Fighting Insects With Insects – OpEd
We tend to think of insects and bugs with the words “harmful “and “pests” unaware that worldwide, just a little bit of fraction, no more than 20 percent of all insects, cause harm to humans or damage crops.
There are far more of the insect population that can help in many ways and benefit mankind enormously.
Insects are one of the many components of an agroecosystem and many entomologists, people who study insects, say humans are not fully aware of the huge diversity of insect species, especially in farms, and their functions in the ecosystem.
Farming Created Pests
The intensification of agricultural production is the main reason why many insect species have become pests, environmental horticulturist Laura Anne Sanagorsky of the University of Florida says.
How? The agricultural scientist explains, through co-evolutionary process driven by reduction of biodiversity (monocropping) and conventional agricultural production. The former provides perfect environment for one or few insect species to thrive and the latter help drive the evolutionary selection of new populations of phytophageous species as the use of pesticides and inorganic fertilizers give rise to insect populations that are tolerant and resistant.
In short, Sanagorsky says “we created our own insect pests”.
The increasing difficulties humans face in controlling insects is the best argument for the drastic change in the world’s agricultural system. The approach then should not only minimize the damage caused by insects but also unlearn the old approach of protecting crops by focusing on pest control and instead look at the interactions where farmers and non- farmers can benefit from the insects, she said.
She said many insects besides bees, are pollinators, others improve soil fertility while many more are parasitoids, insects that naturally kill harmful insects.
The height of agricultural pesticide use killed many beneficial insects, mostly natural enemies of harmful insects, she lamented.
Because of the absence of natural enemies, many insect pests became tolerant to some pesticides, creating a new breed of “Frankenpests” due to biological magnification, the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain, she expounded.
Helping Those That Help Us
There are ways that insects can be helped to be beneficial. This author together with Prof. N.S Talekar of the Taiwan-based World Vegetable Center or AVRDC here and Prof. Eulogio Cardona and Dr. Lucy Villanueva of the Benguet State University did just that and solved one of the worst insect pest infestations in the Philippines that costs farmers millions of US dollars annually.
Working as a team for several months, we bred and reared the beneficial insects Diadegma eucerophaga and Apanteles plutellae at AVRDC’s laboratory. These insects are natural enemies of Plutella xylostella or Diamondback moth (DBM), the worst insect pest of crucifers like cabbage, brocolli, cauliflowers etc.
After mass producing the natural enemies, we brought them from Taiwan to the Cordillera region of the Philippines, convinced farmers to stop spraying (because the beneficial insects will die), released the beneficial insects and let them hunt and kill the DBMs.
It solved the Diamondback infestation.
Diadegma eucerophaga and Apantele plutellae, are by God’s design, natural enemies of DBM but since they were wiped out in the Philippines due to overuse of insecticides, we had to go breed and mass rear them at the World Vegetable Center to reintroduce the population. They are parasitoids, meaning, they hunt their DBM prey, lay eggs on the bodies of their prey and their eggs hatch and feed on the prey.
In Cuba, with the help of the Ministry of Agriculture, there are 200 insect breeding and rearing centers called Centros de Introduction de Entomofagos Y Entomophatigenos. These centers raise nine million Trichogramma wasps yearly to combat insect pests in rice, corn, sugarcane, vegetables and pasture lands.
Cuba also mass rears the parasitoids Bracomidae, Chalcididae, Anthocorida, Entophidae, and predators Coccinilidae, and Anthocorridae to fight insect pest larvae.
On-farm rearing sites are also encouraged. Banana planters, while raising bananas multiply colonies of the predator ants Phidole megacephala which are brought to sweet potato fields to kill the insect pest sweet potato weevil.
Luis Vasquez, agricultural researcher of Cuba’s Instituto de Investigaciones de Sanidad Vegetal say farmers in Central Cuba tolerate the weed sourbroom (Partenium hystophorus) because the plants host Coccinilidae which is a predator of destructive aphids.
“Our farmers also take care of the bush Pinon florido (Gliricidia sepium), called kakawate in the Philippines because it is host to 21 entonomophagous insects that kill 19 known deadly insect pests of vegetables,” Vasquez who is on official visit to Benguet’s vegetable fields, revealed.
