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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

The insecticidal efficiency of Ag-loaded 4A-zeolite (ZAg) and its formulations with Rosmarinus officinalis essential oil (RO) was evaluated against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.). For comparison, different rates of ZAg (0.25, 0.5, 0.75, and 1 g ⋅ kg–1 wheat) were used solely and in a combination with LC50 concentrations of RO. Mortality was assessed after 7, 14, and 21 days of insect exposure to treated wheat. The progeny production was also evaluated. The use of ZAg accomplished a complete mortality (100%) on S. oryzae and 96.67% on R. dominica as well as 100% mortality of progeny against the two insect species after the longest exposing duration (21 days), at the highest rate (1 g ⋅ kg–1). On the other hand, the complete mortalities of ZAg formulations on S. oryzae were obtained after 14 d of treatment with F1 formulation (0.605 g ⋅ kg–1 RO + 0.25 g ⋅ kg–1 ZAg) and after 7 days with the other tested formulations. In addition, the complete mortality on R. dominica was obtained only by F8 (0.059 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulation after 14 days of treatment. Concerning the efficiency of the examined formulations on the progeny of S. oryzae, F1 (0.605 g ⋅ kg–1 RO + 0.25 g ⋅ kg–1 ZAg) and F2 (0.605 g ⋅ kg–1 RO + 0.5 g ⋅ kg–1 ZAg) formulations recorded 100% mortality. In addition, F3 (0.605 g ⋅ kg–1 RO + 0.75 g ⋅ kg–1 ZAg) and F4 (0.605 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulations suppressed the progeny production. Furthermore, the complete mortality of R. dominica progeny was obtained with F7 (0.059 g ⋅ kg–1 RO + 0.75 g ⋅ kg–1 ZAg) and F8 (0.059 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulations. ZAg, especially its formulations with R. officinalis oil, had potential effects against two stored-product insects. F1 and F8 formulations could be treated efficiently on S. oryzae and R. dominica, respectively.
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