Agriculture is dependent on insect pollination, yet in areas of intensive production agriculture, there is often a decline in plant and insect diversity. As native habitats and plants are replaced, often only the weeds or unwanted vegetation persist. This study compared insect diversity on mango, Mangifera indica, a tropical fruit tree dependent on insect pollination, when weeds were present in cultivation versus when they were removed mechanically. The pollinating insects on both weeds and mango trees were examined as well as fruit set and yield in both the weed-free and weedy treatment in South Florida. There were significantly more pollinators and key pollinator families on the weedy mango trees, as well as significantly greater fruit yield in the weedy treatment compared to the weed-free treatment. Utilizing weeds, especially native species, as insectary plants can help ensure sufficient pollination of mango and increase biodiversity across crop monocropping systems.

This study examined if weeds could serve as insectary plants to increase beneficial insect abundance and diversity in mango cultivation in southern Florida. Additionally, we examined how weed presence affects mango tree soil health. We found that weeds significantly increased pollinating and parasitoid insect abundance and diversity. Eight insect orders and eighteen families were significantly more abundant on mango trees with weeds growing beneath them than those where weeds were removed. There was no difference in predatory insects between treatments, and slightly more herbivorous insects on weedy mango trees. Pollinating insects visiting mango flowers in the weed treatment were significantly greater, as well as spiders on weedy mango trees. However, there were more lacewings (Neuroptera) observed on the mango trees without weeds, and leaf chlorophyll in the old and new mango leaves was significantly greater, in the weed-free treatment. Soil conditions, however, significantly improved in soil carbon and a greater pH reduction in the presence of weeds, though weeds affected neither soil nitrogen, phosphorous, nor chlorophyll in productive green leaves. These results show that a tolerable level of selective weed species’ presence may benefit insect, plant, and soil biodiversity in farms. This is important in increasing production, sustainability, and biodiversity in agriculture, which otherwise may be deficient in non-crop life.

Weeds are widely seen in a negative light, as being unsightly and possibly pulling resources away from crop plants. Traditional farming practices use selected beneficial "weeds", however, to provide floral resources to beneficial insects and support them through added biodiversity within farms. The global annual economic value of insect pollination is enormous, with more than a third of all crops dependent on pollinators worldwide. This free ecosystem service is steadily declining as we face a global pollinator decline crisis in areas of intensive agriculture. The loss of natural resources through land conversion has decimated insect populations; therefore, there has been interest in enhancing pollinator populations by providing alternative non-crop resources to increase food production. Weeds may be useful in this goal, as they provide resources that attract and may maintain populations of pollinators. In this review, the possibility of using weeds in agriculture to increase floral resources for pollinators and crop yield will be examined. Weeds can provide extensive, free resources to insects, and understanding their interactions in agriculture needs more focus now than ever in changing environments. Fallow lands have always been used by insects and are an important part of their diets in fragmented ecosystems. Understanding their utility could help shape agricultural practices and ameliorate global pollinator decline.

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