Source of an egg kairomone for Trissolcus basalis, a parasitoid of Nezara viridula

Abstract. The eggs of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), are successfully attacked by Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae) and are recognized as hosts by a secretion applied to the egg chorion. This secretion is produced by the follicular cells in the proximal region of the ovariole of the female pentatomid and functions as an adhesive for attaching the eggs to the oviposition substrate. The adhesive and kairomone activity could be partially removed with water. This water extract elicited host recognition behaviour in T. basalis when applied to glass beads which stuck together as the extract dried. The adhesive and kairomonal activity was removed completely with acetone since acetone-washed host eggs were not recognized by T. basalis. Application of the acetone extract to glass beads stimulated ovipositional probes by T. basalis. The adhesive appeared to be composed of a mucopolysaccharide–protein complex.     

Rates of ingestion and their variability between individual calanoid copepods: direct observations

The goals of this study were to determine rates of ingestionand fecal pellet release, and their variability, for individualplanktonic copepods over extended periods of time (>20 min).Ingestions and rejections of individual cells of the diatomThalassiosira eccentrica by adult females of the calanoid Paracalanusaculeatus were directly quantified by observing individual copepodscontinuously at cell concentrations ranging from 0.1 toli mm³l^–1.Average ingestion rates increased with increasing food concentration,but were not significantly different between 0.3 and 1.0 mm³l^–1(9.8 and 32.7 µg Cl^–1) of T.eccentrica. Rates ofcell rejections were low and similar at 0.1 and 0.3, but weresignificantly higher at 1.0 mm³ l^–1. The coefficientsof variation for average ingestion rates of individual copepodshardly differed between food concentrations, ranging from 17to 22%, and were close to those for average fecal pellet releaseintervals which ranged from 15 to 21%. A comparison betweenindividuals at each food concentration found no significantdifferences at 1.0; at 0.1 and 0.3 mm³l^–1, respectively,ingestion rates of four out of five females did not differ significantlyfrom each other. Average intervals between fecal pellet releaseswere similar at 0.3 and 1.0 mm³l^–1 of T.eccentrica, butsignificantly longer at 0.1 mm³ l^–1. Fecal pellet releaseintervals between individuals were significantly different ateach food concentration; these significant differences wereattributed to rather narrow ranges of pellet release intervalsof each individual female. Potential sources/causes of variabilityin the sizes and rates of copepods in the ocean are evaluated. ³Present address: Great Lakes Environmental Research Laboratory,2205 Commonwealth Boulevard, Ann Arbor, Ml 48105, USA     

Breeding success and chronology of Wood Storks Mycteria americana in northern and central Florida, U.S.A.

The breeding success and chronology of Wood Storks Mycteria americana were studied at eight colonies in northern and central Florida during 1981–1985. Mean ± s.d. clutch size for all colony-years was 3.07 ± 0.56 (n = 2694 nests), with three-egg clutches (72%) most frequent. Mean clutch size among all colonies and years ranged from 2.73 ± 0.55 to 3.41 ± 0.61. Many colonies exhibited significant negative trends in clutch size with, hatching date because of a proportional decrease in four-egg clutches later in the season. Mean colony clutch size was not correlated with nest numbers, nesting density or mean hatching date within most years. Mean ± s.d. number of fledglings for all colonies and years was 1.29 ± 1.16 fledglings per nest (n = 2812 nests). Mean annual fledging rates in colonies ranged from 0 (colony failed) to 2.66 fledglings per nest. Most breeding failure occurred prior to egg hatching, and the second highest mortality occurred between hatching and 2 weeks of age. Four-egg clutches fledged more storks than three-egg clutches, which in turn were more successful than two-egg clutches. However, all clutch sizes showed similar fledgling per egg rates. The seasonal decline in productivity was associated proportionally with smaller clutch sizes later in the breeding season. An increase in mean hatching date was correlated with an increase in latitude. There was greater within-year breeding synchrony among colonies than interyear breeding synchrony within each colony. Breeding synchrony was not correlated with mean hatching date, latitude, longitude, nest numbers or nesting density.     

A New Malaria Parasite Plasmodium (Sauramoeba) heischi in Skinks (Mabuya striata) from Nairobi, with a Brief Discussion of the Distribution of Malaria Parasites in the Family Scincidae

ABSTRACT. A new species of malaria parasite, Plasmodium (Sauramoeba) heischi , is described from African skinks (Mabuya striata). Eleven individuals of 90 specimens collected in Nairobi were found to be infected. The new parasite is a large species, characterized by spindle-shaped gametocytes, the female often with a subterminal nucleus. The schizonts produce up to 65 nuclei and cause great hypertrophy and distortion of the host cell. Although similar to P. (Sauramoeba) giganteum in dimensions and merozoite numbers, P. heischi is easily distinguished by gametocyte and schizont shapes.     

The Spontaneous Formation of Antheridia in Onoclea is not Blocked by Light

Onoclea sensibilis gametophytes were grown from spores on ashedsoil and agar to determine if the spontaneous formation of antheridiacan be blocked by light. Under most conditions, dark-grown gametophytesformed antheridia later than or at the same time as gametophytesgrown in the light. Under no circumstances was there a rapidonset of maleness in the dark. These results contradict thehypothesis that, in Onoclea, antheridiogen is required to inducemaleness because light inhibits the formation of antheridia.In the light, antheridia formed on heart-shaped thalli. In darkness,antheridia formed on filamentous gametophytes. The timing ofonset of maleness was affected by temperature and the presenceof sucrose. The effect of sucrose on the comparison betweenlight and dark treatments depended on both substrate and temperature Onoclea sensibilis, L., sensitive fern, fern gametophytes, sexuality, light-induced block     

Distribution of alloantigens on human Fc receptor-bearing lymphocytes: the presence of B cell alloantigens on sIg-positive but not sIg-negative lymphocytes.

