Honeyeater population changes in relation to food availability in the Jarrah forest of Western Australia

The numbers of honeyeaters present at particular sites in the Jarrah forest varied significantly from month to month, with peak abundance occurring between May and September. Numbers also varied from site to site, depending upon the major plant species present. Honeyeater abundance was not limited by arthropod availability, but in many instances was closely correlated with the availability of nectar, particularly that produced by Dryandra sessilis. Large honeyeaters, such as Anthochaera chrysoptera and Phylidonyris novaehollandiae, were generally most abundant at times and sites of greatest nectar production. Small honeyeaters, such as Acanthorhynchus superciliosis, were never abundant but were present for most of the year. The production of nectar between October and December was such that more honeyeaters could have been supported than were actually present. Low numbers at these times can be explained in terms of reduced foraging efficiency that would have resulted from more widely dispersed flowers, and the possible availability of more rewarding nectar resources at other sites.     

Purine and Pyrimidine Synthesis by the Avian Malaria Parasite,Plasmodium lophurae*

SYNOPSIS. Purine and pyrimidine biosynthesis in the avian malaria parasite Plasmodium lophurae and its host cell, the duck erythrocyte, were investigated in vitro. Pyrimidine synthesis, as measured by the incorporation of C¹⁴-NaHCO₃ into cytosine, uracil and thymine was slight in uninfected duck erythrocytes, whereas infected erythrocytes and erythrocyte-free parasites had high rates of incorporation of NaHCO₃ into these bases. In addition, orotidine-5′-monophosphate pyrophosphorylase and thymidylate synthetase, 2 enzymes of the pyrimidine biosynthetic pathway, were found in cell-free extracts of the plasmodia. Purine synthesis was measured by determining the extent of incorporation of C¹⁴-Na-formate into adenine and guanine. Uninfected and infected erythrocytes had similar rates of Na-formate incroporation into adenine. whereas free parasites incorporated little of this compound into adenine, or guanine. On the other hand, the incorporation of Na-formate into guanine was 54% higher in infected erythrocytes than in uninfected erythrocytes. It is suggested that P. lophurae synthesizes purines to a limited extent, and derives most of its purines from the host erythrocyte. The greater incorporation of Na-formate into guanine by infected cells, and its low incorporation into free parasites may be accounted for by parasite conversion of host cell adenine (in the form of ATP) into guanine. Pyrimidine biosynthesis in infected cells can be accounted for by de novo synthesis by the parasite itself.     

Urceolaria viridis n. sp., a Ciliate (Peritrichida, Mobilina) with Elongate Symbiotic Green Algae

SYNOPSIS. A new peritrichous ciliate containing elongate symbiotic green algae is described from the marine limpet Acmaea digitalis Eschscholtz (1833). Urceolaria viridis n. sp. is characterized as follows: turban-shaped; diam. 40 μ; diam. striated band 30 μ; diam. corona 23 μ; width of corona 2μ; 16–22 denticles; peristome slightly more than one turn; circlet of delicate cirri adoral to ciliary girdle; macronucleus H-shaped with both ends of side pieces widely separated; diam. micronucleus 4.5 μ, endosome 2.5 μ; cytoplasm containing elongate green algae measuring 2–4 by 8–16 μ.     

Dangers in testing statistical hypotheses

Most experiments are intended for the estimation of the size of effects rather than for the testing of a hypothesis of whether or not an effect occurs. Hypothesis testing is often inapplicable, is over-used and is likely to lead to misinterpretations of results. The two types of error possible in hypothesis testing are discussed. Whereas Type I error is usually examined as a matter of course, Type II error is almost always ignored. Investigations in which zero differences are important should recognise the possibility of Type II error in their interpretation. A nonsignificant result should not be interpreted as evidence of a lack of effect. Statistical significance is not synonymous with economic or scientific importance. The importance of choosing the most appropriate design is emphasised and some suggestions are made as to how important sources of error can be avoided.     

