Tests with Insects

The effect of caffeine has been tested with insect herbivores. Tobacco horn-worms, Manduca sexta, die from a diet with 0.3% caffeine, and the beetle Calioso-bruchus chincnsis becomes sterile at a concentration of 1.5% (Nathanson, 1984). However, experiments showed that caffeine does not protect the coffee plant against the leaf miner Perileucoptera coffedla, one of the major pests of coffee (Filho and Mazzafera, 2000). 

Oomen, P.A., De Ruijter, A. and Van Der Steen, J. (1992). Method for honeybee brood feeding tests with insect growth-regnlating insecticides. Bull. OEPP/EPPO 22, 613-616. 

In the search for safe insecticides, hundreds of products have been prepared and subjected to screening tests against insects. This paper presents information on six materials related to piperonyl butoxide, tested in combination with pyrethrins. 

In the search for safe insecticides the authors have prepared hundreds of new products and subjected them to preliminary screening tests against insects. That part of their work dealing with methylenedioxyphenyl derivatives was prompted by the original fundamental studies of 0. F. Hedenburg, with whom they have collaborated in this field. Two materials of this type—piperonyl butoxide (I) and piperonyl cyclonene (II)—have recently been introduced commercially. These products have definite insecticidal properties in themselves, but show their maximum efficiency toward insects and other arthropods when used in combination with pyrethrins. Furthermore, they are at least as nontoxic... 

Chemical weed control in cacao plantations with volatile weed killers is generally considered detrimental to pollinating insects and to the flower and fruit set. Recently Naundorf (28) and Oliver (33) in Colombia conducted tests with compounds derived from 2,4-D and with an ammonium salt of dinitro-o-cresol to determine the effect of these materials on the flowers. They found that dinitro-o-cresol can be used at the dosages commercially recommended, and that only the volatile 2-4-D derivatives at concentrations of 500 to 750 grams per plaza (6400 square meters) can be used. 

Results from these laboratory studies demonstrated that avermectin Bj had high toxicity for the twospotted spider mite (Tetranychus urticae) on bean plants. When applied in solution directly onto adult and nymphal spider mite populations on foliage, avermectin Bj was shown to be 50-200 times as potent as commercially available acaricides, with an LC q of 0.02-0.03 ppm. Additional tests on foliage with insects in the order Lepidoptera, Coleoptera, Homoptera, Orthoptera, Diptera, Isoptera and Hymenoptera confirmed the broad spectrum activity and potency of the avermectin family of compounds and avermectin Bj in particular. Table II provides LC q values for avermectin Bj for the control of larval forms of several of these insects in foliar residue assays (18). 

Different lines, each with Insect resistance, may possess different ratios of antibiotic compounds. Thus, It may be possible to Increase resistance by crossing lines where each contributes genes for biosynthesis of different antibiotic compounds. The tobacco budworm was selected for study In preference to the cotton bollworm because It Is easier to rear and use In the laboratory, Is more resistant to Insecticides In the field, and It Is approximately as susceptible to cotton constituents Incorporated In laboratory diets (14). This present study was carried out to Identify and analyze for cotton constituents that were toxic In laboratory feeding tests, and to determine whether there were positive correlations of their content In leaves and/or other tissue with field resistance. From this Information, the generation of lines with multiple factors for resistance could be Initiated. 

Tests with Aerosol Sprays. Insecticide aerosols may be applied outdoors for controlling insects on crops. The aerosol is released from a line source and is carried by the wind across the area to be treated. A number of tests were made with aerosols of various particle sizes under different weather conditions (6). For satisfactory... 

J3. Johnson, K. S., and Felton, G. W., Plant phenolics as dietary antioxidants for herbivorous insects A test with genetically modified tobacco. J. Chem. Ecol. 27,2579-2597 (2001). 

The activity of a large series of IV,IV-di-n-butylaminomethylsi lanes has been tested as insect repellents against X. cheopsis. The highest activity and the most extensive duration is seen with ethoxy derivatives.14... 

A series of tests with gypsy moths at a number of locations in Northeastern U.S., have similarly shown that mating of this insect can be suppressed by pheromone treatment and that the treatment is especially effective in eradication or suppression of the insect in newly or sparsely infested areas. (See chapter by J. R. Plimmer et al.). 

More detailed aspects of hydrocarbon bouquets acting as pheromones and various problematic aspects in revealing their true biological function have been discussed.2, 29° In many cases, however, only extracts of the insect cuticle are used for bioassays, sometimes roughly separated by chromatography into different chemical classes. Tests with synthetic blends have been less frequently performed only such approaches would allow unequivocal assignment of activity to the compounds tested. Actually, in whole extracts or fractions thereof... 

Terpenoids isolated in large quantities from resistant species were tested with several sunflower insect pests. Since sesquiterpene lactones were present in much higher concentrations than diterpenes in the most resistant species studied, our investigations emphasized sesquiter-pene lactones. Three species of insects were used in these studies Spodoptera eridania, Melanoplus sanquinipes and Homoeosoma electellum. 

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