Temperature and the biology and predation of Ilione albiseta (Diptera: Sciomyzidae) — Potential biological control agent of liver fluke

The effect of temperature on predation by Ilione albiseta (Diptera: Sciomyzidae) on Lymnaea peregra was investigated at 14°, 17°, 20°, 23° and 26°C. The mean dry weight of snail tissue (Lymnaea peregra) attacked and consumed per day by first and second instar I. albiseta larvae was highest at 20°C while for third instar and total larval duration period it was greatest at 23°C. The mean number of snails killed per day during the third instar was also highest at 23°C. The total amount of snail tissue consumed by I. albiseta larvae increased significantly from first to second instar and from second to third instar at each constant temperature. Mean survival period of unfed first instar larvae decreased from 28.4 days at 14°C to 11 days at 26°C and the mean length of the second instar cephalopharyngeal skeleton decreased with increasing temperatures. As temperature increased the rate of consumption of oxygen (dissolved in water) by first and third instar larvae rose.     

Biology of Subanguina picridis,a Potential Biological Control Agent of Russian Knapweed

The knapweed nematode, Subanguina picridis, forms galls on the leaves, stems, and root collar of Russian knapweed, Acroptilon repens. After being revived from a dormant, cryptobiotic state, second-stage juveniles required at least 1 month in a free-living state before becoming infective. Galls were induced on relatively slow-growing host plants that retained their apical meristems at or near the soil surface for 2-5 weeks. Galls developed extensive areas of nutritive tissue. The nematode was introduced from the Soviet Union and released in Canada for the biological control of Russian knapweed.     

Membrane and cytoplasmic resistivity properties of normal and sickle red blood cells

The cytoplasmic resistivities and membrane breakdown potentials of normal (AA), sickle-cell-trait (AS), and sickle (SS) red blood cells have been measured by the biophysical methodology of resistive pulse spectroscopy over a range of osmolalities. At isotonicity, the average membrane breakdown potentials are virtually identical for the three types of cells occurring at about 1150 V/cm. Average isotonic cytoplasmic resistivities are somewhat higher for the SS cells (166.7±7.49 ohm-cm) compared to the AA (147.6±1.98 ohm-cm) or AS cells (148.7±1.79 ohm-cm). As medium osmolality is varied, the differences in resistive properties become enlarged, especially at very low and very high osmolalities. At high osmolalities, both types of sickle cells show a large increase in internal resistivity compared to the normals; at low osmolality, the SS samples exhibit a distinctly different membrane breakdown characteristic, decreasing in this parameter, whereas the other two groups increase. Of the 15 SS samples tested, three displayed much higher cytoplasmic resistivities at isotonicity: 218.2±5.25 ohm-cm, compared to an average of 153.5±3.46 ohm-cm for the other 12. The relationship between these high resistivities and the subfraction of irreversibly sickled cells in the sample is discussed.     

Predation ofOligonychus pratensis [Aca.: Tetranychidae] byPhytoseiulus persimilis andAmblyseius californicus [Aca.: Phytoseiidae] under controlled laboratory conditions

The predator efficacy ofPhytoseiulus persimilis Athias-Henriot andAmblyseius californicus (McGregor) (Acarina: Phytoseiidae) when feeding on the Banks grass mite (BGM),Oligonychus pratensis (Banks) (Tetranychidae), was compared under controlled laboratory conditions. Predation byP. persimilis andA. californicus reduced the BGM densities by 60% and 28%, respectively. In general, phytoseiids preferentially fed upon the more abundant instars. Ovipositional rates forP. persimilis while feeding on BGM approximated rates when feeding onTetranychus spp. The use of a trade name is not an endorsement by Texas A&M University.     

Comparison of glucokinase in C3H/He and C58 mice that differ in their hepatic activity

Partially purified preparations of the hepatic glucokinase from C3H/He and C58 inbred mice have been used to explore the molecular basis for the observed twofold difference in activity between the strains. The single codominant gene that appears to regulate activity, the alleles of which are designated Gk^a and Gk^b, respectively, for the two strains, could represent a structural gene change. This now seems unlikely because the mouse enzyme, although showing small differences from rat glucokinase, appeared to be identical in the two strains with respect to thermal stability, electrophoretic mobility in agarose gels, and kinetic properties such as the apparent K _m values for MgATP^2– and glucose and the unique cooperative interaction with the latter substrate. The enzymes also reacted identically in a range of immunological tests (double-diffusion, immunoelectrophoresis, immune precipitation and immune inhibition assays) and ELISA immune inhibition assays indicated that the twofold difference in activity was due to a similar difference in antigenically active enzyme. Genetic control over the physiologically significant regulation of enzyme amount is therefore probable.This work has been supported in part by a grant from the British Diabetic Association and a Training Studentship to PAJ from the Medical Research Council (U.K.).     

