Bemisia tabaci (Gennadius) is critical pest of chili plants, which are among the most favoured crops by farmers. According to (Bahrun & Rohansyah, 2020), the average yield produced by farmers in the Village of Pulantan was 241.70 kg per farmer. Host plants of B. tabaci belong to various families, including Asteraceae, Malvaceae, Solanaceae, Cruciferaceae, Lamiaceae, Euphorbi-aceae, Fabaceae, Begnoniaceae, Lythraceae, and Zygophyllaceae (Oliveira et al., 2001).

Bemisia tabaci damages plants by sucking leaf fluids, which subsequently damages the cell tissues of leaves, causing necrotic lesion and reducing yield. Additionally, B. tabaci can transmit Pepper yellow leaf curl virus (PYLCV), more commonly known as yellow virus disease in Indonesia. This virus is easily transmitted due to the wide host range of B. tabaci (Sulandari et al., 2006).

Yield loss due to B. tabaci can reach 80% and even cause crop failure. In addition to the application of insecticides, using repellent compounds can be another effective strategy. Interest in repellent compounds against pest has increased due to more reports of insecticide- resistant pests and community concerns of environmental safety.

Repellent not only focus on scents that cause pest to avoid specific crops, but may also hinder pest’s ability to locate hosts (Deletre et al., 2016); (Werner & Avery, 2019). Extracts of Andrographis paniculata, piper betle leaves using n-hexane, and acacia leaves using ethyl acetate have been shown to repel oviposition of Bactrocera carambolae Drew & Hancock (Prakoso et al., 2018). Additionally, utilizing garlic extract to repel birds from the Family Lochura has been reported as effective in reducing attacks, from 5–13 to 3–7 attacks during the afternoon, by 6–12 flocks (Hardiansyah et al., 2020).

Mixed cropping with maize is often practiced by farmers to increase incomes, yet the maize’s effect in repelling certain pests is often overlooked. (M & B, 1991) demonstrated that mixed cropping between chili and maize reduced aphid populations. Similarly, (Smith & McSorley, 2000) showed that mixed cropping between eggplants and maize caused B. tabaci to spend more time on maize to locate their main host.

As insecticides lead to resistance in B. tabaci, alternaltive methods are needed, such as using volatile compounds from maize to repel B. tabaci. Further research is required to explore the potential of this approach and its practical application in pest management. (Tyasningsiwi et al., n.d.) identified maize volatile compounds as B. tabaci repellents, specifically in Bisi-2. However, many maize varieties in Indonesia have been developed to produce different volatile compounds. Hence, this research aims to study the potential of various commercial corn varieties in producing repellent compounds for B. tabaci.

The mechanism of disruptions for B. tabaci caused by maize may be attributed to two reasons: physical and chemical actions. The physical action is triggered by the height maize plants and the density of their leaves, which complicates B. tabaci penetration into the field. The chemical action possibly arises from B. tabaci aversion to compounds released by maize, thus avoiding areas containing maize barrier (Friarini et al., 2017). Olfactometer test demonstrated that repellences of all varieties were highest at 10 weeks-after- planting. According to (Su et al., 1982) repellences between 60–75% are categorized as fairly strong, while those between 75–95% are categorized as strong. Therefore P-21, Pertiwi 3, and Bisi-18 at 10 weeks-after-planting are categorized as strong repellents, while NK-212 is categorized as fairly strong repellents. During the maize plant ages of 3–6 weeks-after-planting, some varieties showed that B. tabaci preferred treatments compared to controls. Bisi-18 at 5 and 6 weeks-after-planting did not exhibit significant differences between the number of B. tabaci individuals choosing treatment and control, even though they were numerically different. Similar results were observed for Pertiwi 3 and P-21 varieties at 3 weeks-after-planting. Bemisia tabaci behavior of preferring treatments over controls during the early stages of maize growth may be attributed to the low amount of repellent volatile compounds emitted by plants during this period. Plants emit volatile compounds from roots, leaves, fruits, and flowers, which provide defense signal by regulating acquired resistance (SAR) against both biotic and abiotic stressors(Deletre et al., 2016) Plant volatile compounds are synthesized through complex processes and vary over time and across plant organs due to differential gene expression (Picazo-Aragonés et al., 2020).

All of the tested maize varieties showed potential for use as barrier plants that function as repellent against B. tabaci. Results from GCMS analysis of each maize variety revealed several compounds with repellent properties against B. tabaci, including 9-otadecenoic acid (Z)-, 9-octadecenamide, (Z)-, delta- guaiene, alpha-guaiene, beta caryophyllene, and patchouli alcohol. These findings corroborate results from (Tyasningsiwi et al., n.d.) which identified citronella, limonene, β-phellandrene, β-caryophyllene, 1.8 cineole, farnesol, caryophyllene, and patchouli alcohol are repellent volatile compounds from maize against B. tabaci. 9-octadecenamide, (Z)- is known to possess larvicidal activities and disrupt insect respiration systems. Additionaly, 9-octadecenoic acid (Z)- has been reported to repel female mosquitoes (Kim et al., 2002) and disrupt mosquito larval growth and hinder pupae formation (Ali et al., 2014). B-caryophyllene also exhibits larvicidal properties and inhibits enzyme activity in Aedes aegypti (Linnaeus) larvae (Albuquerque et al., 2013). Application of β-caryophyllene in coffee reduces coffee fruit borer infestation by 33–45% compared to the control(Góngora et al., 2020). Patchouli alcohol, delta-guaiene, and alpha-guaiene found in Pogostemon cablin have been reported to repel ants (Albuquerque et al., 2013). Additionally, patchouli alcohol has also been reported to repel Coptotermes formosanus Shiraki (Zhu et al., 2003).

olfactometer test To protect themselves from herbivory, plants have evolved physical and chemical defences and release a variety of volatile organic compounds (VOCs). By releasing these VOCs, a signalling plant can both reduce herbivory, sometimes by more than 90%, and also warn neighbouring plants about an attack(Skoczek et al., 2017). A range of volatile organic compounds (VOCs) emitted by maize has been found to repel insects. The natural plant activator cis-Jasmone has been found to prime maize for enhanced production of defensive VOCs, including herbivore repellents (Oluwafemi et al., 2013). The emission of VOCs by different African maize varieties when infested by leafhoppers has also been studied, revealing variability in the emitted compounds (Oluwafemi et al., 2011). Additionally, maize has been found to have repellent and toxic effects on B. tabaci, further supporting the potential of maize as a natural repellent (El-Ghorab et al., 2007). These studies collectively suggest that maize emits a variety of VOCs that can act as insect repellents. Maize can be utilized as a repellent plant in integrated pest management strategies.

Bisi-18, P-21, NK-212, and Pertiwi 3 demonstrated repellence against B. tabaci. The highest repellence was observed at 10 week- after-planting maize. P-21 exhibited the strongest repellences, followed by Pertiwi 3, Bisi-18, and NK-212, which had the weakest repellence. Volatile compounds suspected to repel B. tabaci included 9-octadecenoic acid (Z)-, 9-octadecenamide, (Z)-, delta-guaiene, alpha-guaiene, beta caryophyllene, and patchouli alcohol. The utilization of maize plants to manage B. tabaci has the potential as an environmentally friendly technique. Further studies on this management technique are required to identify more effective and efficient combinations.