Combination of Piper guineense Essential Oil with Cowpea Varietal Resistance in Control of Cowpea Seed Beetle, Callosobruchus maculatus Fabricius(Coleoptera: Chrysomelidae: Bruchinae)

To reduce the risks associated with over-dependence on synthetic insecticides and ensure leguminous food security,an experiment was conducted to evaluate the potentials of integrating Piper guineense essential oil(Pg EO)with cowpea varietal resistance in the control of cowpea seed beetle,Callosobruchus maculatus Fabricius.Four cowpea varieties(Sokoto,Drum,Oloyin and Gwallam)were studied.Data collected included oviposition,progeny emergence,Reproductive Efficiency(RE)and Percentage Seed Damage(PSD).At first filial generation,numbers of eggs laid on Oloyin variety treated with 25μL Pg EO per 25 g cowpea seeds(2.15)were significantly(p<0.05)lower than the values obtained in untreated cowpea(3.61)and hexane-treated seeds(3.07).C.maculatus RE on Oloyin(33.73)was significantly(p<0.05)lower than values obtained on other varieties(47.34-54.67)for seeds without Pg EO;and were significantly greater than 0.00 observed on Oloyin seeds treated with 50μL PgE O.PSD on Oloyin(6.63%)was significantly(p<0.05)lower than the values obtained on Sokoto(10.04%)and Drum(9.79%)for seeds without Pg EO,while there was no damage in Oloyin treated with 50μL Pg EO.Significantly(p<0.05)lower F2 progeny emergence occurred on Oloyin(4.02)and Sokoto(4.71)compared with Drum(9.03)and Gwallam(6.07)from the untreated cowpea seeds.The results implied that application of PgE O to Oloyin gave better protection from infestation of C.maculatus than other varieties.Hence,combination of varietal resistance with PgE O for management of bruchid could be an effective mean of improving cowpea food security.