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1.
R.J. Milner 《Journal of invertebrate pathology》1981,37(3):304-309
A novel milky disease organism has been found causing disease in Aphodius tasmaniae and other scarabaeid larvae in the field in Australia. The sporangium is exceptionally long, measuring 10.5 × 1.5 μm, with a small central spore, measuring 1.0 × 0.6 μm. The vegetative cell is about half the size of the sporangium. The disease was easily transmitted by injection of spores into the hemocoel, with typically milky symptoms developing in 2–4 weeks. Spores will form in vivo at temperatures down to 12°C. For A. tasmaniae third-instar larvae, the ID50 by injection was 3 × 102 spores/larva, yet no infection resulted when larvae were reared in peat containing up to 108 spores/g, i.e., the disease was not successfully transmitted per os. All 10 species of scarabaeids tested were susceptible to the disease when spores were injected; however, all attempts to infect larvae per os were unsuccessful. In vitro culture was also unsuccessful. 相似文献
2.
R. J. Milner 《BioControl》1973,18(3):305-315
The pathogenicity ofNosema whitei was studied using a dose-mortality technique; larvae ofTribolium castaneum were reared for the duration of each experiment in flour mixed with known numbers of spores. The susceptibility of each of
the first 5 larval instars was compared. The LD50 (for mortality after 20 days) increased consistently from the first instar (1.8×106 spores/g) to the fifth instar (1.0×1010 spores/g). The slopes of the probit lines increased consistently as age increased (from b=1.1 to b=3.9). Two factors which
reduce the development time ofT. castaneum, high temperature and high humidity, both reduced the pathogenicity ofN. whitei. Thus pathogenicity decreased as the temperature was increased fram 25°C (LD50=4.2×106) through 30°C (LD50=1.3×107) to 35°C (LD50=3.2×106), also pathogenicity decreased consistently as humidity was increased fram 10%, through 30, 50, 70% to 90% R.H. Adults, emerging
fromNosema free larvae, became infected only when exposed to a very high dose (2×1010 spores/g for 14 days from the day of emergence). Infected larvae were treated for 1 hr. at 45°C in an attempt to cure the
infection. The infected larvae were not cured, rather the treatment had an adverse alfect on their survival.
This work financed by a Science Research Council (U.K.) studentship is based on a thesis submitted for a degree of Ph. D. at the University of Newcastle-upon-Tyne. 相似文献
Résumé La pathogénicité deNosema whitei a été étudiée en élevant des larves deT. castaneum dans de la farine mélangée à des quantités connues de spores. La sensibilité des larves diminue uniformément en fonction de l'age; La DL50 varie de 1,8×106/g (1er stade) à 1,0×1010 spores/g (5e stade). Deux facteurs, qui accélèrent le développement deT. castaneum, des températures et des humidités élevées, réduisent tous les deux la pathogénicité deN. whitei. Les adultes ne peuvent être infectés qu'en les exposant à la dose extrêmement élevée de 2×1010 spores/g. Un traitement par la chaleur (45°C pendant une heure) n'a pas réussi à guérir les larves.
This work financed by a Science Research Council (U.K.) studentship is based on a thesis submitted for a degree of Ph. D. at the University of Newcastle-upon-Tyne. 相似文献
3.
R.J. Milner 《Journal of invertebrate pathology》1976,28(2):185-190
Two methods of infection, i.e., feeding known numbers of spores and rearing larvae in contaminated peat, were used to bioassay the susceptibility of Rhopaea verreauxi to Bacillus popilliae var. rhopaea at 23°C. The susceptibility of the three larval instars was similar as measured by the ID50 and IC50 values. However, within an instar, newly molted larvae were less susceptible than mature larvae when infected by the contaminated peat method. It is suggested that this was due to reduced food intake. The range of ID50 values for all bioassays with R. verreauxi larvae were 1.1 × 107 to 4.0 × 107 spores per larva, and IC50 values were 3.4 × 106 to 5.0 × 107 spores per g of contaminated peat. The slope of the probit line was always low (0.6 to 1.8) except for young first-instar larvae infected by contaminated peat when the slope was 4.0. Disease per se did not affect food intake, though intake was reduced at high doses of contaminated peat. Young larvae often died without developing symptoms but, with increasing age, infected larvae were more likely to develop symptoms. Bioassays with Othnonius batesi and Rhopaea morbillosa indicated a much lower susceptibility per os than for R. verreauxi. It is concluded that the potential for using B. popilliae var. rhopaea to control R. verreauxi is high, but the bacillus is unlikely to be of value in control of O. batesi or R. morbillosa. 相似文献
4.
