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1.
An intact nef gene is essential for rapid development of immunodeficiency in human immunodeficiency virus and simian immunodeficiency virus infections. To assess the role of nef in the immune response, mice transgenic for SIV nef were constructed and the humoral and cellular immune response to herpes simplex virus type-1 (HSV-1), measured. Mice transgenic for SIV-mac239 nef exhibited a significantly increased mortality rate when challenged with HSV-1 and also showed unusual antibody kinetics in response to viral challenge. During a 32-week period following exposure to HSV, it was noted that IgG subclass titers continued to rise in the nef+ animals, while titers of nef– animals decreased. Additionally, following secondary challenge with HSV, nef– mice had a significantly greater rise in HSV-neutralizing antibody titers than nef+ mice. A decreased proliferative response to the T cell mitogen, PHA, was noted in the nef+ animals. These results suggest that the presence of nef+ is sufficient to induce immune dysfunction. 相似文献
2.
Studies on the life history and food habit of Typhlodromus bambusae Ehara were carried out under aboratory conditions of 25±1°C, 60–80% rh and 159 l:d.The egg-to-egg period of the predator which fed on eggs of the long-seta form of Schizotetranychus celarius (Banks) was longer than those of the three phytoseiid species, Amblyseius eharai Amitai et Swirski, A. longispinosus (Evans) and A. paraki Ehara, which fed on Tetranychus urticae Koch. The sex-ratio of T. bambusae was not significantly different from those of the other three species. The long ovipositional period and the rather constant, low, reproductive rate observed in T. bambusae were remarkable.The intrinsic rate of natural increase ( r
m) of T. bambusae was 0.164 per day and it was very similar to the r
m of its prey, S. celarius. This observation supports the idea that there is a coincidence between the life-histories of spider-mite prey and their specific phytoseiid predators.Although females of T. bambusae could feed on eggs of Aponychus corpuzae Rimando or Schizotetranychus recki Ehara which cohabit with S. celarius on Sasa bamboo, their oviposition rate was lower than that on S. celarius eggs. Schizotetranychus celarius is thought to be a profitable prey species for T. bambusae, while S. recki and A. corpuzae are only subsidiary, or alternative, prey. 相似文献
3.
A photoperiod of 8L/16D for two weeks was used to distinguish between diapausing and non-diapausing Typhlodromus pyri Scheuten. A diet of Panonychus ulmi or Tetranychus urticae, or pollen of Vicia faba did not influence preovipositional periods of diapausing mites. In mid-September, 88% of T. pyri collected from an insectary were in diapause. The critical day-length appeared to be between 12.5 and 13.5 h. Diapause duration was greatest in mites collected in September–November, becoming progressively less in mites collected later in the winter. By mid-April, ca. 50% of mites collected from the orchard and insectary oviposited promptly when cultured in the laboratory. Typhlodromus pyri eggs and larvae were present on leaves in early May. At this time, only 4% of P. ulmi winter eggs had hatched. Diapause terminated most quickly in T. pyri kept in an 18L/6D photoperiod, followed by 24L/0D and 0L/24D. Longest preoviposition periods were recorded for mites kept in 8L/16D photoperiods. 相似文献
4.
The predator Thanasimus formicarius (L.) (Coleoptera, Cleridae) and its prey Ips typographus (L.) (Coleoptera, Scolytidae) were studied in the laboratory and the field.
In the laboratory, 11 T. formicarius laid 71–132 eggs (mean=162) during 66–123 days. During this time they ate 66–132 I. typographus adults per pair (male +female). The number of eggs laid per female was not correlated with life span or the number of Ips eaten.
In the field, predation by T. formicarius larvae and other natural enemies on I. typographus brood was studied in the last year of an outbreak. Caged and uncaged spruce bolts attacked by I. typographus were used, and pairs of T. formicarius were released in the cages. The treatments were: uncaged bolts, caged bolts without T. formicarius, caged bolts with 4 T. formicarius pairs, and caged bolts with 8 T. formicarius pairs. The productivity of I. typographus was highest in the caged bolts without T. formicarius (mean=4.5 offspring/female) and lowest in the uncaged bolts (mean=0.9 offspring/female). The density of I. typographus galleries was similar in the different treatments. Hence, the variation in productivity between treatments could not have
been due to differences in the levels of intraspecific competition. There was no difference in bark beetle productivity or
density of T. formicarius larvae between bolts with 4 pairs of T. formicarius and bolts with 8 pairs (mean=2.5 offspring/female). This indicates that some kind of interference occurred between T. formicarius individuals (e.g. cannibalism) and that a maximum level of predation was reached. Predation by larvae of Medetera spp. (Diptera, Dolichopodidae), Thanasimus spp. and other beetles, and parasitism by wasps (Hymenoptera, Pteromalidae) probably caused the low productivity in the uncaged
bolts.
