Resistance in advanced cowpea lines to Aphis craccivora Koch, 1854 (Hemiptera: Aphididae)

The Brazilian cowpea crop has been increasing in recent years due to the launch of new cultivars. However these are, in some cases, susceptible to cowpea aphid. In view of this, studies of the biology of, one of the main insect pests on advanced cowpea lines, is essential, since they form the next new cultivars to be the released. Accordingly, the objective of the evaluate the main advanced cowpea lines that confer resistance over the biological aspects of Aphis craccivora Koch. Eight advanced cowpea lines were studied, plus cultivar VITA 7 to provide a standard for aphid susceptibility. Number of living individuals, the longevity of insects and number of descendants produced were recorded daily. Highest nymph mortality rates, longest inter-generation intervals and the lowest reproductive duration, occurred when the aphids had lines MNCO4-762F-03 and MNCO4-762F-09 as host plants. Daily fecundity values (3.0 to 8.0 nymphs per day) varied according to lineage. Lowest total fecundity values were recorded when aphids fed on MNCO4-762F-03, MNCO4-762F-09 and MNCO4-792F-123 lines. MNCO4-762F-03 and MNCO4-762F-09 lines negatively impacted A. craccivora biology, and were the least suitable as hosts.