Feeding experiments with female Pisaura mirabilis were carried out in the laboratory. Several species of Diptera, ranging in their size from small fruitflies to large blowflies, were offered. Each spider received a single fly, and then the absolute as well as the relative amount of prey consumption was recorded. Absolute consumption was measured as the amount of a fly consumed by the spiders. Relative consumption, i.e. the utilization rate, was calculated as amount of fly consumed by the spiders divided by the initial mass of the fly. Absolute consumption was positively correlated with the mass of the fly, i.e. the larger the fly the more the spider consumed. No satiation effects were observed. P. mirabilis ingested on average 75% of the prey item, but was able to extract up to 95%. The relative consumption showed no relationship with mass of fly, i.e. the prey size did not influence the utilization rate. Also, neither body size nor age of spiders affected absolute or relative consumption. Furthermore, the fly remnants discarded by the spiders, and uneaten control flies were analysed for their C and N contents. Fly remnants showed a significantly higher C and N content, whereas their C/N ratio was lower. The results show that in the single-prey situation P. mirabilis increases absolute biomass intake with increasing amount of prey available. However, low values and a high variance of the utilization rate indicated that it is not only prey quantity which may be essential for the spiders. We therefore conclude that in future studies the nutritional qualities of prey should be considered more closely.

Third and fourth instar larvae of Harmonia axyridis were released in spring into rose beds infested by the aphid Macrosiphum rosae. These biological treatments induced stabilization or a decrease of the aphid populations. Their efficiency is comparable with that of chemical treatments performed in neighbouring rose beds and the subsequent development of aphid populations was the same after these two types of treatments. The rearing condition of H. axyridis, particularly its feeding on a substitute prey (lepidopteran eggs), the climate, particularly the rainfall and low temperatures, sometimes near the development threshold of the coccinellid, and possibly the rose bush variety did not seem to affect its potential predatory efficiency. An aphid density of more than thirty aphids per rose bush appears to be necessary for the larvae to remain on the plants, when fifty larvae were released per four bushes.

Salt D.T. & Whittaker J.B.: Insects on Dock Plants. Naturalists' Handbooks 26. The Richmond Publishing, Slough, 1998, 56 pp.

The effects of 5 pmols of adipokinetic hormone (Lom-AKH-I) on both the locomotion and mobilization of lipids were studied in 10-day-old diapausing adult females of the short-winged (brachypterous) morph of Pyrrhocoris apterus (L.). The results revealed that AKH stimulation of locomotion in this bug is wing-morph independent. The stimulatory effect of AKH on locomotion was shown to be positively correlated with its effect on lipid mobilization.

The profile of hemolymph ecdysteroid was studied in the gram pod borer, Helicoverpa armigera, during larval-pupal transformation. The changes closely correspond to the developmental events occurring at metamorphosis. Two insect growth regulators, plumbagin and azadirachtin, significantly depleted the content and altered the profile of ecdysteroids at crucial stages, when applied at ED₅₀ doses. The activity profiles of two fat body lysosomal enzymes, acid phosphatase and b-galactosidase, were also significantly affected by the insect growth regulators. It is suggested that plumbagin and azadirachtin treatments primarily modify the ecdysteroid titer, which in turn leads to changes in lysosomal enzyme activity causing overt morphological abnormalities during the metamorphic molt.

Fan Zide (ed.), Chen Zhizi, Fang Jianming, Zheng Shensheng & Tao Zhenliang: Diptera: Calliphoridae. Fauna Sinica (Insecta Vol. 6). Science Press, Beijing, 1997, 707 pp.

Four species of Anagrus (A. breviphragma Soyka, A. incarnatus Haliday, A. fennicus Soyka and A. obscurus Foerster sensu Soyka), that live on Carex riparia Curtis (Cyperaceae) in uncultivated areas along the Po river in the Piacenza province in Italy were analysed using RAPD markers in order to investigate their genetic relationships. High levels of RAPD polymorphism were found in the genus Anagrus, which permitted the fingerprinting of the four species. Analysis of average genetic similarities within species and comparison with average values between species confirms that A. breviphragma, A. incarnatus, A. fennicus and A. obscurus represent four genetically distinct species. A dendrogram constructed from molecular data of single families clearly clustered the four species in different groups, their mutual position reflecting morphological and biological observations.

