The species of flea beetles of the genus Chaetocnema Stephens, 1831 occurring in Madagascar are revised. Four new species (C. cachani, C. hygrophila, C. malgascia and C. orophila) are described and five species (C. bamakoensis Bechyné C. confinis Crotch, C. fuscipennis Scherer, C. ganganensis Bechyné and C. picipes Stephens) are added to the Madagascar fauna. The following new synonymies are proposed: C. wollastoni Baly, 1877 = C. fraterna Harold, 1879 syn. nov. = C. monomorpha Bechyné, 1964 syn. nov.; C. pulla Chapuis, 1879 = C. tantilla Weise, 1910 syn. nov.; C. bilunulata Demaison, 1902 = C. sylvia Bechyné, 1964 syn. nov.; C. vadoni Bechyné, 1948 = C. alaotrensis Bechyné, 1964 syn. nov.; C. gregaria Weise, 1910 = C. insularis Weise, 1910 syn. nov. Lectotypes are designated for C. gregaria Weise, 1910, C. insularis Weise, 1910, C. similis Weise, 1910 and C. tantilla Weise, 1910. A key to all the species is presented. Line drawings of male and female genitalia of all the species are included. Ecological and brief zoogeographical data on some species are given.

CABI Publishing, Wallingford, U.K., 2001. ix + 1032 pp.

I investigated the seasonal changes of cold tolerance and polyol content in adults of Harmonia axyridis to elucidate their overwintering strategy. Adults decreased their supercooling point and lower lethal temperature only during the winter. Although the seasonal trends for both values were almost consistent, there seemed to be considerable mortality, without being frozen, at -20°C in mid-winter. The pattern for seasonal change in tolerance at moderately low temperatures differed among the temperatures exposed: the survival time at -5°C peaked in winter, but the time at 5 or 0°C peaked in autumn. Because both autumn and winter adults were completely paralyzed only at -5°C and survived much longer at 0°C than at 5°C, the survival time at -5°C indicates the degree of chilling tolerance, whereas the time at 5 or 0°C seems to show starvation tolerance. This beetle accumulated a relatively large amount of myo-inositol during winter. Myo-inositol content synchronized seasonally with supercooling capacity, the lower lethal temperature and the chilling tolerance, suggesting that myo-inositol may play some role in the control of cold tolerance in this beetle.

The reproductive behaviour of a ladybeetle, Coccinella septempunctata was studied in detail. Males became sexually mature within 8.8 ± 0.3 days at 27°C, while females took 11.2 ± 0.4 days. Males exhibited courtship display in five steps: approach, watch, examine, mount and copulatory attempt. A prominent rejection display was shown by certain females who had not matured sexually, had recently mated or were about to oviposit. Males appeared to recognize females through chemical and some visual cues, such as size and body shape, with the chemical cues possibly playing a more significant role. Multiple matings took place within the same day. There was a gradual decrease with time in reproductive parametres, such as the duration of copulation, the number of copulatory bouts and the latent period from first to subsequent matings on the same day. The interval between mating bouts slightly increased from first to subsequent matings. The sexual status of males and females affected the duration of copulation, which was greatest in the case of unmated males and virgin females. Multiple matings increased the oviposition period, fecundity and percent hatching of eggs.

One new genus and nine new species of Staphylinidae are described from Baltic amber, namely Palaeosepedophilus gen.n. and the species P. succinicus sp.n., Lathrobium balticum sp.n., Lathrobium succini sp.n., Lathrobium ambricum sp.n., Lathrobium jantaricum sp.n., Sepedophilus balticus sp.n., Dictyon antiquus sp.n., Phymatura electrica sp.n., Aleochara baltica sp.n. Their affinity with related species is discussed.

The spermathecae of eleven genera of the family Dinidoridae (Dinidorinae and Megymeninae) were studied. Four types of spermatheca morphology were observed. Possible use of the morphology of spermathecae in the taxonomy of Dinidoridae is discussed.

RFLP clones harbouring multi-copy DNA sequences were isolated from the Pst I sub-genomic library of the indigenous silkworm race, Nistari, and were used for DNA fingerprinting studies in 13 stocks of silkworm, Bombyx mori L. Six multilocus probes produced 180 RFLP markers that showed a high level (98%) of polymorphism and are highly useful in molecular mapping, genotype characterization and marker assisted selection (MAS). The dendrogram derived from UPGMA analysis clearly divides the 13 silkworm stocks into two major clusters: high- and low-yield stocks. Furthermore, adopting multiple regression analyses, the RFLP marker(s) associated with characters of economic importance were identified, a first of its kind for any species of insect of commercial importance. The results obtained create an opportunity of using germplasm stocks directly for isolating specific RFLP band(s) and use it for MAS in breeding programs.

