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Journal ArticleDOI

A method of computing the effectiveness of an insecticide

01 Apr 1925-Journal of Economic Entomology (Oxford Academic)-Vol. 18, Iss: 2, pp 265-267

TL;DR: In order to make experimental studies comparable and statistically meaningful, the article recommends the following formula: per cent control = 100(X - Y)/X, which eliminates errors due to deaths in the control sample which were not due to the insecticide.
Abstract: There are several statistical methods used in biology (entomology) for computing the effectiveness of an insecticide, based on relating the number of dead insects in the treated plat to the number of live ones in the untreated plat. In order to make experimental studies comparable and statistically meaningful, the article recommends the following formula: per cent control = 100(X - Y)/X, where X = % living in the untreated check sample and Y = % living in the treated sample. Calculation using this method eliminates errors due to deaths in the control sample which were not due to the insecticide. An example based on treatments of San Jose scale includes computation of probable errors for X and Y, and the significance of the difference between the two counts. Common biometric convention holds that when the difference between the results of two experiments is greater than three times its probable error, the results are significant and due to the treatment applied.
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01 Jan 2007-

4,025 citations


Book ChapterDOI
16 Dec 2019-
Abstract: The anthropological study of medicinal botany has numerous objectives, one of which is to identify ethnomedically important species that warrant chemical analysis and testing for biological activity. This chapter suggests that intra- and intergroup similarities in the use of medicinal plants have arisen and persist because particular remedies produce reactions that are both predictable and considered to be desirable. It argues that ethnomedical systems contain an anticipated, and perhaps even predictable, level of variation in the use of available remedies. Anthropologists and other researchers have used a variety of approaches to identify potentially effective plant based remedies. However, most of these approaches necessitate investigations that range over broad geographic regions, through extensive periods of time, or across multiple cultures. Patterning in the use of medicinal plants, whether seen among Mexican Americans or other societies, reflects a fundamental human condition—adaptation to a complex web of socioenvironmeiital challenges including, of course, sickness and the maintenance of health.

626 citations


Journal ArticleDOI
TL;DR: The structure of an insect control protein gene from Bacillus thuringiensis var.
Abstract: The structure of an insect control protein gene from Bacillus thuringiensis var. kurstaki HD–1 was determined, and truncated forms of the gene that express a functional insecticidal protein were generated. Two of these truncated genes were incorporated into a plant expression vector for Agrobacterium–mediated transformation. Transgenic tomato plants containing the chimeric genes express the insect control protein gene. Such expression confers tolerance to lepidopteran larvae on the transgenic tomato plants and their progeny. These engineered tomato plants represent a significant step to increased selectivity, specificity and efficiency in insect control.

571 citations


Journal ArticleDOI
TL;DR: Compared with the genomes of related bacteria, the complete genome sequence of strain TT01 reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen.
Abstract: Photorhabdus luminescens is a symbiont of nematodes and a broad-spectrum insect pathogen. The complete genome sequence of strain TT01 is 5,688,987 base pairs (bp) long and contains 4,839 predicted protein-coding genes. Strikingly, it encodes a large number of adhesins, toxins, hemolysins, proteases and lipases, and contains a wide array of antibiotic synthesizing genes. These proteins are likely to play a role in the elimination of competitors, host colonization, invasion and bioconversion of the insect cadaver, making P. luminescens a promising model for the study of symbiosis and host-pathogen interactions. Comparison with the genomes of related bacteria reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen. Moreover, newly identified insecticidal proteins may be effective alternatives for the control of insect pests.

558 citations


Journal ArticleDOI
29 Jul 2011-PLOS ONE
TL;DR: This is the first report of field-evolved resistance to a Bt toxin by the western corn rootworm and by any species of Coleoptera, and suggests that improvements in resistance management and a more integrated approach to the use of Bt crops may be necessary.
Abstract: Background Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

557 citations


Cites methods from "A method of computing the effective..."

  • ...Corrected mortality was determined using the correction of Abbott [21], and was calculated for each population by adjusting mortality of larvae from each bioassay cup with Bt maize by the average mortality on the non-Bt near isogenic hybrid....

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Performance
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No. of citations received by the Paper in previous years
YearCitations
202213
2021707
2020794
2019663
2018652
2017724