Stored product pests are a major challenge in agricultural systems, especially in tropical and subtropical regions. These pests damage grains, reduce nutritional quality and cause significant economic losses. The cowpea weevil, scientifically designated as
Callosobruchus maculatus, serves as a salient illustration of this predicament, as it infests stored legumes, resulting in a reduction of mass and diminished seed viability
(Katoo et al., 2025). Historically, chemical insecticides have been the primary method for controlling these pests. However, over-reliance on synthetic pesticides has led to serious problems such as pest resistance, residues in food products, environmental toxicity and adverse health effects on humans and non-target organisms. The ongoing application of synthetic pesticides has resulted in the emergence of resistance among target pest populations, thereby diminishing their vulnerability to these chemical agents
(Khan and Ahmad, 2019). Such resistance compels the utilization of increased dosages or more hazardous alternatives, thereby exacerbating the existing issue
(Kumari, 2023). It is estimated that approximately 80% of the pesticides that are applied lead to environmental contamination, significantly compromising soil and water quality
(Ali et al., 2021). Biodiversity is profoundly affected, with evidence suggesting a 70% decrease in insect biomass and a 50% decline in farmland avian populations across Europe. In this context, plant-derived insecticides or botanicals have emerged as viable alternatives due to their biodegradability, target specificity and low environmental persistence. Plant-derived insecticides are presented as eco-friendly alternatives to synthetic insecticides. Plants contain alkaloids, flavonoids, triterpenoids, saponins, steroids, glycosides and tannins
(Shunmugadevi and Radhika, 2020) The wide array of bioactive compounds can act as insecticides, repellents, antifeedants, or growth regulators. This review explores the use of botanical extracts in managing stored product pests, compiling results from multiple studies to demonstrate their effectiveness and potential application in IPM programs.
Botanical extracts and their insecticidal potential
Efficacy of plant extracts
Plant-derived products provide eco-friendly and low-cost pest-management options
(Gahukar, 2019). Numerous studies have investigated the insecticidal potential of plant extracts against
T.
castaneum, a major pest of stored grains. Ethanolic and chloroform extracts of pomegranate peel (
Punica granatum) showed 100% mortality at 2.0% concentration after 7 days whereas
Cucumis sativus showed 80% mortality with hexane extract
(Ismail et al., 2025) against red flour beetle (
T.
castaneum).
Ricinus communis showed significant mortality with methanol extract against
T.
castaneum (Jbilou et al., 2006). Amel et al., (2014) reported that the ethanol extract of pomegranate (
Punica granatum) peel caused 56% larval mortality in
T.
castaneum. Similarly,
Bhoye and Bahiram (2021) demonstrated that mortality and repellency against
T.
castaneum increased with rising concentrations of
Bergera koenigii extract.
Ali et al., (2019) found that the methanol extract of
Ricinus communis induced the highest mortality, followed by the chloroform extract, while the n-hexane extract was least effective.
Although these plant extracts exhibit strong insecticidal qualities, their inconsistent efficacy raises the possibility that combining extracts or creating synergistic formulations could improve pest management tactics against
T.
castaneum. This strategy may result in more long-lasting pest control solutions. In addition to
T.
castaneum, several plant extracts were found effective against
Rhyzopertha dominica.
Enzyme inhibition by botanical extracts
Thymus vulgaris inhibits alpha-amylase in
T.
granarium, with optimal inhibition at 10% concentration and pH 7
(Shaker et al., 2023). Eucalyptus globulus and
Allium sativum found to decrease digestive enzyme activity
in Ephestia kuehniella, affecting metabolic processes
(Mehrabadi et al., 2011; Shahriari, 2020). The extracts’ inhibitory effects are attributed to the presence of active substances like flavonoids, saponins and tannins
(Shaker et al., 2023). Concentration and environmental factors like pH and temperature affect how effective these extracts are
(Mehrabadi et al., 2011).
Even though these plant extracts have potential as environmentally friendly pest control techniques, their effectiveness can be impacted by variables and the surrounding environment, indicating the need for more study to maximise its application in farming systems. Various studies have emphasized the enzymatic and physiological impacts of botanical extracts on pest insects.
Shaker et al., (2023) found that aqueous leaf extract of
T.
vulgaris inhibited alpha-amylase enzyme production in
T.
granarium larvae.
Toxic and repellent effects
Plant extracts’ repellent and antifeedant qualities are used in botanical pest control to successfully control insect pests. Plant extracts such as essential oils as eco-friendly and have insecticidal activities including repellency, ovicidal activity, larvicidal activity and antifeedant activity
(Singh et al., 2012). According to research, a variety of botanical extracts have strong poisonous and repellant properties against important pests, increasing their potential as environmentally benign substitutes for synthetic pesticides.
