Showing papers on "Aphididae published in 1976"

Effects of groundnut crop density on the population dynamics of Aphis craccivora Koch (Hemiptera, Aphididae) in Malawi

Abstract: Three plant spacings, 30 cm, 7·5 cm and 2·5 cm within rows 90 cm apart, equivalent to about 36, 143 and 430 thousand plants/ha respectively, were used in three field trials on the population dynamics of Aphis craccivora Koch on groundnuts at Chitedze, Malawi in 1964–1967. Aphid density per infested plant was consistently higher, while numbers of aphid-infested plants per unit area were consistently lower, in 30 cm than in 2·5 cm spacing. Aphid numbers per unit area increased to similar levels at all spacings in crops under 40–50 days old, but subsequently aphid density was consistently lower in 2·5 cm than in 30 cm spacing. This effect could not be related to the intensity of fungus disease infection, parasitism, predation, the availability of feeding sites or the rate of emigration. Aphid groups were, however, consistently smaller in 2·5 cm than in 30 cm spacing in one trial. The potential rate of increase was studied in two trials using the methods of Hughes (1962), and was found to be consistently lower in 2·5 cm than in 30 cm spacing. The rate of plant growth was relatively depressed in 2·5 cm spacing, particularly after 40 days. The effect of spacing on aphid numbers was attributed to the effect of host-plant condition on the potential rate of increase.

Chromosome numbers of parthenogenetic females of fifty-five species of Aphididae (Homoptera) new to cytology

Abstract: The numbers of somatic chromosomes of 55 species of Aphididae are presented. Squashed embryos from apterous viviparous females are stained with crystalviolet. Some relationships between aphid chromosomes and aphid systematics are discussed.

Über das Auftreten der Getreideblattlausarten (Hom., Aphididae) in norddeutschen Weizenanbaugebieten (1974/75)

Abstract: The ocurrence of the different cereal aphids (Hom., Aphididae) in Northern German wheat growing areas 1974 and 1975

Two new species and an undescribed morph of aphids (Homoptera : Aphididae) from Northwest Himalaya

Abstract: Two new species of aphid, viz., Neoacyrihosiphon (Neoacyrthosiphon) indicum and Etiosoma kashmirkum and the hitherto undescribed alate morph of Chattophoruspakistankus H.R.L. are described from Northwest Himalaya, India.

Faba bean: low resistance to pea aphids, acyrthosiphon pisum (homoptera: aphididae), in eleven cultivars

Abstract: Eleven cultivars of faba beans and one of broad bean (Vicia faba L.) were bioassayed for resistance to pea aphids (Acyrthosiphon pisum (Harris)) by determining the fecundity, survival and developmental rate of the aphid on each cultivar. None of the cultivars tested, including the three licensed for production in Canada, possess any significant resistance, although they differ in susceptibility.

Studies on thie Aphids (Homoptera : Aphididae) from Eastern India XXVIH, Acutosihion, Akkaia and Vesiculaphis

Abstract: Taxonomic affinities of Acutosiphon, Akkaia and Vestculaphts, and their species occurring in eastern India are given. Eight species, including descriptions of a new species, V. Kalimpongensis and of the hitherto unknown alate viviparous female of A. Bengalensts are given.