Toxicity and repellence of Citrus jambhiri Lush rind essential oil against maize weevil (Sitophilus zeamais Motschulsky 1855) (Coleoptera: Curculionidae): Poster

Rind of matured fruits of Citrus jambhiri Lush was hydro-distilled to obtain essential oil (EO) which was subjected to Gas chromatography-Mass spectrometry (GC-MS) analysis. The EO was evaluated for fumigant toxicity (at 27- 107µL/L air) and repellence against maize weevil (Sitophilus zeamais Motschulsky). Area preference methodology was used to evaluate the repellence of the EO at 0.15-0.9 µL/cm2, while isopropanol served as control for both bioassays. The experiments were set up in a completely randomized design and data were subjected to analysis of variance and probit analysis. Fifty-two compounds were identified in the EO with the predominant compounds being a-terpineol (8.03%), citral (7.00%), 4-terpineol (6.52%), caryophellene (4.58%), cis-geraniol (4.44%), citronellal (4.38%), ß-bisabolene (4.01%) and n-hexadecanoic acid (4.70%). Others were a- bergamotene (3.74%), lemonol (3.23%), precocene I (3.33%) and ß-copaene (3.09%). Toxicity progressed with EO dose and exposure period and application of EO at 80 and 107µL/L air caused significantly higher mortality (33.75-100.00%) than isopropanol (0.00-22.50%). Lethal time for 50% assayed weevil (LT50) for the EO application at 107 µL/L air {7.51 (6.95-8.13) h} was significantly lower than the values obtained for 27 and 53 µL/L air {44.78 (27.49-312.61) and 21.87 (11.91-45.96) h, respectively}. EO caused significantly higher repellence (75.00-90.00%) than control (15.00%) at 24 hours after treatment. The results indicate that C. jambhiri rind EO has prospects as effective biorational formulation for control of maize weevil.Rind of matured fruits of Citrus jambhiri Lush was hydro-distilled to obtain essential oil (EO) which was subjected to Gas chromatography-Mass spectrometry (GC-MS) analysis. The EO was evaluated for fumigant toxicity (at 27- 107µL/L air) and repellence against maize weevil (Sitophilus zeamais Motschulsky). Area preference methodology was used to evaluate the repellence of the EO at 0.15-0.9 µL/cm2, while isopropanol served as control for both bioassays. The experiments were set up in a completely randomized design and data were subjected to analysis of variance and probit analysis. Fifty-two compounds were identified in the EO with the predominant compounds being a-terpineol (8.03%), citral (7.00%), 4-terpineol (6.52%), caryophellene (4.58%), cis-geraniol (4.44%), citronellal (4.38%), ß-bisabolene (4.01%) and n-hexadecanoic acid (4.70%). Others were a- bergamotene (3.74%), lemonol (3.23%), precocene I (3.33%) and ß-copaene (3.09%). Toxicity progressed with EO dose and exposure period and application of EO at 80 and 107µL/L air caused significantly higher mortality (33.75-100.00%) than isopropanol (0.00-22.50%). Lethal time for 50% assayed weevil (LT50) for the EO application at 107 µL/L air {7.51 (6.95-8.13) h} was significantly lower than the values obtained for 27 and 53 µL/L air {44.78 (27.49-312.61) and 21.87 (11.91-45.96) h, respectively}. EO caused significantly higher repellence (75.00-90.00%) than control (15.00%) at 24 hours after treatment. The results indicate that C. jambhiri rind EO has prospects as effective biorational formulation for control of maize weevil