摘要:

SUMMARYDDT, dieldrin, γ‐BHC, malathion, diazinon and Sevin were all cumulative to some extent in their action on adult mosquitoes,Aedes aegypti.Mosquitoes receiving a sublethal dose of each insecticide were more susceptible to it 48 hr. later than were untreated mosquitoes from the same population. The greatest effect was obtained with dieldrin; the least with γ

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06063.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe joint action of insecticides on adult female mosquitoes,Aedes aegyptiandAnopheles stephensi, has been studied by topical applications of known dosages separately and in mixtures. Results indicated that the two organophosphorus compounds, malathion and diazinon, have a similar action on the mosquitoes. Responses to mixtures of an organophosphate (malathion) and a carbamate (Sevin), an organo‐phosphate (malathion) or a carbamate (Sevin) and a chlorinated hydrocarbon (DDT or dieldrin), and of two chlorinated hydrocarbons (DDT and dieldrin) were less than expected for similar action.In other experiments in which two insecticides were applied separately with an interval of 48 hr. between treatments, the order of application was of importance. Mosquitoes receiving a sublethal dose of malathion were more susceptible to Sevin, DDT and dieldrin than untreated mosquitoes from the same population, whereas pre‐treatment with Sevin did not influence susceptibility to malathion, DDT and dield

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06064.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYUsing wheatfeed as food the rate of development and the developmental mortality ofTribolium madenswere studied at 50 and 70%r.h.over a series of constant temperatures between 17.5 and 37.5°C. and additionally at 10, 30 and 90%r.h.at 22.5, 25 and 30°C.About 80% of eggs hatched at all temperatures except 37.5°C. where only 59% hatched. The egg period was shortest at 35°C; humidity did not affect the duration of this stage.Larvae failed to reach the pupal stage at 17.5 and 37.5°C. In all other conditions except 25°C. and 10%r.h.larval mortality was below 10%. The rate of larval development increased consistently with rise in temperature at 70%r.h., but at 50%r.h.there was an optimum between 30 and 32.5°C. Larval development was fastest at the higher humidities, except at 22.5°C. where the results were irregular. The populations used at this temperature were heterogeneous and one larva needed over 200 days to pupate. At 20°C. many larvae entered a resting stage when fully grown and some failed to pupate after 350 days, but did so when placed at 25°C. It is suggested that this resting stage might be a diapause.The duration of the pupal period was not affected by humidity but it decreased at higher temperatures. The sex ratio was significantly different from unity, with a predominance of females.The lengths of the various stages, that of the total developmental period and the weight of pupae are compared with corresponding data forT. confusumandT. castaneum.In all conditions, these smaller, more important species develop at least as quickly asT. madens.Also the temperature range over which they can breed

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06065.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe effects of a single irradiation at 4000 roentgens on larvae of the powder‐post beetleLyctus brunneus(Steph.) are described. These included a reduced and delayed emergence of the first generation. The number of beetles produced per female returned to normal in subsequent generations. The vigour of emerged beetles as judged by their average weights did not appear to be much affected. Irradiation at a sublethal dosage thus seems unlikely to be a practical method of employing γ‐radiation for the treatment of infestations by wood‐boring insects. One of the chief limiting factors in the employment of lethal dosages for such treatments is the mass of screening required, hence a technique enabling lower dosages to be used would be of

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06066.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYSmall populations ofAphis fabaewere wholly or partially protected by the antLasius nigerwhich drove most predators away. Predators eliminated whole colonies of unprotected aphids or persistently restricted their numbers. Protection of the aphid against predators is probably more important than hitherto thought, and may be more important than the other ways in which ants affect the multiplication rate ofA. fabae.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06067.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe efficiency with which the 5 in. diameter, white, cylindrical sticky trap and suspended tow‐net catch insects was assessed using Johnson's (1950) field comparison of the two with the suction trap recently standardized by Taylor (1962). The aerodynamic efficiency of the sticky trap was also calculated from Gregory's (1951) results. Comparing these two results shows that small insects behave very like inert particles during capture. Efficiency of the sticky trap is almost constant in winds from 2 to 10 m.p.h. Tables are given converting catch of small insects to aerial density in winds from 1 to 10 m.p.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06068.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYTests of cultivated and wild oats for resistance to the cereal root eelworm (Heterodera avenaeWoll.) were based on reaction to eelworm attack in the field and examination of root systems for eelworm cysts. Some resistance was found inAvena sativavar. Heine's Silber II: a higher level of resistance occurred in the wild speciesA. sterilis, which bore no cysts, and in three forms ofA. abyssinica, which bore few or none.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06069.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe failure of beet eelworm to develop on host plants in microplots filled with a sandy soil from an infested field at Cantley, Norfolk, was studied. Using artificial water‐tables it was found that by the time the plants were large enough for many eel‐worms to develop on them, soil conditions were too dry for larval hatch and invasion. Hatched larvae invaded and developed when added to microplots, presumably because they were able to survive the dry conditions until wet weather enabled them to invade the roots.Some areas may be too dry for development of beet eelworm. Conversely, irrigation may encourage beet eelworm.These experiments showed that the uses of microplots are limited, because conditions in them may differ from those in fields, and they are less manageable than p

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06070.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe number of pre‐adult larvae ofDitylenchus dipsaciwhich invaded seedlings of the oat variety Sun II growing in sand was linearly related to the number of larvae in the inoculum. In seedlings growing on pads, invasion rates were higher but were limited to about 200 nematodes per plant. The respective numbers of larvae invading the susceptible varieties Sun II and Powys and the resistant varieties Manod and Pennant were not significantly different after 3 days. Reproduction occurred in the susceptible varieties, and after 28 days the number of nematodes per plant in the susceptible varieties was about double that in the resistant ones.When the resistant variety Manod was infested at germination, 32.5% of the seedlings were killed after 14 days compared with 45% of the susceptible variety, Sun II, and this difference was significant at the 5% level. Oat and lucerne seedlings were invaded by larvae of both the lucerne and oat races ofD. dipsacibut only in the compatible host did reproduction occur. More larvae invaded the pseudostems of oats than the root systems and this difference was significant at the 0.1% level. The nematode reproduced only in the pseudostems.A method for classifying plants attacked by stem nematodes is proposed based on the reaction of the tissues and the multiplication of the nematode within the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06071.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYDitylenchus dipsacicaused cells to enlarge and separate in tissues of the susceptible oat variety, Sun II. Cytoplasm was withdrawn from the cells, the walls of which collapsed to form a cavity around the nematodes. In the resistant variety Manod, separation and hypertrophy were slight, but cytoplasm was withdrawn and cavities formed similar to those in Sun II; hyperplasia or necrosis was not seen.The body and gonads in nematodes from Manod plants were shorter than from Sun II, but the de Man ratios and the ratio of males to females were the same. Fourth‐stage larvae matured to adults more slowly in Manod seedlings. Nematodes grew by a series of steps caused by alternating periods of slow growth before an ecdysis and rapid growth afterwards. In Manod,D. dipsacigrew more slowly but the form of the growth curve was as in Sun II. Gonads lengthened rapidly and continuously during the late fourth larval and early adult stages and especially during the period before the fourth ecdysis when body length stopped increasin

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06072.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY