs between the different physiological and behavioral characteristics influencing their suitability as hosts of C. sonorensis.     

Amino acid and protein changes in the haemolymph of developing fourth instar Chironomus tentans

The concentration of free amino acids, total soluble protein, and haemoglobin in the haemolymph of fourth instar Chironomus tentans was investigated.The concentration of the free amino acid pool increases between the early (15.7 mM/l) and mid-(33.9 mM/l) fourth larval stages followed by a decline during the late (16.9 mM/l) fourth larval period. Alanine, serine, and the amides of aspartic acid and glutamic acid are the predominant free amino acids at all stages. Physiological fluid analysis of late fourth instar haemolymph detected 32 ninhydrin positive components including 18 common amino acids plus homoarginine, ornithine, citrulline, β-alanine, α-aminoadipic acid, α-aminoisobutyric acid, and sarcosine.The concentration of total soluble protein steadily increases during fourth instar larval development to a maximum of $\text{9.3}\text{g}\text{100}\text{ml}$ followed by a decline during the pharate pupal period. A similar pattern of variation occurs in haemoglobin content which comprises from 51 to 66% of Chironomus tentans haemolymph protein.The mM percentage of individual amino acids of total haemolymph protein varies little during the fourth instar. At all stages alanine and aspartic acid are the predominant amino acids.     

Larvae of three sea spider species of the genus <Emphasis Type="Italic">Nymphon</Emphasis> (Arthropoda: Pycnogonida) from the White Sea

Larvae of three Nymphon species are described. For Nymphon brevirostre Hodge, 1863 and Nymphon micronyx Sars, 1888 protonymphon larvae are examined, larvae of N. micronyx have been studied for the first time. The fine external morphology of larvae is studied in detail using SEM methods; the internal structure of N. brevirostre protonymphon is additionally described. SEM data on external morphology and fine surface structures are given for several postembryonic stages of Nymphon grossipes Fabricius, 1780. Different types of postembryonic development are revealed in examined Nymphon species. N. brevirostre and N. micronyx have a “typical protonymphon” developmental pathway. A special developmental pathway named “lecithotrophic protonymphon” is suggested for N. grossipes and other Nymphonidae having large yolky eggs.     

Severe developmental timing defects in the prothoracicotropic hormone (PTTH)-deficient silkworm,Bombyx mori

The insect neuropeptide prothoracicotropic hormone (PTTH) triggers the biosynthesis and release of the molting hormone ecdysone in the prothoracic gland (PG), thereby controlling the timing of molting and metamorphosis. Despite the well-documented physiological role of PTTH and its signaling pathway in the PG, it is not clear whether PTTH is an essential hormone for ecdysone biosynthesis and development. To address this question, we established and characterized a PTTH knockout line in the silkworm, Bombyx mori. We found that PTTH knockouts showed a severe developmental delay in both the larval and pupal stages. Larval phenotypes of PTTH knockouts can be classified into three major classes: (i) developmental arrest during the second larval instar, (ii) precocious metamorphosis after the fourth larval instar (one instar earlier in comparison to the control strain), and (iii) metamorphosis to normal-sized pupae after completing the five larval instar stages. In PTTH knockout larvae, peak levels of ecdysone titers in the hemolymph were dramatically reduced and the timing of peaks was delayed, suggesting that protracted larval development is a result of the reduced and delayed synthesis of ecdysone in the PG. Despite these defects, low basal levels of ecdysone were maintained in PTTH knockout larvae, suggesting that the primary role of PTTH is to upregulate ecdysone biosynthesis in the PG during molting stages, and low basal levels of ecdysone can be maintained in the absence of PTTH. We also found that mRNA levels of genes involved in ecdysone biosynthesis and ecdysteroid signaling pathways were significantly reduced in PTTH knockouts. Our results provide genetic evidence that PTTH is not essential for development, but is required to coordinate growth and developmental timing.     

Variation nycthémérale de la répartition verticale et de l'efficacité de collecte du zooplancton en lagune Ebrié (Côte d'Ivoire)

Vertical distribution and night and day collecting efficiencies of both nets and a Schindler trap, were studied in two shallow (4 m) unstratified bays of the Ebrié Lagoon. Some of the organisms migrate (Mysidacae, copepodite and adult stages of Acartia clausi and Pseudodiaptomus hessei) and others do not (all the nauplii, copepodite and adult stages of Oithona brevicornis, rotifers, mollusca larvae). The first are found more or less near the bottom at noon and are evenly distributed throughout the water at the beginning of the night. Mysidaceae and P. hessei strongly exhibit this pattern, none (Mysidacea) or very few specimens being collected in the water during the day. For A. clausi, depth concentration increases from C1 to adult. Net and trap estimated night densities are higher than the day ones for migrating organisms, except for C1 or A. clausi. The Night/Day ratios are equal to 28 (net) and 25 (trap) for P. hessei, 5 and 13 for the adults of A. clausi and lies between 2 and 5 for the different copepodite stages of this last species. The possible causes and consequences of the vertical distribution are discussed, the interference of turbulence on vertical distribution being outlined.     

The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).     