In: Ramos M.A. et al. (eds): Fauna Ibérica, vol. 14. Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas, Madrid, 2000, 526 pp.

Although some parts of diapause development have been clarified up by endocrinologists, knowledge of the underlying processes remains insufficient. The survey of ecophysiological aspects of diapause development has thus to be limited to inputs and outputs from the blackbox. The terms diapause development, diapause intensity, post-diapause quiescence, horotelic processes of diapause, and tachytelic processes of diapause (reactivation) are defined. Andrewartha's term diapause development has been accepted because it shows diapause as a dynamic event.
In about the last 20 years, some views on diapause development have been updated, while others have fossilised. The assumption that chilling is a general prerequisite for completion of diapause development in all insects still survives in part of the scientific community, in spite of much contradictory evidence and often due to inadequate interpretation of experiments (examples given in figures and tables). On the contrary, it has been generally recognised that in temperate climates overwintering diapause is usually already completed in early/mid winter and the dormancy is then temperature quiescence. The conception of multiple pathways of diapause completion postulates that diapause can be completed either by the normal (slow) progress of diapause development (horotelic processes), or by a faster activation (tachytelic processes). There are important differences between the mechanisms regulating activation and the horotelic processes. Thus, e.g., the photoperiodic response is lost during horotelic completion, while after photoperiodic activation it persists. In addition to photoperiodic activation other kinds of activation are being studied, particularly activation by high temperature.
Some conclusions can be made from modern studies on diapause development. In every individual, several (at least two) possible pathways exist that are evidently interlinked and mutually complementary. Thus the time of diapause passed at any condition has to be considered, as well as the exposure to very low temperatures. In temperature studies the experimental range ought to be adequately wide and less affected by a priori assumptions. Stimulation by temperature increase or improvement in food or other conditions has to be considered.
The success of diapause completion should be measured by at least four parameters: (1) incidence (%) of developmental steps; (2) duration of delay; (3) synchronization; (4) vigour of post-diapause insects (shown by long-term survival or fecundity). The last two parameters have usually been neglected.

The effects of temperatures of 15, 20, 25 and 30°C on the duration of premating and preoviposition periods of Harmonia axyridis reared on the aphid Aphis fabae, were compared in the laboratory. The course of oviposition was monitored at 25°C in females reared on Aphis fabae and the peak of egg laying was recorded at the age of 15 to 45 days. The size of egg groups (batch size), as well as daily and total fecundity was recorded. Half of the total number of eggs was laid in batches of 10-30 eggs. The mean daily and total fecundity reached a maximum of 42 and 1,641.6 eggs, respectively. Adult females oviposited for almost their entire life.

The role of the thermophotoperiod on larval diapause induction and development of Sesamia nonagrioides was investigated under laboratory conditions. The incidences of diapause by TC 12 : 12 thermoperiods under DD, in which the thermophase was 30°C and cryophases varied from 10 to 25°C, were compared to the effects of thermophotoperiods with the same configuration. Higher incidences of diapause were recorded when larvae were exposed to thermophotoperiods with cryophases of 15-25°C, than under thermoperiods under constant darkness. In addition, larvae exhibited significantly lower percentages of diapause when exposed to cryophases < 15°C under either thermo- or thermophotoperiodic condition. Diapausing larvae when exposed to photoperiods 16L : 8D h and different temperatures of 25-30°C proceeded to development in 14-16 days. Moreover time needed for the pupation of diapausing larvae after their transfer to 12L : 12D h, was reduced from approximately 49 to 12 days depending on temperatures of exposures (25-30°C). Diapause termination was also compared under 12L : 12D h and constant temperature of 25°C or a thermoperiod of TC 12:12 (30°: 20°). Days needed for pupation at constant temperature or under the mentioned thermoperiodic regime, were approximately the same when the high temperature of the thermoperiod coincided with the scotophase, while with the co-occurrence of the high temperature of the thermoperiod and the photophase significantly additional time was needed for diapause development. Significantly shorter time was also needed for diapause development after exposure of diapausing larvae to continuous light, than to continuous darkness under 25°C. Thermoperiods of different amplitudes with the same mean temperatures proved that the higher temperature of scotophase led to higher rate of diapause development in spite of the relatively low temperature of the photophase tested. It is suggested that thermoperiod could hasten the time needed for diapause development, but it is not the crucial factor for the termination of diapause.

