Biological pesticides allow for biologically based pest control rather than hydrocarbon or industrially produced chemical control. This is desirable as bio pesticides seem to be ecologically safer as they are less likely to accumulate in the fat cells of animals and magnify up the food chain. In Aquaponic and Hydroponic systems, if pesticide use is deemed necessary it is important to use the least toxic option, due to its potential effects on the entire mini ecosystem.
Last week we identified aphids, white flies, and mites on some of our hydroponic herbs. I investigated several options for control with biological-based products including Neem oil, garlic/onion/pepper spray, and tobacco leaf infusion. In this post I will discuss Neem oil.
Neem oil is made from the fruits and seeds of the Neem tree which is native to India, and its primary active constituent is Azadirachtin. It does not kill on contact like many other insecticides. It enters the insect’s body after ingestion of Neem-coated plant material interferes with hormone regulation and reproduction.
Neem oil also deters insects from feeding. There is a gland responsible for initiating feeding.The gland gives a signal and makes insect larva feel hungry and start eating. Azadirachtin and similar compounds found in the Neem oil cause the opposite of a hunger signal, similar to vomiting and a reduced ability to swallow. This can starve the larva as they avoid eating.
In the case of insect growth regulation, Neem oil prevents expression of the enzyme which promotes molting—ingestion of Azadirachtin prevents larva from molting which leads to deformed, sterile adult insects.
Chemical pesticides often affect non-target organisms. For example, Colony Collapse Disorder which effects honeybees and has the potential to drastically reduce crop production is thought to be caused by neonicotinoid pesticides. Since Neem oil requires ingestion to be effective, it has proven to be benign to beneficial insects such as bees, butterflies, ladybugs and wasps which eat or deter pests.
Furthermore, Neem oil has been found to have exceptional antifungal properties and contains many nutrients which make it a decent fertilizer,however, the pesticidal compounds can be absorbed and transported through the plant body, so it is suggested to not use on plants that are nearing maturity and will be harvested soon.
Next week I will investigate vegetable-based sprays as I continue to search for appropriate bio pesticides to control pests in Aquaponic systems like those here at Nourish the Planet.
Emily Hanna – Blog Post #3 – 6/11/2014