Biocontrol

Biocontrol falls into three categories. (1) Classical biocontrol introduces a natural enemy from the pest's region of origin — successful cases include the cottony cushion scale + vedalia beetle in California citrus (1888) and prickly pear cactus + Cactoblastis moth in Australia. (2) Augmentative biocontrol releases mass-reared beneficials (Trichogramma wasps, Phytoseiulus mites) periodically during the season. (3) Conservation biocontrol creates habitat (flower strips, beetle banks, reduced-pesticide zones) to encourage resident natural enemies.

The most widely used biocontrol product globally is Bacillus thuringiensis (Bt) — a soil bacterium that produces toxic crystalline proteins specifically lethal to caterpillars, beetles, or mosquito larvae depending on the strain. Bt is safe for humans, bees, and non-target insects, and is allowed in organic production. Modern GMO Bt crops (Bt corn, Bt cotton) express the same toxins in plant tissue.

Biocontrol typically delivers 50–90% pest suppression — rarely 100%, but often enough to stay below economic threshold without chemical sprays. It is especially strong in greenhouses, orchards, and high-value vegetable crops where the investment in biological inventory pays off. Challenges include slower action than chemical pesticides, sensitivity to broad-spectrum insecticides (one spray can wipe out the beneficial population for months), and high specificity (one biocontrol agent typically suppresses only one or a few pest species).