Phagocytic response to injected iron saccharate and yeast cells (heat-killed Saccharomyces cerevisiae or viable Candida tropicalis) and haemolymph phenoloxidase (PO) activity were studied im Mamestra brassicae larvae fed on diets contaminated by copper, lead, cadmium of fluorine ions. In copper-stressed larvae, increased and reduced percentage of plasmatocytes and granular cells, respectively, and a reduced phagocytosis of iron saccharate were found. Cadmium- and fluorine-treatment reduced phagocytosis of S. cerevisiae. Cadmium showed a stimulatory effect, copper an inhibitory effect on phagocytosis of C. tropicalis. PO activity was reduced by all toxicants, in copper-stressed larvae it reached only 22% of the activity in the control.

The influence of parasitism by Glyptapanteles liparidis (Bouché) on the development, consumption, growth and food utilization from the third to the fifth instar of its host Lymantria dispar L. was studied on three different host types, each characterized by the stage in which they were parasitized. The first host type was parasitized during premoult into the 2nd instar, the second during premoult into the 3rd instar and the third during the middle of the 3rd instar.

Depending on the relationship between the host's size and the volume of the parasitoid complex inside the host, different developmental patterns of the various host types were found. From the majority of early-parasitized hosts, the parasitoid larvae emerged during the hosts' fourth instar (90%), while parasitoids emerged mainly during the fifth instar (77% and 81%) of both later-parasitized host types. Hosts which were heavily parasitized during their premoult stage, avoided obvious nutritional constraints by inserting a supernumerary host instar. Only from one lightly parasitized host type did parasitoid larvae emerge, after developing through only two host instars. Third-midinstar-parasitized hosts had a supernumerary instar only when they contained a relatively low number of parasitoids compared with those from which the parasitoids emerged during the fifth instar. Unparasitized gypsy moth larvae also differed in their developmental pattern, as (78% of males and 72% of females) pupated after the 5th and 6th instars, respectively. Differences in growth and development time permitted the differentiation between sexes, before larvae moulted to the fifth instar.
Parasitism most influenced host nutrition in early-parasitized hosts, as they showed increased rates of consumption and growth during the 3rd, penultimate host instar. Higher biomass gains during their final fourth instar of these early-parasitized hosts were due to prolongation of both development and the feeding period, which resulted in a relative consumption and growth rate significantly lower than in unparasitized female larvae and later-parasitized larvae. Growth and consumption rates during the 3rd and 4th instar of later-parasitized host types did not differ from female control larvae. In their final 5th instar these host types did not prolong their development or feeding period, but displayed a reduction in growth rate similar to early-parasitized hosts. The approximate digestibility (AD-value) and conversion efficiency of ingested and digested food (ECI- and ECD-values) was not influenced by parasitism.
No correlation was found between the number of parasitoid larvae per host and the duration of the endoparasitic development among most individuals of the three host types. The number of parasitoids per host, however, contributed markedly to the final gross weight, consumption, growth rate and biomass gained during the final host instar.

Further progress in understanding insect cold-hardiness requires a broader perspective than hitherto. Such a broader approach is feasible, given the range of information now available on cold-hardiness and the variety and quality of equipment to study it. Comprehensive information on individual species is required, using the full range of available techniques, instead of piecemeal investigations. Comparisons of species must likewise be based on how their complete cold-hardiness strategies are structured, rather than on any particular contrasts between individual elements. Most importantly, a well based understanding of cold-hardiness requires wider linkages between cold-hardiness and other salient aspects of the life cycle, such as seasonal timing and control, water balance, and metabolism and energy budgets. Cold-hardiness is only one aspect of the adaptive trade-offs that structure the life cycle of any given species.

Three new antisera have been produced in rabbits immunized with E-2/3-hemisuccinate conjugates. In a competitive enzyme immunoassay (EIA) with 20-ecdysone-peroxidase as a tracer, the antisera exhibit high specificity towards the side chain of the ecdysone (E) molecule. Modifications of the A-ring do result in no or small changes of sensitivity.

