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111.
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. 相似文献
112.
光合能量代谢对C_3植物光呼吸的调节作用 总被引:1,自引:0,他引:1
C_3植物光呼吸与光合作用关系受光合能量代谢状况的调节。在外界无CO_2和照光条件下,贮藏性光合产物经某种转化途径能“回迁”光合与光呼吸碳循环并显著地受到光合能量代谢的影响。在无CO_2或低CO_2浓度、高光强条件下,此碳素“回迁”过程对协调光合能量代谢与光合碳素代谢平衡,可能起重要作用。 相似文献
113.
Marjorie A. Hoy J. J. Rob Groot Hugo E. van de Baan 《Entomologia Experimentalis et Applicata》1985,37(1):17-31
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.
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.相似文献
114.
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.
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.相似文献
115.
A new guillotine thermocouple psychrometer was used to make continuous measurements of water potential before and after the excision of elongating and mature regions of darkgrown soybean (Glycine max L. Merr.) stems. Transpiration could not occur, but growth took place during the measurement if the tissue was intact. Tests showed that the instrument measured the average water potential of the sampled tissue and responded rapidly to changes in water potential. By measuring tissue osmotic potential (
s
), turgor pressure (
p
) could be calculated. In the intact plant,
s
and
p
were essentially constant for the entire 22 h measurement, but
s
was lower and
p
higher in the elongating region than in the mature region. This caused the water potential in the elongating region to be lower than in the mature region. The mature tissue equilibrated with the water potential of the xylem. Therefore, the difference in water potential between mature and elongating tissue represented a difference between the xylem and the elongating region, reflecting a water potential gradient from the xylem to the epidermis that was involved in supplying water for elongation. When mature tissue was excised with the guillotine,
s
and
p
did not change. However, when elongating tissue was excised, water was absorbed from the xylem, whose water potential decreased. This collapsed the gradient and prevented further water uptake. Tissue
p
then decreased rapidly (5 min) by about 0.1 MPa in the elongating tissue. The
p
decreased because the cell walls relaxed as extension, caused by
p
, continued briefly without water uptake. The
p
decreased until the minimum for wall extension (Y) was reached, whereupon elongation ceased. This was followed by a slow further decrease in Y but no additional elongation. In elongating tissue excised with mature tissue attached, there was almost no effect on water potential or
p
for several hours. Nevertheless, growth was reduced immediately and continued at a decreasing rate. In this case, the mature tissue supplied water to the elongating tissue and the cell walls did not relax. Based on these measurements, a theory is presented for simultaneously evaluating the effects of water supply and water demand associated with growth. Because wall relaxation measured with the psychrometer provided a new method for determining Y and wall extensibility, all the factors required by the theory could be evaluated for the first time in a single sample. The analysis showed that water uptake and wall extension co-limited elongation in soybean stems under our conditions. This co-limitation explains why elongation responded immediately to a decrease in the water potential of the xylem and why excision with attached mature tissue caused an immediate decrease in growth rate without an immediate change in
p
Abbreviations and symbols L
tissue conductance for water
- m
wall extensibility
- Y
average yield threshold (MPa)
-
o
water potential of the xylem
-
p
turgor pressure
-
s
osmotic potential
-
w
water potential of the elon gating tissue 相似文献
116.
Summary The actin-activated ATPase activityPhysarum myosin was shown to be inhibited of M levels of Ca2+. To determine if Ca2+ regulates ATP-dependent movement ofPhysarum myosin on actin, latex beads coated withPhysarum myosin were introduced intoChara cells by intracellular perfusion. In perfusion solution containing EGTA, the beads moved along the parallel arrays ofChara actin filaments at a rate of 1.0–1.8 m/sec; however, in perfusion solution containing Ca2+, the rate reduced to 0.0–0.7 m/sec. The movement of beads coated with scallop myosin, whose actin-activated ATPase activity is activated by Ca2+, was observed only in the perfusion solution containing Ca2+, indicating that myosin is responsible for the inhibitory effect of Ca2+ onPhysarum myosin movement. The involvement of this myosin-linked regulation in the inhibitory effect of Ca2+ on the cytoplasmic streaming observed inChara internodal cell andPhysarum plasmodium was discussed.Abbreviations ATP
adenosine 5-triphosphate
- DTT
dithiothreitol
- EDTA
ethylenediaminetetraacetic acid
- EGTA
ethyleneglycolbis(-aminoethylether) N,N,N,N-tetraacetic acid
- PIPES
piperazine-N,N-bis(2-ethanesulfonic acid) 相似文献
117.
G. Galili M. Feldman 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,69(5-6):583-589
Summary Total endosperm proteins extracted from both several common wheat cultivars and some intervarietal substitution lines derived from them were fractionated according to their molecular weight in a high resolution one-dimensional gel electrophoresis. The four donor cultivars and the recipient one — Chinese Spring, possessed differentially migrating protein bands in the fractions of high molecular weight (HMW) glutenins and gliadins. Several of these bands were identified for the first time in this study. By utilizing intervarietal substitution lines the control of the HMW glutenins and gliadins by chromosomes of homoeologous group 1 was either reaffirmed or, for the new bands, established. Several HMW gliadin subunits showed a considerable variation in their staining intensity in the intervarietal substitution lines indicating that their expression was dependent on the genetic background.This paper is based on a portion of a dissertation to be submitted by G. Galili in partial fulfilment of the Ph.D. requirements of the Feinberg Graduate School, The Weizmann Institute of Science, RehovotThe Marshall and Edith Korshak Professor of Plant Cytogenetics 相似文献
118.
Jacqueline Cramer 《Aquatic Ecology》1985,19(2):207-216
Due to the rise of environmental concern ecologists have been asked for advice more frequently since the late 1960s. This article discusses how the changing relationship between ecologists and society has affected the behaviour of one particular group of ecologists, namely Dutch fresh water ecologists, by focussing on their behaviour towards job market control and public interest activities. The analysis has been based on interviews with 65 Dutch fresh water ecologists together with an analysis of their publications.In contrast with American ecologists, Dutch fresh water ecologists have made little effort to control their job market by formal arrangements such as formulating a code of ethics and certification procedures. Secondly, Dutch fresh water ecologists generally conceive of their own role in contributing to the solution of environmental problems in relation to that of the environmentalists by doing good research and reliable advisory work. Although a significant number of researchers also address lay publics by writing popular articles and/or holding lectures, only a minority actively participates in environmental politics. 相似文献
119.
During 1981 and 1982, bollworm,Heliothis zea (Boddie), and tobacco budworm,H. virescens (F.), larvae (n=3,666) were collected from 41 cotton fields near Portland, Arkansas (USA) to assess the occurrence of parasitism.
Three strategies were employed to controlHeliothis spp. in these fields: (1) release ofTrichogramma pretiosum Riley; (2) insecticidal control; or (3) inaction (check). Insecticide use in nonchemical control fields was reduced, but
not eliminated.Heliothis spp. larvae collected in cotton had higher parasitism rates in 1981 (30.9%) and 1982 (50.1%) than had been reported for cotton
since the advent of organochlorine insecticide usage. Four species of larval parasites and 1 species of larval-pupal parasite
were recorded. The larval parasiteMicroplitis croceipes (Cresson) comprised 90.6% and 94.5% of all parasitic insects reared from field collectedHeliothis spp. in 1981 and 1982, respectively. No difference (P>0.05) in level of parasitism existed betweenH. zea andH. virescens. Differences between treatments occurred only in 1982 whenH. zea larvae were parasitized at a greater (P<0.05) rate in check fields (68.3%) than in insecticidal control fields (44.3%). Higher
levels of larval parasitism in cotton fields may be a consequence of reduced insecticide usage and changes in materials applied,
particularly the pyrethroids.
Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Dept.
of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. 相似文献
120.