## 5 Biopesticides and Inert Materials in IPM
For example, neon, extracted from the seeds of _Azadirachta indica_, contains azadirachtin, which is an antifeedant that interferes with an insect's hormonal system and disrupts its growth and reproduction [211]. Finally, repellents keep the insect away from the plant, either by emitting an unpleasant odour or by masking the plant's attractants. For example, garlic, obtained from the bulbs of _Allium sativum_, is a repellent that produces sulphur compounds that deter many insects [212]. Essential oils can be considered botanical insecticides due to their natural origins and abilities to control insect pests. Essential oils can therefore also play roles in IPM as they often have natural insecticidal, antifungal, and antimicrobial properties [213; 214; 215; 216]. They can be used as natural insecticides given that certain ones contain compounds that can repel or kill pests. For example, oils from celery, eucalyptus, neem, oregano, peppermint, pepper, and lavender have insecticidal properties [217; 218; 219; 220; 221; 222; 223] and can be used to control pests like aphids, beetles, mites, and mosquitoes [224; 225; 219; 226; 227]. Indeed, essential oils' insecticidal properties have been mostly investigated against tephriti species [226; 227; 228] including _B. olea_[194; 229; 230]. Although citrus, piperaceae, thyme, peppermint, clove, and eucalyptus are essential oils that have been used for integrated pest control in lepidopteran pests [218; 231; 232], research is needed on _Prays olea_. Studies on _P. spumarius_, the main vector of _X. fustidiosa_ in Europe, show that essential oils can be effective as either repellents or traps. However, the results are highly dependent on the oil used, its concentration, and the insect stage. Importantly, these are laboratory tests that need to be confirmed by field trials [233; 234; 235; 236]. Essential oils such as eucalyptus, neem, or peppermint, to name just a few examples of those mentioned above, also have some drawbacks that limit their widespread applications. They can vary in chemical composition and bioactivity depending on the plant source, extraction method, environmental factors, and storage conditions [231; 237]. Therefore, their effects on pests may not be stable or predictable in different situations. In addition, studies on essential oils have been used to be conducted in controlled laboratory or greenhouse settings, which may not accurately reflect real field scenarios where pests are exposed to a variety of biotic and abiotic influences [231; 237; 238; 239; 240]. They are also often expensive to produce and require large amounts of plant material. Moreover, they may need special formulations or delivery systems to enhance their stability, solubility, and penetration. These factors may increase the costs of using essential oils for IPM compared to synthetic pesticides [238; 241; 242]. In a recent work where insecticides, biopesticides, and clay were evaluated for the management of fruit flies, specifically _Bactrocera_ spp. infesting bottle gourd, among the biopesticides, neem oil appeared to be superior to others in its class, but was less effective than, for example, spinosad treatment [243]. As many other compounds, essential oils are subject to strict regulations; they need to undergo rigorous testing and registration processes before they can be marketed as pesticides. This may take several years and require substantial financial resources, which may discourage the development and commercialization of essential oils for IPM [231; 237]. In sum, much more research needs to be conducted on olive crops with these compounds, especially considering the upcoming more extreme environmental conditions and their costs compared to the synthetic insecticides that growers are already used to employing and know what to expect.