Light and electron microscopic studies on osmoregulatory tissue in the developing brown shrimp, Penaeus aztecus

In larval and early postlarval brown shrimp, Penaeus aztecus, portions of the branchial chamber are lined by a tissue which appears ultrastructurally to be modified for osmoregulation. The distribution of this tissue, the larval stages in which it occurs, and its appearance with the light and electron microscope are presented. The significance of the distribution and ultrastructure of this modified tissue is discussed.     

Intraguild predation by the generalist predator Orius majusculus on the parasitoid Encarsia formosa

Intraguild predation of Orius majusculus (Reuter) (Heteroptera: Anthocoridae) on Encarsia formosa (Gahan) (Hymenoptera: Aphelinidae), both natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was studied under laboratory conditions. The experiments quantified prey consumption by 5th instar nymphs and adults of O. majusculus offered unparasitised 3rd, early 4th or 4th instar B. tabaci nymphs or parasitised nymphs containing 2nd or 3rd larval instar or pupal parasitoids. In addition, prey preference of the two stages of O. majusculus for parasitised or unparasitised whitefly nymphs was studied using nine different prey combinations. Both predator stages readily preyed upon on both unparasitised and parasitised B. tabaci. In no-choice experiments, predation on 3rd instar E. formosa by adult predators was the highest, while predator nymphs preyed most on unparasitised 3rd instar B. tabaci and 2nd instar parasitoids. Predation of predator stages was lowest on 4th instar B. tabaci and E. formosa pupae. In all prey combinations, both stages of O. majusculus showed a significant preference for parasitised over unparasitised whitefly nymphs except for the combination of 5th instars of O. majusculus with early 4th instar whiteflies and E. formosa pupae. The results indicate that intraguild interactions between O. majusculus and E. formosa may have negative effects on biological control of B. tabaci.     

Purification and expression of glutathione S-transferase from a Malaysian population of Aedes albopictus (Diptera: Culicidae)

Glutathione S-transferase (GST) from the 4^th instar larvae of the dengue vector Aedes albopictus was purified by glutathione-agarose affinity chromatography and characterised using SDS-PAGE. The expression of the purified enzyme in the life stages and insecticide treated populations of Ae. albopictus as well as its cross-reactivity with larval GST of two dipteran species Aedes aegypti and Batrocera papayae were observed using western blotting. The purified GST had a specific activity of 196.0 ± 11 μmol/min/mg with a purification fold and yield of 28 and 69%, respectively. The SDS-PAGE analysis of the purified GST depicted a single band size of 23 kDa. The GST was expressed in all the larval and adult stages of Ae. albopictus with the exception of the pupal stage. However, the expression level in the adult stage was visibly reduced as compared to the larval stages. Western blotting analysis showed no cross-reactivity with the GST of Ae. aegypti (4^th instar) and B. papayae (3^rd instar) larvae. The expression of this enzyme was not inducible by exposure to the insecticides dichlorodiphenyltrichloroethane (1.25 mg/L) and malathion (0.3125 mg/L).     

Seasonal phenology and stage-specific parasitism of the apple ermine moth, Yponomeuta malinellus Zeller, in Korea

The apple ermine moth, Yponomeuta malinellus Zeller (Lepidoptera: Yponomeutidae), is a tent caterpillar that feeds on Malus spp. in Korea. Populations of the moth in native areas appeared to be regulated by the assemblage of parasitoids. Phenological associations between host stages and parasitoids, susceptible stage(s) of the host for each parasitoid, and stage‐specific parasitism were studied. The egg larval parasitoid Ageniaspis fuscicollis (Dalman) had highest parasitism of first instar larvae (24%), with 14% parasitism of other larval stages. Dolichogenidea delecta (Haliday) was recovered from all larval instars with the highest parasitism rate of second instar larvae (20.1%), followed by 19.9% parasitism of mid‐larval hosts. Herpestomus brunicornis Gravenhorst was reared from second instar larvae through to pupal collection, and had the highest parasitism rate (29.9%) at the pupal stage. The larval pupal parasitoid Zenillia dolosa (Meigen) was recovered from mid‐larval to pupal stages with the highest parasitism rate (5.5%) occurring in third to fourth instar larvae. The host stages for developing A. fuscicollis completely overlap with those of D. delecta, and with those of H. brunicornis to some degree. A statistically significant negative correlation exists between A. fuscicollis and these dominant parasitoids, indicating competitive interaction within the host.     

Life Cycle of Glyphepomis spinosa Campos & Grazia (Hemiptera: Pentatomidae): a New Pest of Rice in Brazil

Nymph and adult biology of Glyphepomis spinosa Campos & Grazia (Hemiptera: Pentatomidae) was studied on rice plants under laboratory and greenhouse conditions. The full life cycle of G. spinosa lasted 50.1?day. Nymph development ranged from 2.7?days for the first instar up to 11.9?days for the fifth instar. The egg stage showed the highest per capita rate of mortality (0.16). Nearly 13% of all eggs were laid on the same day. The sex ratio was 0.5. The average hatching rate was 58.0%. Pre-oviposition, oviposition, and post-oviposition periods took 12.9, 34.4, and 6.2?days, respectively.