Toxicity tests of three strains of Bacillus sphaericus against late instars of 12 culicine mosquito species indicated a wide range of susceptibility. Culex pipiens and C. salinarius were highly susceptible (LC50s < 104 spores/ml) to strain 1593, and C. pipiens and C. restuans were highly susceptible to strain 2013-4. The potency of strain SSII-1 was approximately one-tenth that of strains 1593 and 2013-4 against C. pipiens. Susceptibility of Aedes species to strain 1593 was highly variable. At temperatures ≥ 20°C, A. fitchii, A. intrudens, A. stimulans, and A. vexans were moderately to highly susceptible (LC50s 6 × 103−4 × 104 spores/ml), A. triseriatus was only slightly susceptible (LC50 > 106 spores/ml), and A. aegypti was refractory. Susceptibility of Aedes mosquitoes to strain SSII-1 was less variable, with LC50s against A. aegypti, A. canadensis, A. stimulans, and A. triseriatus all being between 104 and 106 vegetative cells + spores/ml. All species of mosquitoes tested were, in general, highly susceptible to B. thuringiensis var. israelensis (LC50s 2.3 × 103−2.5 × 104 spores/ml). In B. sphaericus toxicity tests, decreased temperatures resulted in up to a 16-fold increase in LC50 and a substantial reduction in probit line slope. First-instar A. aegypti larvae were more susceptible to B. sphaericus strain SSII-1 than the three later instars, which were approximately equally susceptible; however, no significant difference was observed in the susceptibility of the four instars of A. triseriatus. 相似文献
5.
The mosquito pathogen Tolypocladium cylindrosporum was examined with regard to its response to temperature. Similar temperature ranges were found for growth, germination, and infectivity of blastospores and conidia. Germination occurred at 8° and 33°C but not at 6° and 35°C. Optimal germination and growth was noted between 24° and 27°C for both spore types. Infectivity of blastospores and conidia at different temperatures was examined by exposing L2Aedes sierrensis larvae to concentrations of 5 × 105 blastospores/ml or 5 × 106 conidia/ml. Larvae were incubated at 12°, 15°, 25°, and 30°C. Infection occurred at all temperatures tested with LT50 values ranging from 22.7 days (12°C) to 5.6 (25°C) days for conidia and 4.7 days (12°C) to 0.6 day (25°C) for blastospores. These results confirmed earlier findings that blastospores infected and killed host larvae more rapidly than conidia and suggested that this difference is largely due to the more rapid germination rate of blastospores. These experiments demonstrated that T. cylindrosporum can be active against mosquito larvae over a broad range of temperatures encompassing both the cold-water habitat of certain temperate mosquito species as well as the habitat of tropical vector species. 相似文献
6.