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5.
Since Tetranychus evansi Baker and Pritchard had been observed to be unfavorable prey for several species of phytoseiid mite predators, a study was conducted to determine the possible existence of an allomone produced by this species against Phytoseiulus persimilis Athias-Henriot. Instead, P. persimilis was strongly arrested by extracts of eggs, adults and, especially, webbing plus excreta of T. evansi. Methanol extracts of Tetranychus urticae (Koch) showed a stronger arrestment than extracts of T. evansi. 相似文献
6.
The influence of feeding and temperature on life table parameters of Euseius stipulatus (Athias-Henriot) and Typhlodromus phialatus Athias-Henriot was determined in laboratory tests. Both phytoseiids developed and reproduced readily when fed on Carpobrotus edulis (L.) pollen and Panonychus citri (McGregor) Intrinsic rates of increase ( r
m
) at 25°C for E. stipulatus and T. phialatus were 0.197 and 0.126, and, when fed on P. citri, 0.129 and 0.144, respectively. Tetranychus urticae Koch offered as prey allowed normal development and oviposition of T. phialatus, but no eggs were laid by E. stipulatus when fed on this spider mite. Eggs and honeydew of Aleurothrixus floccosus Mask. furnished sufficient nutrition for development of immatures of E. stipulatus. Larvae of Planoccocus citri Risso, and honeydew and eggs of A. floccosus, allowed adult survival but no egg-laying of the predaceous mites. Lorryia formosa Cooreman was not a favoured prey species.Life tables were calculated for E. stipulatus fed on pollen and T. phialatus fed on P. citri at constant temperatures of 18, 25, and 32°C. Maximum development was reached at 32°C, with r
m
values of 0.225 for E. stipulatus and 0.179 for T. phialatus. In general, both phytoseiids showed medium to high total number of eggs per female and long oviposition periods when compared with other phytoseiid species.When mating took place at 32°C, E. stipulatus females were not able to lay eggs, thus suggesting an interference of high temperatures with fertilization in this species. No hatching was observed in eggs of either species when kept at relative humidities of 50% or lower. The possible significance of these responses is discussed in relation to population trends observed in the field. 相似文献
7.
Observations were made on the feeding behavior of the two main phytoseiid species in Spanish Citrus orchards, Euseius stipulatus (Athias-Henriot) and Typhlodromus phialatus Athias-henriot. The experiences were carried out by rearing the predatory mites on excised orange leaves, and always with
an excess of the prey the Citrus Red Mite (=CRM) Panonychus citri (McGregor). In experiments with all stages of CRM, the number of prey killed per hour was 5.12 and 2.00, the percentage of
successful attacks, 58% and 21%, and the mean time spent feeding on each prey was 5.1 and 12.2 minutes for starving females
of E. stipulatus and T. phialatus respectively. E. stipulatus feeds on all stages of the prey except eggs, and T. philatus, on all stages, except males. Both species attack much less successfully females of P. citri rather than immatures. In experiments with adult females and eggs of P. citri as prey, the mean number of prey killed daily was 4.51 females for E. stipulatus, and 2.01 females and 2.12 eggs for T. philatus. Considering this killing rate and the number of eggs laid by the predators in the same period, it can be concluded that E. stipulatus consumes only 30% of the content of the preys killed, whereas T. philatus consumes a percentage of prey variable between individuals and ranging from 40% to 100%. These differences in feeding behavior
between the two species could partly explain differences in their efficiency as biocontrol agents of P. citri observed in the field.
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8.
Laboratory studies showed that ♀♀ of Trichogramma embryophagum (Hartig) and T. semblidis (Aurivillius) when offered an alternative of young and old eggs of the grain moth, Sitotroga cerealella Oliv., prefer ovipositing into young eggs. The fecundity of ♀♀ that are simultaneously offered both young and old eggs was
lower in comparison to ♀♀ offered only young eggs (inspite of the fact that in both variants young eggs were in excess). The
results suggest that old eggs can inhibit the oviposition of some species of Trichogramma.
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9.
A new species of Triumphalisnema is described and illustrated from the gut of a passalid beetle, Cetejus peltostictus, collected from rotting wood in Papua New Guinea. T. bialulaundatum n. sp. is easily distinguished from T. lenkoi, the type-species, by the much shorter dorsal and ventral alae (starting posterior to the vulva in T. bialulaundatum, but well anterior in T. lenkoi) and also by a peculiar ornamentation of the eggs. Scanning electron micrographs of the genus are provided for the first time. A diagnosis of the genus Triumphalisnema is included. 相似文献
10.
