Toxicity and side effects of three insecticides on adult Chrysoperla carnea (Neu.: Chrysopidae) under laboratory conditions

Green lacewing, Chrysoperla carnea (Stephens), is an important predator of arthropod pests such as aphids, psyllids, thrips and whiteflies. Toxicity of endosulfan, imidacloprid and indoxacarb was assessed on male and female C. carnea in the laboratory. Contact bioassays were carried out in glass Petri dishes. The LC50 values for indoxacarb, imidacloprid and endosulfan were 0.011, 0.053, and 0.343 g AI/L for males, and 0.019, 0.098 and 0.398 g AI/L for females, respectively. Males were more sensitive than females to all three insecticides. To assess the sublethal effects, using IOBC (International Organization for Biological Control) method, adults were treated with LC25 of each insecticide. Analysis of variance did not show significant differences among treatments regarding the developmental time of the first, second and third instars, pupae and sex ratio. Differences between treatments and control were significant regarding pre-oviposition, oviposition and post-oviposition periods, fecundity, fertility, longevity of male and female. Mean longevity for control, imidacloprid, endosulfan and indoxacarb were 30 ± 2.3, 24.3 ± 3.3, 21.3 ± 2.4 and 19.7 ± 1.4 days for males, and 36.9 ± 2.5, 31.8 ± 2.9, 27.7 ± 1.7 and 26.7 ± 2.6 days for females, respectively. The highest and the lowest rates of fecundity were 540 ± 49 and 206 ± 42 in control and indoxacarb, respectively. Based on the IOBC classification method, imidacloprid, endosulfan and indoxacarb were slightly harmful (%30 < Total Effect Index < %79) against adults. The adult stage was very sensitive to indoxacarb, imidacloprid and endosulfan. Hence, these insecticides should not be applied when the density of adults is high in the field

Assessment of Sieve Slope, Sieve Range and Fan Suction on Cleaning Efficiency and Loss Rate of Peanut Thresher

IntroductionPeanut (Arachis hypogaea L.) is an annual plant of the legume genus that is cultivated in 109 countries due to its high-quality oil and seed protein. In Iran, this crop is cultivated on an area of 3000 hectares, with an average yield of 4 tons per hectare. Threshing performance significantly affects seed loss and physical damage, including cracking and crushing of seeds during harvest. Therefore, over the last century, extensive research has been conducted on different types of threshing methods, as well as the design and development of various threshing machines.Research on seed crops such as cereals and seeds suggest that factors such as the rotational speed of the thresher, threshing-concave distance, feeding rate, and shape of threshing teeth play a crucial role in determining the threshing efficiency and quality of the threshed seeds. Although limited research has been conducted on peanut threshing, there are currently no combine-machines available for this crop on global markets. Therefore, this study aims to investigate several working parameters of an experimental peanut thresher, including the effect of sieve angle, sieve range of movement, and suction speed on the separation unit.Materials and MethodsThe relevant experiments were conducted in the Parsabad Moghan region of Ardabil province (latitude 39.65 North, longitude 47.91 East). To conduct the experiments and separate the seeds from the pods, we used a peanut threshing machine cultivar Nc2, which is commonly cultivated under agricultural conditions in Ardabil and Gilan Agricultural Research Centers.To achieve the aims of this research, we investigated several effective parameters in the performance of the machine, including sieve angle, sieve movement range, and fan suction speed, to obtain the best settings for maximum threshing performance and separation efficiency. It is worth noting that the average seed weight per kilogram of peanut plant was between 300-400 grams, and the moisture content of the seeds in the tested cultivar was 45%. Before using the machine, workers must first dig up the plants and place them on the ground in a coupe, after which another worker must feed the plants into the machine through the feeder.Results and DiscussionThe study found that changes in sieve angle, sieve movement range, and suction speed significantly affect the separation efficiency and peanut loss rate at a 1% significance level. Increasing the sieving angle leads to a higher speed of material movement on the sieve, which results in insufficient time for separating straw from the seed. Similarly, increasing the sieve movement range causes a rapid decrease in cleaning efficiency. To achieve better straw-seed separation, it is necessary to apply impact shocks to the products located on the sieve within a short period. However, as the range of movement increases, the time interval between impact shocks also increases, which disrupts the straw's separation from the seed.The study found that increasing the sieve range and suction speed leads to a higher rate of peanut loss. This is due to the fact that when the suction speed and sieve movement range are increased, the product spends less time on the sieve, which results in insufficient time for proper separation. Additionally, high speed may exceed the limit of peanut seed and cause it to move out of the machine with the straw. Increasing the sieve movement range leads to a more uniform movement of straw and seed on the sieve; however, achieving better separation of straw from the sieve requires dynamic shocks and sudden acceleration, which decreases as the sieve movement range increases. The optimal farm capacity and material capacity were achieved with a 5-degree slope at 0.55 hectares per hour and 509 kilograms per hectare, respectively, using a sieve range of 3.5 centimeters and a fan suction speed of 8 meters per second.ConclusionThe study concluded that the sieve movement range has the most significant impact on cleaning efficiency, while the sieve angle has the least effect. Similarly, the sieve movement range has the most significant influence on the rate of peanut loss, while the sieve angle has the least effect

