Larval settlement and spat recovery rates of the oyster Crassostrea brasiliana (Lamarck, 1819) using different systems to induce metamorphosis / Taxas de assentamento larval e recuperação de sementes da ostra Crassostrea brasiliana (Lamarck, 1819) com uso de diferentes sistemas de indução à metamorfose

This study aimed at the assessment, in the laboratory, of the larval settlement and spat recovery rates of oysters of the species Crassostrea brasiliana using plastic collectors, epinephrine (C9H13NO3 C4H6O6) and shell powder in settlement tanks. Polypropylene was used attached to bamboo frames. The material was chosen due to its pliability - that favours the spat detachment. Two experiments were carried out; the first between February and April 2008, and the second between November and December 2008 at the Marine Mussel Laboratory of Santa Catarina Federal University (Laboratório de Moluscos Marinhos da Universidade Federal de Santa Catarina). In the first experiment, the scratched plastic collectors were tested consorting them with shell powder; on the second, the plastic collectors were tested consorted with shell powder, only shell powder and epinephrine as the metamorphosis stimulator. The quantification was carried out of the larvae settled in the plastic collectors, and of the recovery and integrity of the spats after their detachment. The first experiment has shown a recovery rate of 48.83 percent of the spats in comparison with the D larvae used. From this percentage, 4.9 percent settled in the plastic collectors and 43.93 percent in shell powder. The second experiment revealed 55.78 percent regarding the settled spats in comparison with the total of larvae used (using epinephrine), 78.62 percent in the treatment with the collector plus shell powder and 58.33 percent in the treatment only with shell powder. Thus, the use of the collector plus shell powder resulted in a greater spat recovery when compared to the other treatments.

O presente estudo teve como objetivo avaliar a taxa de assentamento larval e recuperação de sementes de ostras da espécie Crassostrea brasiliana, em laboratório, através do uso de coletores plásticos, epinefrina (C9H13NO3 C4H6O6) e pó de concha em tanques de assentamento. Foram utilizados coletores plásticos de polipropileno, presos a armações de bambu. O material foi escolhido devido à boa maleabilidade, o que facilita o destacamento das sementes. Foram realizados dois experimentos, o primeiro entre fevereiro e abril de 2008, e o segundo entre novembro e dezembro de 2008 no Laboratório de Moluscos Marinhos da Universidade Federal de Santa Catarina. No primeiro experimento, testaram-se coletores de plástico arranhado consorciado com pó de concha em um tanque de assentamento, enquanto que no segundo foram utilizados dois tanques de assentamento, um contendo os coletores de plástico consorciado com pó de concha e apenas pó de concha, e, no outro tanque, utilizou-se epinefrina como estimulador da metamorfose. Foi realizada a quantificação das larvas assentadas nos coletores plásticos e a taxa de recuperação e integridade das sementes após o destacamento. No primeiro experimento, recuperaram-se 48,83 por cento de sementes em relação às larvas D utilizadas. Deste percentual, 4,9 por cento assentaram em coletores plásticos e 43,93 por cento em pó de concha. No segundo experimento, a porcentagem de sementes assentadas em relação ao total de larvas utilizadas foi de 55,78 por cento com o uso de epinefrina, 78,62 por cento no tratamento com coletor mais pó de concha e de 58,33 por cento no tratamento só com pó de concha. Assim, verifica-se que o uso de coletor mais pó de concha resulta em maior recuperação de sementes se comparado com os demais tratamentos.

Effects of the coastal sediment elutriates containing persistent organic pollutants (POPs) on early reproductive outputs of the Pacific oyster, Crassostrea gigas.

We previously found that embryonic development of the bivalve species was highly vulnerable to xenobiotic chemicals, damaging the coastal ecosystem integrity To further assess their potential damage to ecosystem, the xenobiotic composition of the sediment elutriates from two representative industrialized Korean coasts, Pohang and Ulsan, were determined with gas chromatography/mass spectrometry (GC/MS). The presumed critical dilution of the elutriate was then exposed to early life stages of the Pacific oyster (Crassostrea gigas), embryonic development and metamorphic stage to first spat, at which they were believably more vulnerable by the chemical exposure. The early life damage by the xenobiotic exposure was apparently significant by the significant degree of pollution. Here, we indicated their potential damages to the Pacific oyster

Decreased flight performance and sperm production in drones of the honey bee (Apis mellifera) slightly infested by Varroa destructor mites during pupal development

We developed a bioassay to measure the flying power of drone, in order to determine which drones could reach a drone congregation area. A wind tunnel was used to test unparasitized drones and drones slightly parasitized by one or two mites during pupal development, and counts were made of the number of spermatozoa that they produced. Drones parasitized with one mite flew as long as control drones ( = 6Æ55ö and 6Æ48ö, respectively, P = 0.512); however, those that had been infested by two mites flew significantly less ( = 2Æ16ö, P<0.001). There was a significant positive correlation (P<0.01) between flight duration and the number of spermatozoa per drone in control group (r = 0.53), and in both the one mite (r = 0.43) and two mite (r = 0.54) groups. Drones infested during development with one or two mites produced 24 and 45% fewer sperm, respectively.

Hormonal implication in Bracon-venom-induced paralysation of the host larva of Corcyra cephalonica (Lepidoptera: Pyralidae).

To facilitate oviposition, the ectoparasite Bracon hebetor, injects its venom, a paralysing toxin, to the host Corcyra larva that ultimately dies without showing any metamorphic change, even if allowed to remain unparasitised. At the initial stage of venom injection the rate of heartbeat of the host becomes abruptly high. This has been explained from the synergistic action of the substances of poison gland and calyx. The paralysed larvae subsequent to envenomization die within 240 hr. Application of hydroprene as single dose or with a booster dose after paralysation mostly increases the survival period considering heart beat as the index. The predicted value of survival period (714.4 hr), determined from a fitted equation obtained from the relationship between heart beat and survival period, indicates that a 100 microg treatment/larva with a booster dose of 50 microg/larva most effectively lengthens the period. It is concluded that the venom-induced physiological dysfunction of the immobilised larvae, as indicated in the rate of heart beat and survival period, though can be recovered to some extent after the application of juvenoids, there cannot occur any metamorphic change of these larvae. The parasitoid, therefore, succeeds in completing its development and metamorphosis by arresting the development of its host through an indirect hormonal suppression. The findings indicate an endocrine implication in host-parasite relationship in insect.

Effect of some new insect growth regulators on metamorphosis & reproduction of Aedes aegypti.

Fourth instar larvae and pupae of Ae. aegypti were treated with four most active insect growth regulators from a new series of mixed alkyl and aryl diethers based on geraniol. Considerable reduction in fecundity and fertility of adults was obtained. Treatment of pupae or pharate adults did not affect adult emergence. Topical treatment of adult females caused great reduction in fertility and fecundity in older as compared to younger females. In addition to the effects on reproduction, adult survival was also reduced in the treated younger females.

La gonada larval de Bufo arenarum sometida a hormona tiroidea / The larval gonad of Bufo arenarum exposed to thyroid hormones

La gónada de Bufo arenarum se presenta con características femenminas en todas las larvas dado que esta especie representa un ejemplo de raza sexual "indiferenciada". El sexo genético masculino recién se evidencia luego de la metamorfosis. A fin de comprobar la eventual vinculación entre diferenciación gonadal y hormona tiroidea, se trataron las larvas con tri-iodo-tironina. Los resultados demuestran un incremento en el número y en el grado de maduración de los ovocitos