Adults of Geocoris punctipes (Say), Tropiconabis capsiformis Germar, Nabis roseipennis Reuter and Coleomegilla maculata (DeGeer) were confined inside petri dishes and fed phosphorus-32 ( 32p)-labeled Heliothis virescens (F.) eggs. Observations of bioelimination of 32p over a 72 h period allowed derivation of equations for predicting the number of H. virescens eggs ingested by each species. Twenty-four to 72 h after eggs were eaten, the percentages of 32p eliminated ranged from ca. 14% for G. punctipes to 42 % for T. capsiformis. Cautious use of the results will aid researchers in assessing predation on 32p labeled Heliothis.
Publication N o 5935. Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS 39762. 相似文献
11.
Weight gain of adult females Phytoseiulus persimilis Athias-Henriot was determined after they were fed eggs or adult females of Tetranychus urticae Koch reared on either Lima bean ( Phaseolus vulgaris L.) or nightshade ( Solanum douglasii Dunal). No significant difference was found when the predator was fed eggs of T. urticae reared on either host. Predators were heavier when fed adult female T. urticae reared on bean. Apparently, a factor determining the prey's suitability is incorporated into its hemolymph or tissues and
is not restricted to its gut content.
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12.
Functional responses of deutonymphs of the predatory mite, Allothrombium pulvinum Ewing, on eggs and adult females of two-spotted spider mite, Tetranychus urticae Koch, were determined in the laboratory. Predation experiments were conducted on lima bean leaf discs over a 24-h period at 25±2°C, 30–50% RH and 24L: 0D photoperiod. Prey densities ranged from 10 to 120 T. urticae eggs per disc or 2 to 32 adult females per disc. Allothrombium pulvinum deutonymphs were more effective against T. urticae eggs than its adult females. The role of A. pulvinum deutonymphs in integrated and biological pest control is discussed. 相似文献
13.
We studied the effect of Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) parasitism of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) eggs on the foraging behavior of Nabis pseudoferus Remane (Hemiptera: Nabidae) feeding on T. absoluta eggs of different ages. Older parasitized eggs (48–72 h old) were rejected after probing with the probosis. A separate experiment showed that probing did not harm developing parasitoids. Bugs greatly reduced their feeding times on older parasitized eggs and spent more time grooming and probing eggs and leaves. Predators exhibited a type III functional response to 24 h-old eggs, but a type II response to older eggs, whether parasitized or not. 24 h-old eggs suffered higher attack rates, and required less handling time than older eggs. Although the predatory efficiency of N. pseudoferus was reduced in the presence of parasitized eggs, the partial refuge enjoyed by T. brassicae in older eggs may permit an additive impact on the pest, and should facilitate the joint augmentation of both species against T. absoluta. 相似文献
14.
A strain of Fusarium solani sensu Snyder & Hansen invaded the eggs of the insect Panstrongylus geniculatus in a vivarium. None of the invaded eggs hatched. To establish experimentally the pathogenicity of this Fusarium species against the eggs of P. geniculatus, the fungus and the eggs were incubated together under different relative humidities and temperatures. At 64% relative humidity and 26 °C, the fungus grew well colonizing and penetrating all of the chorions.Three embryos died and were also colonized by F. solani. Only 4 nymphs hatched and survived to day 20. It is concluded that the isolate of F. solani was capable of colonizing and invading the chorion of the eggs under certain humidity and temperature conditions and cause the death of the embryos. 相似文献
15.
Mechanisms used by a scelionid egg parasitoid to locate its gerrid host eggs were studied using field experiments. Parasitism by Tiphodytes gerriphagus was higher in exclosures containing adults of Limnoporus dissortis than in cages without gerrids. Higher densities of adult gerrids were associated with higher rates of parasitism, but dispersion of aquatic vegetation did not apparently affect rates of parasitism. T. gerriphagus may use visual cues, chemical cues, or a combination of both to locate their hosts. We discuss the possible influence of T. gerriphagus on the reproductive behavior of its hosts. 相似文献
16.
The effect of 9 insecticides recommended for the control of cotton bollworms was studied, under laboratory conditions, on
the emergence of Trichogramma brasiliensis Ashmead from the parasitized eggs of Corcyra cephalonica (Stainton) of different age groups. The insecticide concentrations tested were equivalent to those recommended for field
application viz. phenthoate 0.14%, phosalone 0.15%, endosulfan 0.25%, permethrin 0.014%, monocrotophos 0.13%, fenvalerate
0.014%, cypermethrin 0.014%, fenitrothion 0.30% and quinalphos 0.14%, quinalphos and fenitrothion caused complete inhibition
of emergence of the parasitoid from parasitized host eggs of all ages (1 to 7 days); but in general, adverse effect of insecticides
on the disruption of emergence decreased with the advancement in the age of the parasitized eggs. For 1 day old parasitized
host eggs, emergence of T. brasiliensis adults varied from 33 to 57% for the remaining 7 treatments. For the 7 days old parasitized host eggs, emergence of parasitoids
from the treatments with endosulfan, phosalone and phenthoate was similar to that from control. However, 46 to 59% inhibition
of emergence was observed for permethrin, monocrotophos and cypermethrin. Fenvalerate treatment also significantly inhibited
the emergence but at a comparatively lower level (40%). Out of 9 insecticides tested, phosalone and fenvalerate were considered
to be relatively safe to T. brasiliensis.
