Skeletochronological estimation of age and growth of loggerhead sea turtles (Caretta caretta) in the western South Atlantic Ocean

Age and growth are important parameters for better understanding of life history and population dynamics of animal species, as well as for formulating management strategies. However, these data are difficult to obtain for sea turtles because of overall slow growth, delayed maturation and highly migratory behaviour. The loggerhead sea turtle, Caretta caretta, is a widely distributed species, globally listed as endangered. Although the species has been well‐studied in some regions, little is known about various aspects of its biology in other populations, such as those in the waters of the western South Atlantic Ocean, especially outside nesting areas. To address age and growth, loggerhead turtles found dead stranded on the northern coast of the state of Rio Grande do Sul during a period of 16 years (1994–2010) were utilized for estimation of age and growth rates using skeletochronology. The individuals analyzed were predominantly neritic juveniles, ranging from 53 to 101 cm curved carapace length (CCL; mean = 71 cm), with estimated ages between 10 and 29 years (mean = 15 years). Mean estimated annual growth rate was 2.1 cm CCL year^?1 (1.9 cm SCL yr^?1), showing large variation among individuals and between successive years in the same individual. Generalized additive mixed models analysis indicated that growth response was influenced by age, CCL and year. The results demonstrated that the southern coast of Brazil is an important area for the development of neritic juveniles of this species, which appear to recruit to this region beginning at about 12 years of age and sizes greater than 55 cm CCL.     

Vertical stratification of beetles in tropical rainforests as sampled by light traps in North Queensland,Australia

How arthropods are distributed within the vertical structure of tropical rainforests is of considerable interest to ecologists. Here, we examine how light trapped beetles are distributed in tropical rainforest in North Queensland, Australia. In January and July 2012, traps were suspended 0 m, 10 m, 20 m and 30 m above the ground in five locations with no more than one trap at any single location on any night. Maximum canopy height at the sites was 35 m. A total of 7299 individuals of 492 morphospecies and 66 families were collected. The species abundance‐based coverage estimator predicted a total species richness of 765. Sample completeness decreases with increasing height from the ground suggesting higher strata were less well sampled. Distance‐based redundancy analysis showed species richness was significantly different between 30 m and all other levels but not between other paired strata. In contrast, both species composition and family composition were significantly distinct for all strata pairs except 10 m with 20 m, and 20 m with 30 m, suggesting that the most distinct strata were 0 m and 30 m. The first two axes of ordination and hierarchical clustering accounted for 46.5% and 17.4% of species composition variation corresponding with season and stratum, respectively. Family level analyses gave similar results to those at the species level. We found stratification of different feeding guilds with herbivores comprising a larger percentage of species in higher strata, whereas saprophages were restricted to the lower strata, reflecting the availability of key resources for these guilds. Fewer species or families were found to be indicators of strata, as measured using IndVal, than for Malaise and flight interception traps (FIT). Dytiscidae and Hydraenidae were abundant but had not been collected using Malaise and FIT. Which species or families are indicators of strata depends on sampling method suggesting multiple sampling methods should be used to establish indicators.     

Tree colonization by the Asian longhorn beetle,Anoplophora glabripennis (Coleoptera: Cerambycidae): effect of habitat and tree suitability

Tree colonization and feeding activity of the invasive wood‐borer Asian longhorn beetle (Anoplophora glabripennis), an Asian pest introduced into North America and Europe, was studied in a newly invaded area in Italy. The hypothesis being tested was that the reproductive success of the insect depend on habitat type and tree suitability. Adult beetles were caged on branches of host and nonhost species, in both urban and forest habitats. Two months later, number and size of feeding patches on plant tissues, eggs laid, and surviving larvae were assessed. Bark concentration of C and N was also measured from the same trees. Results indicated that the mean area of plant tissues consumed by adult feeding was significantly larger on trees growing in forest than in urban habitat, although within the same habitat there were no differences between susceptible and nonsusceptible trees. ALB tree colonization, in terms of number of eggs laid and young larvae survival, was not affected by habitat while it was higher on susceptible trees. Although trees growing in forests had a lower nitrogen concentration, they allowed colonization rates similar to those of trees growing in the urban habitat. Hence, the amount of carbon and nitrogen did not fully explain tree suitability or habitat selection. We suggest compensatory feeding as a potential mechanism that might explain this peculiar situation, as supported by a more intensive feeding activity recorded on trees in the forest. Suitability of different trees may be due to other factors, such as secondary chemical compounds.     

The occurrence of apical labial sensilla in the Aleyrodidae and evidence for a contact chemosensory function

Scanning electron microscopy of the apex of the labium of six species of whitefly [Aleurothrixus floccosus (Maskell), Aleyrodes spiraeoides Quaintance, Bemisia tabaci (Gennadius), Dialeurodes citri (Ashmead), Parabemisia myricae (Kuwana), and Trialeurodes vaporariorum (Westwood)], revealed that all possess seven pairs of sensilla symmetrically positioned on either side of the labial groove. Transmission electron microscopy revealed that in P. myricae, sensilla 1, 5, 6 & 7 are innervated each by a single dendrite, sensilla 2 & 4 are innervated by three dendrites each, and sensillum 3 is innervated by four dendrites. Multiple innervation of sensilla 2, 3 & 4 suggests a chemosensory or mechano-chemosensory function. Longitudinal sections of sensilla 2 & 4 showed that the sensilla were hollow with an apical pore, providing further morphological evidence for a chemosensory function. One dendrite appeared to end at the base of sensillum 2, suggesting that at least sensillum 2 has a dual mechano-chemosensory function. The presence of contact chemoreceptors on the labial tip may help explain how P. myricae can discriminate between hosts before probing.

