Effects of aldicarb and benomyl on nematodes, vesicular arbuscular mycorrhizas and the growth and yield of forage maize

The effects of aldicarb and benomyl on plant-parasitic nematodes, vesicular arbuscular mycorrhiza and the growth of forage maize were measured in 1980—1982 in two field experiments at Woburn, Bedfordshire and in a pot experiment using loamy sand soil from the field site. The most numerous migratory nematode, Tylenchorhynchus dubius increased three to four-fold during each season in untreated soil and was effectively controlled by aldicarb. Pratylenchus species were fewer but equally well controlled. The cereal cyst-nematode (Heterodera avenae), a serious maize pathogen in Northern France, was relatively scarce in untreated roots and was further decreased by aldicarb treatment; post-harvest H. avenae egg numbers were not affected by treatments; they declined equally because maize is such a poor host. Significant yield benefits (up to 37%) followed aldicarb treatment and were ascribed to nematode control in the absence of attribution to insect or other pests. Benomyl did not increase yields nor did it significantly affect the incidence of mycorrhiza. The results confirm that considerable losses of forage maize can be caused by nematodes in light soil and that aldicarb is an effective nematicide even at the rate of 1·7 kg a.i./ha.     

Life history responses to larval food shortages in four species of necrophagous flies (Diptera: Calliphoridae)

The effects of artificially reduced amounts of larval food on various life history parameters of Lucilia cuprina, Calliphora stygia, C. vicina, and C. hilli were measured to assess the likely reaction of these blowflies to competition in carrion. With increasing food shortage the puparia were reduced by up to 12% of the weight attained under conditions in which food was unlimited. The size of eggs laid by adults which had been subject to food deprivation as larvae was unchanged, but all species showed a reduction in the number of ovarioles. An index of mass-specific reproductive investment varied considerably between the species, and the relationships between this index and the preferred habitats and dispersal strategies of the species are discussed.     

Studies in the Regeneration of Horseradish: II. Correlation Phenomena

Regeneration has been studied in fragments of various sizes,and complete plants, together with the effect of externally-appliedß-indolylacetic acid (I.A.A.). The main conclusionsare as follows: (1) In the intact plant regeneration is inhibited by the growingcrown; in cuttings, I.A.A. will reduce the rate of primordium-formation,but cannot entirely suppress it. (2) The bud/root ratio among differentiated primordia is about0·5–0·9 in long cuttings; it rises sharplyin cuttings less than 2 cm. long, and falls in the presenceof I.A.A. Most, though probably not all, of the observationsconcerning this ratio can be explained on a simple auxin-levelhypothesis. (3) I.A.A., at an appropriate concentration, depresses the extensionof buds and promotes that of roots. On each cutting, only one(proximal) bud will normally extend—but this form of dominancecannot be exactly simulated by I.A.A., and more than one hormoneseems to be involved. The results are discussed from the point of view of hormonetheories of regeneration, and it is concluded that direct measurementsof internal auxin-content will be essential before the phenomenacan be interpreted with consistency.     

Changes in Melaleuca forest density on the Magela floodplain,Northern Territory,between 1950 and 1975

The stability of the Magela floodplain prior to the development of uranium mining at Ranger, in the Magela catchment, was estimated by comparing aerial photographs taken in 1950 and 1975, using the density of Melaleuca swamp forest as an index of change. The 1975 photographs were interpreted in the light of a ground survey carried out in the dry season of 1976. There was no increase in the area occupied by Melaleuca trees, indicating that infilling of perennial swamp and plant succession were not significant agents of change in this period. Thirty-eight per cent of the forested area suffered a significant decrease in tree density: fire, wind and buffalo are among the probable causes, and these hazards should be taken into account in monitoring the effects of the uranium mining.     

Characterization and Quantitation of Membrane Antigens of New World Leishmania Species by Using Monoclonal Antibodies in Western Blot and Flow Microfluorometric Assays1

ABSTRACT. Membrane-specific monoclonal antibodies generated against promastigotes of New World Leishmania species were used in Western blot, ELISA, and flow microfluorometric assays to characterize their antigen specificity and to determine the external surface distribution of the reactive epitopes. Three major membrane antigens of molecular weight 72 KD, 55 KD, and 42 KD were identified as well as a dominant antigen that migrated as a broad band on SDS-PAGE, corresponding to a molecular weight of 10–15 KD. By dot-ELISA this antigen was also found to be excreted by promastigotes into their culture medium. One minor membrane antigen of 25 KD and a triplet component of 66, 58, and 56 KD were also identified. While assays performed on air-dried promastigotes revealed the almost ubiquitous presence of the 72 KD and 55 KD antigens, indirect immunofluorescent staining of live promastigotes followed by flow cytometric analysis revealed that these antigens had no external exposure. Antibodies binding the 55 KD component were also reactive toward purified mammalian tubulin. The remaining antigens had a variable distribution on the eight isolates utilized, and these quantitative differences could be used to distinguish isolates of the Leishmania mexicana complex from those belonging to the Leishmania braziliensis complex.     

Mode of action studies of the acaricidal agent,epingaione

Summary

Activity directed isolation studies of the ethanol extract of Bontia daphnoides L (Myoporaceae) leaves and stems led to the isolation of epingaione, a sesquiterpene furan. This compound was previously described by Chinnock et al. (1987) from the same plant. The compound showed growth regulatory activities on gravid adult female Boophilus microplus Canestrini (the southern cattle tick). The dose required for inhibiting the hatching of B. microplus eggs by 50% (Fid₅₀)was 0.4±0.06 mg/g of the tick body weight. The Fid₅₀ dose inhibited the sequestration of protein into eggs oviposited by 80%. These eggs were non-agglutinated and wrinkled. Histological examination of ovarian sections from the treated ticks revealed significant degeneration of funicle cells and reduction in yolk content.