## 5 Biopesticides and Inert Materials in IPM
When insects come into contact with the kaolin-coated surfaces, they find it difficult to move and feed, which can help to reduce the populations of a wide range of insect pests in a wide variety of crops, including olive groves [160; 161; 182; 183; 184; 185; 186; 187]. One of the main advantages of using kaolin in IPM is that it does not leave harmful residues on the products and even mitigates the deleterious effect of drought on some plants [188; 189]. However, it contains aluminium, which has raised concerns about how it ends up in the food chain and how it affects human health [190; 191], and even kaolin is generally considered safe for beneficial insects, pollinators, and other non-target organisms [192]; this should be taken with caution [161; 193]. Additionally, kaolin's effectiveness may vary depending on the pest species and the environmental conditions [160; 192]. Trials on the efficacy of spinosad-based clay baits to control the olive fruit fly showed that spinosad-based baits were less effective than kaolin sprays in controlling _B. oleae_ infestations [194]. Similar results were found when comparing copper and kaolin treatments, as copper treatments provided some protection that was insufficient at high infestation levels [167]. In addition, spinosad has been shown to have a significant detrimental effect on natural enemies in the medium term [172]. On the contrary, spinosad did not have a significant effect on either the feeding behaviour or the survival rate of _P. spumarius_, and nor did kaolin [195]. Laboratory tests with kaolin and copped-based products and some natural enemies of the olive fruit fly and olive moth have shown that, despite some negative effects, the negative impact on natural enemies is less than that caused by products that are commonly used in olive crops to control these pests [196; 197]. However, field trials found a lower arthropod diversity and a significant change in the natural enemy community in the kaolin-sprayed plots [167]. In an attempt to avoid these drawbacks, the combined use of spinosad and kaolin was tested and proven to be an effective strategy to control this pest in organic olive groves. The combined treatment reduces the total and damaging infestation, but not the active infestation, without adversely affecting the natural agonists of the olive fruit fly [160]. To continue with a group comprising a diverse range of compounds, botanical insecticides are formulated from plant materials with minimal processing or modifications. Among the products that have been used for the longest periods of time are natural pyrethrins, which are among the organic alternatives to conventional synthetic insecticides. They are natural insecticides derived from the flowers of certain species of chrysanthemum, _Dalmatian pyrethrum (Tanacetum cinerarifolium)_[198]. Pyrethrins have certain advantages as IPM tools such as their low toxicity to mammals, birds, and beneficial insects, such as predators and pollinators [198; 199; 200; 201; 202; 203], and their short environmental persistence as they break down quickly in sunlight and air, leaving no residues [203; 204]. However, pyrethrins also have some limitations and challenges such as reductions in longevity and fecundity in certain parasitoids [205], a repellent effect in some insects [206], and the emergence of resistance [207; 208; 209; 210]. Depending on the active ingredients and target insects, botanical insecticides work in a variety of ways. Some of the most common modes of action are contact toxicity or their uses as antifeedants or as repellents. The former kills the insect via direct contact, either by disrupting its nervous system, cell membranes, or metabolic processes. For example, pyrethrum, extracted from the flowers of _Tanacetum cinerariae-folium_, is a contact toxin that affects the sodium channels of insect nerve cells [210]. As antifeedants, they reduce or prevent the feeding behaviour of the insect, either by repelling it or by making the plant unpalatable or toxic.