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Zusammenfassung Untersuchungen mit dem Rasterelektronenmikroskop an sechs Spezies von Weißen Fliegen [Aleurothrixus floccusus (Maskell), Aleyrodes spiraeoides Quaintance, Bemisia tabaci (Gennadius), Dialeurodes citri (Ashmead), Parabemisia myricae (Kuwana), und Trialeurodes vaporariorum (Westwood)] zeigten, daß bei allen Arten die Spitze des Labiums mit sieben Paaren von Sensillen versehen ist, die symmetrisch auf jeder Seite der Lippenspalte angeordnet sind. Die Sensillen sind klein (ca. 1–4 m lang, 0.1–0.6 m breit) und in beiden Geschlechtern aller Arten ähnlich gestaltet. Mittels Transmissionelektronenmikroskopie wurde gezeigt, daß in P. myricae die Sensillen 1, 5, 6 & 7 durch jeweils einen einzigen, die Sensillen 2 & 4 durch jeweils drei und die Sensille 3 durch vier Dendriten innerviert werden. Die multiple Innervierung der Sensillen 2, 3 & 4 läßt eine chemosensorische oder mechanisch-chemosensorische Funktion vermuten. Längsschnitte durch die Sensillen 2 & 4 lieferten weitere Hinweise auf eine chemosensorische Funktion: die Sensillen sind hohl und an der Spitze mit einer Pore versehen. Wir erhielten keine schlüssigen Beweise für die Existenz von apikalen Poren an den anderen Sensillen. Einer der Dendriten an der Sensille 2 scheint an der Sensillenbasis zu enden; dies deutet darauf hin, daß zumindest diese Sensille ein Rezeptor sowohl für mechanische als auch für chemische Reize ist. Die Existenz dieser Kontakt-Chemorezeptoren an der Labiumspitze könnte erklären, wie P. myricae bereits vor dem Probestich zwischen Wirtspflanzen zu unterscheiden vermag. Diese Ergebnisse lassen außerdem vermuten, daß die sensorischen Aspekte des Wirtsfindung bei Weißen Fliegen grundsätzlich verschieden sind von denjenigen bei Blattläusen, welche nur über mechanische Rezeptoren an der Spitze der Unterlippe verfügen.

     

Virgin male mating advantage in a primitive acoustic insect (Orthoptera: Haglidae)

Male reproductive behavior in the relict flightless haglid, Cyphoderris strepitans,entails the generation of sound signals and the provision of nuptial gifts to mates. These food gifts take two forms: (1) a gelatinous mass (spermatophylax) augmenting the spermatophore and (2) fleshy metathoracic wings adapted to be eaten. The female consumes a portion of the male's underwings during courtship and copulation and the spermatophylax afterward. The incidence of wing-feeding wounds can be used to monitor the mating success of field-caught males. If, when a male mates, he compromises his ability to provide subsequent nutritive gifts, females would benefit by mating with virgin rather than nonvirgin males. To test this, mating success of virgin and nonvirgin males was compared in a field population. Virgins were found to obtain more matings than explained by their numbers relative to nonvirgins in the population. We conclude that, having mated, a male is at a disadvantage, relative to his virgin competitors, in securing further matings.     

Activity budget and diet of patas monkeys in Kala Maloue National Park,Cameroon: A preliminary report

A preliminary study was carried out on the feeding ecology of patas monkeys in the rainy season in Cameroon. Their daily activity rhythm revealed two active peaks. The proportion of time spent on feeding with respect to waking time was 30%. Patas monkeys largely depended on the flowers and buds of herbaceous plants and the larvae of insects for their diet as they ranged widely. Patas monkeys spent more time in feeding and travelled for a longer distance per day than the sympatric primate species, the tantalus monkey. It is considered that these findings reflected the large amount of food requirement due to the large body size, as well as the low density and high degree of dispersal of their food.     

Digestion rate in relation to alternative feeding in three species of polyphagous predators

Abstract. 1. Disappearance of different amounts of aphid ingested by three species of polyphagous predators, the carabids Bembidion lampros (Herbst) and Nebria brevicollis (F.) and the staphylinid Philonthus cognatus Stephens, was monitored by a quantitative enzyme-linked immunosorbent assay (ELISA). The effect on the rate of inactivation of prey antigens by the ingestion of subsequent, non-aphid food was also studied.
2. Antigen inactivation was significantly more rapid in the staphyilinid than in the carabids.
3. No statistically significant differences were found in the rate of antigen inactivation between beetles which consumed only aphids and those which were given a different type of food after feeding on aphids; the detection period was longer in the former groups. A higher proportion of beetles with low levels of aphid antigen were found earlier in the latter group.
4. The results did not unequivocally support the prediction derived from optimal digestion theory that beetles without continuous access to food would retain an initial meal longer than beetles with unlimited access.     

