|Throne, James - Jim|
Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/26/2004
Publication Date: 8/31/2004
Citation: Qureshi, J.A., Buschman, L.L., Ramaswamy, S.B., Throne, J.E., Whaley, P.M. 2004. Rubidium chloride and cesium chloride sprayed on maize plants and evaluated for marking Diatraea grandiosella (Lepidoptera: Crambidae) in mark-recapture dispersal studies. Environmental Entomology. V. 33(4): 930-940. Interpretive Summary: The southwestern corn borer is an important pest of corn in the U.S., and transgenic BT-corn hybrids are now used for control of this pest. Attempts are being made to minimize the potential for development of insect resistance to the corn hybrids, and studies on dispersal of southwestern corn borers will aid in developing resistance management strategies. Dispersal studies usually are conducted by marking, releasing, and recapturing insects, but no methods are currently available for marking southwestern corn borers. We determined that two elemental markers, cesium chloride and rubidium chloride, could be sprayed on corn plants and used to mark southwestern corn borers, and that the markers had little effect on biological parameters of the insects. There were slight effects of cesium chloride to the plants at the highest application rate of 10,000 ppm. The Flame Atomic Absorption Spectrophotometer (F-AAS) detected rubidium and cesium in plants but not in insects. Both the Graphite Furnace-AAS and Neutron Activation Analysis (NAA) methods reliably identified rubidium and cesium in adults. The two markers should be suitable for dispersal studies on southwestern corn borers when used at the 1,000 ppm rate, which should aid in making resistance management decisions.
Technical Abstract: Rubidium chloride (RbCl) and cesium chloride (CsCl) were evaluated for effects on corn plants and Diatraea grandiosella Dyar and for their usefulness in marking adults with rubidium (Rb) and cesium (Cs). Plants were sprayed with aqueous solutions containing 100, 1,000, and 10,000 ppm RbCl or CsCl and inoculated with D. grandiosella neonates. There was slight leaf phytotoxicity at 10,000 ppm CsCl rate and some minor effects on D. grandiosella at all the tested rates. Rubidium and cesium were absorbed and translocated in plants at all the tested rates. The Flame Atomic Absorption Spectrophotometer (F-AAS) detected Rb and Cs in plants but not in insects. Both Graphite Furnace-AAS and Neutron Activation Analysis (NAA) reliably identified Rb and Cs in adults. Males and females developed on 1,000 ppm RbCl or CsCl treated greenhouse plants were not different for Rb or Cs contents detected using NAA. Rubidium and Cs contents in males were not different, but females had higher Rb than Cs content. Neutron Activation Analysis could not detect Rb or Cs in unmarked adults. Graphite Furnace-AAS detected Rb and Cs in feral unmarked adults and they had higher Rb than Cs content. Rubidium content was not different between sexes, but Cs content was higher in males than females. Adults developed on 1,000 ppm CsCl treated field corn had higher Cs content than adults from untreated plants. An application of 1,000 ppm RbCl and CsCl on plants was effective in marking adults with Rb and Cs and thus should be useful for mark-recapture dispersal studies.