A method of computing the effectiveness of an insecticide
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 1998
TL;DR: The Typhlodromus pyri test group was established as one of the 13 testing groups, or rings, to develop standardized methods for the evaluation of pesticide effects on different non-target arthropod key species.
Abstract: For the authorization of plant protection products in the European Union under Directive 91 /414/EEC, data about the effect of pesticides on non-target arthropods are required. As a consequence of the recommendations of the Workshop on ‘European Standard Characteristics of Beneficials Regulatory Testing’ in 1994 (Barrett et al., 1994) the Typhlodromus pyri test group (consisting of 11 laboratories) was established as one of the 13 testing groups, or rings, to develop standardized methods for the evaluation of pesticide effects on different non-target arthropod key species.
2 citations
TL;DR: The behavioural basis for the reduction in feeding caused by the formamidine pesticide chlordimeform was investigated in second‐instar larvae of the large cabbage white butterfly, Pieris brassicae L. Brassicae.
Abstract: The behavioural basis for the reduction in feeding caused by the formamidine pesticide chlordimeform was investigated in second-instar larvae of the large cabbage white butterfly, Pieris brassicae L. Normally, these caterpillars feed communally. On chlordimeform-dipped leaves (10-6 M-10-2 M) they rapidly became excited, locomotion increased and only unstable aggregations formed in which any feeding was usually transient. Over 24 h excitation declined, aggregations re-formed and feeding was resumed. However, between 24 and 30 h, on leaves treated with chlordimeform solutions of 10-4 M or greater, larvae dispersed again.
By altering the density of larvae on control discs a direct link was revealed between clump size and larval growth rates.
It is concluded that, in species which feed gregariously, interference with larval aggregation contributes significantly to chlordimeform's effects on feeding and its involvement in a sublethal control mechanism in the field is discussed.
Resume
Alteration du comportement d'agregation des chenilles de Pieris brassicae par le chlordimeforme
Un des effets subletaux du chlordimeforme, insecticide formamidine, est une reduction de la prise de nourriture, par suite de l'alteration du comportement. Celle-ci implique une action stimulant l'activite locomotrice du quatrieme stade de P. brassicae L., moins sensible aux effets sur l'alimentation. Le but de ce travail est d'examiner comment le chlordimeforme agit sur le comportement des chenilles du second stade. Des chenilles sur des feuilles trempees dans le chlordimeforme (10-6 a 10-2) sont vite excitees, leur deplacements s'accelerent et les groupements formes sont tous instables, l'alimentation y etant generalement ephemere. L'excitation se reduit au bout de 24 heures, le groupements se reforment, et l'alimentation reprend, bien que pour les concentrations ≥ 10-4 M, les chenilles aient ete encore dispersees entre 24 et 30 heures, au moment ou elles commencaient a s'alimenter sur les residus de chlordimeforme. La perturbation de la concentration des chenilles sur des disques temoins a montre une relation directe entre la taille du groupe et le taux de croissance larvaire.
Nous en avons conclu que chez les especes de lepidopteres qui consomment groupees, une interaction avec l'agregation larvaire contribue significativement a l'effet du chlordimeforme sur l'alimentation. La discussion porte sur les consequences pour la croissance et la survie larvaire, particulierement en ce qui concerne l'installation des chenilles neonates.
2 citations
Cites methods from "A method of computing the effective..."
...For each leaf dipping concentration, or 'dose', the percentages of larvae 'single' and in locomotion, corrected for the control response (Abbott, 1925) were regressed against time....
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03 May 2018
TL;DR: Three of the essential oils (sweet acacia, basil and star anise) showed high toxicity and were selected for the residuality test to mortality by contact with a surface of treated petri dish and glass jar, and revealed that diluted 7.5 μl and 205.0 μl of essential oils from three plants achieved a high mortality of the tested insects at 100% within 36 h after exposure to surface oftreated petri Dish andGlass jar respectively.
Abstract: The objective of the current study was to determine the fumigant toxicity of essential oils for control stored product insects pest. Essential oils from ten plant species currently found in Thailand: pine (Pinus Palustris), lemon grass (Cymbopogon citratus Stapf), peppermint (Mentha Piperita), citronella grass (Cymbopogon nardus Linn), sweet acacia (Acacia farnesiana), cinnamon (Cinnamomum verum J.S. Presl), sweet orange (Citrus sinensis Pers), basil (Ocimum basilicum L.), clove (Syzygium aromaticum L.), and star anise (Illicium verum Hook) were extracted by steam distillation and tested for their insecticidal activities against maize weevil (Sitophilus zeamais Motshulsdy). Fumigant toxicity test was evaluated on adult of the maize weevil under laboratory conditions. Mortality of the maize weevil was observed and recorded every 12 h until 72 h. Responses varied with the test applied 100 and 10 μl of essential oils from the ten plants species on the tested insects. Three of the essential oils (sweet acacia, basil and star anise) showed high toxicity and were selected for the residuality test to mortality by contact with a surface of treated petri dish and glass jar. The results revealed that diluted 7.5 μl and 205.0 μl of essential oils from three plants (star anise, basil and sweet acacia) achieved a high mortality of the tested insects at 100% within 36 h after exposure to surface of treated petri dish and glass jar respectively.