Lethal and sublethal effects of endosulfan, imidacloprid and indoxacarb on first instar larvae of Chrysoperla carnea (Neu.: Chrysopidae) under laboratory conditions

The common green lacewing is an important natural enemy used for pest control in greenhouses. It is also very common in many agricultural systems. Hence, studying lethal and sublethal effects of insecticides on this predator would be useful. Toxicity of endosulfan, imidacloprid and indoxacarb was assessed on 1st instar larvae of Chrysoperla carnea (Stephens) in laboratory. Residual bioassays were carried out in glass Petri dishes. The LC50 values, for endosulfan, imidacloprid and indoxacarb were estimated 251, 24.6 and 133 mg ai/l, respectively. Imidacloprid was the most toxic among insecticides tested. To assess the sublethal effects, the 1st instars were treated with LC25 of each insecticide. Thereafter, these effects were studied using fertility life table experiments. The analysis of variance revealed significant difference between treatments and control with respect to developmental time of the 1st instar larvae. However, no significant difference was observed among endosulfan, imidacloprid and indoxacarb treatments considering the larval developmental time. Differences between treatments and control were not significant for the developmental time of the 2nd and 3rd instars, pupae, sex ratio, adult longevity, and adult fertility. The results showed that only net reproduction rate (R0) was significantly affected by treatments. The gross reproductive rate (GRR), intrinsic rate of increase (rm), doubling time (DT), mean generation time (T) and finite rate of increase (λ) were not affected. The highest and the lowest amounts of rm were 0.178 and 0.169 in control and indoxacarb, respectively. Imidacloprid was the most toxic of the insecticides tested on the 1st instar followed by indoxacarb and endosulfan. If results similar to laboratory findings are obtained in field conditions, these insecticides might be appropriate candidates for IPM programs

Lethal and sublethal effects of dinotefuran and thiamethoxam on the population growth parameters of the green lacewing, Chrysoperla carnea (Neu.: Chrysopidae), under laboratory conditions

