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USGS Western Ecological Research Center
Conservation genetics of the Coastal Silk Spinning Cricket (Cnemotettix miniatus)

AMY VANDERGAST1,3, DAVID WEISSMAN2, TOD REEDER3, AND ROBERT FISHER1

1 USGS, Western Ecological Research Center, San Diego Field Station, San Diego, CA 92123
2 California Academy of Sciences, Department of Entomology, San Francisco, CA 94118
3 San Diego State University, Department of Biology, San Diego, CA 92182
  avandergast@usgs.gov



C. miniatus female from Tijuana Estuary (photo by Chris Brown)
C. miniatus female Project Description

Yet another fascinating and poorly understood insect resides in Southern California:  the silk spinning cricket (Cnemotettix miniatus).  These insects are the only Orthoptera known to spin silk (produced from their maxillary glands). This silk is used to to reinforce their burrows in sandy areas.  

    There are five described silk-spinning crickets known in Califorina (Cnemotettix spinulus, C. caudulus, , C. pulvillifer, C. bifasciatus, and  C. miniatus). The first three species are restricted to the Channel Islands, while C. bifasciatus is distributed along the central coastal range and through the mountains of Southern California.  Until recently, C. miniatus was thought to occur only on Santa Catalina Island, and in the Tijuana Estuary. But,  intensive sampling of Southern California coastal habitats (as part of a long-term monitoring project currently conducted by the San Diego Field Station) has uncovered several populations residing  in patches of coastal sage scrub and maritime scrub habitats in San Diego and Orange County.

    Most of the natural coastal habitats in Southern California have been lost to development, and the little that remains is highly fragmented.  Within these fragments, C. miniatus appears to be very rare, suggesting that populations may be threatened due to reduced habitat and reduced habitat connectivity.  Again, we are using a molecular approach to assess the status of C. miniatus populations throughout Southern California.  With this study, we hope to answer the following questions:

  1. What is the distribution of genetic diversity within and among remnant populations?  
  2. Have populations undergone recent genetic bottlenecks due to loss of habitat ?   
  3. Do remaining populations require special conservation protection?
Coastal Sage Scrub at Torrey Pines State Park
Coastal Sage Scrub at Torrey Pines State Park (Photo by Chris Brown)
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Last update: 18 April 2003