Resistance of Selected Sorghum Genotypes to Maize Weevil (Coleoptera: Curculionidae).

The maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is a major insect pest of stored grain. This study evaluated resistance of grain of 26 sorghum genotypes, Sorghum bicolor (L.) Moench, to maize weevil under laboratory conditions. Three female and two male newly emerged maize weevils were reared with 5 g of grain in each of 10 vials for each of the 26 sorghum genotypes in a laboratory experiment. The weevils and grain of each genotype were scored once every 3 wk for a total of five times during 105 d. The numbers of live and newly emerged maize weevils, dead weevils from the initial population, damage score (scale of 1-5), and grain weight loss were used to indicate resistance. The least percentage weight loss of 23.9 and 24.1% was recorded for sorghum genotypes Sureño and (5BRON151*Tegemeo)-HG7, respectively. Genotypes B.HF8 and (A964*P850029)-HW6 had the most weight loss, 70.6 and 67.7%, at 105 d after infestation. Genotypes B.HF8 and (A964*P850029)-HW6 consistently exhibited the highest numbers of maize weevil, 63 and 84, per vial at 105 d after infestation. Sorghum genotypes Sureño, (SV1*Sima/IS23250)-LG15, (5BRON151*Tegemeo)-HG7, and (B35*B9501)-HD9 ranked among the top four genotypes with least damage rating more often than any other genotype across the five sampling dates. On the other hand, genotypes B.HF8, (A964*P850029)-HW6, (Segaolane*WM#322)LG2, and (Tx2880*(Tx2880*(Tx2864*(Tx436*(Tx2864*PI550607)))))-PR3-CM1 were more often ranked among the top four genotypes with the highest damage rating. Our results indicate that grain of genotype Sureno is most resistant to the maize weevil among screened genotypes.

Comparing the detection of iron-based pottery pigment on a carbon-coated sherd by SEM-EDS and by Micro-XRF-SEM.

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Effect of biotype and temperature on fitness of greenbug (Hemiptera: Aphididae) on sorghum.

The greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), is a major aphid pest of small grains and sorghum, Sorghum bicolor (L.) Moench. Greenbugs extract juice and inject toxin, killing seedlings or limiting the yield of older plants. Understanding greenbug biology and how biotypes develop is important for evaluating and developing sorghum with durable resistance. Prereproductive period, fecundity, and longevity of greenbug biotypes E and I were assessed on susceptible 'RTx430' sorghum at four cycling temperatures of 10-23, 14-27, 18-31, and 22-35 degrees C in an incubator. A photoperiod of 14:10 (L:D) h corresponded with daily warm and cool temperatures. Greenbug fitness was more affected by temperature than biotype. Greenbug prereproductive period, total fecundity, and longevity did not differ among temperature regimes except at the warmest regime (22-35 degrees C), at which all parameters were greater for biotype E than biotype I. The prereproductive period of greenbug biotypes E and I combined was more than twice as long at the coolest temperature of 10-23 degrees C as at 22-35 degrees C. Greenbugs produced a maximum average of 3.3 more nymphs per day at warmer than cooler temperature regimes. Average total fecundity was greatest at 10-23 degrees C, with fewest nymphs being produced at 22-35 degrees C. Longevity of greenbug biotypes E and I combined was 6 times longer at 10-23 degrees C than at 22-35 degrees C. This study provides information on optimal temperatures under which to evaluate damage to sorghum being developed for resistance to different biotypes ofgreenbug.

Morphometric and mating compatibility of Dectes texanus texanus (Coleoptera: Cerambycidae) from soybean and sunflower.

The cerambycid Dectes texanus texanus LeConte that infests soybean, Glycine max (L.) Merr., is thought to be the same Dectes that damages sunflower, Helianthus annuus L. However, morphometric characteristics and mating compatibility between individuals from soybean and sunflower fields have not been assessed. Eight hundred eighty stalks of soybean and sunflower residues infested with Dectes were collected from Texas and Kansas. Outside stalk diameter of sunflower (22.6 mm) was 3.2 times greater than that of soybean. Diameters of tunnels by Dectes in sunflower and soybean were 7.0 and 3.4 mm, respectively. Widths of head capsules and pronotums were approximately 1.3 times greater for Dectes larvae from sunflower than soybean. Larval, pupal, and adult Dectes from sunflower were approximately 2.5 times heavier and 1.3 times longer than from soybean. Adults reared from residues of soybean and sunflower were paired to evaluate mating compatibility. Although individuals collected and reared from different crop residues differed significantly in size, percentage of mating success by Dectes from the two crops (26.2%) did not differ significantly from that by adults from the same kind of crop (34.9%). Results indicated that Dectes that infest soybean and sunflower are the same species and reconfirmed that farmers should not plant soybean and sunflower in rotation or in adjacent fields.