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I. Annan ; G. Schaefers ; W. Tingey | 1996Impact of initial density of cowpea aphid Aphis craccivora Koch (Aphididae) at infestation on the growth and yield of aphid-susceptible cowpea cultivar ICV-1 and aphid-resistant cultivar ICV-12, was investigated. Plants at the seedling, flowerin[...]
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I. Annan ; G. Schaefers ; W. Tingey | 1995The influence of duration of infestation by cowpea aphid Aphis craccivora Koch on aphid-resistant (ICV-12) and aphid-susceptible (ICV-I) cultivars of cowpea Vign?a unguiculata (L.) Walp, were compared to uninfested controls. Five apterous adult [...]
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I. Annan ; K. Ampongnyarko ; W. Tingey ; G. Schaefers | 1997Field and greenhouse studies were conducted in 1990 and 1991, to assess the effects of fertilizer application on the bionomics and population dynamics of cowpea aphid, Alphis craccivora Koch, and on the growth and yield of cowpea, Vigna unguicul[...]
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I. Annan ; W. Tingey ; G. Schaefers | 1997Survivorship, growth, and reproductive performance of cowpea aphid, aphis craccivora Koch, were studied on whole plants and excised plant tissues of aphid-resistant ('ICV-12') and aphid-susceptible ('ICV-1') cultivars of cowpea, Vigna unguiculat[...]
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I. Annan ; W. Tingey ; G. Schaefers ; K. Saxena | 1996Membrane feeding studies were conducted to determine the effects of raw juices and chemical extracts of leaves of aphid-resistant (ICV-12) and aphid-susceptible (ICV-1) cultivars of cowpea [Vigna unguciculata L. (Walp.)], on the survival, growth[...]
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I. Annan ; G. Schaefers ; W. Tingey ; W. Tjallingii | 1997Electrical penetration graph recordings using direct current (DC-EPGs) were used to analyze aspects of the probing behavior of cowpea aphid, Aphis craccivora Koch, on intact plants and on hexane, ethyl acetate, and methanol extracts of leaves of[...]
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I. Annan ; W. Tingey ; G. Schaefers ; W. Tjallingii ; E. Backus ; K. Saxena | 2000Direct current electrical penetration graphs (DC-EPGs) were used to analyze the styler penetration activities of cowpea aphid, Aphis craccivora Koch, on plants of aphid-resistant (ICV-12) and aphid-susceptible (ICV-1) cultivars of cowpea, Vigna [...]
