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Abstract

Biological parameters of the larval parasitoid Cephalonomia tarsalis (Ashmead) (Hymenoptera : Bethylidae) and its host the saw-toothed beetle Oryzapehilus surinamensis (L.) (Coleoptera : Silvanidae) were studied in the laboratory. The duration of the immature period, survival during development, as well as adult longevity and the number of progeny of both insects were recorded. Our data were used for the estimation of several demographic parameters and life table construction of both the host and the parasitoid. The wasp managed to complete its development (egg – adult) in 19.8 days at 25oC, whereas the adult female lived for 24.3 days. The host O. surinamensis demonstrated a longer developmental period (30.5 days) and adult female longevity (103.0 days). Female wasps laid an average of 66.4 eggs throughout their lifetime whereas their beetle hosts laid five times more eggs (313.9). Life table parameters of C. tarsalis were estimated for the first time. The intrinsic rate of natural increase (rm) was 0.124 which was almost double that of its host (0.056). Our results are discussed on the basis of evaluating and improving the performance of C. tarsalis as a biocontrol agent against O. surinamensis in storage facilities.
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Abstract

Control failure of pests and selectivity of insecticides to beneficial arthropods are key data for the implementation of Integrated Pest Management (IPM) programs. Therefore, the aim of this study was to assess the control failure likelihood of Plutella xylostella and the physiological selectivity active ingredients to parasitoid Oomyzus sokolowskii (Hymenoptera: Eulophidae) and to predators Polybia scutellaris (Hymenoptera: Vespidae) and Lasiochilus sp. (Hemiptera: Anthocoridae). In bioassays, P. xylostella larvae and O. sokolowskii, P. scutellaris and Lasiochilus sp. adults were used. Concentration-mortality curves of six insecticides for P. xylostella were established. These curves were used to estimate the mortality of P. xylostella at the recommended concentration, in order to check a control failure of insecticides to this pest. Furthermore, the lethal concentration for 90% of populations (LC90) and the half of LC90 were used in bioassays with the natural enemies to determine the selectivity of these insects to insecticides. All tested insecticides showed control failure to P. xylostella, indicated by high LC90 and low estimated mortalities (less than 80%). The cartap insecticide was selective in half of LC90 to Lasiochilus sp. and moderately selective in LC90 and the half of LC90, to Lasiochilus sp. and P. scutellaris, respectively. Deltamethrin was moderately selective in the half of LC90 to predator Lasiochilus sp. Cartap, carbaryl, and deltamethrin reduced the mortality of Lasiochilus sp. in the half LC90. The results also showed that the insecticides methamidophos, carbaryl, parathion methyl and permethrin were not selective to any of the tested natural enemies. The role of insecticides in IPM systems of Brassica crops is discussed based on their control failures to P. xylostella and selectivity to their natural enemies.
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Abstract

The use of suitable mass rearing methods is crucial to establish successful inundative or inoculative biological control programs. The development of an artificial diet considerably reduces costs of mass rearing. In this study, the efficacy of a new meridic artificial diet for rearing the predatory bug, Orius albidipennis (Het., Anthocoridae), was studied. The artificial diet was composed of some natural materials including lamb liver, hen yolk, whey protein, honey, royal jelly and some specific vitamins. To determine the artificial diet efficacy life table parameters of the bugs, using the two-sex life table method, fed artificial and factitious diets, Ephestia kuehniella egg + date palm pollen, were compared. Results showed that O. albidipennis could complete its life stages and reproduce when reared on the recommended artificial diet. However, its fecundity and survival rate when fed the artificial diet was lower than the controls. Overall, due to lower production costs the artificial diet can be recommended for mass rearing of O. albidipennis despite the lower fecundity and survival rate.
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