P. L. Sherlock 《BioControl》1984,29(1):73-81
Larvae of noctuids were inoculatedper os with spores of a species ofPleistophora isolated fromAgrotis exclamationis (L.). The mean median lethal dose for mainly 3rd instar larvae ofA. exclamationis was 1.38×105 spores per larva accumulating 34 or 35 days after inoculation and the mean slope for the regression of mortality on dose was 0.82. Third instar larvae ofA. exclamationis andSpodoptera frugiperda (J.E. Smith) inoculated with 2.5×104 spores gained weight quicker than uninfected ones until between 8 days (A. exclamationis) and 13 days (S. frugiperda) post-inoculation. Thereafter they grew slower than uninfected individuals. Correspondingly, the feeding rate of inoculated larvae ofA. exclamationis was greater than that of untreated ones until 14 days post-inoculation but thereafter was less. Larvae ofNoctua pronuba (L.)Phlogophora meticulosa L. andSpodoptera littoralis (Boisduval) but notAgrotis segetum (Denis & Schiffermüller) were also susceptible to infection. The species ofPleistophora considered here corresponds toP. schubergi noctuidae (Veremtchuk & Issi) in spore morphology, tissue specificity and host range, except that is was non-infective for the typehostA. segetum. It is probably insufficiently pathogenic for use in the biological control of noctuids. 相似文献
7.
Microbial control of the fruit tree leafroller,Archips argyrospila [Lep.: Tortricidae] in California
Field populations of larvae of the fruit tree leafrollerArchips argyrospila (Wlk). were practically eliminated following spray application ofBacillus thuringiensis Berliner serotype III at 192 and 80×106 I.U. per litre on the host trees,Cercis occidentalis. Spray applications of lower rates ofB. thurienginsis serotype III at 18.9 and 32.1×106 I.U. per litre and mist application ofB. thuringiensis serotype 1 at 8.0 and 16.0×106 I.U. per litre gave partial control of populations ofA. argyrospila larvae. A granulosis typeBaculovirus, applied by hand sprayer at 1.4×109 granules/ml produced approximately 50% reduction of 5th instarA. argyrospila larvae onC. occidentalis trees. It was concluded thatB. thuringiensis and the granulosis typeBaculovirus are promising control agents forA. argyrospila larvae. 相似文献
8.
George G. Soarés Jr. 《BioControl》1982,27(3):283-299
The mode of infection and cycle of development ofTolypocladium cylindrosporum Gams was examined inAedes sierrensis andCulex tarsalis. Larvae were found to be infected through the external cuticle, the pharynx and the midgut. Blastospores and conidia were both infective although for equal numerical concentrations blastospores proved more virulent causing high mortality within the first 48 h after inoculation (80 % for L2 larvae exposed to 5×105 spores/ml), while conidia generally took 7–10 days to produce the same results. Sporulation did not occur on submerged cadavers. Conidia were produced only on floating cadavers in contact with air. Conidial production on floating 4th instar larvae was found to average 1.8×107 conidia/larva. Invasion of the haemocoele and fairly extensive growth of the fungus almost invariably occurred before larvae were killed. This was particularly true forAedes sierrensis larvae. Details are presented of growth within the host and post-mortem penetration of the fungus out of the cadaver. AdultA. sierrensis sprayed with a conidial suspension proved susceptible to infection with 100 % mortality being recorded at 10 days. Infections originated in the thorax, suggesting, the integument or possibly the thoracic spiracles to be the most probable site of infection. 相似文献
9.
Résumé L'étude de la sensibilité des chenilles deSpodoptera littoralis
Boisd. à des doses croissantes de spores deNomuraea rileyi (F.)Samson, montre que le 6e et dernier stade est plus résistant que le 1er et surtout les 4e et 5e stades larvaires. La virulence du pathotypeN. rileyi no 5 à l'égard des larves de cette noctuelle est élevée puisque le temps léthal 50 % (TL 50) est de 6 j en moyenne. Pendant
l'incubation de la maladie les chenilles continuent de s'alimenter mais l'infection peut réduire jusqu'à 60 % la prise alimentaire
par rapport à la consommation des larves des lots témoins.
Toutes conditions égales par ailleurs, la mortalité provoquée parN. rileyi no 5 après traitement des larves nouvelles-nées est supérieure lorsque les insectes sont maintenus à 25°C par rapport à celle
constatée à 20°C. Cependant pour une dose d'inoculum élevée, les conditions thermiques (20°, 25° ou 28°C), ne modifient pas
sensiblement la réponse à l'infection parN. rileyi no 5 alors qu'elles limitent l'efficacité d'un pathotype moins virulent:Paecilomyces fumoso-roseus
Wize noo 39.
