Alternation of cowpea genotypes affects the biology of Callosobruchus maculatus (fabr.) (Coleoptera: Bruchidae)

Abstract

Callosobruchus maculatus (Fabr.) is an important pest in stored cowpea, Vigna unguiculata (L.) Walp., with ample distribution in tropical and subtropical regions. The effect of alternation of cowpea genotypes, susceptible (S) and resistant (R), on the biology of (C. maculatus) was studied after four generations. A no-choice test was carried out in a completely randomized design, factorial scheme, with five treatments, four host combinations (RR, RS, SR and SS) and five replications. Each replication consisted of 30 grains of each genotype infested by two insect couples. The number of eggs per female was not different within or between combinations, evidencing that the genotypes and their alternation did not affect C. maculatus fecundity. Egg viability, however, varied between genotypes and between combinations. In combination RR, the longest duration of the immature stage was verified for genotype IT89KD-245; in addition, all genotypes presented the smallest survival for the same stage, resulting in a higher mortality of the pest. The resistance index categorized combination RR as moderately resistant for genotypes IT89KD-245, BR14-Mulato and BR17-Gurguéia, and as susceptible (S) only for IT89KD-260, demonstrating that these combinations were not very adequate for the development of C. maculatus, a fact that was confirmed by the better performance of the pest on the genotype from combination SS, and because of a reduction in its performance when it returned to resistant genotypes.

Lethal and Sublethal Effects of Essential Oils fromEucalyptus camaldulensisandHeracleum persicumAgainst the Adults of Callosobruchus Maculatus

“…C. maculatus infests cowpea before harvest and causes quantitative and qualitative seed losses in storage facilities (Ajayi and Laie 2001; Lima et al 2004; Erler et al 2009). The cowpea weevil larvae feed inside the grain seeds and cause weight losses of up to 80% after six months in storage (Aboua et al 2010).…”

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

“…Such values found are higher than those reported by De La Palva and Sepúlveda-Cano (2015) for A. craccivora on V. unguiculata (4.64 to 4.60 days). Accordingly, it may be possible that the ability of the lines used in the current study to retard A. craccivora development may indicate that the multiplication rate or increase in insect numbers may have been reduced due to the longer average between generation intervals (LIMA et al, 2004).…”

“…Os valores encontrados são superiores aos reportados por De La Palva e Sepúlveda-Cano (2015) com A. craccivora em V. unguiculata, com período de uma geração em torno de 4,64 a 4,60 dias. Nesse caso, é possível considerar que a capacidade dessas linhagens em retardar o desenvolvimento de A. craccivora pode ser um indicativo de que a taxa de multiplicação ou o aumento do número de insetos poderá ser reduzido devido ao maior tempo médio entre cada geração (LIMA et al, 2004).…”

Inheritance and combining ability of cowpea resistance to bruchid (Callosobruchus maculatus F.)

“…It is a warm-weather crop, drought tolerant and well-adapted to the drier regions of the tropics (Aliyu and Wachap, 2014). The crop represents one of the main sources of protein in human diet (Lima et al, 2014). Despite its relevance to agriculture in the developing world and its stress resilience, actual yields of cowpea are much lower than the known yield potential (Amatriaín et al, 2016).…”