Effect of Gibberellic Acid, (2-Chloroethyl) Phosphonic Acid, Actinomycin-D and Cycloheximide on the Activity and Leaching of Some Hydrolases in Pollen Suspension Cultures of Crotalaria juncea

Gibberellic acid (GA₃) 20 mg 1^?1 and (2-chloroethyl) phosphonic acid (Ethephon) 10 mg 1^?1 enhanced pollen tube length in Crotalaria juncea L. GA₃ markedly increased the activity of amylase, acid phosphatase and β-glucosidase and enhanced leaching of amylase and acid phosphatase enzymes. The rise in the activity level and leaching of amylase and acid phosphatase after Ethephon treatment was comparatively less than that of GA₃ and the response to Ethephon was restricted to the 45 and 90 min period of culturing. Ethephon did not affect the activity/leaching of β-glucosidase significantly. Actinomycin-D (Act.D) 25 mg l^?1 and Cycloheximide (CH) 10 mg 1^?1 reduced the tube growth as well as activity of these enzymes suggesting their de novo synthesis during pollen tube growth.     

Consistently high incidence of Wolbachia in global fig wasp communities

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Statistical power analysis of a 2-year field study and design of experiments to evaluate non-target effects of genetically modified Bacillius thuringiensis corn

Abstract 1. A 2‐year field study was conducted in 2000 and 2001 at a farm in Monmouth, Illinois to evaluate the effect of MON 863, a transgenic corn event that expresses the Cry3Bb1 protein for control of corn rootworms, on diverse groups of arthropod populations in a corn ecosystem. 2. The field study employed a split‐plot design with MON 863 and conventional corn as the main plots and several insecticide treatments as subplots; each main plot was replicated four times (i.e. n = 4 block replications for each corn variety). A large number of arthropod taxa were trapped, taxonomically characterised, and counted in all plots. A mixed linear repeated‐measures model was used for analysis of each taxon collected to determine if there was an effect of MON 863 or insecticide regime on that taxonomic group. 3. This report describes the results of a power analysis to determine the ability of the study design to detect an effect of MON 863 corn on the abundance of different groups of arthropods. A 50% difference in average taxon abundance between MON 863 and conventional corn plots was the criterion used in assessing the power. 4. A statistical power analysis of the taxonomic group comparisons made in the 2‐year field study (with independent assignment of treatments each year) showed that only about 28% (22 of 56) of the statistical comparisons made with single years of data achieved ≥80% power to detect a 50% difference in population density. When data from both years of the study were analysed jointly, this level of power was obtained for 86% (24 of 28) the comparisons made. 5. Graphical examination of the mean abundance and coefficient of variation (CV) for different taxa indicated that high abundance (> 5 trap captures per plot per sampling period) and low CV (< 100%) contributed to high statistical power (> 80%). Taxa with extremely low abundance (mean trap captures < 1 individual per plot per sampling period) generally had high CV (> 100%), and statistical comparisons for those taxa had lower power (< 80%). 6. The relevance of these findings for designing field studies on the effects of genetically modified crops on non‐target arthropods with desired levels of power is discussed.     

Effects of selected insecticides on Diadegma semiclausum（Hymenoptera： Ichneumonidae） and Oomyzus sokolowskii （Hymenoptera： Eulophidae）, parasitoids of Plutella xylostella （Lepidoptera： Plutellidae）

Abstract Field doses of six selected insecticides were tested against the immature (pupae) and mature (adult) stages of Diadegma semiclausum (Hellén) and Oomyzus sokolowskii (Kurdjumov), parasitoids of the diamondback moth, Plutella xylostella (L.). Effects of contact toxicity (direct spraying) of the six insecticides on emergence of parasitoids were found negligible on both species except permethrin which caused 37.5% mortality. All adults of both parasitoid species died 24 hours after exposure to chlorfenapyr, emamectin benzoate and permethrin. In contrast, the three insect growth regulators (IGRs), chlorfluazuron, flufenoxuron and teflubenzuron, were found harmless to both species, and adult mortality of both parasitoid species was 0–16.7%. However, parasitism by the females of both parasitoid species was severely impaired when the females were offered the three IGR diluted solutions for 24 hours. Effects of oral toxicities of the IGRs on longevity of both parasitoids after 12 hours exposure were found to be significantly different between males and females. Compatibility of tested insecticides with D. semiclausum and O. sokolowskii and integration of compatible insecticides with these parasitoids in integrated pest management programs of crucifers are discussed.     

