Hagen B. Gillenwater

Dichlorvos applied as a vapor in a warehouse containing packaged foods

Abstract Field studies were conducted to determine the residues deposited on various packaged commodities exposed to weekly applications of dichlorvos, and to determine the effectiveness of these applications against adults of Tribolium confusum duVal and larvae of Attagenus megatoma (F.). A machine especially designed for dispensing dichlorvos as vapor into large storage areas was used to make the applications. Concentrations of dichlorvos vapor and its distribution were determined by chemical analysis of air samples. The test was continued for 21 weeks. Uniform concentrations and distribution of dichlorvos were provided with the vapor dispenser. The rapid decrease in dichlorvos in the air soon resulted in a concentration below 1 μg/l., the tolerance established for humans by the American Conference of Governmental Industrial Hygienists. Results of the bioassay and residue analysis indicated that dichlorvos vapor is a safe, effective, space treatment for use in food storage areas to protect a variety of non-perishable, packaged commodities against insects.

Dichlorvos space treatment for protection of packaged flour against insect infestation

Abstract Dichlorvos vapor was applied weekly from dichlorvos-impregnated resin pellets into 42·5 m3 (1500 ft3) chambers. The chambers contained insect-free flour packaged in cotton sheeting, and in multiwall paper bags stacked at various distances from similar bags of infested flour. The dichlorvos concentration attained in the chambers from the weekly application of vapor was about 3 μg/1. After 5 months of storage, the number of insects found in the flour indicated that the dichlorvos applications retarded the infestation of flour in cotton bags and prevented the infestation of flour in the multiwall paper bags. Chemical analysis showed that dichlorvos residues were less than 0·1 ppm in the flour and, in general, less than 1·1 μg/dm2 (10 μg/ft2) on the packaging materials.

Lindane and Dichlorvos for Protection of Herbarium Specimens against Insects

The protection of herbarium specimens from the ravages of insects and fungi has always been a concern to collectors of plants and to curators of herbaria, especially in the warmer parts of the world. Literature on the subject is extensive and methods employed to impart protection are various (e.g., Fosberg and Sachet 1965, Archer 1952, Lundell and Kirkham 1966, Eusebio and Stern 1964, Merrill 1948). Each method has its advantages and disadvantages (Cf. Lawrence 1951 for an evaluation of methods in use to that date.) and none seems to fit all situations under all herbarium conditions. Assessment of efficacy in killing or controlling the offending organisms has for the most part been subjective and increasing concern is evident on possible deleterious effects of toxicants, where used, on human beings. Therefore, among other items of information, newly introduced or revised methods for the protection of herbarium specimens should include a scientific evaluation of the degree of control of the offending organisms, as well as a report on possible danger of the toxicant to humans in the herbarium environment. Ideally, methods used for protection of dried plant collections against insects or fungi should meet the following criteria: 1) simple application, 2) long-lasting, 3) effective, 4) non-toxic to humans in concentrations required for herbarium protection, 5) easily obtainable, 6) inexpensive, 7) useful under a wide variety of herbarium conditions, 8) harmless to plant specimens, paper, adhesives, inks, cloth strips, wood, paint, and metal, and 9) aromatically inoffensive. Admittedly, there is probably no presently used method of herbarium protection which meets all of these criteria. The toxicants employed in our testing, lindane and dichlorvos, meet most of these requirements and the use of one or the other is recommended under the conditions described for the protection of herbarium specimens against insect infestation.

Exploratory Tests with Bromodan as a Protectant for Wheat Against Stored-Product Insects

Bromodan (5-(bromomethyl)-l,2,3,4,7,7-hexachloro-2-norbornene) was tested as a protectant for Soft Red Winter wheat against infestation by 3 species of stored-product insects. Immediately after treatment a deposit of 20 ppm killed all rice weevils, sitophilus oryzac (L.), and cigarette beetles, Lasioderma serricorne (L.), and a deposit of 80 ppm killed all confused flour beetles, Tribolium confusum Jacquclin duVal. Eight months after treatment at the rate of 20, 40, and 80 ppm, respectively, rice weevil mortalities of 12, 66, and 100% were obtained. Based on development of progeny, a deposit of 20 ppm prevented reproduction of each species.