Effects of propoxur exposure on females of the German cockroach, Blattela germanica and their oothecae

Susceptible and insecticide resistant females of Blattella germanica (L.), Dictyoptera, were exposed to propoxur treated surfaces. They carried oothecae that were expected to hatch in 48 to 72 h. Hatch was delayed in females that retained their oothecae throughout the exposure period. Oothecal hatch and nymphal survival were reduced when oothecae hatched on a treated surface but not when oothecae were retained and hatched on an insecticide-free surface. Over half of the susceptible strain females dropped their oothecae during the exposure period while very few resistance females dropped oothecae prematurely. Mortality of susceptible females that dropped their oothecae was higher than among those that retained oothacea. A tendency in this direction was apparent among the few resistant females that dropped their oothecae. The number of nymphs that emerged on the treated surface and also that survived for 24 h was higher in the resistant than in the susceptible strain. Newly hatched nymphs were frequently attached to the oothecae due to an inability to shed the embryonic cuticle.

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Résumé Des femelles de B. germanica, sensibles ou résistantes aux insecticides, ont été mises en présence de surfaces traitées au propoxure. Elles portaient des oothèques dont l'éclosion était attendue entre 48 et 72 h plus tard. Les éclosions ont été retardées, les femelles ayant conservé leurs oothèques pendant toute la période d'exposition. Lex taux d'éclosion des oothèques et de survie larvaire ont été normaux quand il y a eu rétention de l'oothèque et émission sur une surface saine, par contre ils étaient réduits quand l'oothèque a été émise sur une surface traitée. Plus de la moitié des femelles de la souche sensible ont laché leur oothèque pendant la période d'exposition tandis que très peu de femelles de la souche résistante ont abandonné leur oothèque prématurément. La mortalité était plus élevée chez les femelles sensibles qui ont perdu leur oothèque que chez celles qui l'avaient conservée. Une tendance du même type était décelable parmi les quelques femelles de la souche résistante qui perdirent leur oothèque. Le nombre d'écolosions de larves et le nombre de survies larvaires à 24 h étaient plus élevés dans la souche résistante que dans la souche sensible. Les larves néonates étaient souvent fixées à l'oothèque par suite de leur incapacité à se dépouiller de la cuticle embryonnaire.

     

Ovarian and haemolymph titres of ecdysteroid during the gonadotrophic cycle in Diploptera punctata

The free (non-conjugated) ecdysteroid in the ovaries during the first gonadotrophic cycle of Diploptera punctata was identified as 20-hydroxyecdysone. The hormone, quantified by radioimmunoassay and by ultraviolet absorbance, was detectable in the ovary toward the end of vitellogenesis; the quantity increased rapidly during chorion formation. Ovaries with chorionated eggs contained 67 μg of 20-hydroxyecdysone per g fresh weight. The haemolymph free-ecdysteroid, not identified physicochemically, was quantified by radioimmunoassays. The highest concentration was observed at adult emergence; the titre declined between days 1–3 and then remained at a relatively constant level through oviposition (which occurs between day 7 and 8); titres in pregnant females were higher. Ovariectomized females exhibited the same pattern of ecdysteroid titres in the haemolymph as the sham operated controls throughout the period corresponding to the first gonadotrophic cycle. Thus the ovary may not be the only source of haemolymph ecdysteroid related to reproduction in adult females.     

Larval development of Diploptera punctata reared alone and in groups

Larvae of the cockroach Diploptera punctata were reared in isolation, in pairs, or in groups of 8–10. Duration of larval development, age at each ecdysis, weights at birth and ecdyses, and adult head-capsule width were measured. Duration of larval development was longer and adult size was larger in isolated animals than in animals reared in pairs and groups. The effect of isolation on development was more pronounced in males. All females had 4 larval instars, whereas males had 3 or 4 instars. The proportion of males with 4 larval instars was higher among animals reared in isolation. There was no difference in the duration of larval development or adult size between pair- and group-reared animals. The sex of animals in the group did not affect adult size or the duration of larval development. Males which underwent 3 or 4 larval instars had different schedules of moulting. Rates of growth of males of both instar types reared in isolation and pairs were similar. Greater adult weight of isolated animals and 4-instar-type males was a result of their longer duration of larval development. Both a higher rate of growth and longer duration of larval development contribute to the larger adult size of females than males.     

