INSECTICIDAL POTENTIALS OF DENNETTIA TRIPETALA (LINN.) (PEPPER FRUIT-ANNONACEAE) APPLIED AS SINGLE AND MIXED WITH ZINGIBER OFFICINALE (ROSC.) (GINGER-ZINGIBERACEAE) CRUDE EXTRACTS AGAINST MUSCA DOMESTICA (HOUSEFLY) LARVAE

Abstract

Musca domestica is a common nuisance insect pest that is cosmopolitan. It also causes serious health problems to humans and livestock because it is a mechanical vector of many diseases. Crude extracts of Dennettia tripetala were used individually and mixed with Zinigber officinale in equal proportion (50:50) at various concentrations (200 to 1000ppm) to determine their toxic efficacy against newly emerged larvae of Musca domestica. Each concentration was replicated twice. The bioassay was done using feeding and dipping method under laboratory conditions and was monitored every 12 h for 72 h. Distilled water was used as control for the experiment. Mean mortality was recorded to obtain Median Lethal Concentration (LC50) and Median Lethal Time (LT50). The study also compared the efficacy of feeding or dipping the larvae in the extracts. The results showed that as concentration increased from 200 to 1000ppm, mortality was generally significant (P 0.05), as duration of exposure increased from 12-72 h when D. tripetala was applied individually; but when they (D. tipetala and Zingiber officinale) were mixed in a 50:50 proportion, mortality was significant (P<0.05) with time, as duration of exposure increased from 12-72 h. The mixture of plant extracts (D. tripetala and Z. officinale in a 50:50 ratio) had a lower LC50 and LT50 (0.2754 mg/ml (275.4ppm) and 30 h). It was observed that dipping the insects in plant extracts caused more mortality when compared to feeding the insects with plant extracts. This result showed that plant extracts used for this study could be promising bioinsecticides especially when mixed in equal proportions and should be considered in integrated pest management (IPM) of houseflies