Elaboration and testing of insecticidal varnish in aerosol containers for the control of synanthropic cockroaches

A formula for the filling of aerosol containers has been elaborated on the basis of a mixture of hexachlorocyclohexane (HCH) gamma isomer and tetrametrin, in a ratio 3:1 with the addition of furniture varnish NC-62 to produce the film, Khladon 11/12 (5050) served as propellent. The study of the process of crystallization of the insecticides on the surface of the film has shown that the effectiveness of insecticidal varnishes is the higher, the smaller the size of the crystals and the easier they can be removed from the surface of the film. This can be achieved by including tetrametrin along with HCH gamma isomer in the formula. The testing of the insecticidal activity and toxicity of aerosols prepared according to the elaborated formula has demonstrated high insecticidal activity of the composition with respect to synanthropic cockroaches and fairly low toxicity with respect to warm-blooded animals.     

The evaluation of the mutagenic activity of pertussis vaccinal preparations]

Two vaccine preparations obtained from Bordetella pertussis, whole-cell vaccine constituting one of the components of adsorbed DPT vaccine and acellular vaccine, were tested for mutagenicity. The doses of the preparations covered the range 1-100 ED50. Ames' test and the metaphase analysis of marrow cells of C57BL/6J mice were used. The acellular preparation was also tested on thymectomized mice, taking into consideration chromosomal aberrations in marrow metaphases. Whole-cell and acellular pertussis vaccines did not induce mutations in Salmonella typhimurium and chromosomal aberrations in mouse marrow cells.     

The biology of insecticidal activity and resistance

Identifying insecticide resistance mechanisms is paramount for pest insect control, as the understandings that underpin insect control strategies must provide ways of detecting and managing resistance. Insecticide resistance studies rely heavily on detailed biochemical and genetic analyses. Although there have been many successes, there are also many examples of resistance that still challenge us. As a precursor to rational pest insect control, the biology of the insect, within the contexts of insecticide modes of action and insecticide metabolism, must be well understood. It makes sense to initiate this research in the best model insect system, Drosophila melanogaster, and translate these findings and methodologies to other insects. Here we explore the usefulness of the D. melanogaster model in studying metabolic-based insecticide resistances, target-site mediated resistances and identifying novel insecticide targets, whilst highlighting the importance of having a more complete understanding of insect biology for insecticide studies.     

The insecticidal activity of some norditerpene dilactones

The effects on housefly (Musca domestica) of six norditerpene lactones (nagilactones B, D, E, podolide, hallactone B and 14-epi-ponalactone A) in a defined diet were tested. Nagilactone D was the most active, with an LD₅₀ of 0.7 ppm. Nagilactones C and D were also toxic to light-brown apple moth (Epiphyas postvittana) and codling moth (Laspeyresia pomonella).The relationship between lactone structure and toxicity to housefly is discussed.

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Zusammenfassung Viele aus Podocarpus-Arten isolierte Norditerpenlactone sind für Stubenfliegen toxisch. Es wird über die Resultate der Fütterung von sechs Lactonen an die Stubenfliege in einem definierten Nährboden berichtet und die LD₅₀ von zwölf Verbindungen werden verglichen. Der aktivste Stoff ist Nagilacton mit einer LD₅₀ von 0,7 ppm. Nagilacton C und D sind auch toxisch für Epiphyas postvittana und für den Apfelwickler. Die wirksamsten Verbindungen haben eine kurze nichtpolare Seitenkette und eine elektronenreiche, funktionelle Gruppe bei C-8, ferner sind sie Epoxyalkohole in Ring-A. Diese in der Natur vorkommenden Lactone spielen wahrscheinlich eine Schutzrolle in der Pflanze.

