The stored grain insects cause great damage to grains under storage conditions. Synthetic insecticides and fumigants are considered as key measures to control these stored grain insect pests. However, the major issue with these chemicals is grain contamination with chemical residues and development of resistance by insect pests to these chemicals. Biological control is considered as a potential alternative to chemical control especially with the use of pathogens, alone or in combination with selective insecticides. The present study was conducted to evaluate the synergism of Metarhizium anisopliae with diatomaceous earth (DE) and thiamethoxam against four insect pests on the stored wheat grains. In the first bioassay, the M. anisopliae was applied at 1.4 × 10 and 1.4 × 10conidia/ml alone and in integration with two concentrations (250 and 500 ppm) of tested DE. The tested fungus when combined with DE and thiamethoxam possessed synergistic impact as compared to their individual efficacy. Adult mortality increased with respect to increased exposure interval and doses. In the second bioassay, M. anisopliae was applied at 1.4 × 10 conidia/ml individually and in combination with three concentrations (0.50, 0.75, and 1.00 ppm) of thiamethoxam. Results concluded that M. anisopliae integrated with DE and thiamethoxam provides more effective control of stored grain insect pests.
Drosophila suzukii Matsumura (Diptera: Drosophilidae) is an invasive pest in Europe and is a major threat to the soft fruit industry. Because of an ample temperature range, the pest spans from low to high elevation crops in mountain areas of the Southern Alps. Starting from field observations on the variable efficacy of insecticides under different temperatures, experiments were designed to test the efficacy of chemical families of insecticides available against this pest. Pyrethroids and spynosins proved to be the most effective under all temperature conditions (14, 22, and 30°C) in all assays. Organophosphates and neonicotinoids showed significantly lower efficacy at low temperatures, indicating that they are not suitable to protect crops under those conditions. The management of the pest in cold habitats, which are suitable for the cultivation of high-quality berries as for example in mountain farming systems, is constrained by a limited number of molecules available for fruit protection. Temperature has to be considered among factors affecting the decision-making process for the choice of registered formulations to be used in pest control.
Background
The demographic parameters of the predacious seven spotted ladybird beetle Coccinella septempunctata Linnaeus (Coleoptera: Coccinellidae) reared on the following four host aphid species were compared: Rhopalosiphum padi Linnaeus (Hemiptera: Aphididae), Rhopalosiphum maidis Fitch (Hemiptera: Aphididae), Sitobion avenae Fabricius (Hemiptera: Aphididae), and Schizaphis graminum Rondani (Hemiptera: Aphididae).
Methods
The developmental period, fecundity, adult preoviposition period, total preoviposition period and population parameters were evaluated based on the two-sex age-stage life table. The duration of the developmental stages and the population parameters were calculated with the TWOSEX-MSChart program, whereas population size was projected based on the two-sex age-stage life table data with the TIMING-MSChart program.
Results
The intrinsic rate of increase (r) was the highest in the R. padi predators (0.1946 per day), followed by the S. graminum (0.1435 per day), S. avenae (0.1400 per day), and R. maidis (0.1180 per day) predators. The differences in the net reproductive rate (R0) and the finite rate of increase (λ) when C. septempunctata was reared on the four aphid species were consistent with the r values. This trend was reversed for the mean generation time (T), which ranged from 29.02 days for the lady beetles reared on R. padi to 39.75 days for the lady beetles reared on R. maidis. Interestingly, R. padi was the most suitable host, while the congeneric R. maidis was the least suitable. The results of this study may be useful for future investigations regarding the ecological effects of predatory species and the mass-production of C. septempunctata in the laboratory for an augmentative release of an aphid predator.
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