*4.1. Pre-Harvest Applications*

Several studies have investigated the control potential of essential oils from basil plants against pests during pre-harvesting (Table 3). The volatile organic constituents in the essential oils of some *Ocimum* species influence the behaviour of insects; for example, the ability to attract the Oriental fruit flies [66] and *Ceraeochrysa cubana* (herbivore predator) [83] as well as the repellent effect on *Allacophora foveicollis*, a serious pest that causes severe damage to pumpkin [84]. In addition, essential oils from *O. basilicum* and *O. gratissimum* were shown to have the ability to prevent egg hatching and adult emergence in *Callosobruchus maculatus*, the cowpea seed beetle [85]. Therefore, basil plants have been used as an intercrop in integrated pest managemen<sup>t</sup> that has proven to reduce the total pest infestation in the cotton field [86] and greenhouse tomato production [87]. Methyl eugenol has been found in almost all types of basil essential oils, and it is the most active attractant for the Oriental fruit flies [66], while essential oil of the sweet basil is attractive to green lacewings *Ceraeochrysa cubana* Hagen (Neuroptera: Chrysopidae) [83]. The toxicity of methyl eugenol against larvae of the tobacco armyworms, *Spodoptera litura* has also been well defined [88]. Furthermore, the toxicity of *Ocimum* essential oils to fruit flies have been investigated [89]. Chang et al. [89] tested the toxicity of the three main components detected in the essential oil of *O. basilicum* L. viz., trans-anethole, estragole, and linalool. It successfully eliminated the flies, especially the estragole was the most effective.

The essential oil of sweet basil also illustrated the promising effect in controlling symptoms of wilt or root rot disease of cumin caused by *Fusarium* spp. [90]. It was also found that the mycelial growth of *Botrytis fabae* was significantly reduced by the basil oil types that were rich in methyl chavicol (or estragole) and linalool, while methyl chavicol, linalool, eugenol, and eucalyptol significantly reduced the overall growth of the fungus [10].