Mechanisms of inducible resistance against Bacillus thuringiensis endotoxins in invertebrates

Resistance in insect pests against the endotoxin of Bacillus thuringiensis （Berliner） （Bt） is a major threat to the usefulness of this biopesticide, both used as traditional formulations and in transgenic crops. A crucial requirement for the development of successful resistance management strategies is a molecular understanding of the nature and inheritance of resistance mechanisms. This information can be used to design management strategies that will delay or counteract Bt resistance. The best known Bt resistance mechanism is inactivation of brush border membrane receptors. This type of resistance has a largely recessive mode of inheritance, which has enabled the design of resistance management approaches involving high dose and refuge strategies. Recent observations suggest that other resistance mechanisms are possible, including a mechanism that sequesters the toxin in the gut lumen through inducible immune reactions. The elevated immune status associated with tolerance to the toxin can be transmitted to subsequent generations by a maternal effect, which has implications for resistance management in the field. The high dose/refuge strategy may not be appropriate for the management of these alternative resistance mechanisms and other strategies have to be developed if inducible dominant resistance or tolerance mechanisms occur frequently in the field.     

Pyrethroid-sprayed tents for malaria control

Field trials were undertaken in the North West Frontier Province of Pakistan to determine the effects of pyrethroid-sprayed tents on feeding success, mortality and biting-rates of wild mosquitoes attracted to bait cows confined within the tents. Under natural conditions, endophagic mosquitoes rested only briefly in untreated tents during the night, followed by complete exodus at dawn. In tents sprayed on the interior surface with permethrin 0.5 mg/m² or with deltamethrin 0.03 g/m² the biting rate of Anopheles stephensi was reduced by about 40%; detergency against culicines and other anophelines was much less. Mortality-rates of bloodfed mosquitoes from the treated tents were 75%An.stephensi, 65%An. subpictus but only 10% of culicines. Outer fly-sheets prolonged the effective life of the treatment; bioassays on the sprayed inner-sheets showed that insecticidal efficacy remained high for over a year, whereas on tents without fly-sheets permethrin residual efficacy declined rapidly 20–40 weeks post-treatment. It is concluded that tent-spraying with fast-acting photostable residual pyrethroid insecticide would probably provide effective protection against malaria transmission for the inhabitants of tents in any part of the world where the vector mosquitoes are endophilic and susceptible to pyrethroids.     

Seasonal Rhythms of Structure and Behaviour of Vascular Cambium in Ficus rumphii

Cambial structure and activity of Ficus rumphii Blume vary withthe changes in local climate. The cambial cells start swellingearly in April prior to the onset of periclinal divisions whichare most frequent in August. Cell division stops in October.During the growth season, initiation as well as cessation ofthe phloem production precedes that of xylem. A moderately hightemperature is correlated with the cambial reactivation. Onceinitiated, the activity continues at relatively low temperatures.Hot and dry environment favours the phloem production, whereashot and moderately humid conditions induce xylogenesis. Thesize and relative proportion of cambial initials also changewith season. Fusiform initials are shorter and broader duringthe rainy season (July–September) than for the rest ofthe year. Multiseriate and triseriate rays, as also the tallrays, outnumber the other types of rays throughout the year. Ficus rumphii, vascular cambium, phenology, climatic variation     

Novel urease inhibitors from Daphne oleoids

Phytochemical investigations on the chloroform and ethyl acetate soluble fractions of the roots of the Daphne oleoids led to the isolation of the coumarin glycosides 1–6. Compound 5 with IC₅₀ values 22.05 and 26.30 μM repectively, was found to be the most active of these compounds when screened against Bacillus pasteurii and jack bean urease enzymes in a concentration-dependent fashion.     

CHANGES IN PROTEIN BIOSYNTHESIS DURING GIBBERELLIC ACID INDUCED INDUCTION AND FORMATION OF ANTHERIDIUM IN THE FERN ANEMIA PHYLLITIDIS

Changes in protein biosynthesis have been studied during the induction and formation of antheridium in Anemia phyllitidis .
Based on incorporation of ¹⁴C-amino acid mixture into TCA precipitable material two distinct phases of accelerated protein biosynthesis were observed. First phase initiates at 4th day, while the second at 8th day of development. The first phase is likely associated with antheridium induction and second with spermatogenesis. From electrophoretic pattern of proteins on stained acrylamid gels and from radioactivity profiles of labelled proteins distinct quantitative differences between vegetative and reproductive prothalli were observed at different stages of antheridial development. Radioactivity profiles reveal characteristic pattern of each stage of antheridial differentiation.