Philippine E-Journals

Insecticidal Activity of Eucalyptus camaldulensis Hydroalcoholic Crude Leaf Extract Against Red-Striped Soft Scale Insects (Pulvinaria tenuivalvata)

Athena T. Alojipan | Aprilyn M. Alano | Eva Marie A. Doblar | Neon Genesis O. Medel | Ken Francis Molato | Vinjhamen D. Solis | Christy Ann G Banguanga

Discipline: Pharmacology

 

Abstract:

Reports from the Sugar Regulatory Administration (SRA) - Visayas have documented a severe infestation of red-striped soft scale insects (Pulvinaria tenuivalvata) affecting approximately 3,656.69 hectares of sugarcane plantations since May 22, 2025. The outbreak has reportedly reduced sugar content by nearly 50%, threatening farmers’ livelihoods and the productivity of the local sugar industry. This preliminary study investigated the potential insecticidal efficacy of Eucalyptus camaldulensis hydroalcoholic crude leaf extract against P. tenuivalvata under controlled laboratory conditions. Treatments consisted of extract concentrations of 0.05% v/ v, 0.075% v/v, and 0.1% v/v, alongside two control groups: distilled water and a commercial insecticide (Malathion). A total of 180 insects were collected through systematic sampling along predetermined transect walks and randomly assigned using a completely randomized design. Mortality rates were recorded at 24-hour intervals over a 72-hour exposure period. Results showed that mortality increased over time and varied across treatment concentrations. Exploratory repeated-measures ANOVA indicated statistically detectable differences in mortality rates across treatment concentrations under the experimental conditions. Pearson correlation analysis likewise revealed a strong positive association between extract concentration and mortality rate (r = 0.982, p < .001). Notably, the 0.05% v/v treatment achieved 100% mortality after 72 hours, approaching the mortality levels observed in the chemical control, whereas higher concentrations did not consistently produce complete mortality. These findings suggest that E. camaldulensis leaf extract exhibits potential insecticidal activity against P. tenuivalvata. However, the results should be interpreted cautiously because of the observed non-linear dose–response pattern and the limited sample size, which constrain the robustness and generalizability of the findings. Further field-based studies and farmer-oriented extension initiatives are recommended to validate, optimize, and assess the practical applicability of the extract under actual agricultural conditions.