Identification of an Apically-Located Antigen That Is Conserved in Sporozoan Parasites

ABSTRACT. Sporozoan parasites of the phylum Apicomplexa all possess common apical structures. The current study used a monoclonal antibody (mAb-E12) to identify a conserved antigen in the apical region of merozoites of seven species of Plasmodium (including rodent, primate and human pathogens), tachyzoites of Toxoplasma gondii , bradyzoites of Sarcocystis bovis , and sporozoites and merozoites of Eimeria tenella and E. acervulina. The antigen was also present in sporozoites of haemosporinid parasites. Immunofluorescence studies showed that the antigen was restricted to the apical 3rd of these invasive stages. Using immunoelectron microscopy, labeling was demonstrated in the region of the polar ring, below the paired inner membranes of the parasite pellicle, and near the subpellicular microtubules radiating from the polar ring of merozoites and sporozoites of E. tenella . The majority of the antigen could be extracted with 1% Triton-X 100, but a portion remained associated with the cytoskeletal elements. The molecule has a relative rate of migration (M_r) of 47,000 in Plasmodium spp. and 43–46,000 in coccidian species. Since the epitope recognized by mAb-El 2 is highly conserved, restricted to motile stages, and appears to be associated with microtubules, this antigen could be involved in cellular motility and cellular invasion.     

Evolution of Delphacidae (Hemiptera: Fulgoroidea): combined‐evidence phylogenetics reveals importance of grass host shifts

The planthopper family Delphacidae is a speciose lineage of phloem‐feeding insects, with many species considered as pests of economic significance on essential world food commodities (including rice, maize, wheat, barley and sugar cane). Despite their economic importance, evolutionary relationships among delphacids, particularly those within the speciose tribe Delphacini, are largely unknown. Presented here are the results of a phylogenetic investigation of Delphacidae based on DNA nucleotide sequence data from four genetic loci (18S rDNA, 28S rDNA, wingless and cytochrome oxidase I) and 132 coded morphological characters. The resulting topologies are used to test the higher classification of Delphacidae and to examine evolutionary patterns in host–plant associations. Our results generally support the higher classifications of Delphacidae proposed by Asche, Emeljanov and Hamilton, and suggest that the rapid diversification of the Delphacini was associated with host shifts to, and within, Poaceae, and specifically from C3 to C4 grasses.     

The effects of different blend ratios and temperature on the active space of the Oriental fruit moth sex pheromone

Abstract The wing-fanning activation response of male Oriental fruit moths (OFM), Grapholita molesta (Busck), in the field to the three-component pheromone containing the female-produced ratio of components (Z8-12:OAc + 6% E8-12:OAc + 3% Z8-12:OH) was compared with the response to blends containing 2,10 and 20% E with 3% OH, and the 6% E blend containing 30 and 100% OH. Comparisons were made over three temperature ranges: 15–17, 20–21 and 26–28^oC. Both the maximum response distance and male response specificity were significantly altered by changes in odour quality as well as temperature. For blends containing different Z/E ratios the maximum response distance increased significantly with temperature. Response specificity was most pronounced at the 20–21^oC range, with males displaying a lower threshold for the natural 6% E ratio, evidenced by the fact that fewer males responded and at closer distances to the source with off-ratios. At 26–28^oC response specificity for the Z/E ratios was much reduced, primarily due to more males activating to off-ratios. With blends containing different proportions of Z8-12:OH in the 6% E blend, increasing temperature increased the maximum response distance for all treatments, but in addition increasing the proportion of OH alone from 3% to 30% significantly increased the maximum response distance over the three temperature ranges tested. This increase occurred without affecting the proportion of responders or the distribution of response distances around the mean value. However, with 100% OH added to the blend, whereas male response was high at 20–21^oC, the distribution of response distances was significantly more variable than with 3% or 30%, and male response was eliminated or very low at 15–17^oC and 26–28^oC. Our results support previous studies showing that peak response levels in this species are dependent on male perception of the natural blend of components, and that males have a high degree of specificity for the qualitative properties of the pheromone. However, the present results also extend those of previous flight tunnel tests in which response specificity was most pronounced in the upwind flight phase of the sequence, by showing that male OFM also display a