Biological pest control

Lore & Background

The term 'biological control' was first used by Harry Scott Smith at the 1919 meeting of the Pacific Slope Branch of the American Association of Economic Entomologists in Riverside, California. It was later popularized by entomologist Paul H. DeBach, who worked on citrus crop pests. However, the practice is much older: the earliest known report comes from 'Nanfang Caomu Zhuang' (c. 304 AD), attributed to Western Jin dynasty botanist Ji Han, describing the use of huang gan ants (Oecophylla smaragdina) to protect citrus fruits in southern China.

Modern biological control began emerging in the 1870s. In the US, state entomologists C. V. Riley and W. LeBaron started redistributing parasitoids within states. The first international shipment of a biological control agent was made by Charles V. Riley in 1873, sending predatory mites to France to combat grapevine phylloxera. The USDA initiated classical biological control research after 1881, leading to the successful introduction of the vedalia beetle from Australia to California in 1888–1889 to control cottony cushion scale, a major citrus pest.

A landmark program began in 1905 when the USDA sent entomologists to Europe and Japan to find natural enemies of the spongy moth and brown-tail moth. Nine parasitoids and two predators became established, reducing outbreak severity. In Australia, the cactus moth and scale insect were introduced between 1926 and 1931 to control prickly pear cacti, destroying most of the infestation by 1932. In Canada, the first classical biological control attempt involved releasing Trichogramma minutum wasps in Ontario in 1882.

Reader's Guide

Biological pest control is significant as an environmentally targeted alternative to chemical pesticides, forming a core part of integrated pest management. Its history spans over 1,700 years, from ancient Chinese citrus growers using predatory ants to modern programs involving parasitoids, predators, and pathogens. The method has achieved notable successes, such as the control of cottony cushion scale in California by the vedalia beetle, and the suppression of prickly pear cactus in Australia by the cactus moth. However, biological control can have side-effects on biodiversity if introduced agents attack non-target species, emphasizing the need for thorough understanding before release. The field distinguishes three strategies: classical (importation of natural enemies), augmentation (mass release for quick control), and conservation (maintaining existing natural enemies). Regulatory frameworks differ between macroorganisms and microorganisms, with the latter registered as biopesticides in the US and Europe. The legacy of biological control includes not only practical pest management but also the development of concepts and procedures that guide modern IPM programs worldwide.

Did You Know?

• The term 'biological control' was first used by Harry Scott Smith in 1919.
• The earliest recorded use of biological control is from c. 304 AD in China, using ants to protect citrus.
• The vedalia beetle was introduced from Australia to California in 1888–1889 to control cottony cushion scale.
• Between 1926 and 1931, tens of millions of cactus moth eggs were distributed in Queensland, Australia, to control prickly pear cacti.