Aphid feeding deterrency of ellagitannins, their phenolic hydrolysis products and related phenolic derivatives

Feeding deterrent activities of ellagic acid, two ellagitannins, gallic acid, pyrogallol, and several gallic acid derivatives towards three species of aphids were determined. The most sensitive species tested was Schizaphis graminum (Rondani), the least sensitive was Acyrthosiphon pisum (Harris). Myzus persicae (Sulzer) was of intermediate sensitivity. Ellagic acid (ED₅₀=15 ppm) and n-decyl gallate (ED₅₀=16 ppm) were particularly potent against S. graminum, while n-octyl gallate was the most active compound tested against A. pisum (ED₅₀=182 ppm) and M. persicae (ED₅₀=56 ppm). The ellagitannins, geraniin and pedunculagin, were active against S. graminum and M. persicae, but not against A. pisum. Methylation of the free hydroxyl groups of gallic acid resulted in a large decrease in activity, while esterification of its carboxyl group with alkyl chains of increasing length resulted in increasing activity against S. graminum. Against A. pisum and M. persicae, ellagic acid, gallic acid and 3,4,5-trimethoxybenzoic acid were inactive, whereas pyrogallol and the gallate esters were at least moderately active as feeding deterrents.

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Résumé L'examen a porté sur l'action répulsive, lors de l'alimentation de trois espèces de pucerons, de l'acide ellgique, de deux ellagitanins, de l'acide gallique, du pyrogallol et de plusieurs dérivés de l'acide gallique. Schizaphis graminum Rondani a été l'espèce la plus sensible, tandis que Acyrthosiphon pisum. Harris a été la moins sensible; la sensibilité de Myzus persicae Sulzer était intermédiaire. L'acide ellagic (ED₅₀=15 ppm) et le n-décyl gallate (ED₅₀=16 ppm) ont été particulièrement actifs contre S. graminum, tandis que le n-octyl gallate a été le produit le plus actif contre A. pisum (ED₅₀=182 ppm) et M. persicae (ED₅₀=56 ppm). Les ellagitanins, géraniine et pédunculagine ont été actifs contre S. graminum et M. persicae, mais pas contre A. pisum. La méthylation des groupes hydroxyl libres de l'acide gallique a réduit fortement l'activité, tandis qu l'estérification de son groupe carboxyl avec des chaînes alkyl de longuers croissantes a augmenté l'activité contre S. graminum. Les acides ellagique, gallique et 3,4,5-triméthoxybenzoïque ont été inactifs contre A. pisum et M. persicae, tandis que le pyrogallol et les esters de gallate on été pour le moins des répulsifs modérément actifs au cours de l'alimentation.

     

A laboratory study of feeding and assimilation in Euchlanis dilatata lucksiana

Feeding of Euchlanis dilatata lucksiana, a brachionid rotifer isolated from the Loosdrecht Lakes (The Netherlands), was examined in the laboratory using ¹⁴C-labelled food. The gut-filling time at a food concentration of 9.6 µg C ml^–1 was about 15 minutes. Animals which were fed on 3 size fractions of the lake seston (< 7 µm, 7–15 µm, and 15–33 µm) showed a clear preference (Jacobs' selectivity index) for the largest size fraction. This fraction was composed predominantly of filamentous cyanobacteria. For animals weighing 0.37–0.49 µm C ind.^–1 the daily ration (daily food consumption per unit body weight × 100) ranged from 50 to 100% at food levels of 2 mg C l^–1 and below, but increased to 150–250% at food concentrations of 5 mg C l^–1 and above. The assimilation efficiency was 100% up to 5 mg C l^–1 of food, but decreased to about 80% at higher food levels.     

Sap feeding by the marsupial Petaurus australis: an enigmatic behaviour?

Summary The Yellow-bellied Glider, Petaurus australis, was observed to feed sporadically but extensively on eucalypt sap. Gliders extracted sap by making incisions into the bark with their procumbent lower incisor teeth and licking the resulting exudate. Less than 1% of possible trees were incised for sap. Sap flow and sap-sugar concentration were estimated for eight sap-site trees and eight non sap-site trees at intervals during an 18 month period. Measurements of sap-sugar concentration differed substantially among trees but fluctuated between sample periods independent of glider use. Sap flow measurements, were always higher for those trees currently in use by gliders, although the particular sap-site trees comprising this group varied between sample periods. The variation in sap flow occurred indenpendent of the incidence of rainfall or the type of microhabitat the tree occupied. Experimental incising of trees, designed to mimic the effects of feeding by gliders, failed to show any effect on sap flow. This suggests that the incidence of sap feeding is determined by a tree's pattern of sap flow and that there may be trees with unusual patterns of sap flow which gliders select as the most favourable trees to incise.