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151.
Comparison of centrifugal and other methods for standardization of extraction of nematodes from soil 总被引:2,自引:0,他引:2
The extraction of many genera of nematodes from four different soil types by sedimentation, mobility, sieving and centrifuging was compared. All methods were found to extract similar numbers of nematodes. Centrifuging was the most versatile technique and the best for clay soils. Baerman sieving was generally poor and particularly so for sands and for the genus Tylen-chorhynchus. Rotylenchus was the only genus of those identified that was extracted equally well by all techniques. Centrifugal extraction was selected as the routine method for surveys as it was effective on all soil types, was less likely to be subject to variation and, although poor for Longidorus, extracted a wider spectrum of nematodes. 相似文献
152.
153.
The courtship of butterflies begins with a general attractionof males to moving objects. If the object of the attractionis a receptive female, her response wil1 elicit further courtshipbehavior from the male. Male courtship pheromones are disseminatedduring the aerial phases of courtship and after the female haslanded. While female butterflies generally lack specific courtshippheromone glands, females of some groups do possess these. Courtship pheromones of males of four members of the subfamilyDanainae in the family Nymphalidae have now been identified.Three of these share the same active component, but each hasspecific additional components. Although the courtship pheromonesecretions of butterflies have odors which are very distinctiveto humans, the active compound of these pheromones is odorlessto humans and elicits responses from antennal receptors of allbutterflies tested. The pheromone receptors are short thin-walledpegs on the antennae of both male and female butterflies. 相似文献
154.
Studies in the vegetational history of the Northern Pennines 总被引:1,自引:1,他引:0