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41.
Johannes M. Zanker Martin Egelhaaf Anne-Kathrin Warzecha 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(2):127-134
Summary In tethered flying houseflies (Musca domestica), the yaw torque produced by the wings is accompanied by postural changes of the abdomen and hindlegs. In free flight, these body movements would jointly lead to turning manoeuvres of the animal. By recording the yaw torque together with the lateral deflections of either the abdomen or the hindlegs, it is shown that these motor output systems act in a highly synergistic way during two types of visual orientation behavior, compensatory optomotor turning reactions and orientation turns elicited by moving objects. This high degree of coordination is particularly conspicuous for the pathway activated by moving objects. Here, orientation responses either may be induced or may fail to be generated always simultaneously in all three motor output systems. This suggests that the pathway mediating orientation turns towards objects is gated before it segregates into the respective motor control systems of the wings, the abdomen and the hindlegs. 相似文献
42.
Alison Blackwell 《Entomologia Experimentalis et Applicata》1988,48(2):149-156
Larvae of the large cabbage white butterfly, Pieris brassicae L. are important pests of cruciferous crops. Third and fifth instars were treated topically with sublethal doses of the formamidine pesticide chlordimeform. A number of excitable actions were induced but they did not persist beyond 24 hours. Following the initial period, however, subsequent development was delayed and mortality increased, particularly when third instars were treated. Dosing fifth-instar larvae caused few further deaths. A link is suggested between these results and the nutritional status of the insects, and they are discussed in terms of how they might contribute towards control.
Résumé Les chenilles de troisième et cinquième stades de P. brassicae L. ont reçu une application superficielle de chlordiméforme, insecticide à la formamidine. Les doses inférieures à 335 g/g ont été sublétales, provoquant plusieurs formes d'excitation. Bien que leur comportement soit redevenu normal en 24 heures, les troisièmes stades traités ont eu leur développement retardé et une mortalité accrue. Le traitement des chenilles plus âgées a eu moins d'effets. Une relation est suggérée entre ces observations et le régime alimentaire de cet insecte; une réduction de l'alimentation, plus importante chez les chenilles de troisième que de cinquième stade de P. brassicae, accompagne le début des altérations du comportement provoquées par le chlordiméforme. La discussion porte sur le mécanisme de contrôle sublétal du chlordiméforme, impliquant des effects immédiats et retardés.相似文献
43.
A. K. Watson 《Journal of nematology》1986,18(2):149-153
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. 相似文献
44.
45.
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
46.
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
47.
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
48.
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
49.
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
50.
The identification and efficiency of arthropod predator and parasites related to natural control of cotton leafworm eggs,Alabama argillacea (Huebner), were studied in a cotton field, Jaboticabal, SP, Brazil. Plants were marked randomly and the eggs found on them were indicated by arrow tapes for predation and parasitism observations. To evaluate and identify the arthropod fauna in the row-meter containing the marked plant, visual countings and collections using D-Vac ® and “beat sheet” were used. The average predation rate during the season, in the presence of 23.0 predators per row-meter, was 50.6% and the parasitism byTrichogrammatoidea annulata was 44.9% totaling 95.5% of egg reduction. In decreasing order of abundance, the arthropod predators found were the antPheidole sp., the spiderChrysso clementinae Petrunkevitch, the hemipteraOrius insidiosus Say andCeratocapsus mariliensis Carvalho & Fontes, and the coccinellidHyperaspis festiva (Mulsant). 相似文献