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This paper proposes the design and optical evaluation of a solar dish collector with changeable structure using TracePro software with native conditions of Iran for solar dryers. The designed dish concentrator has a diameter of 1.5m. TracePro's goal is to design and evaluate complex optical systems. Modeling a parabolic concentrator in TracePro can be achieved using several methods. All segments of dish collectors are made of glass (perfect parabolic mirror with a reflection coefficient of 95%). In the ray-tracing simulations, the two cavity receiver model (cylindrical and semi-sphere) is added to study the influence of physical parameters of the cavity. The simulation result shows that semi-spherical receiver is better and it has got better optical performance. Thereby it is highly recommended for various types of solar dryers such as direct drying (solar box dryer), or indirect drying (solar cabinet dryer).

In this research work, the susceptibility of egg and four larval instars of Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae) to Insect Growth Regulators (IGRs) compounds (lufenuron 25% EC and fenoxycarb 25% WP) was determined. Different larval instar groups were separated by measuring the head capsule width and were used in all bioassays. The data were analysed with log-probit transformation using the SPSS software. The LC 50 for egg was determined by dipping egg masses in different concentration of either compound for 10 s, and LC 50 values for each group of larvae was estimated by using treated potato plants. The LC 50 values of lufenuron on egg, first, second and third instars of larvae were 682.65, 40.58, 47.83 and 261.38 ppm, respectively, and for fenoxycarb, these were estimated as 897.50, 35.60, 57.91 and 355.23 ppm, respectively. The LD 50 values of lufenuron and fenoxycarb on second instar larvae were 139.56 and 228.42 ppm, respectively.