One antiserum (RUD-2) allows the direct quantification of total ecdysteroids in samples containing E and 3-dehydroecdysone in varying ratios, without further sophisticated sample treatment. At least one of the other antisera allows the direct quantification of mixtures of E and 25-deoxyecdysone (RUD-1). Thus, these antisera may be a useful tool in studying molting control in arthropods.

Freshly hatched Japanese quails of the strain Faraon were fed for 50 days by diets containing graded amounts of pulverized seeds of an Asiatic plant Leuzea carthamoides Iljin. The dry seeds of this plant contained 1.8%-2.1% of 20-hydroxyecdysone, together with some smaller amounts of other ecdysteroids. In additional experiments the quails were also offered the standard diet plus whole seeds of Leuzea ad libitum and the standard diet enriched with certain commercially available biostimulating preparations for birds, Biostrong and Ecovit.

The effects of the diets were evaluated first at the age of 37 days and then at the age of 50 days, which covered the reproduction period. Investigations related to the effects on growth, behaviour and overall developmental conditions were completed by RIA analysis of ecdysteroid concentrations circulating in the blood of the quails.
The basic experimental series involved testing of the following diets: 0) Standard diet (SD); 1) SD + 0.2% Leuzea seed; 2) SD + 1.0% Leuzea; 3) SD + 5.0% Leuzea; 4) SD + 5.0% Biostrong; 5) SD + 3.0% Ecovit, and; 6) SD + the whole seeds of Leuzea ad libitum. At the age of 37 days we found the following percentage increase of the living mass (Control group = 100%): 1) 102.8%; 2) 109.5%; 3) 120.4%; 4) 101.9%; 5) 104.9%:, and 6) 103.5%. These results confirm previous findings of strong anabolic effects of Leuzea in growth of the vertebrate animals. However, since the plant contains a number of other biologically active classes of the secondary plant substances, the true responsibility of ecdysteroids for the described effects cannot be guaranteed, without further studies with pure ecdysteroid. The results of RIA analyses revealed that the amount of 20-hydroxyecdysone circulating in the blood of Japanese quails was directly proportional to the amount of dietary ecdysteroid. The largest concentrations, around 80 ng/ml of blood were found in quails which consumed the whole seeds of Leuzea.

The silkworm, Bombyx mori was reared on artificial diets supplemented with 20-hydroxyecdysone (20E) during the 4th instar and on diets supplemented with various concentrations of either 20E or ecdysone (E) in the 5th (last) instar. The larvae transferred to diet containing E molted to the 6th instar earlier than the control larvae and their mortality was within norm. On the other hand, most of the larvae that were transferred to the diet supplemented with 300 ppm 20E continued to feed until they died without apolysis. The amount of 20E in their hemolymph was higher than in the larvae fed 200 ppm E. Larvae transferred to a diet containing both E and 20E did enter apolysis and their ecdysteroid level was similar as in the non-molting larvae receiving 300 ppm 20E. These results suggest that ingested ecdysone might change the sensitivity of epidermis to 20E.

A 3.1 Kb fragment of a Drosophila melanogaster ecdysone receptor (EcR) cDNA (splice product, EcR B1) comprising the 2.6 Kb coding region with 218 base pairs of 5' and 258 base pairs of 3'-untranslated sequence, was cloned into the mammalian expression vectors pH beta APr-1 and pSG5 (which place EcR under the control of a human beta-actin and a SV40 early promoter, respectively). Chinese hamster ovary cells have been stably transfected with the beta-actin promoter construct. Antiserum, prepared against an EcR-fusion protein has been used to demonstrate the synthesis of an apparently complete ecdysone receptor in a stable cell line produced in this way. Nuclear extracts from this line exhibit specific binding activity for the D. melanogaster hsp 27 ecdysone response element in mobility shift analyses.

Ecdysteroid induction of reporter gene activity has been demonstrated in Chinese hamster ovary cells both by transient transfection analysis and in stably transfected cell lines which constitutively produce the D. melanogaster ecdysone receptor.

