Utilization of Salicylic acid Pre-Hardening Treatments for the Control of Pod Sucking Bug, Clavigrallatomentosicollis Stal (Hemiptera: Coreidae)

Abstract

The experiment was conducted at the Agric. Research farm Bayero University Kano (11°58 ‘N, 8° 25' E and 457m above sea level) to evaluate the potential of SA-treatment in the control of Pod sucking bug of cowpea. The mean annual rainfall was within the range of 865-1250mm with mean annual temperature of about 22-38°C and relative humidity of 65-90mmHg. Four different cowpea varieties (IT97K-1069-6, IT98K-205-8, IT89KD-288 and Dan'ila) pre-hardened with Salicylic acid were established in various replicated field cages in completely randomized design. Five-pairs each of fresh pre-mated Clavigrallatomentosicollis were introduced into the various cages, allowed for 2-weeks to mate and oviposit after which all adult insects are removed. The different cowpea varieties screened showed variable response to the bugs attack (P<0.001). Cowpea varieties IT97K-1069-6 and IT89KD-288 recorded low indices of susceptibility and damage to pod bug attack, delayed development time of nymphal bugs with few progeny emergence. Pre-treatment effects also varied significantly with hormone concentrations (P<0.001) with 10ppm Salicylic acid (SA)being more effective than the lower (5ppm) concentrations and the controls. The interaction of treatments and varieties was also found significant (P<0.002). Of the four Cowpea varieties screened, IT97K-1069-6 and IT89KD-288 pre-hardened with high (10ppm SA) concentration of SA were found tolerant owing to their lower susceptibility indices (9.58 and 9.26) and mean percentage pod damage levels of19.97% and 24.51% respectively, while Dan'ila and IT98K-205-8of the same treatments were however susceptible. Phytochemical analysis of the treatments showed appreciableconcentrations of cumene, eugenoland sesquiterpenes in the tolerant varieties. These relations should be explored extensively toward sustainable plant protection.