     

The insecticidal activity of recombinant garlic lectins towards aphids

The heterodimeric and homodimeric garlic lectins ASAI and ASAII were produced as recombinant proteins in the yeast Pichia pastoris. The proteins were purified as functional dimeric lectins, but underwent post-translational proteolysis. Recombinant ASAII was a single homogenous polypeptide which had undergone C-terminal processing similar to that occurring in planta. The recombinant ASAI was glycosylated and subject to variable and heterogenous proteolysis. Both lectins showed insecticidal effects when fed to pea aphids (Acyrthosiphon pisum) in artificial diet, ASAII being more toxic than ASAI at the same concentration. Acute toxicity (mortality at 3d exposure) was observed over the concentration range 0.125-2.0mgml(-1). The recombinant lectins caused mortality in both symbiotic and antibiotic-treated aphids, showing that toxicity is not dependent on the presence of the bacterial symbiont (Buchnera aphidicola), or on interaction with symbiont proteins, such as the previously identified lectin "receptor" symbionin. A pull-down assay coupled with peptide mass fingerprinting identified two abundant membrane-associated aphid gut proteins, alanyl aminopeptidase N and sucrase, as "receptors" for lectin binding.     

The insecticidal activity of foliage from New Zealand conifers

When incorporated into artificial diets, the milled foliages of many New Zealand conifers are toxic to larvae of housefly (Musca domestica), codling moth (Laspeyresia pomonella) and light-brown apple moth (Epiphyas postvittana). The most toxic foliages are those of Podocarpus nivalis which contains diterpene lactones, and Dacrydium laxifolium, which has a high concentration (1%) of phytoecdysones. The insecticidal activities of the plants are discussed in relation to their insect associations, chemistry and taxonomy.     

The insecticidal activity of beauvericin and the enniatin complex

The insecticidal activity of a complex mixture of enniatins, cyclohexadepsipeptides produced by Fusarium lateritium, a pathogen of the scale insect Hemiberlesia rapax, is compared with that of enniatin A and beauvericin in two bioassays against Calliphora erythrocephala and Aedes aegypti.     

杀虫灯诱杀昆虫的有效距离及生态学参数

采用人工标记释放回收技术,探讨了杀虫灯诱杀斜纹夜蛾Spodoptera litura Fabricius和甜菜夜蛾Spodoptera exigua Hübner的有效距离及不同安装高度的诱杀效果。诱杀结果表明,标记释放虫源离灯越远,其灯下回收率越低;灯高0.8m的灯下回收率显著高于灯高1.3m。提出了用"可控距离CID"、"诱杀中距离MTD50"、"诱杀黄金距离GTD61.8"3个生态学参数量化与规范杀虫灯对昆虫的诱杀距离。拟合结果表明,高0.8m杀虫灯诱杀斜纹夜蛾和甜菜夜蛾的可控距离分别为115.1m、110.9m,诱杀中距离分别为71.8m、67.4m,诱杀黄金距离分别为61.5m、57.1m,可控面积分别是4.2hm2、3.9hm2;高1.3m杀虫灯诱杀斜纹夜蛾和甜菜夜蛾的可控距离分别为108.1m、107.8m,诱杀中距离分别为66.6m、64.7m,诱杀黄金距离分别为56.7m、54.5m,可控面积分别是3.7hm2、3.6hm2。     

Molecular parameters of gangliosides in monolayers: comparative evaluation of suitable purification procedures

The molecular area, collapse pressure, and surface potential of gangliosides obtained by different methods were systematically compared in monolayers at the air-water interface. Different values of these parameters are obtained depending on the purification procedure employed for the isolation of pure gangliosides. This is due to impurities (such as peptidaceous material) that remain in different amounts in the various preparations and that modify the ganglioside surface behavior. Routine purity checking by HPTLC analysis of gangliosides usually fails to reveal these impurities. On the other hand, even if the monolayer technique cannot identify the nature or amount of contaminants, it is extremely sensitive to reveal alterations of the surface molecular parameters caused by relatively small amounts of other components coextracted with the ganglioside or adventitiously introduced with the solvents or subphases employed. This is a serious problem for the obtention of correct and reproducible values of such important parameters as the molecular area of gangliosides, their electrostatic potential in oriented interfaces, and their interactions with other lipids and proteins. A procedure leading to consistent molecular parameters that remain reproducible after several repurification cycles is to perform an alkaline treatment on previously purified gangliosides species with NaOH, this is followed by dialysis against bidistilled water, rechromatography on DEAE-Sephadex A25, silicic acid or Iatrobeads, and Sephadex LH-20 columns; repurified gangliosides are stored in chloroform-methanol-0.01 M NaOH (60:30:4.5).     