The synthesis of dopamine melanin in the wing scales of Precis coenia depends on pattern specific activity of dopa decarboxylase (DDC) at the end of pupal development when hemolymph ecdysteroids decrease. DDC activity in forewings increased in 6 days old pupae and is maximal on day 6 at midnight. DDC activity increased also in isolated wings incubated in Grace's medium on day 5 at midnight, following the same time profile as in vivo. The wings developed their typical colour pattern. However, at most time points DDC activity in vitro was lower than in vivo. Wings incubated in medium containing 10 µg/ml 20-hydroxyecdysone (20E) did not melanize. 20E inhibited the DDC activity in a dose dependent manner.

A new technique was used to continuously supply 20E to an almost intact pupa. The pupal cuticle covering the left forewing was removed and the wing was hung in medium containing different concentrations of 20E. 20E was distributed in the pupa and inhibited melanization in the intact right pupal wing. In control incubations with pure Grace's medium different coloured portions of the wing pattern showed different DDC activities being high in the black eyespot and medium and low in grey and white wing pieces, respectively. A high concentration of 10 µg/ml 20E supplied to the left wing totally inhibited DDC in all differently coloured wing pieces. With decreasing ecdysteroid concentrations, DDC activity increased earlier and to higher levels in black than in grey wing pieces and was almost constant in white pieces. Therefore, melanin synthesis started earlier and was at a higher level in black than in grey scales, which caused their different pigmentation. This result suggests that the time point of initial melanin synthesis in differently melanized scales is triggered by the decreasing ecdysteroid titer causing differential activation of the DDC.

The influence of ovary and ecdysteroids on pheromone biosynthesis was investigated in D. melanogaster. Strains mutant for ovo produced enhanced amounts of cuticular hydrocarbons in both sexes. Female sex pheromone production was not affected by the mutation, except homozygous females for ovo^Dlrsl which exhibited a higher proportion of the pheromone, 7,11 heptacosadiene.

The amount of hydrocarbons in wild-type (CS) flies was stable at 21 and 25°C but dramatically increased at 29°C whereas the cuticular hydrocarbon pattern was unchanged. In contrast, ecdysone-less 1^ls (ecd-1) flies showed an increase in overall hydrocarbon production at both permissive and restrictive temperatures. At restrictive temperature they showed also a decrease in pheromonal dienes production for females with an increase in monoenes and an inversion of the 7 tricosene-7 pentacosene ratio for males. These effects were partially reversible since a switch from 29 to 21°C restored an intermediary hydrocarbon pattern.
It is suggested that the regulation of female sex pheromone might be under the control of the ecd-1 gene.

Severe defoliation of Prunus padus saplings in spring 1987 significantly affected growth and nutrient characteristics for the next five years. Trees that experienced 50% or greater defoliation at age 2 and 3 years were significantly smaller than the controls for up to three years after experimental defoliation had ceased. After five years, trees that had experienced the most severe defoliation were still significantly smaller than those trees that had experienced less severe defoliation regimes. Trees that had experienced high levels of defoliation had significantly higher total leaf nitrogen levels and significantly lower calcium levels two years after defoliation than lightly defoliated trees. Four years after the initial defoliation treatments the situation was reversed, nitrogen levels were higher and calcium levels lower in the controls and lightly defoliated treatments than in the heavily defoliated treatments.

The colonisation of the trees by insect herbivores was significantly affected by the initial defoliation treatments. The number of overwintering eggs of the specialist bird cherry feeding aphid Rhopalosiphum padi were significantly greater on the control and lightly defoliated treatments from 1987-1990. Only in 1991 were egg numbers not significantly different between treatments, and in that year populations overall were extremely low. In addition, damage by mid-season generalist herbivores was significantly lower on those trees that had experienced severe initial defoliation. In all other years bar 1989 and 1991, damage levels were significantly higher on those trees. Colonisation by the other bird cherry specialist, the small ermine moth Yponomeuta evonymellus, did not occur until 1991. All trees colonised were from the severe defoliation treatments. These results are discussed in relation to the probable effects on the population dynamics of the two bird cherry specialists.

