Kairomones and their use for management of entomophagous insects. XV. : Identification of several acids in scales ofHeliothis zea moths and comments on their possible role as kairomones forTrichogramma pretiosum.

Acids found in moth scales of laboratory-rearedHeliothis zea (Boddie) moths are hexanoic, heptanoic, octanoic, nonanoic, 2- (or 3-) furan carboxylic, phenylacetic, benzoic, sorbic, and 4-hydroxybenzoic acid. The last two of these acids are preservatives added to the artifical diet as sorbic acid and methyl-p-hydroxybenzoate. FemaleTrichogramma pretiosum Riley exhibited increased rates of parasitization ofH. zea eggs in the presence of some of these compounds in laboratory experiments. Exposure to a mixture of all of these compounds did not increase parasitization, and the elimination of acids from the crude moth-scale extract did not reduce parasitization by the wasps.

Arachidonic acid: Occurrence in the reproductive tract of the male house cricket (Acheta domesticus) and field cricket (Gryllus spp.).

Reproductive tissues from male house and field crickets were investigated for the presence of arachidonic acid. Arachidonic acid was identified by retention behavior on 3 gas liquid chromatographic column systems-SE-30, OV 225, and Silar 10C-and by gas liquid/positive ion chemical ionization mass spectrometry. Arachidonic acid constituted 0.3 and 1.2% of total fatty acids in the house and field cricket, respectively. Freeze-dried male reproductive tissues from house and field cricket contained ca. 0.02 and 0.16% arachidonic acid and 8.2 and 8.6% total fatty acids. Other fatty acids found in reproductive tracts of both species of crickets were 16∶0, 18∶0, 18∶1, 18∶2, 20∶0, 20∶1 and 20∶3.

Extraction, cleanup, and quantitative determination of aflatoxins in corn.

A method is proposed for extraction and cleanup of corn samples for the quantitation of 4 aflatoxins by high pressure liquid chromatography (HPLC). After aqueous methanol extraction, ammonium sulfate treatment, and partition of aflatoxins into chloroform, sample extracts are partially purified on Sep-Pak cartridges or small columns packed with HPLC grade silica; cleanup requires only 13 mL solvent/sample. Aflatoxins B1, B2, G1, and G2 in the purified extract are resolved in ca 10 min by normal phase HPLC on a microparticulate (5 mum) silica gel column with a 50% water-saturated chloroform-cyclohexane-acetonitrile-ethanol solvent, and are measured by ultraviolet fluorescence in a silica gel-packed flowcell. Recoveries of added aflatoxins B1, B2, G1, and G2 were 84-118% at levels of 1.5-125 micrograms/kg.

High pressure liquid chromatographic determination of methomyl and oxamyl on vegetable crops.

A reverse phase high pressure liquid chromatographic method is presented for the separation and determination of residues of the carbamates oxamyl and methomyl on vegetables. A liquid-liquid extraction and cleanup procedure is applied to the vegetable extract. Samples are eluted from a muBondapak C18 column and quantitated by ultraviolet absorbance at 240 nm. Recovery data for vegetable samples spiked at 2 ppm are presented.