The aphid parasitoid Aphidius ervi was collected and subsequently reared on Sitobion avenae on wheat or Acyrthosiphon pisum on alfalfa. Parasitoids from both origins were exposed in an olfactometer to alfalfa or wheat volatiles after plant experience (wheat or alfalfa) or after oviposition experience (S. avenae on wheat or A. pisum on alfalfa). The results showed the importance of adult experience, conditioning and innate preferences on the responses of A. ervi toward volatiles and provided a mechanistic explanation to the high prevalence of A. ervi on aphids on cereals and legumes in central Chile.

Voltinism and larval growth pattern were investigated in an edge-of-range population of Coenagrion mercuriale. Coenagrion mercuriale is semi-voltine in Britain and growth is inhibited in winter. The 2^nd year group overwinters in a range of instars between the antepenultimate and final instar consistent with the early, asynchronous emergence pattern of this species. A facultative autumnal diapause in the penultimate instar is the most likely mode of seasonal regulation. The broad size distribution of larvae produced by this growth pattern was wider than that found in co-occurring populations of Pyrrhosoma nymphula, a "spring" species with synchronous emergence. The broad size distributions may lead to considerable intraspecific interference between C. mercuriale larvae. Sex ratio in the last three larval instars of C. mercuriale did not differ significantly from unity. A laboratory investigation of the effect of temperature and photoperiod on growth and diapause in C. mercuriale is recommended to determine whether high minimum temperature thresholds for development limit both the width of the temporal niche and microhabitat use by this species at its range margin.

More than 60 neuropeptides that inhibit juvenile hormone synthesis by the corpora allata have been isolated from the brains of various insect species. Most of them are characterized by a common C-terminal pentapeptide sequence Y/FXFGL/I/V (allatostatin A family, allatostatin superfamily). Besides the allatostatin A family, allatostatic neuropeptides belonging to other two peptide families (W²W⁹)-allatostatins or allatostatin B family; lepidopteran allatostatin) were reported. So far, only one allatotropin has been identified. Here we discuss latest literature on the multiplicity and multifunctionality of the allatoregulating neuropeptides, their physiological significance as well as their evolutionary conservation in structure and function.

The effects of oviposition-deterring larval tracks of four aphidophagous coccinellids and two chrysopids were investigated on females of four coccinellid species in choice tests. Aphidophagous coccinellids Cycloneda limbifer Casey, Semiadalia undecimnotata (Schneider) and Coccinella septempunctata L. laid significantly fewer eggs on sites with tracks of unfed conspecific first instar larvae than on clean sites, but Leis dimidiata (F.) laid similar numbers of eggs on both sites.
In some but not all species, tracks of heterospecific predators also deterred coccinellid females. Interspecific effects were stronger between some allopatric species than between the sympatric coccinellids C. septempunctata and S. undecimnotata. C. limbifer laid relatively few eggs on sites previously exposed to larvae of S. undecimnotata and L. dimidiata. S. undecimnotata avoided sites with tracks of L. dimidiata larvae. The two smaller species, C. limbifer and S. undecimnotata, laid considerably fewer eggs per batch than the larger coccinellids, C. septempunctata and L. dimidiata. C. limbifer and S. undecimnotata oviposited similar numbers of eggs on clean sites and sites with tracks of chrysopid larvae of the species Chrysopa oculata and Chrysopa perla. Females of C. septempunctata laid fewer eggs on sites previously exposed to larvae of C. oculata but not C. perla.
Densities of faecal spots of coccinellid females on clean substrates and substrates with tracks of predatory larvae differed significantly in only one choice test (C. limbifer females exposed to tracks of S. undecimnotata larvae). This indicates that the presence of larval tracks affects where females lay eggs more than where they search.

