Phytochemical screening and insecticidal effect of dendrobium crumenatum on lasius niger (black ant) / Nur Hafizah Hamzah

The aim of this study is to identify the phytochemical screening and insecticidal
effect of D. crumenatum on L. niger. The two different types of extract stems of D.
crumenatum were screened for secondary metabolite constituents and insecticidal
effect on L. niger (black ant). The stem sample were extracts with different solvent,
hexane and methanol. The percentage yield of crude extracts calculated found that
methanol showed the highest percentage followed with hexane with 10.18% and
4.40% respectively. Phytochemical screening of the extracts revealed the presence
of alkaloids, saponins, tannin and terpenoids in the plants investigated. However,
flavonoid absence in the hexane extract and methanol extract absence of flavonoid
and tannin. The extracts stem of D. crumenatum of different concentrations were
also investigated for their insecticidal effect on 1. niger. The concentration was
used at 1.875 mg/l, 3.75 mg/l, 75 mg/l, 150 mg/l and 300 mg/l. Average mortality
indicated that the extracts caused significant mortality on the target insects. The
bioassay has indicated that the toxic effect of the extracts was proportional to the
concentration and higher concentration has stronger effect. From the study, hexane
extract stem of D. crumenatum could cause the highest significant mortality
compared to methanol extract. The thin layer chromatography (TLC) analysis is
used as confirmation of secondary metabolite found in the extracts stem of D.
crumenatum. The TLC analysis revealed that hexane extract has the most number
of compound present with 15 compounds and methanol extract with 12 compounds
respectively. Thus, stem of D. crumenatum plant extract could be used as biopesticide
against L. niger.