Avec la collaboration technique deH. Vermeil de Conchard. 相似文献
Summary Laboratory studies were conducted to determine the susceptibility of various larval instars of the cotton leafworm,Spodoptera littoralis Boisd. to different spore doses ofNomuraea rileyi (F.)Samson to investigate the influence of temperature on the infection by this fungus and byPaecilomyces fumosoroseus Wize. Contaminations were obtained by direct spraying on larvae in tower apparatus or by feeding of larvae on treated pieces of leaf during 48 h or 72 h. The influence of cryptogamic infection on food consumption was studied by measuring surfaces of standard cabbage leaf disces submitted to treated and control larvae. Angular values mortality rates were submitted to the 2- or 3-way analysis of variance and comparisons of means were made by theDuncan's test. In some cases we have also considered the time-mortality and the dose-mortality curves. The 6th instar was more resistant than all other tested instars. TL50 were found to be 6 days in most cases. During incubation of the disease, larvae continued to feed, but food consumption could be reduced at 40 % of controls. Larval mortality due toN. rileyi No 5, recorded after 8 days of incubation, was higher at 25°C than at 20°C. Nevertheless, at high dosage, efficiency ofN. rileyi No 5 was not affected by temperature at 20°, 25° and 28°C. The other pathotype,P. fumoso-roseus No 39 was more effective at 20°C than at 25° and 28°. At 32°C, the temperature, unfavourable to fungal growth, limited mortality at non significant rates.
Avec la collaboration technique deH. Vermeil de Conchard. 相似文献
10.
Charles P. Schwalbe G.Mallory Boush Wendell E. Burkholder 《Journal of invertebrate pathology》1973,21(2):176-182
Factors that regulate development of Mattesia trogodermae in Trogoderma glabrum were defined, and their quantitative effects were determined. The rate of and the extent to which spore formation proceeds is strictly governed by temperature. More spores are produced at 30° than at 25°C and very low numbers of spores are formed when the incubation temperature is 35°C. When insects are incubated at 35°C for 1–10 days and transferred to 30°C for the remainder of the 30-day experiment, spore production capacity gradually declines with increasing time at 35°C. Two hypotheses are proposed for this phenomenon. Larval size also regulates the extent of spore production, larger larvae having greater potential for spore development. This is not influenced by dosage. Spore production in pupae and adults was always retarded.Dosage and environmental conditions which influence the virulence of M. trogodermae were investigated. These studies show that rates of mortality are higher at higher temperatures. Low doses of spores result in longer LT50's than do high doses at 25° and 30°C. No differences in rates of mortality were found between different doses at 35°C. 相似文献
11.
S. Tvermyr 《BioControl》1969,14(3):245-250
Larvae ofNeodiprion sertifer (Geoff.) were reared on twigs from Scots pine at three different temperatures, 12°C, 18°C and 24°C. The LT50 of virus-infected larvae was 19.3, 9.5 and 4,6 days respectively. In the control the median length of the larval period was 45.7, 29.8 and 22.1 days at the same temperatures. From this results it is concluded that both the LT50 and the length of the larval period are prolonged by low temperature. The medium length of the larval period, however, is relatively more prolonged than is the LT50. Therefore, nuclear polyhedrossis virus may be an effective control agent againstN. sertifer in cool areas even if the LT50 is relatively long. 相似文献
12.
B. Zelazny 《BioControl》1985,30(2):121-124
Bioassay indicated that 1 st instar larvae ofOryctes rhinoceros are resistant to infections by the nematodeSteinernema feltiae (estimated LD50: 90 nematodes) but thatTirathaba rufivena larvae larger than 15 mm are highly susceptible (estimated LD50: 3 nematodes). The “All” strain and the “mexican” strain ofS. feltiae gave very similar responses. In a field trial 300,000 nematodes were sprayed on each of 25 palms to controlT. rufivena. Although some mortality from nematodes was observed, the treatment failed to reduce the pest population significantly. 相似文献
13.