A phylogeny of fifty-eight cockchafer species belonging to the genus Amphimallon Berthold, 1827 is proposed, based on sixty-five morphological characters. The cladistic analysis provides seventy-two equally parsimonious trees. The genus Amphimallon is redefined and species-groups are introduced and defined: A. pini-group (seven species), A. vernale-group (five species), A. solstitiale-group (seven species), A. arianae-group (two species), A. peropacum-group (one species), A. fuscum-group (eleven species), A. naceyroi-group (seven species), A. majale group (five species), A. lusitanicum-group (six species). Other species previously placed in Amphimallon are considered species incertae sedis in this paper: amphibolum Peyerimhoff, 1949, and a monophyletic group composed of six North African species: altifrons Baraud, 1971, julieni Baraud, 1972, melillanum Baraud, 1972, scutellare Lucas, 1846, subcristatum Fairmaire, 1879, subparallelum Escalera, 1913. Four new Amphimallon species are described: A. adanense sp. n. from Turkey, A. maniense sp. n. from Greece, A. jeannae sp. n. and A. safiense sp. n. from Morocco. The following taxonomic conclusions are proposed: A. seidlitzi Brenske, 1891 = A. trisinuatum Reitter, 1902 syn. n.; Amphimallon jeannei (Baraud, 1971) comb. n.; Miltotrogus caucasicus Gyllenhal, 1817 comb. n.; Amphimallon vernale (Brullé, 1832) stat. n.; A. furvum (Germar, 1817) stat. n.; A. javeti Stierlin, 1864 stat. n.

The activity and number of protocerebral neurosecretory neurons of the dorsolateral group (L1, L2 and L2'), as well as the size of the corpora allata were investigated in 5th instar larvae of the gypsy moth (Lymantria dispar) from two populations (oak and locust-tree forests) fed one of two host-plants (oak is a suitable and locust-tree an unsuitable host-plant).
The monitoring of activity related cytological parameters and the number of protocerebral dorsolateral neurosecretory neurons revealed that differently adapted populations respond to nutritive stress differently. The activity of the L1 neurosecretory neurons in the protocerebra of the caterpillars is low in those from the locust-tree forest regardless of host-plant quality. The L2 neurosecretory neurons in the oak population become active when they were fed the unsuitable host-plant whereas their activity was high in locust-tree caterpillars regardless of the host-plant. A decrease in the number of neurosecretory neurons in a response to a novel food was noticed in both populations. The activity of the L2' neurosecretory neurons was similar in all caterpillars, but their number was increased in those from the locust-tree forest. The corpora allata of the locust-tree caterpillars were large whereas those of the oak forest caterpillars only increased in size when they were fed locust-tree leaves.
It is obvious that nutritive stress results in neurosecretory reorganization and changes in the titre of hormones that modulate the morphogenetic programme.

Phylogenetic systematics comprise the principles and methods by which we reconstruct the evolutionary history (phylogeny) of organisms and transform this reconstruction into a biological classification of these organisms. The most important progress in designing the tools for phylogenetic reconstruction was initiated by the German entomologist Willi Hennig (1913-1976), who clarified or redefined the goals of phylogenetic systematics in a book published in 1950: Grundzüge einer Theorie der phylogenetischen Systematik. An extensively revised, English translation was published in 1966: Phylogenetic Systematics. W. Hennig's "phylogenetic systematics" undoubtedly was a very significant contribution to systematics, by some systematists and philosophers even characterized as a "revolution". Hennig's redefinition and clarification of the concepts of monophyly and phylogenetic relationships created a sound foundation for systematics in general. After decades of focussing on species-level problems, Hennig redirected the interest of systematists towards the study of higher taxa and the reconstruction of phylogenetic relationships between them. A phylogenetic system is now almost universally accepted as the most useful general reference system for biology. It has been able to accommodate new developments in systematics (such as quantitative cladistics and molecular systematics), evolutionary biology (such as ecological phylogenetics), and historical biogeography.

Academic Press, London, 1997, 409 pp., 102 ill., 4 tab.

This paper concerns the life-cycle of Carabus dufouri Dejean 1829, one of the most representative species of Carabus in the south of the Iberian Peninsula. The study is based on data of the annual activity patterns in the natural habitat, on anatomical observations related to the sex and age of the specimens, on the reproductive condition of females and, finally, on the results of laboratory rearing experiments carried out to study the oviposition patterns and the course of development of immature stages. The results indicate that C. dufouri shows the annual rhythm of autumn breeders. However, the rhythm may also be related to the winter-breeder type of North Africa.

Megaselia metropolitanoensis Disney, sp. n., M. sakaiae Disney, sp. n. and Puliciphora pygmaea (Borgmeier, 1960) comb. n. are reported developing in the flowers of Aristolochia inflata H. B. K. and A. maxima Jacq. in Panama. The new species are described, as is the hitherto unknown male of Puliciphora pygmaea. The latter is transferred to the the genus Puliciphora Dahl, 1897 from the genus Myrmomyia Silvestri, 1911 which is formally synonymised with Puliciphora, along with P. brachymyrmecis (Silvestri, 1911) comb. n. and P. nigroflava (Borgmeier, 1958) comb. n.