Karakas (2016) found that extracts of
Anethum graveolens and
Ocimum basilicum had both toxic and repellent effects on
Sitophilus granarius, with dill leaf extract showing the highest antifeedant activity.
Epidi and Odili (2009) concluded that
Dracaena arborea and
Vitex grandifolia powders were more protective of groundnuts from
T.
castaneum than ginger and pumpkin powders highlighting their antifeedant properties
(Chugh et al., 2023).
Moon et al. (2021) reported increased mortality and repellency in
R.
dominica with rising concentrations of
Jatropha curcas and
Linum usitatissimum extracts. According to
Alkan and Ertürk (2020), trans-anethole was very efficient against
T.
castaneum and showed diverse degrees of mortality and repellency against various stored product pests. Many plants with strong antifeedant qualities were found by
Pavela et al., (2025), indicating a wide range of possibilities for creating botanical insecticides. Although botanical pest management has potential, there are still issues with its consistency of effectiveness and the need for more study to improve application techniques and comprehend the underlying mechanisms.
Broader-spectrum efficacy
Broader-spectrum efficacy has also been recorded.
Gariba et al., (2021) found that dried powders and aqueous extracts of
Lantana camara,
Moringa oleifera,
Citrus sinensis and
Hyptis suaveolens significantly reduced grain damage and insect survivorship in
Sitophilus zeamais and
Prostephanus truncatus.
Atta et al., (2020) compared several botanicals and concluded that
Zingiber officinale was more effective in repelling and killing
T.
castaneum than neem, clove, or tobacco.
Joel (2015) supported the insecticidal potential of various plants such as
A.
indica,
Lawsonia inermis and
Annona senegalensis against
T.
castaneum, reinforcing their post-harvest utility.
Other significant contributions include
Adjou (2019), who demonstrated that essential oil from
Hyptis suaveolens caused 100% mortality in
Tenebroides mauritanicus at low concentrations.
Bossoua et al., (2015) emphasized that essential oils from
Cymbopogon schoenanthus and
Eucalyptus citriodora could be employed to counteract resistance to synthetic insecticides in
T.
castaneum. In another study,
Bouayad et al., (2013) found that extracts of
Rosmarinus officinalis and
Centaurium erythraea reduced pupation and adult emergence and even induced cannibalism in
Plodia interpunctella larvae.
Other valuable findings include
Osipitan et al., (2014), who observed that botanical extracts exhibited strong contact toxicity against
Prostephanus truncatus, particularly at 5-10% concentrations.
Jadhav (2009) recorded that
Annona squamosa,
Tephrosia purpurea and
Acorus calamus extracts were highly effective against
Corcyra cephalonica, with larvae darkening and dying post-treatment.
Nazari (2022) highlighted the antifeedant and growth-inhibiting effects of
Murraya paniculata on
Cadra cautella and
Spodoptera litura. Finally,
Yooboon et al., (2019) demonstrated that ethanolic crude extracts from
Piper retrofractum and
Acorus calamus exerted strong pesticidal effects against
Spodoptera litura.
Although they present a number of real-world difficulties, botanical insecticides provide a sustainable substitute for synthetic pesticides in grain storage systems. Plant extract composition fluctuation, stability during storage, formulation problems and limitations in large-scale use are some of these difficulties. For botanical insecticides to be used effectively in grain storage management, certain issues must be resolved.
Variability in plant extract composition
Plant species, growing circumstances and extraction techniques can all have a substantial impact on the phytochemical makeup of plant-based insecticides. The uniformity and effectiveness of the pesticides may be impacted by this variability
(Chugh et al., 2023; Uikey, 2024). For instance, depending on their concentration and the particular pest they are intended to kill, neem and eucalyptus extracts have demonstrated differing degrees of insecticidal activity
(Kousar et al., 2025).
Formulation issues
A major difficulty is creating efficient formulations that guarantee the steady distribution of active chemicals. Formulations must be created to minimise degradation and maximise the insecticides’ bioavailability and effectiveness
(Vijayan et al., 2023; Uikey, 2024).
The compatibility of botanicals with other control techniques must be carefully considered before including them into current pest management systems
(Vijayan et al., 2023).
Constraints in large-scale application
Cost, availability and the requirement for specialised equipment are some of the barriers to the widespread use of botanical insecticides in grain storage systems
(Chugh et al., 2023).
Environmental factors, which might fluctuate between storage facilities, can affect how effective botanical insecticides are
(Vijayan et al., 2023). Although there are drawbacks to using botanical pesticides, there are also many advantages, like less toxicity to non-target organisms and less of an influence on the environment. To overcome these obstacles and improve the usefulness of botanical pesticides in grain storage systems, more research and development is required
(Uikey, 2024).
