**1. Introduction**

*Ocimum* is one of the important genera within the wealthiest essential oil-bearing plant family, the Lamiaceae. It is represented by more than 150 species cultivated and distributed throughout the tropical and temperate regions [1]. They are collectively known as the "basils" that retain the commercial demand for their nutritional, aromatic, ornamental, culinary, religious, and medicinal importance [2]. Different basil types are commonly used, including holy basil (*O. sanctum*), sweet or Thai basil (*O. basilicum*), lemon basil (*O. citriodorum*), and tree basil (*O. gratissimum)* [3,4]. It is well established that different basil cultivars have the genetic potential to create and maintain distinct sets of volatile components, resulting in a wide variety of chemotypes within the same basil species [5]. The essential oils of these basils are predominantly constituted of phenylpropanoids such as estragole, eugenol, and methyl eugenol; however, they also contain common monoterpenes such as geranial, neral, and α-ocimene, as well as sesquiterpenes such as β-caryophyllene, α-cubebene, and γ-muurolene [6]. Most of which are biologically active on living organisms, especially the antimicrobial and antioxidant properties for food and medicinal uses [7,8]. It was discovered that eugenol has antimicrobial and analgesic effects on humans [9]. Additionally, the essential oils also possess a wide range of biological functions that theoretically minimise post-harvest deteriorations. Volatile organic compounds have been shown to inhibit the growth of microorganisms, especially those responsible for post-harvest diseases such as *Aspergillus* spp. [10–12], *Colletotrichum acutatum* [13], *Botrytis cinerea* [14], and *Penicillium italicum* [15]. They have also been extensively used in insect pest managemen<sup>t</sup> to control rice weevil (*Sitophilus oryzae*) [16], bean weevil (*Acanthoscelides obtectus*) [17], and cotton bollworm (*Helicoverpa armigera*) [18]. Prominently, methyl eugenol has been claimed for its ability to attract Oriental fruit flies (*Bactrocera dorsalis*) [19], the most important tropical fruit pest [20,21]. The estimated annual loss from this pest alone is roughly over US\$ 100 million, and mangoes have been the most susceptible crops [20,21]. Aside from the infestation of the Oriental fruit flies that cause physiological damage to fresh fruits, biological stress could encourage post-harvest biochemical mechanisms such as browning and physiological decay [22]. A study of fresh apple has also proven that spraying the sweet basil essential oil on the fruit skin illustrated the preservative effect, thereby extending its shelf life [23]. With all these advantages, it is interesting to use basil essential oils as biological controls during the production of tropical fruits. However, the instability of essential oils at ambient conditions, as well as harsh environmental exposure, are the limitations. Moreover, volatile organic compounds decompose quickly with the presence of light, heat, humidity, and oxygen [24].

This review aims to serve as a guide to using the volatile components obtained from commercially available *Ocimum* species in the development of functional products for the sustainable production of tropical fruits. It attempts to provide the relevant data, both taxonomical and chemotypes, with particular attention to the biological activities and applications. The typical constraints of these applied uses are discussed, along with the recent approaches to improve efficiency.
