Drosophila Zic family member odd-paired is needed for adult post-ecdysis maturation

Specific neuropeptides regulate in arthropods the shedding of the old cuticle (ecdysis) followed by maturation of the new cuticle. In Drosophila melanogaster , the last ecdysis occurs at eclosion from the pupal case, with a post-eclosion behavioural sequence that leads to wing extension, cuticle stretching and tanning. These events are highly stereotyped and are controlled by a subset of crustacean cardioactive peptide (CCAP) neurons through the expression of the neuropeptide Bursicon (Burs). We have studied the role of the transcription factor Odd-paired (Opa) during the post-eclosion period. We report that opa is expressed in the CCAP neurons of the central nervous system during various steps of the ecdysis process and in peripheral CCAP neurons innerving the larval muscles involved in adult ecdysis. We show that its downregulation alters Burs expression in the CCAP neurons. Ectopic expression of Opa, or the vertebrate homologue Zic2 , in the CCAP neurons also affects Burs expression, indicating an evolutionary functional conservation. Finally, our results show that, independently of its role in Burs regulation, Opa prevents death of CCAP neurons during larval development.

Seasonal feeding on giant cuttlefish (Sepia apama) by Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western Australia

We report on observations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) feeding on giant cuttlefish (Sepia apama) from March 2007 to April 2013 in the temperate waters off Bunbury, south-western Australia. Seventeen feeding events were observed during the cooler months between July and September in relatively shallow coastal waters, with 12 dolphins identified as adult females. We observed behavioural sequences of complex prey-handling of cuttlefish where dolphins’ used multiple steps to remove the cuttlefish head, ink and cuttlebone before consuming the flesh of the cuttlefish mantle. Our study provides valuable information to the limited knowledge on the complex prey-handling by T. aduncus on cuttlefish in Australia, and is complementary to other known specialised foraging behaviours of bottlenose dolphins. This study also details a different behavioural sequence of cuttlefish prey-handling to that of the bottlenose dolphins in the Sado estuary, Portugal, where only the head is consumed, and to the Spencer Gulf, Australia, in that the dolphins in Bunbury carry the cuttlefish mantle over their rostrum before removing the cuttlebone. Information on S. apama in Bunbury is scarce, therefore studies on abundance, distribution and egg-laying sites are recommended in order to enable informed decision making and to understand the importance of S. apama to the diet of T. aduncus.

Evasive behaviours of female dusky dolphins (Lagenorhynchus obscurus) during exploitative scramble competition

When males engage in scramble competition, are females non-evasive recipients of male coercion or evasive? Small groups of male dusky dolphins (Lagenorhynchus obscurus) engage in exploitative (non-interference) scramble competition for access to oestrous females near Kaikoura, New Zealand. We conducted behavioural sequence analyses of videos of 48 mating groups with continuous records and focal individual follows of females. We determined (1) the frequency and type of behaviours (non-evasive vs. evasive), (2) the variation in simple transition probabilities of behaviours leading to a copulatory position associated with female resistance and non-resistance and (3) the variation in female responses to male behaviours throughout focal follows. Females exhibited frequent active evasive manoeuvers following male behaviours. Copulation sequences were highly variable and most complex when terminated by females. Females altered responses to male signals, one aspect of mate choice potentially favouring male endurance.

Host detection and rate of parasitism by Acroricnus seductor (Hymenoptera: Ichneumonidae), a natural enemy of mud-dauber wasps (Hymenoptera: Sphecidae)

The behavioural ecology of ichneumonid wasps that attack aculeate Hymenoptera is still largely unknown. Field observations and morphological analyses were devoted to investigate host detection and rate of parasitism by Acroricnus seductor (Scopoli), a natural enemy of the black and yellow mud dauber wasp Sceliphron caementarium (Drury). At the study site, about half of the host nests suffered parasitism by A. seductor. No significant difference was found between the rate of parasitism in sheltered (inside human building) and unsheltered (outside building) nests. Larger nests did not suffer a higher rate of parasitism, and larger brood cells were not more likely to be parasitized. As revealed by contents of parasitized cells, A. seductor appeared to act as a kleptoparasitoid, devouring spider prey and young host larvae. Analysis of video recordings obtained in the field revealed the basic behavioural sequence of host detection. Acroricnus seductor female taps with the antennae the host nest surface and, once a suitable host brood cell is found, inserts the ovipositor through the mud wall, possibly facilitated by the secretion of a mud-softening substance. Behavioural data, together with the presence of modified tips on the apex of female antennae and the relative thicknesses of female fore tibiae, strongly suggest that A. seductor uses echolocation to detect the host.

Mating behaviour of the European leafminer Scaptomyza flava (Diptera Drosophilidae)

European leafminer Scaptomyza flava (Falln) is an important pest of brassicas peas and gypsophila in New Zealand This study examined the mating behaviour of this species for the first time under laboratory conditions Males were the active sex in the entire mating behavioural sequence involving approaching courting and mounting females and copulation Copulation lasted for about 20 min There was no significant difference in pre courtship courtship and mating durations between virgin and mated males However mated males were significantly more likely to perform courtship and to achieve mating than virgin ones It is suggested that males learn from mating experience which helps them achieve higher mating success Both virgin and mated males tended to disrupt mating couples but could not separate them

Molecular cloning and function of ecdysis-triggering hormones in the silkwormBombyx mori

SUMMARYInka cells of the epitracheal endocrine system produce peptide hormones involved in the regulation of insect ecdysis. In the silkworm Bombyx mori, injection of Inka cell extract into pharate larvae, pupae or adults activates the ecdysis behavioural sequence. In the present study, we report the identification of three peptides in these extracts, pre-ecdysis-triggering hormone (PETH), ecdysis-triggering hormone (ETH) and ETH-associated peptide(ETH-AP), which are encoded by the same cDNA precursor. Strong immunoreactivity associated with each peptide in Inka cells prior to ecdysis disappears during each ecdysis, indicating complete release of these peptides. Injection of either PETH or ETH alone is sufficient to elicit the entire ecdysis behavioural sequence through the direct action on abdominal ganglia;cephalic and thoracic ganglia are not required for the transition from pre-ecdysis to ecdysis behaviour. Our in vitro data provide evidence that these peptides control the entire ecdysis behavioural sequence through activation of specific circuits in the nervous system. Ecdysis of intact larvae is associated with the central release of eclosion hormone (EH) and elevation of cyclic 3′,5′-guanosine monophosphate (cGMP) in the ventral nerve cord. However, injection of ETH into isolated abdomens induces cGMP elevation and ecdysis behaviour without a detectable release of EH,suggesting that an additional central factor(s) may be involved in the activation of this process. Our findings provide the first detailed account of the natural and hormonally induced behavioural sequence preceding larval,pupal and adult ecdyses of B. mori and highlight significant differences in the neuro-endocrine activation of pre-ecdysis and ecdysis behaviours compared with the related moth, Manduca sexta.