Repellent and insecticidal efficacy of some botanical extracts against Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae)
Siddique AB, Bachchu MAA, Uddin MN, Nomun MAA and Rana MS
Botanical insecticides are considered to be the alternative to synthetic chemical pesticides since these compounds are biodegradable and less persistent in the environment. To investigate the repellent and insecticidal efficacy of six selected botanical extracts against Bactrocera cucurbitae (Coquilliett) (Diptera: Tephritidae) at ambient laboratory conditions (27±20C, RH 65±5%) using acetone solvent was used. The results indicated that all the plant extracts had the repellent and insecticidal effect through ovipositional deterrent against B. cucurbitae that inhibited progeny development as well. The order of toxicity of the plant extracts based on repellency and ovipositional deterrent were found as tobacco > water pepper > neem> eucalyptus> bullock’s heart> castor. However, progeny recovery, repellency and ovipositional deterrent rate acted as dose dependent manner where repellency and ovipositional deterrence was decreased with the decreased doses of plant extracts. Tobacco and neem plant extracts were showed the complete oviposional deterrent (100%) whereas the lowest oviposional deterrent was in castor (52.63%) followed by bullock’s heart (58.63%) at 5% concentration of the plant extracts applied. The minimum numbers of progeny were found at 2% concentration in tobacco (0.67), water pepper (1.00) and neem (1.67) whereas the highest at 0.5% concentration in neem (10.00) and tobacco (3.67) meanwhile 4.0% concentration of all extracts totally protects the oviposition. The repellency and ovipositional deterrent activity was increased with the increase of the doses of the plant extract and were found statistically significant (p< 0.01).It is evident from the results that at all plant extracts exhibited a remarkable decrease in adult settled, larvae and pupae recovery, and adult emergence through repellent and ovipositional deterant activities as compared with control.