Life table and population parameters of cowpea aphid, Aphis craccivora Koch (Homoptera: Aphididae) on five cowpea Vigna unguiculata (L. Walp.) varieties

Abstract

The cowpea aphid, Aphis craccivora Koch, is an important pest of cowpea Vigna unguiculata (L. Walp.) in most tropical regions where cowpea is grown. We used life table and population parameters of the cowpea aphids reared on five cowpea varieties to assess the degree of host plant resistance. The five varieties were Blackeye, B005-C, INIA-37, IT835-720-20 and TVX3671-14C-OID. The parameters measured were fecundity, survival, intrinsic rate of natural increase, pre-reproductive period and relative growth rate of cowpea aphids. Our hypothesis was that cowpea varieties resistant to A. craccivora would have significant effects on life table parameters of the aphid when compared to a susceptible variety. Mean fecundity, age-specific fecundity, survival rates, intrinsic rate of natural increase (r m ), pre-reproductive period and relative growth rate differed significantly among varieties. Fecundity, survival, intrinsic rate of natural increase and mean relative growth rate were significantly lower on variety IT835-720-20 compared to susceptible variety Blackeye. The pre-reproductive period was significantly delayed on variety IT835-720-20 compared to other varieties. The adverse effects of variety IT835-720-20 on life table parameters of A. craccivora indicate the presence of host plant resistance. Prolonged pre-reproductive period and reduction in reproductive performance of A. craccivora on variety IT835-720-20 may suggest that antibiosis is the modality of resistance. However, further detailed studies that include determination of biochemical and morphological characteristics that mediate resistance need to be carried out. IT835-720-20 is, therefore, a promising variety with useful genetic resource for cowpea breeding programs aimed at developing resistant varieties against A. craccivora.

Genetic Structure of the Aphis craccivora (Hemiptera: Aphididae) From Thailand Inferred From Mitochondrial COI Gene Sequence

“…During the seedling stage, the aphids feed on stems and terminal shoots, and later as the plants mature they move to flowers and pods (Ofuya, 1997, Obopile and Ositile, 2010). High infestation with cowpea aphids results in stunted plant growth and delayed flower initiation (Blackman and Eastop, 2000), and if the infestation is not controlled, around a half of crop yield may be lost (Obopile, 2006).…”

How the aphids got their spots: predation drives self‐organization of aphid colonies in a patchy habitat

“…To determine how the deviation from the log‐normal distribution arose, we calculated the daily rate of population increase r A = ln(N t+ y + 1/N t + 1) for all aphid colonies (Turchin 2003, Obopile and Ositile 2010). We analyzed the data using time lags (y) of 1 and 5 days, which approximate the ideal colony doubling time of 1–2 days (Hosseini et al 2010), and the aphid development time of 5–7 days (Obopile and Ositile 2010, Hosseini et al 2010).…”

Preferences and demographic parameters of cowpea aphid on advanced lines of semiprostrate cowpea

“…bras., Brasília, v.54, e00230, 2019 DOI: 10.1590/S1678-3921.pab2019.v54.00230 least favorable genotypes for aphids. Various studies report that some cowpea genotypes negatively impacted A. craccivora demographic parameters, including a decrease of intrinsic growth rate (Obopile & Ositile, 2010;Machacha et al, 2012;Aliyu & Ishiayaku, 2013). However, r m values found by these authors were lower than those obtained in the present study, which can be attributed to environmental conditions and differences between the studied cowpea genotypes.…”