Optimal Release Rates for Attracting Meloidogyne incognita, Rotylenchulus reniformis, and Other Nematodes to Carbon Dioxide in Sand

Abstract

Movement of vermiform stages of Meloidogyne incognita, Rotylenchulus reniformis, Ditylenchus phyllobius, Steinernema glaseri, and Caenorhabditis elegans in response to carbon dioxide was studied in 40- and 72-mm-long cylinders of moist sand inside 38-mm-d acrylic tubes. Meloidog,yne incognita, R. reniformis, and S. glaseri were attracted to CO[sub2] when placed on a linear gradient of 0.2%/cm at a mean CO[sub2] concentration of 1.2%. When CO[sub2] was delivered into the sand through a syringe needle at flow rates between 2 and 130 [mu]l/minute, the optimal flow rate for attracting M. incognita and R. reniformis was 15 [mu]l/minute, and maximal attraction of the two species from a distance of 52 mm was achieved after 29 and 40 hours, respectively. After 24 hours, a total CO[sub2] volume of 20 cm³ was sufficient to induce 96% of all M. incognita introduced to move into the half of the cylinder into which CO[sub2] was delivered and more than 75 % to accumulate in the 9 cm³ of sand volume nearest the source. Results indicate it may be possible to use a chemical or biological source of CO[sub2] to attract nematodes to nematicide granules or biocontrol agents. Key words: behavior, Caenorhabditis elegans, carbon dioxide, chemotaxis, Ditylenchus phyllobius, Meloidogyne incognita, nematode, Rotylenchulus reniformis, Steinernema glaseri.