Use of regression analysis in the quantitative evaluation of the activity of biological preparations]

Use of regression analysis in the assessment of the activity of biological preparations under experimental conditions permitted not only to assess the quantitative effect (ED50) more strictly, but also to find other parameters of importance for the results of comparison, for example with the standard, i.e. in standardization. To these belong regression coefficient, parallelism of regressions, and the relative potency. By the presence of a parallelism one can judge the similarity between the activity mechanism of the active principle of the preparations being compared. Relative potency characterizes the activity of the preparation in the relative values in comparison with the standard, with a statistical evaluation of this value with the aid of the confidence interval. The authors suggest a program for Mir-2 computer facilitating the calculations in using the analystical method which is more objective than the graphic method of assessment of the linear dosage-response curve.     

Modulation of a lectin insecticidal activity by carbohydrates

Lectins from plants present an insecticidal activity most probably through their carbohydrate binding properties; as a consequence, their toxicity should vary with the presence of a competitive sugar in the ingested food. In order to test this hypothesis, we performed competition experiments between insecticidal activity and carbohydrate binding. For this purpose, we used a lectin from Lathyrus ochrus and the specific carbohydrate for this protein, glucose. In toxicological tests with Drosophila melanogaster, we observed a decrease of lectin toxicity when glucose was added to the larva-rearing medium. This result suggests that the toxicity of the lectin is correlated to its ability to bind sugar in the insect digestive tract and stresses the importance of sugar composition of the nutriment used for toxicological testing of lectins or in genetically modified plants.     

Comparative evaluation of diagnostic preparations

The diagnostic value of preparations is commonly characterized by sensitivity and specificity. But not all these characteristics make it possible to decide unequivocally which of the preparations to be compared is superior to the other one with respect to its diagnostic value. It is proposed that in the choice of a diagnostic preparation its capacity to provide data for exact diagnosis should be considered, i.e. the additional characteristic indicating the spread of the disease under study. As an example, the comparison of the diagnostic value of conventional methods and the polymerase chain reaction in the diagnostics of helicobacteriosis is presented. The described method for the evaluation of the diagnostic value of the preparation is well-grounded, simple and obvious.     

Biochemical identification and comparative insecticidal activity of nucleopolyhedrovirus isolates pathogenic for Heliothis armigera (Lep., Noctuidae) larvae

Three Nucleopolyhedrovirus (NPVs) originally isolated from Heliothis armigera larvae, collected from Portugal (HearNPV-PO) and two places in Spain (HearNPV-SP1 and HearNPV-SP2), and three previously described NPVs were compared biochemically and biologically. Restriction endonuclease analysis of the virus genome with several enzymes revealed that isolates HearNPV-SP1 and HearNVP-SP2 are unique but closely related genotypes which represent two new strains of the NPVs of H. armigera. The DNA fragment profiles of HearNPV-PO were distinct from those of the HearNPV-SP1 and HearNPV-SP2, with all the enzymes used, while they were identical to the Mamestra brassicae NPV strain present in the commercial product MAMESTRIN^®. Bioassays in third-instar H. armigera larvae showed that the LD₅₀ value obtained for HearNPV-SP1 (68 occlusion bodies/larva) was about two- and six-times lower than those of HearNPV-SP2 and a Russian isolate, HearNPV-RU, respectively. The corresponding LT₅₀ values were not found to differ significantly between these three virus isolates at comparable doses.