Human peripheral blood lymphocyte subpopulations were analyzed for the presence of B cell alloantigens with a microcytotoxicity assay. B cell alloantigens were found exclusively on sIg-positive lymphocytes and were not present on sIg-negative, Fc receptor-bearing lymphocytes or sIg-negative, Fc receptor-negative T lymphocytes.     

Ecophenotypic strategies of dalmanellid brachiopods

General ecophenotypic patterns, of particular interest when they apply to all, or most, taxa of the group concerned, can never be demonstrated until after monophyletic taxa have been recognized, that is, until after the initial stages of phylogeny construction have been carried out. In criticizing certain dalmanellid phylogenies, and based in large part on a study of five 'species subgroups'. Hurst & Watkins (1978; Geologica et Palaeontologica 12 ) postulate ecophenotypic patterns for Isorthis , and Hurst (1978; Palaeontology 21 ) postulates general patterns of ecophenotypic variation for dalmanellid brachiopods. These patterns may be invalid for four reasons: (1) Univariate and 'bivariate' statistical analysis of the samples used to define the five subgroups reveals no significant differences between subgroups, or vertical trends, for the very morphological characters claimed to exhibit the ecophenotypic patterns; (2) Hurst & Watkins' discriminant function analysis contains procedural errors and its results are ambiguous; (3) several of the five subgroups represent mixtures of unrelated taxa; (4) in recognizing the alleged patterns, Hurst & Watkins ignored contrary evidence from many taxa (and from many dalmanellid studies). □ Brachiopoda, Dalmanellidae, Silurian, ecology, evolution, systematics.     

THE ORIGINS OF ADAPTIVE INTERSPECIFIC TERRITORIALISM

1. In order to understand fully the evolution of a behavioural trait one must not only consider whether it is adaptive in its present environment but also whether it originated as an adaptation to existing selective forces or as a fortuitous consequence of selection for a different role in other environments (i.e., as a pre-adaptation) or of selection for different traits (e.g., as a pleiotropic effect). In this paper interspecific territorialism is examined in species of humming-birds, sun-birds, tropical reef fishes, stingless bees, stomatopods, crayfish, and limpets as a means of determining its adaptiveness and its origins. 2. Humming-birds form complex assemblages with species sorted out among the available resources. Dominant species establish feeding territories where flowers provide sufficient nectar. A few large, dominant species, usually uncommon, are marauders on others' territories. Subordinate species establish territories where flowers are more dispersed or produce less nectar, or they fly a circuit from nectar source to nectar source when flowers are even more dispersed, a foraging pattern called ‘traplining’, or they steal nectar from the territorial species by being inconspicuous while foraging. Two species, Amazilia saucerottei and Selasphorus sasin, subordinate in one-to-one encounters, are able to take over rich resources by establishing several small territories within a territory of a dominant and forcing it to forage elsewhere. 3. Among humming-birds, territorial individuals attacked not only subordinate competitors but marauding humming-birds and some insects, which stayed in the territory and foraged at will, and seemingly inappropriate targets, such as non-competitors. This suggests that the stimulus for aggression is ‘any flying organism near the food resources’, regardless of its appearance. The behaviour rather than the identity of the intruder is the stimulus. 4. Sun-birds resemble humming-birds to the extent that dominants establish territories on rich nectar sources and subordinates establish territories on less rich nectar sources or steal from the territories of dominants. The diversity of foraging patterns is not so great as in humming-birds, perhaps because so few species of sun-birds have been studied. However, the advantage of territorialism has been measured in the sun-bird Nectarinia reichenowi. Individuals with territories lose much less nectar to competitors than do those without territories. 5. Field work on three species of tropical reef fishes involved a single aggressive species whose individuals attacked a wide range of species intruding on their territories. The stimulus for aggression in Pomacentrus jenkinsi seemed to be an “object moving through [its] territory”. As suggested for humming-birds, the stimulus is the behaviour rather than the identity of the intruder. 6. The relationships found in stingless bees, stomatopods, crayfish, and limpets are simpler. The dominant and subordinate species divide the resources in their habitat, the dominants' aggression preventing the subordinates from using resources that were otherwise available to them. 7. A general pattern emerges. Mutual interspecific territorialism occurs between species that (i) have different geographic ranges, (ii) occupy different habitats, or (iii) use different resources within the same habitat. Examples of two species holding separate territories on the same resources within the same habitat are rare and occur when the dominant species is rare relative to the available resources. These observations are contrary to the usual view that interspecific territorialism is an adaptation that permits co-existence of potential competitors within the same habitat. 8. Interspecific territorialism is sometimes adaptive and sometimes maladaptive, depending upon the species and the situation. 9. The general pattern of occurrence of the behaviour and the general nature of the stimulus for aggression, i.e., the behaviour rather than the identity of the intruder, suggest that interspecific territoriality is a fortuitous consequence of selection for intraspecific territorialism, the latter being not only an adaptation to the presence of conspecific competitors but a pre-adaptation to the presence of competitors of other species, should they occur.