Among more than 50 isolates ofBacillus thuringiensis Berliner (B.t.) tested, 7 incited 100% mortality when 2nd instar larvae ofSpodoptera littoralis Boisduval were fed on alfalfa leaves dipped in a spore-crystal suspension of 108 colony forming units/ml. Among those isolates,B.t. 24 demonstrated the highest activity. Larvae of instars 1 and 2 were the most susceptible toB.t. Susceptibility decreased with larval development. However, larvae of all instars were killed by isolateB.t. 24. Larvae that survived after feeding withB.t. 24 were retarded and fed less. Their weight relative to the controls was lower as the spore concentration on the leaves on which they fed was higher. Survival of the spores in the field dropped drastically to 2% after 4 days. Insecticidal activity of the sprayed suspension on those leaves, however, remained significant.B.t. 24 was also effective against larvae on cotton plants in the greenhouse and in a preliminary field experiment. Numbers of colony forming units recovered from leaves dipped in suspension of various spore concentrations showed significant correlation with the initial concentrations as did sprayed leaves. However, colony forming units recovered from sprayed leaves were 5–7.5 fold lower than from dipped leaves. Dipped cotton leaves showed 3.1×10?5 ml attached to 1 mm2 leaf surface whereas sprayed ones had 6×10?6 ml. Those data are important for the determination of spore concentrations in suspensions required for spraying. The isolateB.t. 24 was serotyped byH. de Barjac as H-6B. thuringiensis entomocidus. 相似文献
14.
Barbara M. Pilley Elizabeth U. Canning Jill C. Hammond 《Journal of invertebrate pathology》1978,32(3):355-358
Nosema eurytremae, a microsporidian parasite of Malaysian trematodes, was injected at the rate of 1 × 104 spores/larva into Pieris brassicae. The larvae, which subsequently pupated, were incubated at 25 to 26°C and on harvesting 19 days later yielded an average of 6 × 108 spores/pupa. This was equivalent to 60,000 times the initial dose. Purity of filtered, washed spore suspensions ranged from 80 to 99% with up to 20% host debris. 相似文献
15.
R J Milner 《Journal of invertebrate pathology》1974,23(3):289-296
The effect of various factors on the yield of Bacillus popilliae var. rhopaea spores formed in Rhopaea verreauxi larvae have been studied. Lack of adequate food, temperatures above and below 23°C, and infecting doses above 106 spore larva, all significantly lowered spore yield per larva. Larval age had a pronounced effect; second-instar and young third-instar larvae produ ed about 1 × 1010 spores while old third-instar larvae produced about 4 × 1010 spores. Incubation of larvae for longer than 4 weeks did not increase spore yield per larva. Yields were similar whether larvae were infected by injection or per os. Three other host species could be used to mass-produce B. popilliae var. rhopaea spores but all were less efficient than R. verreauxi. Milky third-instar R. verreauxi larvae, which were field collected, yielded 1.57 × 1010 spores per larva. 相似文献
16.
《Plant science》1988,56(3):261-264
In greenhouse tests, Alternaria crassa (Sacc.) Rands killed > 80% of inoculated jimsonweed (Datura stramonium L.) seedlings within 14 days following a 9-h dew period at 25°C with 1 × 105 spores/ml, and after 8 h of dew at 1 × 106 spores/ml. At least 10 h of dew with 1 × 105 spores/ml and 9 h of dew with 1 × 106 spores/ml were required to obtain 100% mortality of fungus-inoculated plants. Growth stage and inoculum concentration studies revealed that higher concentrations of inoculum were required to obtain 100% mortality of larger plants. Weed control was significantly reduced by day/night air temperatures of 35°C and 24°C, respectively, at all inoculum concentrations as compared to the controls at lower air and dew temperature regimes. The results of these studies indicate that A. crassa has potential as a biological herbicide for the control of jimsonweed. 相似文献
17.