Conidia of Metarhizium anisopliae and Beauveria bassiana were evaluated for activity against adults of the Japanese beetle, Popillia japonica, under laboratory conditions. The LC₅₀ values 7 days after exposure to M. anisopliae and B. bassiana were 0.7 and 0.026 mg of conidia/100 adults, respectively at 22-24°C. A sharp increase in mortality was observed 3 and 4 days after treatment with either 10 mg of B. bassiana/100 adults or 10 mg of M. anisopliae/100 adults, respectively. The LT₅₀ values at 10 mg/100 beetles for M. anisopliae and B. bassiana were 4.2 and 3.1 days. respectively. Onset of mortality was further delayed at lower dosages of both fungi. Mortality of adults that were exposed to beetles treated with 10 mg of conidia of M. anisopliae/100 adults immediately following application of conidia or 24 hrs posttreatment was an average of 60 and 43% cumulative mortality. respectively, within 9 days of exposure. Similar exposures of healthy adults to beetles that had been treated with 10 mg of B. bassiana conidia/100 adults resulted in an average of 79 and 43% cumulative mortality, respectively. Beetles killed either by M. anisopliae or B. bassiana and subsequently placed on damp soil manifested signs of patent infection with the fungi, with subsequent production of conidia. The infectivity of M. anisopliae and B. bassiana for adult Japanese beetles and the delay in mortality following treatment provide potential for dispersal of these entomopathogens within populations of P. japonica.

In response to a blood meal, the fat body of the female mosquito produces several yolk proteins (YP) which are accumulated by the developing oocytes. 20-hydroxyecdysone (20E) stimulates high levels of YP gene expression in fat bodies cultured in vitro, but initiation of this expression was eliminated with cycloheximide. In the 1.5 kb upstream region of the gene encoding vitellogenic carboxypeptidase, a mosquito YP, there are several putative regulatory sequences that resemble steroid response elements (SRE), but they do not match the ecdysteroid response element (EcRE) consensus. A cDNA encoding a mosquito ecdysteroid receptor (AaEcR) has recently been cloned and found to possess P-Box and D-Box domains nearly identical to those found in the Drosophila and Chironomus EcRs, indicating that its DNA binding sequence will likely match the EcRE consensus. Taken together, these results indicate that the control of YP genes in the vitellogenic mosquito fat body by 20E is indirect. It may involve several factors in a hierarchy, with a factor other than the AaEcR directly controlling the YP genes.

In the mosquito fat body, lysosomal enzymes are involved in termination of YP secretion. The mRNA of a mosquito lysosomal aspartic protease (LAP) reaches its peak 12 hr before the peak of LAP protein and enzymatic activity. The level of LAP protein rises as the titer of 20E declines. This suggests a translational inhibition of LAP mRNA by a high titer of 20E. We obtained direct experimental confirmation of this novel function of 20E. In addition, the 5'-untranslated region of the LAP mRNA shares similarity with elements conferring negative translational control by steroids. The LAP gene is controlled by dual promoters, one of which is dominant during enhanced expression. The identification of putative regulatory elements should help in determining the regulation of the gene during both housekeeping and enhanced expression.

Fourth-instar gypsy moth (Lymantria dispar; Lepidoptera: Lymantriidae) larvae, infected with the gypsy moth baculovirus (LdNPV), show an elevated and prolonged extension of the hemolymph ecdysteroid titer peak associated with molting. The ecdysteroid immunoreactivity associated with this peak elutes as two peaks following HPLC on a C₁₈  reverse-phase column. Both peaks elute in a region more polar than 20-hydroxyecdysone, but less polar than the highly polar ecdysteroid immunoreactivity associated with the apolysis peak of control animals. Glycosylated ecdysteroid standards, produced by in vitro incubation of UDP-glucose with ecdysone or 20-hydroxyecdysone and culture medium from LdNPV-infected gypsy moth cells, show elution times identical to the two immunoreactive peaks. Enzymatic hydrolysis studies verified this identity. The data suggest that the hemolymph of LdNPV-infected L. dispar larvae contains both glucose-conjugated ecdysone and glucose-conjugated 20-hydroxyecdysone which, by analogy with the literature, are presumably 22-O-beta-D-glucopyranoside and 20-hydroxyecdysone 22-O-beta-D-glucopyranoside.

