Influence of mango chemicals on the mango pulps weevil, sternochetus frigidus (Fabr.)
2004
de Jesus, L.R.A., Calumpang, S.M.F.; Medina, J.R.; Ohsawa, K.(Department of Agriculture Regional Field Unit-Region 4, Lipa City (Philippines))
The mango pulp weevil Sternochetus frigidus (Fabr.) is an important quarantine pest that infests cultivated and wild mango species in Palawan [Philippines]. This research was conducted to determine the chemicals from mango that mediate recognition and elicit attraction and oviposition responses of the mango pulp weevil. An investigation of one volatile components of the full bloom mango flower was made by trapping in tenax AG. The attractancy of some of the floral components to the weevil was determined using the Y-tube bioassay. The component fatty acids present on the surface of green mango peel were determined by GC-MS. Stimulation of oviposition of gravid females by the active fractions and standard chemicals was detrmined by Petri-dish bioassay. A six component blend of floral volatiles containing acetic acid (0.70%), decane (0.3%), acetone (4.4%), linalool (82.2%), ethyl benzoate (11.4%) and 2-methyl heptenone (1.0%) elicited 70% attracti on response by the mango pulp weevil. This blend was better than each individual component. The hexane extract of 70-day-old-green "carabao" mango fruit yielded two active fractions (fractions 5 and 6 at 4.6 mg and 11.7 mg per kg. fruit, respectively) eliciting oviposition by gravid female weevils. When the fatty acids found in the active fractions were tested in the oviposition bioassay but using their corresponding standard, it was found that myristic and oleic acids elicited significantly higher oviposition response (Averages of 5.7 and 4.0 eggs, respectively) compared to all other treatments including the control (average of 1.5 eggs). These findings represent an important step in the development of bait traps. The use of bait traps could enhance current control strategies for the mango pulp weevil and could provide an important quarantine tool for monotoring weevil populations in the field.
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