The plant vigour hypothesis (PVH) predicts that females of galling insects preferentially oviposit on the most vigorous plants or plant modules, where their offspring's performance is highest. In the years 1995 to 1998, we evaluated the responses of species of two different guilds, two chewing species, Pantomorus sp. and Naupactus lar (Coleoptera: Curculionidae) and one galling species, Contarinia sp. (Diptera: Cecidomyiidae), to the length of shoots that were assumed to show the vigour of the tropical shrub Bauhinia brevipes (Leguminosae). The abundance of the chewing herbivores was not influenced by shoot length, since attack rates were randomly distributed among shoot length classes. The abundance of Contarinia galls increased with increasing shoot length, as proposed by the PVH. However, when we related the attack rate to unit length of shoot (cm), which denotes the resource availability per unit length, there was no effect of shoot length on Contarinia sp. These data corroborate the idea of a continuum of responses to plant quality, even when different herbivores feed on the same host plant.

The larval morphology of the western Palaearctic zygaenid species Aglaope infausta (Linnaeus, 1767) is described and figured in detail. Unlike other members of the zygaenid subfamily Chalcosiinae, the last instar larva of A. infausta has numerous secondary setae and a multitude of cuticular cavities that are devoid of openings. The other chalcosiine genera have primary setae and cuticular cavities with specialized openings through which a defensive secretion can be discharged. Imaginal characters, on the other hand, provide strong evidence for placing Aglaope in the Chalcosiinae.

The coccinellid H. axyridis shows considerable intraspecific variability of elytral patterns. In this paper, we suggest that a genotype that confers a specific pattern of elytra could also confer other specific autecological attributes. The aim of this paper is to compare fitness parameters of two phenotypes (aulica and nigra). Aulica is a common morph characterized by two light red areas that nearly cover the whole elytra, leaving a narrow black border, whereas nigra is completely black; the latter is a rare morph that was naturally obtained from mass cultures. Intraspecific differences occur between H. axyridis phenotypes. The aulica phenotype is more voracious than nigra. Consumption rate of males is higher in aulica than in nigra, but there is no difference for females. Larval biomass of aulica is generally higher than that of nigra. The maximum body-weights reached by larval instars and adults are significantly higher for aulica. Aulica also has greater longevity and reproductive capacity. Only life stage duration of eggs and pre-pupae differ between the two phenotypes. Nigra shows lower fecundity and fertility. Our study showed that the strong differences in phenotype traits of the coccinellid H. axyridis could affect its fitness.

So far, available cytogenetic data on 24 species of Rhopalidae reveal a male diploid chromosome number of 13, with a pair of m chromosomes and an X0/XX (male/female) sex chromosome determining system. As a rule Heteroptera have holokinetic chromosomes and a pre-reductional type of meiosis: the autosomal bivalents and the m pseudobivalent segregate reductionally at first meiotic division, while the X chromosome segregates equationally. In the present study, the meiotic chromosome behaviour was analyzed in males from different Argentinean populations of Jadera haematoloma and J. sanguinolenta. Our results corroborate the diploid chromosome number and general patterns of male meiosis previously reported by other authors in samples from Brazil and Texas (USA). Among bivalents, one is remarkably larger and may present one or two terminal chiasmata. Comparison of mean chiasma frequency between Jadera haematoloma (5.63) and J. sanguinolenta (5.14) revealed that differences are significant. In most individuals of both species the largest pair appears as univalents in a variable number of cells and shows a regular meiotic segregation. Autosomal univalents orientate axially at metaphase I (with their long axis parallel to the spindle axis) and segregate equationally at anaphase I. At metaphase II they associate end-to-end forming a pseudobivalent that segregates reductionally at anaphase II. An hypothesis is suggested to explain the appearance of the largest pair, either as a ring/rod bivalent or as univalents within the same individual, although an asynaptic or desynaptic origin of the univalents cannot be ascertained. The highly regular meiotic behaviour of this autosomal pair could ensure a high fertility of the individuals, and could be considered a selectively neutral condition or, at least, not detrimental.

Adults of Copestylum tamaulipanum and C. lentum were reared from larvae collected from decaying platyclades of the cactus Opuntia in the state of Veracruz (Mexico). The larvae and puparia of both species, as well as preliminary data about their life cycles are described. The feeding behaviour of the larva in relation to the morphology of the cephalopharyngeal skeleton is analysed.