A strategy is described for receptor-based phytochemical screening of plant extracts for ecdysteroid agonists and antagonists. Milligram amounts of seed are methanol extracted. Lipids and pigments are removed by hexane partioning. Agonist and antagonist activities are detected with a microplate-based specific bioassay using the Drosophila melanogaster ecdysteroid-responsive BII cell line. Extracts are also screened with ecdysteroid-specific RIAs to identify extracts containing phytoecdysteroids. Over 1,700 species of plant have been screened in this way so far. Extracts are being sought which (i) contain large amounts of phytoecdysteroid, (ii) which contain novel phytoecdysteroids, (iii) which contain non-steroidal agonists and (iv) which contain antagonists. The aim of this paper is to describe the rationale behind the strategy, to describe its operation and to present, as an example, the results obtained with members of the Poaceae and of one genus, Briza, in particular. It is hoped that this approach will result in the identification of new sources of phytoecdysteroids, provide new phytoecdysteroid structures for structure/activity relationship studies, throw light on the phylogenetic distribution of phytoecdysteroids in the plant kingdom and provide useful agonists and antagonists for the investigation of ecdysteroid receptor function and as potential lead compounds for new classes of insect control agents.

Results from field samples indicate that the percentage of eggs laid by the monophagous leaf beetle, Zygogramma suturalis directly on the host plant (Ambrosia artemisiifolia) changes during the course of the season. These changes in oviposition were not associated with changes in the host specificity of larvae or adult beetles. In June-August the percentage of eggs laid on A. artemisiifolia was inversely correlated with Z. suturalis larval population density. It is speculated that high larval density deterred ovipositing females.

The intention of this study was to falsify a hypothesis of interspecific avoidance of semiochemicals from egges by ovipositing tortricid females. The oviposition responses of Cydia pomonella (L.) females to apples baited with blends of semiochemicals identified in another tortricid species, Lobesia botrana (Den. et Schiff.) were investigated. Experiments were conducted in binary choice tests using natural oviposition substrates (apples). In each experimental arena, 4 mated females were offered 16 apples (8 treated and 8 untreated) and the number of egges was compared. Females avoid ovipositing on apples treated with a blend of nine components characteristic of methanolic extracts of L. botrana eggs (fatty acids and esters) (complete blend), as well as a binary blend of palmitic acid and methyl palmitate (binary blend). Oviposition avoidance was already observed with these two blends at a dose of 72 eggs equivalent of L. botrana per apple and this effect increased with the dose. The blend of three major esters from complete blend (ternary blend) did not provoke significant avoidance. In the control, only 8.3% of apples bore no egges, this percentage was increased with complete blend and binary blend (720 Lobesia eggs) respectively up to 37.5% and 26.4%, but only to 18.1% of apples with ternary blend. Complete blend and binary blend used at high dose strongly reduced the mean number of eggs/apple on treated fruits (1.6 ± 1.8; 9 compounds) (1.8 ± 2.2; 2 compounds) against 4.6 ± 4.0 in the control. This reduction was not observed with the blend of 3 esters. It is concluded that, from the present results, apples treated with compounds associated with L. botrana eggs are avoided by C. pomonella ovipositing females. Esters alone cannot explain such an avoidance, and palmitic acid may partly cause the avoidance response.

Females of the aphid parasitoid Praon volucre were attracted to lures containing synthetic aphid sex pheromone components, particularly (+)-(4aS,7S,7aR)-nepetalactone, when these were placed on water traps in cereal fields in autumn. Trap catches were greatest at a site in S.W.England and fewest at sites in northern England 'and northern Germany, presumably due to climatic differences. Responses to the pheromones were not detected for any other cereal aphid parasitoids in the field trials, although Aphidius rhopalosiphi appears to possess olfactory receptors for (+)-(4aS,7S,7aR)-nepetalactone. A potential strategy for the use of aphid sex pheromone lures to manipulate aphid parasitoids in the field, in order to enhance their impact on aphid populations, is outlined.

Selection for resistance to fenpropathrin (a pyrethroid insecticide) was performed by exposing adults of two field-collected populations of the whitefly, Bemisia tabaci, to increasing doses of fenpropathrin for four generations. Concurrently, samples of adults were used for colorimetric measurements of esterase (EST) activity.

