Abstract
Abstract: The objective of this work was to evaluate the resistance of advanced semi-erect cowpea (Vigna unguiculata) lines, by means of a screening assay for resistance and the elaboration of fertility-life tables of Aphis craccivora (Hemiptera: Aphididae). The experiments were carried out in a screenhouse. For the resistance trial, 15 advanced cowpea lines were used, as well as two standard genotypes for resistance and two for susceptibility, which were arranged in six blocks. After resistance was determined, two lines with the highest and lowest resistance were selected for the development of the fertility-life tables which were used to estimate demographic parameters. The MNCO4-762F-03 and MNCO4-762F-09 cowpea lines were classified as resistant, for which cowpea aphids showed the lowest values (in parentheses, respectively) for: net reproductive rate (RO = 3.0 and 2.5), intrinsic rate of increase (rm = 0.16 and 0.15), and finite rate of increase (λ = 1.18 and 1.16). The highest values were obtained for the 'Vita-7', MNCO4-795F-168, and 'BRS Tumucumaque' genotypes. The MNCO4-762F-03 and MNCO4-762F-09 lines show antibiosis-type resistance, which directly affects the reproductive potential of the cowpea aphid population.
Highlights
Cowpea, Vigna unguiculata (L.) Walp., is one of the most widely cultivated legumes in tropical and subtropical regions worldwide (Torres et al, 2015)
Lines MNCO4-762F-03 and MNCO4762F-09 did not differ from the standard resistant genotypes for the number of adults, and showed a lower number of individuals
According to the protocol used, the variable number of adults on a plant may discriminate between antibiosis, or nonpreference resistance (Silva & Bleicher, 2010), whereas a production decrease of the offsprings is indicative of an antibiosis resistance
Summary
Vigna unguiculata (L.) Walp., is one of the most widely cultivated legumes in tropical and subtropical regions worldwide (Torres et al, 2015). In Brazil, according to Freire Filho et al (2017), cowpea has been cultivated by small family farmers and by medium- and large-scale producers in the Brazilian Cerrado soils of the North, Northeast, and Central-West regions, for which the planted area and productivity of cowpea was 40.636 ha and 810 kg ha-1, 980.69 ha and 303 kg ha-1, and 109.27 ha and 982 kg ha-1, respectively, during the period between 2010 and 2014. Among the limiting factors of cowpea cultivation is infestation by the cowpea aphid Aphis craccivora Koch (Hemiptera: Aphididae), considered a key-crop pest (Moraes & Bleicher, 2007; Huynh et al, 2015) that causes direct injury by sucking sap, and indirect damages through virus transmission (Oliveira et al, 2012). A safer alternative for both the environment and producers would be to use crop plants with genetic resistance to this insect
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