(Brief report) Evaluation of Suitable Host Plant, as Banker Plant for Eretmocerus mundus, Whiteflies Parasitoid

Introduction: Whiteflies (Homoptera; Aleyrodidae) are the key pests of agricultural crops worldwide. Two species, which seriously damage crops, are the Silver leaf whitefly “Bemisia tabaci (Gennadius)” and the Greenhouse whitefly “Trialeorodes vaporariorum (Westwood)”. These pests are active on the underside of the leaves where they are relatively protected from insecticide. Moreover, emergence of resistant biotypes of whitelies impose much more costs on its chemical control. Therefore, during falling the past population, several researches have been carried out to find and use efficient biocontrol methods. One of the biocontrol agents to control B. tabaci is “Eretmocerus mundus” (Hy., Aphelinidae). The parasitoid should be introduced to control pest in the greenhouses. One of the methods, which is used in introducing of biological control agents, is ‘Banker Plant System’. In this system, the host plant has a population of reproducing natural enemy used as a reservoir. Therefore, as soon as the pest infection occurs, the parasitoids can find them and control the damage. İn a banker plant system, several aspects should be considered. Some of the behavioral and biological aspects are important. For example characteristics of leaf surface influence on the host finding time of the parasitoid. The biochemical characteristics of the host plants affect the parasitoid fitness. Therefore, we tried to compare these aspects of E. mundus in two host plants (eggplant and cotton) from banker plant point of view, to control B. tabaci in the greenhouses. Materials and Methods: The two host plants (eggplant and cotton), were planted in the greenhouse and a culture of B. tabaci was reared on the plants. After two weeks, some of the infested plants were put in separate cages, and the parasitoid, E. mundus, that was collected from the egg plant and cotton fields of the Varamin region were released on the plants. Then, the biological characteristics of the parasitoid were evaluated on the two different host plants. The sex ratio was recorded in two different ways; 1) 100 pupae developed on each plants were put in vials, and 2) the wasps that emerged daily from collected leaves. In the next experiment, a leaflet of each host plant (2.5 3 cm), that was infested with the second and third stages of B. tabaci), was fixed upside down on a piece of wet cotton in a Petri dish. Then, a female parasitoid was release on each to record the host finding time for one minute. Finally, the four female parasitoids were released on an infested host plant for 48 hours, then the wasps were removed and the plants were kept in a climate room. Two weeks later, the leaves were collected and put up side down on cotton pieces in Petri dishes and the duration of the larval stages, the mortality and the number of females and males that come out from them were recorded for the two hosts. Results and Discussion: In total, 438 wasps form the eggplant leaves and 297 from cotton leaves were collected, while 14 and 17 dead pupa were recorded on them, respectively. The data analysis did not show significant differences between them. In host finding experiment, 9 of 15 parasitoids could find the host during one minute on the eggplants leave, whereas, all female parasitoids could find the host on cottons leave, which was significantly different (P value of Fisher's exact test= 0.01689). In the biology parameter experiments on leaves, 192 parasitoid wasps form cotton and 158 from eggplant leaf were collected that were not significantly different (F=5.6; p=0.026). In contrast, on whole plant experiment, 156 wasps (76 females and 80males) from cotton plants and 134 wasps (66 females and 68 males) from eggplants were collected that were not significantly different (f=1.2; P= 0.32). Conclusion: The results showed that the number of parasitoid and the sex ratio were not significantly different between two host plants, whereas the movement and searching activity of the parasitoid were better on cotton than eggplant. Base on the results and all of the factors that were considered in this work, eggplant could be a good host in a banker plant system for Bemisia tabaci and its parasitoid Eretmocerus mundus

Perfomance investigation of thresher T30 at threshing some common wheat varieties

