Abstract:
The experiments were conducted in the Laboratory of Entomology and Agricultural Zoology, Department of Plant Protection, College of Agricultural Studies (Shambat), Sudan University of Science and Technology (SUST), during May to August, 2018.The average temperature is between 27- 30°C and relative humidity (RH) is between 30 to 35 %..
The aim of this studyis to investigate the activity of some plant leaf extracts (Chewing tobacco Nicotiana glauca, Usher Plant Calotropis procera and Ghubaych plant Guiera senegalensis) against cotton mealy bug (Phenacoccus solenopsis) under laboratory condition.
In the first experiment four different concentrations of each plant extracts alone (2.5 %, 5 %, 7.5% and 10 %) were tested. In the second experiment we used the same concentrations of same plant extractions plus one drop of sesame oil and one drop of liquid soap as surfactant. In the third experiment sesame oil was replaced by surfactant material (Agral® - Alkyl Phenol ethylene oxide) at recommended dose 200ml\100L. Each treatment was replicated four times and the mortality % was recorded after 1day, 2 days, and 3days post treatment.
The results showed different insecticidal activity between the threeplant extracts alone and also between the other treatments (extracts plus Agral® and extracts plus sesame oil). The extracts of (Ghubaych, Usher and Tobacco) alone gave only mortality (%) of 10%, 26.7 and 50%, respectively, while the same extracts showed a significant insecticidal effect when mixed with Agral® and sesame oil and the mortality (%) reached (43.3% ,93.3% and 93.3%) and (50%, 73.3% and 90%), respectively after three days post treatment. These results provedthat sesame oil and Agral® substance have a synergistic action.Fromthe above mentioned results we conclude that Ghubaych have a little effect against cotton mealy bug when compared to Tobacco and Usher extracts which can be considered as promising botanical insecticides in the future.