2 citations
Cites methods from "A method of computing the effective..."
...As the mortality rate in the control was lower than 5%, this was corrected with the Abbott formula (Abbott, 1925)....
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TL;DR: The aqueous fruit extracts of the pepper Capsicum annuum L. annuum were very effective against the larvae of T. absoluta, and highly significant differences existed between the time of exposure and the concentrations under study.
Abstract: The aqueous fruit extracts of the pepper Capsicum annuum L. (Solanales: Solanceae) were tested against the four larval stages of the tomato leafminer (TLM) Tuta absoluta Povolny (Lepidoptera: Gelechiidae). Random samplings were made from two greenhouses of Biskra, in the Southeast of Algeria. About 750 to 800 plants of the Sahara variety of tomatoes were planted in both greenhouses. In the laboratory, conditions with temperature, relative humidity (RH) and the photoperiod were 25° to 30°C, from 50% to 60% and 16L: 8D, respectively. A breeding of our species in the laboratory was made during six months of the study. For the toxicological assessments, three concentrations were chosen; 50 mg/L, 100 mg/L and 200 mg/L of the extracts. The results revealed that the extracts of C. annuum were very effective against the larvae of T. absoluta. After 24 h post-treatment, the mortality was less than 25% compared to that after 48h and 72h post-treatment which exceeded 50%. There was a non-significant difference in mortality rates between the four larval stages (F3, 140 = 1.12; P = 0.344). In contrast, highly significant differences existed between the time of exposure (F2, 141 = 26.2; P = 0.001) and the concentrations under study (F3, 140 = 59.6; P = 0.001).
J. bio-sci. 26: 25-30, 2018
2 citations
01 May 2019
TL;DR: Pupae of B. zonata more tolerable than that of C. capitate to Glory 5%EC (lufenuron), Marisol 1.8% EC (abamectin) surpassed the other tested compounds at LC50 and LC90, respectively, while pupae of P. capitata showed tolerance level to the two insecticides by 7.78, 14.16 and 6.47 fold, respectively.
Abstract: The full grown larvae and pupae of 3-days oldof both Bactrocera zonata and Ceratitis capitata were sandy-soil-treated under laboratory conditions with five different insecticides to determine their comparative toxicity. The toxicity of the used compounds differently varied against the 3rd larval instar of B. zonata, where Marisol 1.8% EC (abamectin) surpassed the other tested compounds at LC50 (5.343 µl/L), while Opal 5%EC (lufenuron) was the most effective insecticide against the 3rd larval instar of C. capitata showing the lowest value of LC50 of 11.299 µl/L. Respecting to the three-day old pupae of the two tested species, Marisol 1.8%EC was the most potent compound at LC50 (395.461 µl/L for B. zonata and 151.373 µl/L for C. capitate). The full grown larvae of B. zonata were the most susceptible to Heater 3%SC (lufenuron+emamectin benzoate) and Marisol 1.8%EC at both LC50 and LC90, where those of C. capitata showed tolerance level to the two insecticides by 7.78, 14.16 and 6.02, 8.47 fold at LC50 and LC90, respectively. But, pupae of B. zonata more tolerable than that of C. capitate to Glory 5%EC (lufenuron), Marisol 1.8%EC and Cymax 5%EC (lufenuron) at LC50 and LC90 by 5.54, 2.61, 1.87 and 8.29, 2.32, 3.28 fold, respectively.
2 citations
Cites methods from "A method of computing the effective..."
...4- Statistical Analysis The observed mortality was corrected with Abbott’s formula (Abbott, 1925) and plotted against concentrations as log/probit regression lines....
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...The observed mortality was corrected with Abbott’s formula (Abbott, 1925) and plotted against concentrations as log/probit regression lines....
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...4- Statistical Analysis The observed mortality was corrected with Abbott’s formula (Abbott, 1925) and plotted against concentrations as log/probit regression lines. LC50 and LC90 values as well as the slope of the toxicity lines were calculated using Ld-p Line® software. [http://embakr. tripod.com/ldpline/ldpline.htm]. Toxicity index was obtained by comparing the efficiency of different insecticides at LC50 and LC90 with that of the highly potent compound according to the equation of Sun (1950)...
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