Kinetic properties of IAA oxidase from mung bean cotyledons

A crude enzyme preparation from mung bean cotyledons was separated into peroxidative and non-peroxidative IAA oxidase on a DEAE-cellulose column. Both fractions differed in their pH optima, K_m and V_max. The K_m and V_max of non-peroxidative IAA oxidase were higher than those of peroxidative IAA oxidase. Peroxidative IAA oxidase showed a linear increase in absorption at 247 and 254 nm after a short lag of 2–3 min. The addition of catalytic amounts of hydrogen peroxide eliminated the lag period and also enhanced the rate of IAA degradation. The non-peroxidative IAA oxidase fraction, however, did not exhibit any significant increase in absorption at 247 and 254 nm and showed a lag period of 5 min which was not affected by hydrogen peroxide. Instead, addition of the same catalytic amount of hydrogen peroxide inhibited the rate of IAA degradation. The peroxidative IAA oxidase fraction exhibited the reaction kinetics characteristic of peroxidase-catalysed IAA degradation. The rate of IAA oxidation by purified non-peroxidative IAA oxidase was very low. The slow rate of catalysis shown by non-peroxidative IAA oxidase appears to be due to the presence of inhibitor(s).     

Influence of aerial dispersal on persistence and spread of pesticide-resistant Metaseiulus occidentalis in California almond orchards

Aerial dispersal of the phytoseiid Metaseiulus occidentalis (Nesbitt) was evaluated as a component in managing pesticide-resistant populations established in California almond orchards. Peak dispersal occurred in late July and early August during 1982 and 1983. Most predators (and spider mites) left the orchards on the prevailing winds from the northwest. Within the orchard, the prevailing winds had less influence, and dispersal was usually random. Both spider mites and predators dispersed randomly with regard to height from the almond trees, but data obtained during one 24-h interval suggest they do not disperse randomly throughout the day. Most aerial movements occurred between 16–22 h when relative humidity and wind speeds increased and temperatures decreased. Spider mites and predators were trapped on panels located 200 m from the orchard. A survey of carbaryl resistance levels in M. occidentalis collected from almond orchards surrounding the release sites indicates that carbaryl-resistant M. occidentalis dispersed at least 800 m between 1981–83. However, growers wishing to use the resistant strains should release them in their orchards as natural dispersal appears to be too slow. Migration of native M. occidentalis into the release sites appeared to be sufficiently rare that dilution of carbaryl-resistant populations was minimal during a 2–4 year period.

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Résumé La dispersion aérienne du phytoseïdae, M. occidentalis (Nesbitt), a été estimée comme élément de la lutte contre les populations résistantes aux insecticides établies dans les vergers de Californie. La dispersion maximale s'est produite fin juillet et début a oût en 1982 et 1983. La plupart des prédateurs (et des acariens) quittent les vergers avec les vents dominants du nordouest. Dans le verger, les vents dominants sont moins importants et la dispersion est généralement au hasard. Tant les acariens que les prédateurs se dispersaient au hasard par rapport à la taille des amandiers, mais les relevés sur 24 heures laissent supposer qu'il n'y a pas une distribution aléatoire pendant la journée. La plupart des mouvements aériens se produisirent entre 16 et 22 heures quand HR et vitesse du vent augmentaient et température diminuait. Les acariens et prédateurs ont été piégés sur des panneaux à 200 m du verger.

     

Release and establishment in Nigeria of Epidinocarsis lopezi, a parasitoid of the cassava mealybug, Phenacoccus manihoti

The encyrtid wasp Epidinocarsis (= Apoanagyrus) lopezi (De Santis) was imported from Paraguay into Nigeria for the biological control of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero. It was mass-reared and released at four localities in Nigeria. The parasitoid is now established and it is dispersing throughout cassava growing areas of Nigeria.

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Libération et installation au Nigéria d'Epidinocarsis lopezi, parasitoïde de la cochenille du manioc Phenococcus manihoti

Résumé Epidinocarsis lopezi (Apoanagyrus) lopezi a été introduit du Paraguay au Nigéria pour lutter contre la cochenille du manioc, Phenacoccus manihoti. Il a été lâché dans quatre champs de manioc pour étudier son acclimatation et son installation au Nigéria. Trois ans après les lâchers, les résultats ont permis de conclure que E. lopezi s'est établi avec succès et se disperse dans la plupart des zones de culture du manioc au Nigeria; il a aussi survécu à trois saisons pluvieuses pendant lesquelles les populations de P. manihoti ont été très faibles. Quatorze mois après les premiers lâchers, cet encyrtide a été obtenu à environ 150 km du lieu de libération.

     

A user-friendly biological workstation

Learning methods developed by artificial intelligence research teams are very efficient for biological sequences analysis but they need running on large computers accessed by terminals. These computers are interfaced with standard displays involving long and unpleasant alphanumerical data handling. The "biological work station" is a personal computer with a color graphic screen providing a user-friendly interface for the artificial intelligence learning programs running on large computers. It provides to biologist a graphical convenient tool for sequence analysis built with efficient man-machine communication methods such as multiwindows, icons and mouse selection. It allows the biologist to edit and display sequences in an efficient and natural way, showing off directly on color pictures the data and the results of learning programs.     

Immobilization of pig muscle 3-phosphoglycerate kinase

3-Phosphoglycerate kinase (ATP:3-phospho-d-glycerate 1-phosphotransferase, EC 2.7.2.3) has been covalently immobilized on a polyacrylamide-type support containing carboxylic groups activated by water-soluble carbodiimide. The activity was 88 units g^?1 xerogel. The activity versus pH profile showed a sharper maximum at pH 6.5 in the case of the immobilized enzyme. The immobilized enzyme had a broad apparent optimum temperature range between 40 and 50°C. The apparent K_m values of the immobilized 3-phosphoglycerate kinase were lower for both 3-phosphoglycerate and ATP than those of the soluble enzyme. In the case of the immobilized enzyme stabilities were enhanced.