Juvenile hormone biosynthesis and oocyte development in adult female Blattella germanica: Effects of grouping and mating

The roles of grouping and mating in modulating the activity of the corpora allata (CA) in adult female cockroaches were investigated using the in vitro radiochemical assay of juvenile hormone (JH) biosynthesis. Isolated virgin females have longer, asynchronous cycles of CA activity and oocyte maturation than do isolated females mated on day 8. Three factors were identified as the major contributors to this difference: (1) an experimental artifact of selection for sexually receptive females, (2) a positive effect of grouping on JH synthesis and oocyte maturation, and (3) a positive effect of copulation on oviposition and retention of the ootheca. Mated females constitute a subpopulation of receptive females that differ significantly from other females by having higher rates of JH synthesis prior to mating. The relative importance of such selection is substantial when the rate of mating is low, as in experiments with isolated females that are exposed to males for a short period of time. Long-term exposure of females to males introduces a grouping effect, which obscures any additional effect of mating on CA activity and oocyte development. However, mating influences ootheca formation and its retention. The effect of grouping can be mimicked in isolated females by transection of the nerves connecting the CA–corpora cardiaca complex to the brain, suggesting that in this insect isolation causes brain inhibition of the CA, and grouping provides disinhibitory stimuli that release the CA from brain inhibition.     

Cockroach mating behaviors,sex pheromones,and abdominal glands (Dictyoptera: Blaberidae)

Two chemical signals are essential in all cockroach sexual behavioral sequences: the sex pheromone released by one partner, generally the female (for long distance attraction), and an aphrodisiac sex pheromone produced exclusively by male tergal glands (for female mounting and tergal contact or feeding behavior). Unlike the other cockroach groups, the males of the Oxyhaloinae species produce both chemical signals: the pheromone and the aphrodisiac. The occurrence of three patterns of mating behavior (A, B, and C), the production of male sex pheromones, and the existence in the male of developed sternal and tergal glands in seven related Oxyhaloinae species, make these cockroaches a useful model for studying the evolution of mating behavior patterns. The various types of mating behavior were not classified in the previous studies by Roth and Barth. In this report, they have been named type A (female in upper position), B (male in upper position), and C (male and female end to end). In type A mating, the male tergal glands, which are licked by the females, are well developed, whereas in types B and C, there is no licking of the male's tergal secretion by the females and the tergal glands are much less developed; the aphrodisiacs secreted by the tergal glands may no longer act in this case through contact chemoreception, but through an olfactory process involving volatile components. One common sex pheromone component seems to be acetoin. I suggest that the mating behavior tends from A toward B and C during the evolutionary process with a concomitant regression of the tergal glands and changes in the aphrodisiac emission levels. The mating behavioral sequences of cockroaches (Dictyoptera) and crickets (Orthoptera) show a striking degree of similarity and are probably examples of convergent evolution.     

Food and water resources used by the Madagascan hissing-cockroach mite,Gromphadorholaelaps schaeferi

We determined the food source and water balance properties of the hissing-cockroach mite, Gromphadorholaelaps schaeferi. The food source for mites was identified using Evans blue dye by direct injection into a fasting host cockroach, Gromphadorhina portentosa, or by incorporation into cockroach food. No coloration was observed in mites on dye-injected cockroaches, but coloration was present in mites when only the food for the cockroaches had been stained. Thus, the mites are scavengers of cockroach food, and are not parasitic as previously thought. Our results demonstrate that the mites can absorb water from the air anywhere between 0.84 and 0.93 a _v (%RH/100), and wax-block experiments revealed that the mouth is the site of uptake. The mites are normally clumped together on the host, typically in between the cockroach's legs and around the spiracles. Water loss rates for mites in groups (0.16% h^-1) were far lower than for isolated mites (0.30% h^-1), suggesting a group effect with regard to water balance. Above the transition temperature of 30°C rate of water loss was rapid. The sites occupied by mites on the cockroach's body seem to be highly specific for feeding and absorption of water vapour.     