The green lacewing, Chrysoperla carnea (Stephens), is a common natural enemy of various agricultural pestsand widely used as a biocontrol agent in integrated pest management (IPM) programs. The lethal and sublethal effects of the insecticides dinotefuran and thiamethoxam on the first instar larvae of C. carnea was assessed in the laboratory conditions at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16: 8 (L: D). The LC50 values for dinotefuran and thiamethoxam were 19.382 and 9.880 mg ai/l, respectively, that showed the high toxicity of thiamethoxam on the first instar larvae of C. carnea. To assess the sublethal effects, the first instar larvae were treated with the LC30 for dinotefuran and thiamethoxam at 3.532 and 1.692 mg ai/l, respectively. The estimated rm values in the control, dinotefuran and thiamethoxam were 0.185, 0.186 and 0.143 day-1, respectively. Finite rate of increase (λ) in the control, dinotefuran and thiamethoxam were 1.204, 1.204 and 1.154 day-1. Generation time and doubling time values in the control, dinotefuran and thiamethoxam were 30.77, 30.46 and 35.14 as well as 3.73, 3.72 and 4.82 days, respectively. The gross and net reproductive rates in the control, dinotefuran and thiamethoxam were 459.89, 439.08 and 309.42, and also 298.01, 278.45 and 155.03 (female/female/generation), respectively. Dinotefuran caused no significant adverse effects on the population growth parameters of C. carnea. If similar results are obtained for dinotefuran in the field, it might be an insecticide with low toxicity to C. carnea by using the reduced doses of the insecticide in IPM context. Studies under the laboratory conditions can help us to select some insecticides for additional studies under more natural conditions and for application of suitable insecticides along with natural enemies in pest management

Effects of imidacloprid, indoxacarb and endosulfan on egg, third-instar larva and pupa of green lacewing Chrysoperla carnea (Neu.: Chrysopidae)

The common green lacewing is a known biocontrol agent because of its wide geographical distribution, high compatibility with different agricultural systems, high searching ability and ease of rearing. Adults and larvae were reared on artificial diet and eggs of Anagasta kuehniella (Zell.) respectively. The toxicity of insecticides was assessed on eggs (dipping method), third-instar larvae (contact method), and pupae (topical application) of Chrysoperla carnea Stephens. In order to study the sublethal effects, the third-instar larvae were treated with recommended field rate of each insecticide. The effects of the insecticides were assessed using demographic toxicology methods. Rearing conditions were 26 ± 2ºC, 60 ± 10% relative humidity and a photoperiod of 16: 8 h (L: D). The results revealed that the insecticides did not affect eggs even at doses higher than recommended field rates. The LD50 values, of endosulfan, imidacloprid and indoxacarb for pupal stage were estimated to be 144, 33, and 21 µg ai/insect respectively. Since the insecticides did not affect the third-instar larvae at the recommended field rate, the LC50 was not estimated for this stage. The results showed that, only net reproduction rate (R0) was significantly affected by treatments. The highest and lowest amounts of rm were 0.176 and 0.152 for control and indoxacarb treatmnets respectively. Based on both acute toxicity and demographic toxicology methods, the rate of toxicity of the tested insecticides was as follows: indoxacarb > endosulfan > imidacloprid

Including cognitive aspects in multiple criteria decision analysis

"First Online: 21 December 2016"Many Multiple Criteria Decision Analysis (MCDA) methods have been proposed over the last decades. Some of the most known methods share some similarities in the way they are used and configured. However, we live in a time of change and nowadays the decision-making process (especially when done in group) is even more demanding and dynamic. In this work, we propose a Multiple Criteria Decision Analysis method that includes cognitive aspects (Cognitive Analytic Process). By taking advantage of aspects such as expertise level, credibility and behaviour style of the decision-makers, we propose a method that relates these aspects with problem configurations (alternatives and criteria preferences) done by each decision-maker. In this work, we evaluated the Cognitive Analytic Process (CAP) in terms of configuration costs and the capability to enhance the quality of the decision. We have used the satisfaction level as a metric to compare our method with other known MCDA methods in literature (Utility function, AHP and TOPSIS). Our method proved to be capable to achieve higher satisfaction levels compared to other MCDA methods, especially when the decision suggested by CAP is different from the one proposed by those methods.This work was supported by COMPETE Programme (operational programme for competitiveness) within project POCI-01-0145-FEDER-007043, by National Funds through the FCT – Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within the Projects UID/CEC/00319/2013, UID/EEA/00760/2013, and the João Carneiro PhD grant with the reference SFRH/BD/89697/2012.info:eu-repo/semantics/publishedVersio