Inhibitory Effect of Calmodulin Antagonists and Calcium Antagonists on Fertilization-Induced Cyanide-Insensitive Respiration in Sea Urchin Eggs

During initial several minutes after fertilization, sea urchin eggs exhibited high rate of respiration which was only slightly inhibited by cyanide. This cyanide-insensitive respiration was inhibited by calcium antagonists, diltiazem and verapamil, and calmodulin antagonists, N-(6-aminohexyl)-5-chloro-1-naphthalensulfonamide hydrochloride (W-7), N-(6-aminohexyl)-1-naphthalenesulfonamide hydrochloride (W-5) and chlorpromazine, which were added within 1 min after insemination. The inhibitory effect of W-7 on cyanide-insensitive respiration was higher than that of W-5. Cyanide-sensitive respiration of fertilized eggs observed after this initial period was not inhibited by these compounds. Ca²⁺ influx in eggs just after fertilization was inhibited by calcium antagonists but was rather enhanced by calmodulin antagonists. Fertilization-induced stimulation of cyanide-insensitive respiration probably results from calmodulin-dependent reactions which are activated by Ca²⁺ influx.     

Reproductivity of early males of the temperate paper wasp Polistes rothneyi iwatai

In Polistes paper wasps, haploid early males can mate with early emerging females and leave viable offspring. In contrast, diploid early males are eventually sterile because they contribute triploid offspring via diploid sperm. Clarifying the ploidy of early males is important for determining whether early male production is a reproductive strategy for the species. We examined the mating behavior and the ploidy of early males in the Japanese paper wasp, Polistes rothneyi iwatai van der Vecht. Thirteen early males from four colonies were all diploid. Two of the nine early males (22.2%) attempted to mate with females, but only one individual (11.1%) was successful (the female's spermatheca contained spermatozoa). These results suggest that although most early males of P. rothneyi iwatai do not produce offspring, their mating may be linked to the occasional production of triploid females.     

Rearing method for the sporophagous thrips Bactrothrips brevitubus (Thysanoptera: Phlaeothripidae: Idolothripinae)

Mycophagous and particularly sporophagous thrips are difficult to rear under laboratory conditions, and this has been a major constraint in studying the life histories of such thrips in any detail. We developed a rearing method for Bactrothrips brevitubus, a sporophagous Japanese thrips, that can be modified readily to rear other sporophagous species. This method can maintain all developmental stages of the thrips by controlling humidity, temperature and fungal spore density. The method enables rearing over multiple generations, thereby facilitating investigations of the relationship between environmental conditions (e.g. food quantity) and breeding system (e.g. reproductive mode and offspring sex ratio).     

Elimination of a specialised facultative symbiont does not affect the reproductive mode of its aphid host

Abstract.  1. Microorganisms that manipulate the reproduction of their hosts through diverse mechanisms including the induction of parthenogenesis are widespread among arthropods.
2. The pea aphid, Acyrthosiphon pisum , shows a variation in its reproductive mode, with lineages reproducing by cyclical parthenogenesis (obligate alternation of parthenogenetic and sexual generations each year) and others by obligate parthenogenesis (continuous asexual reproduction all year round). In addition, the pea aphid harbours, along with Buchnera the primary aphid endosymbiont, several facultative symbionts whose prevalence differs among host populations.
3. The possible influence of a Rickettsia facultative symbiont on the reproductive mode of its host was tested on two pea aphid clones by comparing the response of infected and uninfected individuals with the same genetic background to conditions that typically induce the production of sexual morphs.
4. No significant effect of the Rickettsia infection was found on the type of reproductive morphs produced (sexual vs. asexual) or on their quantities for the two clones.
5. However, the Rickettsia had a detrimental effect on the fitness of its aphid host, in apparent contradiction to the high prevalence of this symbiont in some host populations. It is suggested that this negative impact may disappear under specific environmental conditions, transforming a parasitic association into a mutualistic one.     

Polymorphic microsatellite loci for the swarm-founding wasp Polybia paulista (Hymenoptera: Vespidae)

A polymorphic microsatellite locus was isolated and characterized from Polybia paulista, one of the most common polygynic, swarm‐founding social wasps in Brazil. Three other microsatellite loci for which the primer sets were originally developed in independent‐founding paper wasps also showed polymorphism in the size of amplification products in P. paulista.     

Application of microsatellite primers for the social wasp Polistes to another social wasp genus, Parapolybia, to estimate genetic relationships among nestmates

We tested 14 pairs of microsatellite primers that had been developed for the genus Polistes to assess their applicability for determining genetic structure in a colony of the genus Parapolybia. At least one of the 14 Polistes primer sets was useful for Parapolybia indica, and the locus identified by this primer set was highly polymorphic. Using this primer set, we estimated the average relatedness among female nestmates of Parapolybia indica to be 0.82 ± 0.05 (mean ± SE), indicating that in this species single mating is normal, although some cases of multiple mating was found.     

Six polymorphic microsatellite loci in the Japanese Spanish mackerel,Scomberomorus niphonius

Six polymorphic microsatellite loci were isolated for genetic structure studies of the Japanese Spanish mackerel, Scomberomorus niphonius, a severely exploited marine fish species. The number of observed alleles for each locus ranged from seven to 41, and the values of expected and observed heterozygosities were 0.546–0.946 and 0.602–1.000, respectively. These microsatellite markers should prove to be a useful tool for estimating the population genetic structure and genetic variability of Japanese Spanish mackerel.     

Artificial diet for the Japanese nine‐spotted moth Amata fortunei fortunei (Arctiidae: Syntominae)

The Japanese nine‐spotted moth Amata fortunei has not been successfully reared using artificial diets. We investigated three diets for rearing A. fortunei from egg to adult: (i) leaves of common dandelion Taraxacum officinale (DL); (ii) an artificial diet used to rear the silkworm Bombyx mori (Insecta LFS^®; AD); and (iii) a mixture of AD and an artificial mouse diet (MF). The survival rate from the first instar to adult emergence on AD + MF (80.77%) was significantly higher than that on AD or DL (30.77 and 20.0%, respectively). No significant differences in developmental periods at each stage were found among the diets. Moreover, body size indices of larvae reared on AD + MF were the same as or greater than those of larvae reared on the other diets and of wild individuals. Larval nutritional indices showed that food requirements changed after the third instar; this agrees with our observations of cannibalism and survival rate. Our results suggest that AD + MF is a suitable artificial diet for A. fortunei.     

Size-dependent reproductive dominance in foundresses of Ropalidia plebeiana, an Australian paper wasp forming nest aggregations (Hymenoptera: Vespidae)

The relationship between reproductive status and body size in foundresses of Ropalidia plebeiana, an Australian endemic paper wasp forming huge aggregations of nests, was examined. Foundresses with developed ovaries (laying foundresses) in multifoundress colonies tended to be larger than foundresses in single‐foundress colonies and foundresses with undeveloped ovaries (non‐laying foundresses). However, the laying foundress was not always the largest of the foundresses in a colony. Body shape in foundresses varied according to simple allometric growth, while foundresses and first brood females diverged in their growth parameters in the preimaginal stage.