Efficacy of homemade botanical insecticides based on traditional knowledge. A review

Abstract

Homemade botanical insecticides are widely used by subsistence and transitional farmers in low-income countries. Their use is often driven by the limited availability or cost of commercial pesticides. Homemade botanical insecticides are often recommended by agricultural extension services and some development organizations. However, this could be questioned because scientific evidence of their efficacy and safety may not be available or accessible. Although botanicals with insecticidal properties have been widely studied, a synthesis focusing specifically on homemade preparations used in realistic field or storage conditions is missing. In this paper, we review efficacy assessments of botanicals used to prepare homemade insecticides. This covers twelve botanicals recommended by national extension partners in 20 countries within the global agricultural Plantwise program. These are as follows: garlic (Allium sativum), neem (Azadirachta indica), chili pepper (Capsicum spp.), Siam weed (Chromolaena odorata), mother of cocoa (Gliricidia sepium), chinaberry (Melia azedarach), moringa (Moringa oleifera), tobacco (Nicotiana tabacum), clove basil (Ocimum gratissimum), tephrosia (Tephrosia vogelii), tree marigold (Tithonia diversifolia), and bitter leaf (Vernonia amygdalina). This review shows that (1) all the selected botanicals contain active ingredients with insecticidal, antifeedant, or repellent properties, and (2) homemade insecticides based on all the selected botanicals have been used with some success to control pests or prevent damage, although efficacy was variable and often lower than the positive controls (synthetic pesticides). Factors affecting the efficacy of homemade botanical insecticide include variation in active ingredient content and concentration in plant material, as well as variation in the preparation process. In conclusion, there is some evidence that homemade botanical insecticides could contribute to reducing losses in food production. Since further research is needed to better understand their variable efficacy and potential health and environmental risks, those who promote the use of homemade botanical insecticides should also communicate those "unknowns" to the farmers who use such products.

Phytochemical Analysis of Tephrosia vogelii across East Africa Reveals Three Chemotypes that Influence Its Use as a Pesticidal Plant

“…Our results indicate that T. vogelii is most widely used for pest control among other uses as shown in the survey results. Farmers' responses in this study, align with reports about the use of T. vogelii in controlling pests in vegetables and in stored products [15] and ectoparasite control in domestic animals [12,24,27]. The wider use of T. vogelii for small-scale farmers could be associated with previous projects that promoted integrated pest management using T. vogelii and research on soil improvement [28,29].…”

“…This highlighted the need to ensure that effective chemotypes of pesticidal plants were available when promoting their use to farmers to ensure effective control of pests. However, this is challenging in the absence of suitable local facilities to undertake such quality control and establish variation when pesticidal plants are harvested, processed, and used locally [24]. Natural variation in the chemistry of bioactive components in pesticidal plants is reported [25] and can have consequences for use and ultimately trust in pesticidal plants as an alternative to synthetic inputs by farmers.…”

The Efficacy of Alternative, Environmentally Friendly Plant Protection Measures for Control of Fall Armyworm, Spodoptera Frugiperda, in Maize

“…Other biopesticides are based on pods or leaves from neem trees (Azadirachta indica Juss. ), of which extracts from pods or leaves are known to possess pesticidal properties [20][21][22], and which are readily available across most of Africa. Another insecticidal product that is known to be effective against a range of insect pests is maltodextrin.…”

Insecticidal Activity and Chemical Composition of Moringa oleifera Extract Against The Leguminous Aphid, Aphis craccivora Koch on Broad Bean Plants

“…Using plant extracts as bio-pesticides offering the farmers many unique benefits, it is usually are inherently less harmful than conventional the pesticides (John and Jimmy, 2015). Botanical extracts were used for control of the agricultural pests in Egypt since 2006 and decreasing losses in the food production (Dougoud et al, 2019).Because the label formulation is easy to obtain and prepare and could be an alternative bio-pesticide for the control of insect pests. Our results suggest that, farmers could apply these bio insecticides first in the field to reduce infestation and these products are readily available, bio-degradable and environmentally friendly.…”

“…According to Fugile (2000) the many uses for M. Oleifera include: fertilizer, biopesticide, medicine etc. Botanical pesticides are namely, biopesticides and it is important alternatives to reduce or replace the use of the synthetic pesticides (Halder et al, 2007 andDougoud et al, 2019). It is also, not available and may be expensive (Amoabeng et al, 2014 andDougoud et al, 2018).…”