Activity of the corpora allata of diapausing females of Tetrix undulata (SWRB) (Orthoptera-Tetrigidae)]

The implantation of one or two pairs of corpora allata of diapausing females in another diapausing females (two weeks old) induces vitellogenesis and laying of one, two or three egg-pods in a great number of females. The denervation of the corpora-allata of a diapausing female also induced vitellogenesis. These results suggeste that corpora-allata of diapausing females are not active. The denervation induces the break of the inhibition "travelling" by the corpora-allata-cardiaca nerves or stimulates the corpora-allata.     

The influence of juvenile hormone on the feeding behaviour of last instar larvae of the codling moth,Laspeyresia pomonella (Lep., Tortricidae), reared under different photoperiods

Summary Duration of the feeding stage and corresponding weight increase during the last larval instar of the codling moth,Laspeyresia pomonella, are controlled by JH. Larvae reared under short day conditions have a relatively high titer of JH during the last larval instar and enter diapause as mature larvae. They feed longer and become heavier than larvae reared under long day conditions, which have no JH during the last larval instar and pupate when mature. By application of the JH mimetic Altosid^® during the first 2 or 3 days of the last larval instar, the duration of feeding activity of larvae reared under respectively long and short day conditions was prolongated and the larvae became significantly heavier. The feeding behaviour could only be influenced by the juvenoid as long as the feeding activity of the larvae had not yet ceased.     

Oxygen permeability of the chorion in relation to diapause termination in Bombyx eggs

Oxygen permeability of the chorion of the silkworm, Bombyx mori, was measured in relation to embryonic diapause. It did not change appreciably when the eggs were freed from diapause by being kept under long chilling. This finding suggests that the increase in oxygen permeability of the chorion is not a pre-requisite for the termination of the diapause and resynthesis of glycogen from 2 polyols.     

Effects of diapause and host species on some morphometric characters inTrichogramma (Hym.: Trichogrammatidae)

Adult morphology ofTrichogramma is modified by environmental conditions during the preimaginal development. For instance, the low temperatures inducing diapause cause a decrease of the ratio length of longest seta on male flagellum/width of flagellum inT. evanescens. The species of the host also influences numerous body ratios. So, in females, the development of tibiae with regard to wings is more important withScotia ipsilon than withGalleria mellonella. These results confirm the necessity of performing comparative morphological studies on individuals reared in the same conditions.     

Eine Mutante mit vergrösserten Männchen-Eiern beiDinophilus gyrociltatus (Archiannelida)

Summary In a mutant strain ofD. gyrociliatus, a certain portion of eggs expected to develop the male sex give origin to females. This is connected with an enlargement of the male type of eggs in this strain.

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Herrn Prof. Dr. G. deLattin danke ich für die stete Förderung dieser Arbeit. Für ihre Hilfe bei den Messungen und bei den Kulturen bin ich Frau cand. rer. nat. H.Scharwath sehr dankbar.     

Ecdysteroid titre and caste determination in the ant,Pheidole pallidula (Nyl.) (Hymenoptera: Formicidae)

Summary In the antPheidole pallidula, ecdysteroid level is higher in worker-biased eggs than queen-biased eggs. Moreover queens laying worker-biased eggs exhibit a higher ecdysteroid level than queens laying queen-biased eggs.     

Influence of host plant and larval diet on ovarian productivity inAcrolepiopsis assectella Z. (Lepidoptera: Acrolepiidae)

Summary Females ofAcrolepiopsis assectella, reared on a semi-synthetic diet and laying on artificial substrates, do not respond to external stimuli by increasing ovarian production. When returned to the natural host (Allium porrum) for only one generation, ovarian production again rises and reaches the same level as in wild females, but its variability is strongly reduced. We conclude that selection under artificial conditions eliminates individuals which strictly depend on host plants for stimulation of larval nutrition and of reproduction.     

Insect photoperiodism: various ways of regulating univoltinism in lacewings (Planipennia: Chrysopidae)

Summary Reproduction inTjederina gracilis adults depends on short-day followed by long-day conditions. InNineta pallida, development of overwintering first-instar larvae is retarded by short days; later on, that of second-and third-instar by long days.Nineta flava andChrysopa perla prepupae automatically enter diapause, but inN. flava, photoperiod regulates diapause eermination, and long days may retard egg laying     

Delayed effects of juvenile hormone analogues on metamorphosis ofPyrrhocoris apterus are not mediated by the corpus allatum

Summary While it is clear that juvenile hormone analogues disturb metamorphosis, there is some controversy about their effect on the activity of the corpus allatum in the course of metamorphosis. The present experiments showed that juvenile hormone analogues applied to eggs did not prevent inactivation of the corpus allatum at the onset of the last larval instar ofPyrrhocoris apterus.     