呲虫啉、杀虫双对美洲蜚蠊中枢神经的电生理影响

本文运用美洲蜚蠊(Periplaneta americana)第V1腹神经节突触后电位细胞外记录方法研究了吡虫啉、杀虫双对中枢神经活动的影响。结果显示：1.73x10^-7mol/L吡虫啉和 1.38XlO^-5Stool/L杀虫双处理后初期均能引起自发性突触后电位发放增强,随后导致突触传递阻断。而吡虫啉较杀虫双阻断传递快,且用Ringer生理溶液冲洗不易恢复,表明吡虫啉较杀虫双激动剂活性更强。以3.37×10^-5mol/L甲胺磷预处理中枢神经样品后,再进行杀虫双处理,则突触后电位的发放频率和幅值有明显增强,产生连续超幅排放(overshooting)现象,相反,甲胺磷预处理对随后进行吡虫啉处理无明显影响。这些结果说明,吡虫啉、杀虫双和乙酰胆碱受体发生相互作用过程存在差异。     

Ostéologie et position systématiquedu genre Thrissops Agassiz, 1833 (sensu stricto) (Jurassique supérieur de l'Europe occidentale) au sein des Téléostéens primitifs

The osteological study of the genus ThrissopsAgassiz, 1833 (sensu stricto) from the Upper Jurassic of Germany and France allows to define the systematic position of that fossil fish within the primitive Teleosts. The general shape of the skull, the jaws, the ethmoidal area, the circumorbital bones, the fronto-parieto-supra occipital area, the parasphenoid and the opercular bones are all characters which prove that Thrissops belongs to the family Ichthyodectidae (order Ichthyodectiformes, super-order Osteoglossomorpha). However Thrissops is more primitive than the other Ichthyodectidae which are all of Cretaceous age. It possesses indeed two parietals bearing pit-lines, a premaxillary and a maxillary normally developed, a palatine and a metapterygoid without any contact, a denticulated entopterygoid, three free epurals and six uroneurals, while, in the Cretaceous Ichthyodectidae, the parietals are fused in one bone without any pit-line, the premaxillary and the maxillary are hypertrophic, the palatine touchs the metapterygoid, the entopterygoid is toothless, the epural disappear or fuse with the terminal neural arches to form supplementary neural spines, and the uroneural are only five.     

Biochemical changes in tissue composition of Periplaneta americana (Linn.) acclimated to high and low temperatures

1. 1.|Cold acclimation apparently favours an increase of water content in fat body, but not in coxal muscle, of cockroaches.

2. 2.|A remarkable enhancement in the accumulation of total protein in fat body characterizes the cold acclimation of cockroaches, particularly adult males (175% increase in protein/DNA ratio). The increase in protein content of coxal muscle during acclimination to 15°C, observed in nymphs (16%) and males (16%) but not in females, is less pronounced than that of fat body.

3. 3.|A diminution (28–32%) in the free amino acid/DNA ratio due to cold acclimation has been recorded in both coxal muscle and fat body of nymphs and females, but not in males.

4. 4.|No qualitative change occurs in the free amino acid spectrum of haemolymph and tissues of this insect during acclimation to 15 and 35°C.

5. 5.|An augmentation (15–30%) of the RNA/DNA ratio occurs in fat body and coxal muscle of nymphs and males but in fat body alone of females following cold acclimation.

6. 6.|The glycogen reserve has been shown to increase by up to 30% in fat body and coxal muscle of cold acclimated cockroaches compared to warm acclimated ones.