Mass production and storage methods were evaluated for maximization of spores of Vairimorpha necatrix, a promising protozoan for microbial control due to its virulence and prolificity in lepidopterous pests. In vivo spore production was at a maximum when 3rd instar Heliothis zea were exposed to 6.6 spores/mm2 of artificial diet surface and reared for 15 days. Approximately 1.67 × 1010 spores/larva were produced, or ca. 1 × 1010 spores/larva after partial purification of the spores by homogenization of the larvae in water, filtration, and centrifugation. The spores were inactivated by relatively short exposures to several chemicals which were tested to counteract contamination of the diet surface by fungi in the spore inoculum. Spores of V. necatrix were stored at refrigerated and freezing temperatures for up to 2 years and bioassayed periodically with 2nd instar H. zea. Spores lost little infectivity after 23 months at 6°C if they were stored in a purified water suspension plus antibiotic, but they were noninfective after 18 months at 6°C if stored in host tissue. Storage at ?15°C caused little loss of infectivity whether the spores were stored in water and glycerine, in host tissue, or after lyophilization. The spores withstood lyophilization in host cadavers better than in purified water suspension. Samples of a dry V. necatrix-corn meal formulation, which was prepared for field efficacy tests and stored at ?15° and 6°C, were highly infective after 9 months. Large numbers of V. necatrix spores can thus be produced and later made available for microbial control field trials with little loss of infectivity. 相似文献
18.
J. Eilenberg 《BioControl》1987,32(4):425-435
A method for maintaining anin vivo culture ofEntomophthora muscae (C) Fres. on its original host, adult carrot flies (Psila rosae F.), is described. The lethal time for adult carrot flies was greatly influenced by temperature, both for infected and for
uninfected flies. In the range 8.2°C–20.2°C the LT50 for infected flies was about 5.4 times shorter than the estimated average life-span for uninfected flies. The discharge of
primary spores was also strongly dependent on temperature. The total number of primary spores discharged per fly at 100% RH
and in darkness ranged between 1.2×104 and 9.6×104 with a mean of 5.1×104.
相似文献
19.
Nondiapausing pupae ofBathyplectes curculionis (Thomson) were studied under laboratory conditions. The mortality caused by 8 temperatures between 25–48°C at 20% and 70% relative humidity was measured at 10 exposure times between 15 min-24 h. There was no significant mortality at 25°C. Between 30 and 40°C, mortality occurred from long exposures only, with lethal effects becoming greater at each increase in temperature. At 43°C mortality occurred from relatively short exposures, with 100% at 4 h. Exposure times for 50% mortality averaged 16.58 h at 38°C, 1.08 h at 43°C and 0.31 h at 48°C. A slightly higher mortality occurred at 20% relative humidity than at 70% at temperatures between 35 and 40°C. At temperatures above 43°C no effects of relative humidity were noted. Afternoon soil surface temperatures in recently cut alfalfa fields commonly exceeded 50°C during July in northern Utah. 相似文献
20.
R.J. Milner 《Journal of invertebrate pathology》1981,38(3):419-425
Experiments were conducted to study the effects of time, temperature, and light regime on primary spore formation at 100% RH for the three major pathogens of Acyrothosiphon kondoi. Only small differences were detected between the continuous light and continuous dark regimes. Entomophthora obscura produced between 6 and 10 × 103 primary spores mostly during the first 48 hr. Total primary spore production was similar at the five temperatures tested from 5° to 25°C. Entomophthora planchoniana produced large numbers of primary spores (about 5 × 104 per aphid) only at temperatures between 10° and 20°C. The majority of primary spores were formed during the first 24 hr. Primary spore production with Entomophthora nr. exitialis ranged from about 105 per aphid at 5° and 10°C to 3 or 4 × 105 at 15° to 25°C, with most spores being formed during the first 48 hr. It is suggested that rainfall is more likely to be important for transmission of E. obscura and E. nr. exitialis than for transmission of E. planchoniana, and that E. obscura is likely to be the most important pathogen during cool or cold weather. 相似文献