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Title:	Toxicity of four selected non - host plants on the diamondback moth, Plutella xylostella (Lepidoptera : plutellidae)
Authors:	Imtithal Ismael Jaloot (P69897)
Supervisor:	Idris Abdul Ghani, Prof. Dr.
Keywords:	Toxicity testing
Issue Date:	20-Feb-2018
Description:	Identification of a novel plant-derived insecticidal agents for combating the ever-increasing rate of insecticide resistance occurrence is essential. These phytochemicals usually have minimal residual effects and more environmental friendly compared to conventional pesticides. In this study, insecticidal effects of selected herbal plant species (Catharanthus roseus, Pandanus amaryllifolius, Solanum melongena, Capsicum frutescence and Solanine compound) tested extracts on the diamondback moth, Plutella xylostella L. were evaluated. Fresh plant samples were collected from Sungai Siput, Lubok China, Malacca in Malaysia. Leaves/fruit of plants were dried using three different drying methods and were crushed into powder, mixed with different solvents and extracted using Soxhlet apparatus and soaking method. The leaf disc immersion method was used to assess the insecticidal effects of plants extract on the DBM 2nd instar larvae which were allowed to feed on the leaf discs treated with different concentrations (0.5, 10, 20, 40 and 80 mg/ml) of leaf extract in laboratory environments [Temperature 25 - 27oC, RH of 65% and light dark cycle (L:D) of 12:12]. Larvae mortality was recorded at every 24 h intervals until the larvae pupated. The LC50 value for each plant extract was analyzed using Probit analysis. Major compounds of the crude extracts of the selected plants species were determined using phytochemical screenings and GC-MS analysis. Results showed that the crude extract of plants had a significant negative effect (p < 0.05) by larval survival rate and was directly proportional to the concentration of extract. Highest larvicidal activity was exhibited by C. roseus with 90% followed by P. amaryllifolius (86.7%), S. melongena (80%) and C. frutescence (73.3%) at 80 mg/ml concentration, while the highest mortality rate of the DBM following feeding with solanine treated cabbage leaf was 55% at 8 μg/ml at day 4. The highest LC50 values were observed after 24 h of exposure for C. roseus and P. amaryllifolius at concentration of 6.63 and 9.500 mg/ml, respectively. Whereas the highest LC50 observed after 48 h of exposure were 3.299, 4.443 and 4.586 mg/ml for S. melongena, C. frutescence and Solanine respectively. The present study also investigated the chemical constituents of the traditionally used ethnobotanical selected plants using GC-MS analysis. Interestingly, the phytochemical constituents were identified and characterized by GC-MS and these include the presence of Hexadecanoic acid, ethyl ester; Bis (2-ethylhexyl) phthalate; Capsaicin; Naphthalene; n-Hexadecanoic acid; alpha.-Amyrin; Phytol and Squalene which have shown insecticidal activity against DBM. Significant protective activities against different ailments were found. Oviposition deterrent index (ODI) and Percentage repellency (PR) was used to determine effects of plants extract in inhibiting oviposition and feeding of diamondback moth. P. amaryllifolius showed the strongest deterrent and repellency effect with 100% and 92.8 % (ODI) and (PR) value respectively. Of all the ratios tested, the chloroform extract of C. roseus and P. amaryllifolius were observed to be more efficient than the rests. For biological control of DBM, the use of botanical pesticides derived from these selected plants seems to be possible as they contained some active compounds that can be integrated for the management of P. xylostella.,'Certification on Master's/Doctoral Thesis' is not available
Pages:	300
Call Number:	QL561.P55J335 2018 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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