Abstract
Abstract: The objective of this work was to determine the preference and the demographic parameters of cowpea aphid (Aphis craccivora) in advanced lines of semiprostrate cowpea (Vigna unguiculata), and to verify both the existance and type of plant resistance to this insect attack. Aphid preference to 20 cowpea genotypes was tested in a randomized complete block design, with six replicates. Lines showing the highest levels of resistance and susceptibility in the preference tests were selected for use in the demographic parameter tests. Based on aphid birth rate and mortality, fertility life tables were constructed. The MNCO4-792F-123 line was classified as resistant. The lowest values for cowpea aphid intrinsic and finite growth rates were obtained for the MNCO4-792F-123, and the highest ones for MNCO4-782F-108 and 'BRS Novaera' genotypes, whose levels exceeded those of 'Vita 7', the standard genotype for susceptibility. The MNCO4-792F-123 line is the least favorable for the development of cowpea aphid, while MNCO4-782F-108 and 'BRS Novaera' are the most susceptible ones.
Highlights
Cowpea [Vigna unguiculata (L.) Walp.] is a widely cultivated legume in the semiarid tropics of Africa and the United States (Huynh et al, 2015)
Using genotypes and lines provided by Embrapa Meio-Norte (Table 1), in the municipality of Teresina, in the state of Piauí, Brazil, a cowpea aphid genotype preference trial was carried out on plants from 16 advanced semiprostrate lines, besides two standardresistance and two standard-susceptibility genotypes to Aphis craccivora to allow of comparison between lineages
Preference studies showed that the number of surviving adult aphids and live nymphs was influenced by cowpea genotype
Summary
Cowpea [Vigna unguiculata (L.) Walp.] is a widely cultivated legume in the semiarid tropics of Africa and the United States (Huynh et al, 2015). Among the phytosanitary problems that can negatively influence cowpea productivity are attacks by Aphis craccivora Koch (Hemiptera: Aphididae), known as cowpea aphid. This pest species causes great damage to the crop, as it can cause both direct effects (from sap sucking), and indirect ones, as the insect is a vector for several viruses that cause diseases for which there is no treatment (Moraes & Bleicher, 2007; Valente et al, 2014; Huynh et al, 2015)
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