YOU'LL spot them in many cars of Malaysians; bundles of pandan leaves placed on dashboards, tucked behind sun visors or draped over the rear-view mirror.
Many believe having these aromatic leaves in the vehicle cabin keep cockroaches away – but does this traditional method actually work?
Verdict:
TRUE
Yes, scientific research shows pandan leaves do have cockroach-repelling properties but the reality is more complicated than simply placing a few leaves in the car.
A study conducted by researchers Li J. and Ho S.H. from the School of Biological Sciences at the National University of Singapore (NUS) evaluated seven compounds and fractions prepared from pandan leaves and found that certain pandan compounds were indeed repellent to cockroaches.
Specifically, 2-acetyl-1-pyrroline, pandan essence and the hexane-pandan extract were repellent at all concentrations tested, showing 65% to 93% repellency.
The study noted that pandan leaves contain low levels of essential oils, including 2-acetyl-1-pyrroline, styrene, linalool and β-caryophyllene. It's primarily the linalool component that provides the insect-repelling properties.
However, there's a crucial caveat – the same NUS study found that not all pandan preparations work the same. The acetone-pandan extract was actually attractive to cockroaches at increasing concentrations, showing a minimum of 62% attractancy. Similarly, undiluted crude aqueous pandan extract displayed an attractancy of 62%.
This means that depending on how the pandan compounds are extracted or presented, they could actually attract cockroaches rather than repel them.
The study concluded that whilst pandan leaves do have potential as a natural, environmentally friendly pest management tool, the concentration required to effectively keep cockroaches away is much higher than what you'd get from simply placing a few leaves in your car.
In other words, placing fresh pandan leaves in the car will not provide reliable protection against cockroaches. As the leaves dry out and age, their essential oil content decreases further, making them even less effective.
The research also shows that pandan leaf extracts are simply not as effective as commercial cockroach repellent products.
The bottom line? Pandan leaves contain scientifically proven cockroach-repelling compounds, so this isn't pure myth.
If you really want to use pandan to repel cockroaches, you'd need to use concentrated pandan essence or extract, regularly refresh the leaves to maintain potency and use a significant amount of leaves to achieve effective concentration.
For practical cockroach prevention in your car, you're better off keeping your vehicle clean; avoiding eating inside; regularly vacuum and remove any food crumbs or wrappers that might attract pests; and use proper cockroach bait or commercial repellents in problem areas.
That said, if you enjoy the fragrance of pandan and it makes your daily commute more pleasant, there's no harm in keeping a few leaves in your car. Just don't rely on them as your primary defence against cockroaches.
References:
3. https://herbaria.plants.ox.ac.
