Legume seeds protecting grains

Natural Pest Control: Can Legume Flours Protect Your Grains?

Lena Kashyap in Climate & Environment December 2025 • 3 min read.

"Discover how common beans and peas can replace harmful insecticides and keep your stored grains safe from pests."

In many parts of the world, especially in regions like northern Cameroon, cereals are a crucial food source. Protecting these grains during storage is vital, but the widespread use of chemical insecticides poses risks to both the environment and human health.

This has led researchers to explore natural alternatives, with a growing interest in the potential of entomotoxic proteins found in leguminous seeds. These proteins could offer a safer, more sustainable way to combat pests.

A recent study investigated the effectiveness of flours made from common legumes—peas (Pisum sativum), beans (Phaseolus vulgaris), and soybeans (Glycine max)—as botanical insecticides against the Sitophilus oryzae weevil, a common pest of stored grains.

Pea and Bean Flours: A Powerful Defense Against Weevils

The study revealed that flours made from peas and beans exhibited significant insecticidal activity against S. oryzae. In contrast, soybean flours showed limited effectiveness. The lethal dose (LD100) for pea flour was found to be 5 grams, killing all weevils within 20 days. Bean flour required a higher dose of 10 grams to achieve the same effect, taking 50 days.

These findings suggest that common legumes readily available in many regions, can serve as effective pest control agents. But what makes these flours so effective?

Entomotoxic Proteins: Legumes are rich in proteins that are toxic to specific insects like S. oryzae.
Anti-feeding Properties: Some legumes contain compounds that deter insects from feeding, further protecting the grains.
Biodegradability: Unlike synthetic insecticides, legume flours are biodegradable, minimizing environmental impact.

Further research is needed to fully understand the specific mechanisms of action and to optimize the application of these flours for maximum effectiveness. For example, how finely should the flour be ground? What is the optimal concentration for different types of grains and storage conditions?

A Sustainable Solution for Grain Protection

The study highlights the potential of legume flours as a sustainable alternative to chemical insecticides for grain storage. By utilizing locally available and edible legumes, farmers can protect their crops, reduce environmental risks, and ensure food security.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.4314/ijbcs.v10i3.1, Alternate LINK

Title: Bioactivity Of Flours Of Seeds Of Leguminous Crops ≪I≫Pisum Sativum, Phaseolus Vulgaris≪/I≫ And ≪I≫Glycine Max≪/I≫ Used As Botanical Insecticides Against Sitophilus Oryzae Linnaeus (Coleoptera: Curculionidae) On Sorghum Grains

Subject: General Medicine

Journal: International Journal of Biological and Chemical Sciences

Publisher: African Journals Online (AJOL)

Authors: Léonard Simon Ngamo Tinkeu, Béranger Raoul Tamgno, Maurice Gandebe

Published: 2016-12-06

Everything You Need To Know

How can legume flours protect stored grains from pests?

Legume flours, specifically those made from peas (Pisum sativum) and beans (Phaseolus vulgaris), can act as natural insecticides to protect stored grains from pests like the Sitophilus oryzae weevil. These flours contain entomotoxic proteins that are toxic to certain insects. They also possess anti-feeding properties, deterring insects from consuming the grains. Unlike synthetic insecticides, legume flours are biodegradable, thus reducing environmental harm. Soybean flour (Glycine max) was found to have limited effectiveness.

Why is the insecticidal activity of legume flours considered important?

The insecticidal activity of legume flours is significant because it offers a sustainable and environmentally friendly alternative to chemical insecticides. Chemical insecticides can pose risks to both human health and the environment. The use of legume flours, which are derived from edible plants, reduces these risks while still effectively protecting stored grains, especially in regions where cereals are a primary food source. It can also help in preserving biodiversity by reducing the damage caused by the use of synthetic chemicals.

What does 'lethal dose (LD100)' mean in the context of using legume flours for pest control?

The lethal dose (LD100) refers to the amount of a substance, in this case, legume flour, required to kill all of the test population of insects, specifically Sitophilus oryzae weevils, within a certain timeframe. For pea flour, the LD100 was found to be 5 grams, killing all weevils within 20 days. Bean flour required a higher dose of 10 grams to achieve the same effect, taking 50 days. This measurement helps determine the effectiveness of different legume flours as botanical insecticides.

What are entomotoxic proteins, and why are they important for pest control?

Entomotoxic proteins are proteins found in legumes that are toxic to insects, such as the Sitophilus oryzae weevil. These proteins disrupt the physiological processes of the insects, leading to their death or inhibiting their ability to feed and reproduce. The presence of these proteins in pea and bean flours is a key factor in their effectiveness as natural pest control agents for stored grains. Further study is needed to explore the exact mechanisms by which these proteins act on different insect species.

What are the potential implications of using legume flours for grain protection?

Using legume flours such as pea flour and bean flour for grain protection has several potential implications. It can reduce the reliance on synthetic insecticides, lowering the risks of environmental contamination and health issues associated with chemical exposure. The biodegradability of legume flours ensures a reduced ecological footprint. Further research is needed to optimize the application of these flours, including determining the ideal flour fineness and concentration for various grain types and storage conditions. Also, additional studies are needed to analyze the cost effectiveness of the legume flours versus traditional insecticides.