The two populations differed in their response to selection. EST activity increased as a correlated response to pyrethroid selection in one population but not in the. other. No changes in either resistance or esterase activity were detected in the unselected control lines. The data suggest that both resistance and EST activity have a genetic basis, and that the frequency of high EST-activity alleles may have been different in the two populations.

The levels of progesterone radioimmunoassay-positive material in the gonads, intestine and haemolymph of the cockroach Nauphoeta cinerea during adult ontogenetic development were studied. The animals were divided into two groups: group 1 - control males and females reared for a period of 36 days after adult ecdysis at temperature 29 ± 1°C; group 2 - experimental males and females reared from day 8 to day 18 at 15°C and then at the same temperature as cockroaches of group 1. The immunoreactive progesterone concentration in gonads and intestine of females from group 1 reached the highest value on day 24 and 27. In females from group 2, the progesterone peak shifted to days 35-38. Females from group 1 gave birth to nymphs on day 36, females of group 2 on days 42-45. In males of group 2, a similar shift of the progesterone peak was observed.

Females of the endophagous parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) respond positively to the cornicle secretion of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae). The parasitoid response has been assessed in a Petri dish choice test by presenting an aphid dummy consisting of a glass bead coated with cornicle secretion along with an untreated bead, which acted as a control. Naive females responded similarly to the treated glass beads and aphids, while experienced females responded less to the treated beads than to aphids. The kairomonal activity of the cornicle secretion decreased as the wax dried. The behavioural response registered seems to be innate and not induced by associative learning.

Hyperparasitoids are, considered to reduce the effectiveness of primary parasitoids as biological control agents of aphids in a variety of crops. Recently it was shown that volatiles produced by the hyperparasitoid Alloxysta victrix (Westwood) elicit a dispersal in female primary parasitoids thereby potentially reducing primary parasitoid activity in the field at certain times. The active chemical was identified as 6-methyl-5-heptene-2-one (MHO) which is produced by both male and female A. victrix. The function of this chemical in the intraspecific communication of A. victrix was studied. Y-tube olfactometer experiments revealed corresponding effects of MHO and natural odour sources. Males were attracted to females especially when not mated. Females were repelled by females. These effects could partly be mimicked with pure MHO in the olfactometer. In Petri dish experiments the behaviour of A. victrix in the presence of MHO odour was video-analysed. As in the olfactometer, males were attracted to the odour and females repelled. We conclude that MHO is a sex pheromone which attracts A. victrix males and as spacing pheromone enables an even distribution of females in the field.

Because of their economic importance as biological control agents, the basic biology of phytoseiid mites has been studied extensively. Diapause induction has been investigated in a number of species, with consistent results; however, very few studies have addressed cold hardiness of these mites. Recent studies of cold hardiness and cold storage of Phytoseiulus persimilis Athias-Henriot and Amblyseius cucumeris (Oudemans) indicate that cold exposure had greater adverse effects on nondiapausing A. cucumeris, which normally overwinter in diapause, than on P. persimilis, which do not diapause. This might be explained in terms of adaptations for winter survival in their native environments. Phytoseiid mites are easily mass-reared and enter diapause in a facultative manner, and thus may be ideal subjects for investigation of the relationship between cold hardiness and diapause.

Two races of Muscidifurax raptorellus Kogan & Legner (Hymenoptera: Pteromalidae) reveal combinations of extranuclear and chromosomal inheritance for the quantitative trait, gregarious oviposition. In the first extranuclear phase prior to chromosomal inheritance, unknown substances transferred at mating cause a portion (<= 1/2) of the intensity of a particular quantitative trait present in the males' genome to be expressed phenotypically in the inseminated females within an hour of mating. The ability to change the adult female's expression of the quantitative character, either positively or negatively, challenges accepted views of polygenic loci, and it is suggested that such loci may not be inherited, but rather another group of genes which have the capability to switch on or off the loci. Such genes may influence DNA methylation of the loci controlling oviposition behavior. All polygenic loci may be perpetually present for a given quantitative trait in all individuals of both races, but they are either activated or inactivated by substances under the control of another group of genes. An enhanced significance for haploid males is indicated through an ability to activate expressions of part of their own genetic make-up within their own generation, which may quicken natural selection and the pace of evolution.