Hyssopus pallidus (Askew) (Hymenoptera: Eulophidae) is a gregarious ectoparasitoid of late larvae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). In the present work reproduction and the development and morphology of the immature stages were studied. Five larval instars were differentiated by the shape and size of the mandibles. The larvae are hymenopteriform with a weakly sclerotized head and 13 segments. The first instar has four pairs of spiracles, while the other four instars have nine pairs. Under laboratory conditions of 22-24°C and 60-80% RH the egg stage lasted 1.5 days, the larval instars 6.3 days, and the pupal stage 7.9 days in females and 7.2 days in males. The duration of each of the five larval instars (L1-L5) is approximately 1, 0.5, 0.75, 0.75 and 3.5 days, respectively. Male and female development time does not differ significantly in the egg and larval stages, but differences are highly significant in the pupal stage. Male and female pupae can be differentiated by their sexual rudiments. Copulation takes place immediately upon emergence of the females between siblings, adult males appearing before the females. Females in culture with access to an energy source can survive for more than 60 days. They are synovigenic: they emerge with no mature eggs in their ovaries and take the first two days after emergence to mature the full set of around 24-30 eggs. They continue paralyzing hosts, ovipositing and maturing eggs for as long as they live. After an oviposition a female needs two to three days to mature a new full set of eggs. Age and feeding influence egg load. Oösorption is significant in starved females, but also occurs in older fed females with no host contact.

The distribution of arthropod species on a 400 m elevational gradient (equivalent to a temperature decrease of 2.5°C) on Snowdon, North Wales, was examined and compared with the British distribution. Preferred temperature, an indication of optimal body temperature (T_b), and supercooling point (SCP), an indication of cold tolerance, of several species on the gradient were determined experimentally. The alpine beetle species Patrobus assimilis and Nebria rufescens had low preferred T_b, of 5.6 and 7.1°C respectively, whereas the more widespread upland species had higher preferred T_b, between 12.9 and 15.5°C. The SCP of both alpine and widespread beetles were similar, being between -6.9 and -5.8°C. The alpine species, which were smaller, were freeze intolerant, whereas the widespread species, which were larger, were freeze tolerant. On the national scale there was significant correlation between preferred T_b and species elevation, but no correlation with SCP. It is concluded that the alpine species survive on Snowdon because their optimal T_b is close to the ambient temperature at the time of day and year when they are active and because they are able to tolerate winter temperatures, by a combination of cold tolerance and shelter. Although a species' optimal niche will tend to shift upwards as mean temperatures rise with global climatic change, complex microclimatic and biotic factors make changes in distribution difficult to predict.

Polyclonal antibodies against PBAN were used to map the distribution of PBAN-like antigenic sites in the brain-suboesophageal ganglion (Br-SOG) complex, associated neurohaemal structures, ventral nerve cord ganglia and in the alimentary canal. A pair of lateral neurosecretory cells immunopositive to the antiserum were found in each half of the deutocerebrum. PBAN-like immunoreactivity (PLI) was also noticed in the tritocerebral region of the brain and in the aorta. Two groups of immunopositive cells of four and two cells respectively, were found in the SOG. Small and weakly immunoreactive neurons were identified in the prothoracic ganglion, whereas in the pterothoracic ganglion a pair of cells reacted positively to the antibody. Immunoreactive cells were also identified in the corpora cardiaca. Some of the epithelial endocrine cells of the midgut also showed immunoreactivity to PBAN antiserum.

Monoctonus paulensis is a solitary parasitoid of several species of aphids, including the pea aphid, Acyrthosiphon pisum. We evaluated host-instar selection by comparing the parasitoid's preference for the four nymphal instars of the pea aphid, presented two at a time in dichotomous choice tests. Females parasitized more, and laid more eggs in, the relatively smaller aphids among those available. This preference was independent of aphid instar: L1 > L2 > L3 > L4. Preference was not influenced by female size or age. Normal and anaesthetized aphids were accepted equally. The total time needed by a female to capture, position, and parasitize an aphid varied among host instars, with fourth instars requiring nearly twice as much time as first, second, and third instars. The probability of an attacked aphid escaping or avoiding parasitism increased with aphid instar, from ~10% in first and second instars to ~50% in fourth instars. Although fourth-instar pea aphids contain more resources for offspring development than smaller counterparts, it may not be profitable for a female to invest opportunity time in attacks on large aphids.