Introduction: In many rural areas, manual threshers are still in use because of the small farming units. However, research sections, have been used manual threshers particularly in breeding unites in many cases due to the low volume of crop. Manual threshers for the first time were manufactured by Iran Ashtad Cooperative in two models (T25 and T30) and then they were made available to the farmers across the country. The threshers due to having wire loop drum had a good performance for threshing rice crop. According to the mentioned application, manual threshers expected to have been capable of threshing wheat crop. A type of this thresher (modelT30) was available in University of Mohaghegh Ardabili. Therefore, It was decided that the performance of this thresher was assessed at threshing some common wheat varieties in Ardabil province. Effects of drum speed levels (800, 900 and 1000 rpm) of threshing unit of john deere combine (model 955) on damaged grains percent showed that the minimum of this dependent factor was obtained at two levels of drum speed 800 and 900 rpm, clearance between drum and concave 25 mm and forward speed 1.8 km.h-1 (Lashgari et al., 2008). Research performed by Vejasit and Salokhe (2004) on a axial flow thresher revealed that the threshing efficiency can be 98 to 100% at tests for soybean, drum speed 600 to 700 rpm, feed rate 540 to 720 kg h-1 and grain moisture content 14.34 to 22.77 w.b.%. Alizadeh and Khodabakhshipour (2010) found at moisture content 17 to 23 w.b.% and drum speed 450 to 850 rpm at test of an axial flow thresher on paddy, ,the most damaged grains percent obtained at the most level of drum speed 850 rpm and the least level grain moisture content 17 W.b.%. Threshing losses due to mechanical damaged wheat grains during threshing process were reported 5.0, 8.1, 10.0 and 19.9% at tests at drum speed 800, 900, 1000 and 1100 rpm, respectively, by King and Riddols (1962). The results of research reported by Mitchell and Roundthwaite (1964) on investigation of two varieties of wheat resistance at grain moisture content 15 to 25 w.b.% and drum speed levels 17 to 36 m s-1 showed that damaged grains percent mean were 94.8 and 86.8 % at tests at the least and most drum speed levels. Materials and Methods: The tests were accomplished with three varieties wheat (Azar2, Sardari and Rasad), three speed drum levels (400, 500, 600rpm) and three feed rate levels (600, 900, 1800 kg h-1). Grain moisture content varied from 12 to 13 w.b. %. For supplying requirement powerof thresher, AMitsubishi diesel motor (13.5 hp) was used. Preliminary tests on these wheat varieties showed that this thresher did not have desired threshing efficiency. Therefore, it was decided to use of a concave with less curvature radius. So that the minimum distance between the drum and concave was 6 mm. For adjustment of drum speed, a digital tachometer (Lutron DT-2236) was used some pulleys were used for transmission power from engine to drum shaft, The weight of each sample was 1 kg. To create different levels of feed rate, crop feeding times were considered 2, 4 and 6 seconds. The factorial experiment in a randomized complete block design has been used for analyzing data, Data mean comparison was done by Duncan's Multiple Test. Results and Discussions: The results of analysis variance showed that effects of variety of the drum speed and feed rate were significant on threshing losses. Damaged grain percent was negligible. The results of mean comparison showed that the most (15.632%) and the least (4.154%) threshing losses obtained at tests on Azar2 and Rasad varieties, respectively. As increasing feed rate from 600 to 1800 kg h-1, threshing losses was decreased significantly. It was due to clusters compression at between drum and concave. The results of mean comparison of triplet interactions showed that the lowest threshing losses (0.147%) obtained at tests on Rasad variety, feed rate of 600 kg h-1 and rotational speed drum level of 600 rpm. the highest threshing losses (39.387%) obtained at tests on Azar2 variety, feed rate 1800 kg h-1 and rotational speed drum level of 400 rpm. Conclusions: 1. Modified thresher was not able to thresh Azar2 variety. But it was able to thresh Sardary and Rasad wheat varieties with desirable threshing efficiency. 2. According to low and high threshing losses at tests on Rasad and Azar2 varieties, respectively, It must be conclude that shattering of Rasad variety is very high. 3. Damaged grain percent was negligible at test on each three varieties

Knowledge Transfer Genetic Programming with Auxiliary Population for Solving Uncertain Capacitated Arc Routing Problem

The uncertain capacitated arc routing problem is an NP-hard combinatorial optimisation problem with a wide range of applications in logistics domains. Genetic programming hyper-heuristic has been successfully applied to evolve routing policies to effectively handle the uncertain environment in this problem. The real world usually encounters different but related instances due to events like season change and vehicle breakdowns, and it is desirable to transfer knowledge gained from solving one instance to help solve another related one. However, the solutions found by the genetic programming process can lack diversity, and the existing methods use the transferred knowledge mainly during initialisation. Thus, they cannot sufficiently handle the change from the source to the target instance. To address this issue, we develop a novel knowledge transfer genetic programming with an auxiliary population. In addition to the main population for the target instance, we initialise an auxiliary population using the transferred knowledge and evolve it alongside the main population. We develop a novel scheme to carefully exchange the knowledge between the two populations, and a surrogate model to evaluate the auxiliary population efficiently. The experimental results confirm that the proposed method performed significantly better than the state-of-the-art genetic programming approaches for a wide range of uncertain arc routing instances, in terms of both final performance and convergence speed

Guided Subtree Selection for Genetic Operators in Genetic Programming for Dynamic Flexible Job Shop Scheduling

© 2020, Springer Nature Switzerland AG. Dynamic flexible job shop scheduling (DFJSS) has been widely studied in both academia and industry. Both machine assignment and operation sequencing decisions need to be made simultaneously as an operation can be processed by a set of machines in DFJSS. Using scheduling heuristics to solve the DFJSS problems becomes an effective way due to its efficiency and simplicity. Genetic programming (GP) has been successfully applied to evolve scheduling heuristics for job shop scheduling automatically. However, the subtrees of the selected parents are randomly chosen in traditional GP for crossover and mutation, which may not be sufficiently effective, especially in a huge search space. This paper proposes new strategies to guide the subtree selection rather than picking them randomly. To be specific, the occurrences of features are used to measure the importance of each subtree of the selected parents. The probability to select a subtree is based on its importance and the type of genetic operators. This paper examines the proposed algorithm on six DFJSS scenarios. The results show that the proposed GP algorithm with the guided subtree selection for crossover can converge faster and achieve significantly better performance than its counterpart in half of the scenarios while no worse in all other scenarios without increasing the computational time