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17.
A comparative study of the functional response of Coleomegilla maculataDeGeer (Coleoptera: Coccinellidae) fourth instars was conducted under laboratory, greenhouse, and field conditions. In the laboratory, individual larvae were placed in 9-cm petri dishes for 24 h, with 1, 3, 5, or 7 Colorado potato beetle ( Leptinotarsa decemlineata[Say]) (Coleoptera: Chrysomelidae) egg masses. Each egg mass was standardized at 15 eggs. In the greenhouse and field, C. maculatalarvae were provided with an equivalent of 0.5 to 35 L. decemlineataegg masses/m 2of potato leaf. Fourth instars of C. maculataexhibited a type II functional response to L. decemlineataeggs under laboratory, greenhouse, and field conditions. Predator search efficiency was inversely related with prey density. The maximum mean attack rate (8.7 eggs) by C. maculatalarvae in the field was about half the mean attack rate in the laboratory (17.6 eggs) and greenhouse (20.1 eggs). The difference in prey density between the laboratory and field seems to have been a major contributing factor in determining the rate of predation, whereas differences in environmental conditions (e.g., temperature and possible alternate food) may explain the differences observed in the predation rate in the greenhouse and field. 相似文献
18.
Summary
O. plebs (Hurley 1965) is a dominant bottom species of amphipoda, occuring in the investigated area at 10 to 760 m. Population structure and sex proportions depend upon the depth and the season of the year of sampling. Development of eggs occurs in winter; the young hatch in spring; the number of eggs produced is proportional to the volume of females. A relationship has been established between length and wet/dry body weight of O. plebs. The species is necrophagus, long enduring without food. At -1.8°C retention of food in the gut may last from several hours to several days. Heart beat frequency oscillates between 40–80 beats/min at -1.8°C and depends on temperature. A temperature near 8°C is lethal. Oxygen consumption of O. plebs depends on their developmental stage and sex and on trophic conditions. The level of metabolism of starved animals can be half that of fed animals. The greatest differences in oxygen consumption occur at-1.8°C, the ambient temperature. Oxygen consumption as a reaction to higher temperatures is different for starved and fed animals. O. plebs are hypostenothermic organisms; that is, they can adapt to the lowest temperature occuring in the marine environment.In memory of Mary Alice McWhinnie (1922–1980) 相似文献
19.
Phytoseiulus persimilis Athias-Henriot successfully controlled Tetranychus urticae Koch on rose hedges in an integrated mite control programme in two unheated plastic-covered tunnels at Cleveland in southern Queensland. Mite populations were monitored fortnightly for nearly three years in one tunnel and for two years in a second. Once established, P. persimilis quickly suppressed T. urticae and then persisted. A relatively stable, long-term, low-level interaction developed between the two species under normal commercial conditions. In one tunnel, the production (upper) level of the four rose hedges contained fewer mites of both species per compound leaf (1.71 of all stages of T. urticae, 0.38 motiles; 0.25 of all stages of P. persimilis, 0.12 motiles) than the maintenance (lower) layer (2.02 of all stages of T. urticae, 0.75 motiles; 0.35 of all stages of P. persimilis, 0.21 motiles). On 68% of sampling occasions, 10% or less of compound leaves in the production layer were infested with T. urticae (all stages including eggs) and control was excellent throughout the 30-month period after P. persimilis was established, there being no economic losses. In the second tunnel, there was no significant difference between mite numbers in the production and maintenance layers of the two hedges examined. The overall mean number of all stages of T. urticae per compound leaf was 3.2 (1.45 motiles), and of P. persimilis 0.46 (0.25 motiles). Control here was slightly less effective than in the first tunnel, but was still satisfactory, with 10% or less of leaves being infested on 45.5% of sampling occasions (20% or less on 66% of sampling occasions) with T. urticae (all stages including eggs). Phytoseiulus persimilis was not reintroduced or redistributed during the course of the observations. An auxiliary miticide (clofentezine) was applied on only one occasion to selected areas in the second tunnel. The influence of high temperatures on control by P. persimilis is discussed. 相似文献
20.
Summary The Author describes from Morocco a new species of Asolcus which is closely related to the sibling species A. basalis
Wollaston and A. nigribasalis
Voegelé. The species is named A. bennisi and parasitizes in nature the eggs of Graphosoma lineata
L. The separation of A. bennisi from the species of the basalis group is based on biological tests and on a characteristic pigmentation of the parasitized host eggs reared under optimal
laboratory conditions.
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