Pests and Their Management

WEIGHING IN AT 1,078 pages and 27 chapters in hardcover, Springer’s Pests and Their Management was heavyweight champion in the book exhibits in Vancouver, Canada at the joint Annual Meeting of the Entomological Societies of America (ESA), Canada (ESC) and British Columbia (ESBC). Edited by Professor Omkar of the University of Lucknow’s Ladybird Research Laboratory in Uttar Pradesh, India, the 27 chapters range from major world commodities such as rice, wheat, maize, pulses, oilseeds, cotton, soybeans, sugarcane and stored grains to vegetables, fruits (banana, apple, mango, citrus, jackfruit, guava, grapes), medicinal crops (walnuts, seed spices, aromatics, Indian tea) and plagues of locusts, aphids, termites and rodents. Plus a final chapter on control methods. Persons sourcing crops internationally, concerned with agriculture sustainability, and having computer access to university and research libraries may want to add chapters to their digital devices. Digital downloads total almost 17,000, according to Bookmetrix stats on the Springer site. Libraries interested in crops and agriculture will want the hardcover version for their reference shelves.

Insects and plants originated on planet Earth 480 million years ago, but only within the past 12,000 years when humans adopted monoculture farming (large expanses planted exclusively to one crop such as wheat, barley, rye) did crop insect problems come to the fore. Only a miniscule number of Earth’s millions of insect species (estimates range as high as 30 million, many yet to be described and named) are detrimental. But “often only one, two or three (pest insect species) on a plant species can destroy a crop or cause sufficient damage,” writes Professor Omkar. “Globally, an average of 35% of potential crop yield is lost to preharvest pests.” Although crop losses in India “have declined from 23.3% in post-green revolution era to 15.7% at present,” the annual loss of US$36 billion dollars “is a major dent to the economy.”

Global trade routes and human movements have helped previously isolated regional or local pest species spread and evolve into the global insect pests featured in Springer’s compendium, though it is more fashionable and politically correct to carp about climate fluctuations. “Another cause for increased spread and incidence of crop pests is the large monocultures that have replaced the natural diversity-rich ecosystems,” writes Omkar. “Unabashed use of pesticides has led to pest resurgence of old as well as new species, owing to pesticide resistance as well as removal of natural enemies from the ecosystem due to the use of broad spectrum insecticides.” Indeed, “the intensity of crop protection has increased considerably as exemplified by a 15-20-fold increase in the amount of pesticide used worldwide.”

“To provide targeted, cost-effective, ecofriendly management of insect populations to the end user, it is essential for us as students, teachers, researchers and scientists to be aware of the potential pests that target our crops, the ways in which they damage them, and the various control measures available to us,” says Omkar. “The upcoming chapters deal with the diagnostic features, life cycle, damaging stage, mode of damage and control measures of pests of various agricultural and horticultural crops, including some rarely dealt with crops such as tea, seed spices, walnut, medicinal and aromatic plants, etc.”

Wisely, the tea chapter restricted itself to India. At the Vancouver entomology conference I had the chance to listen to Eric Scott of Tufts University in Massachusetts talk about his experiences (see blog links) with premium-priced “bug-bitten” Chinese teas. Oddly enough, tea green leafhopper (Empoasca onukii), a major pest often sprayed with pesticides, improves the quality of certain Chinese black (fermented) teas marketed with names such as Concubine Wulong, Honey-Aroma and Eastern Beauty Oolong. Though tea leafhoppers reduce yields up to 20% and are bad for most green teas, leaves of certain varieties fermented into black teas have a better blend or ratio of volatile flavor and aroma compounds for which Chinese consumers will pay premium prices. Plants with bug-bitten tea leaves are also favorable for natural pest management, being higher in polyphenols, caffeine, L-theanine and compounds that kill microbial pathogens and attract spiders and other insect natural enemies.

Chinese farmers and tea plantation managers who welcome tea leafhoppers as harbingers of much higher quality, higher-priced “bug-bitten” fermented black teas are learning to manage leafhopper populations for optimum size. The idea is to create tea plantations where leafhopper levels are neither too low nor too high, but rather just right to produce the highest economic yield of bug-bitten leaves, versus the traditional pesticide eradication paradigm where damaged tea leaves go unharvested.

With 9 to 15 leafhopper generations per year in Taiwan and mainland China and different tea plant varieties or genotypes responding differently to leafhoppers, as well as climate, altitude, leaf age and other factors in play, pest management is not easy (yield losses must be weighed against premium prices for damaged leaves). Lessons from managing leafhoppers in grapes are being applied to managing leafhoppers in tea: Namely, pest managers wear inexpensive orange goggles and shine blue LED flashlights to count leafhopper eggs, which fluoresce as green points inside stems. Indeed, monitoring populations of pests and beneficials is the key to success, along with having an open mind.