Juvenile hormone and reproduction in the cricket. II. Effect of rearing temperature on corpus allatum activity (in vitro) in adult females

Summary In the Mediterranean field cricket,Gryllus bimaculatus, reproduction is controlled by temperature and the corpus allatum (CA) hormone JH III. In CA of females reared at 24°12°C(168 h) (high reproduction rate) a first peak in JH III synthesis is reached about 4 days earlier than in those of 20°C females (low reproduction rate). Furthermore, in 20°C animals CA activity is low during the entire oviposition period, whereas at 24°12°C high CA activity is found during this period of adult life. The results indicate a stimulation of CA activity and reproduction by thermoperiods around a constant low temperature.Supported by the DFG (SFB 87 A 4).     

Maternal regulation of wing polymorphism inPyrrhocoris apterus: Effect of cold activation

Summary In a macropterous strain ofPyrrhocoris apterus the offspring of females kept under long-day conditions are invariably mostly macropterous, whereas the offspring of females from short-day conditions become macropters under long-day and brachypters under short-day conditions. The brachypterizing effect of short days was removed by the chilling of mothers for 70 days.     

H-Y antigen expression in heterogametic males (XY) and females (ZW): a factor in reproductive strategy?

The cells of heterogametic females with ZW sex chromosomes express H-Y or H-W antigen. A hypothesis is formulated to explain why these animals are capable of 'practicing' amphigonia retardata, i.e., delay in actual fertilization of eggs by retaining viable sperm within the oviduct for a considerable time (several months).     

Protein content of various developmental stages of three strains of the pink bollworm,Pectinophora gossypiella

Summary Comparison of the total body protein of male and female larvae, pupae, and adults of a diapause and 2 nondiapause strains of the pink bollwormPectinophora gossypiella indicated that the protein content of larvae of the diapause strains was significantly higher than of the non-diapause strain.I thank Drs D.R. Nelson and R.A. Bell of the U.S.D.A. Metabolism and Radiation Research Laboratory, Fargo, for facilities and guidance.     

Genetic studies on gynandromorphism (sgm,gm) inCulex pipiens fatigans

Summary Individuals showing anterior-posterior gynandromorphism or somatic mosaicism of palpi respectively have been found in a laboratory strain ofCulex pipiens fatigans. The origin of the gynanders on the basis of binucleated eggs bearing anm factor and independently fertilized by male gemetes ofM andm genotype respectively has been suggested.This study was supported by the grant (No. 7/112/919/81 EMR-1), Council of Scientific and Industrial Research Govt., of India.     

Microorganism-associated variation in host infestation efficiency in a parasitoid wasp,Trichogramma bourarachae (Hymenoptera: Trichogrammatidae)

InTrichogramma bourarachae (Hymenoptera: Trichogrammatidae), the infestation efficiency presents important variation among strains: 60 eggs/5 days/female in the High (H) strain and 25 eggs/5 days/female in the Low (L) strain. Crosses show that between-strains variation is inherited by the matrocline route. Antibiotic and heat treatments reduce infestation efficiency in the H strain and have no effect on the L strain. The hypothesis of cytoplasmic-symbiotic microorganisms accounting for the higher infestation efficiency in the H strain is supported by microscopic observations. The origin and the significance of this between-strains variation are discussed.     

The acceptance response ofEphestia cautella (Walker) (lepidoptera: Phycitidae) females,obtained in the absence of courting males

Summary Ephestia cautella females will respond to a jet of air with an acceptance posture, and will respond more frequently when the air carries volatiles, probably male sex pheromones, from the male wings.     

Effect of relative humidity on the free-living stages of Strongyloides papillosus (Rhabdiasoidea: Nematoda)

The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 degrees C and 25 degrees C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 degrees C than at 25 degrees C and 35 degrees C, and also they exhibit a poor resistance to desiccation.     

The choice of oviposition sites by the lady bird beetleAdalia bipunctata (L.)

Summary Adalia bipunctata females lay eggs on brussels sprout leaves in presence or absence of aphids, but the latter furnish an additional stimulus. The glass walls of the jar attracted the adults to lay eggs on it to some extent. Presence of cemented eggs did not hinder the oviposition of the adults on the brussels sprouts leaves.     

Juvenile hormone in larval diapause of the codling moth,Laspeyresia pomonella L. (Lepidopterae,Tortricidae)

Summary Whereas in last instar larvae ofL. pomonella kept under long-day-conditions (LD), the JH-titer is temporarily reduced to zero, it stays relatively high in short-day-conditioned (SD) larvae which enter diapause. Application of JH or a juvenoid to LD-larvae results in diapause, if the treated insects are kept under SD-conditions. From these results it is concluded that inL. pomonella diapause is initiated by a relatively high titer of JH during the last larval instar.     

Effect of relative humidity on the free-living stages ofStrongyloides papillosus (Rhabdiasoidea: Nematoda)

Summary The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 °C and 25 °C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 °C than at 25 °C and 35 °C, and also they exhibit a poor resistance to desiccation.Acknowledgment. The author is grateful to Dr. Devendra Prasad of Patna University for his supervision and constant help in the work. The assistance of State University Grants Commission through a research scholarship is gratefully acknowledged.