Linda Benedict, Carlton, Christopher E. | 9/13/2013 12:30:48 AM
Christopher Carlton and Benjamin Adams
The humble beginnings of the cricket industry in the United States can be traced back to the 1950s when their use as fish bait became widespread. Bait crickets typically purchased from neighborhood bait shops or hardware stores are the species Acheta domesticus, the house cricket or brown house cricket. The relatively recent, and expanding, trend of keeping reptiles and amphibians as exotic pets contributed to rapid growth of the commercial cricket industry. The economic impact of cricket growers in the United States is difficult to assess, but major cricket producers may ship more than 5 million crickets a week. Individual operations may see revenue of millions of dollars annually and employ dozens of individuals.
During the first decade of this century, European cricket operations were devastated by the virus Acheta domesticus densovirus. It paralyzes and kills crickets before they reach reproductive age. The Europeans began replacing their cultures with an alternative species, the Jamaican field cricket, Gryllus assimilus, which is apparently not susceptible to the virus. Around 2009, an identical or similar virus entered North America and began wiping out domestic Acheta domesticus operations. Development of an alternative cricket became an urgent issue for U.S. and Canadian cricket producers. A number of operations have succumbed to the virus and suspended operations.
Researchers in Canada are exploring antivirus therapies to mitigate the effects of the virus, but so far without success. The situation in the United States is not as simple as it was in Europe. The Jamaican field cricket is a tropical species unable to survive in the wild in most of Europe. In the United States, the concern is that it may become established outside its normal range. Also, in limited trials in the United States, the Jamaican field cricket has not met expectations for growth and productivity for optimal commercial use. Numerous other domestic species of field crickets occur in the United States. Most, however, have a resting phase (diapause) during the year that renders them unsatisfactory for year-round cultivation, and reproductive potentials are suboptimal for commercial production.
During September 2010, LSU AgCenter scientists at the Louisiana State Arthropod Museum began a series of studies in cooperation with Fluker Farms, of Port Allen, La., to explore additional alternative species for possible use as a commercially viable alternative to Acheta domesticus. The studies consisted of a series of trials using various locally available cricket species. Several species underwent screening, and Gryllodes sigillatus, the tropical house cricket, emerged as a leading contender as a commercial alternative. The tropical house cricket is a non-native species that originated in south Asia. It is established from Florida to Texas and probably exists as scattered populations across the southern tier of states all the way to California. A local population on the LSU Baton Rouge campus was the source of the rearing stock.
Cricket husbandry is relative easy. The study used 15-gallon plastic storage totes with the tops cut out to within 2 inches of the margin. Fiberglass window screen was glued around the perimeter to form a screened lid. Cardboard egg carton inserts and layers of newspaper in the totes provided surface area, and water dishes with cotton balls or a layer of small gravel provided moisture for the crickets. Trays containing a 2-inch layer of moist peat moss served as a substrate for egg laying. This setup has proven useful for continuous rearing, with crickets transferred every couple of months to a clean tote to maintain adequate hygiene. Containers were kept at temperatures of 82-90 degrees F, with fastest growth occurring at the higher temperature. Records noted onset of egg laying, the first appearance of hatchlings (pinheads), general growth and development, and ambient light and temperature conditions.
Tropical house crickets raised under these conditions completed development from egg to adult in as few as 33 days. This is more rapid growth than that of the commercial house cricket, which completed development in 48 days under the same conditions. The tropical house cricket is tolerant of a wide variety of densities and sanitation conditions and appears unaffected by light/dark cycling.
Based on experiences of LSU AgCenter researchers after three years of study, the tropical house cricket is a viable candidate for commercial rearing and marketing. Mature adult tropical house crickets are slightly smaller than those of A. domesticus, with adults of the former typically measuring 0.7 inch and the latter 0.8 inch. Tropical house crickets possess shorter wings than A. domesticus and are incapable of flight. The tropical house crickets showed no apparent reductions in size or vigor during 36 months of continuous rearing in laboratory cultures.
Efforts are now underway to address regulatory issues with the U.S. Department of Agriculture and state agencies that will allow interstate shipping of tropical house crickets. Regulatory and quarantine requirements are less stringent for this species than for non-native, nonestablished species. Although the species originated in south Asia, it is well-established across the South as a species that lives in and around human habitats. The tropical house cricket is being seriously investigated for commercialization by American growers, though some questions remain about the long-term viability of the industry.
Although the level of virulence is unclear, tropical house crickets also can be infected by the virus that infects the domestic house cricket. Crickets in the AgCenter laboratory, however, have tested negative. Growers not affected by the virus are still marketing brown house crickets as their preferred commercial crickets, but the tropical house cricket represents an immediately available alternative.
Christopher Carlton is the John Benjamin Holton Alumni Professor, and Benjamin Adams is a former graduate assistant in the Department of Entomology.
(This article was published in the summer 2013 issue of Louisiana Agriculture magazine.)