Radio frequency plasma (RFP) could provide reliable, compact, cost-effective irradiation applications against insect pests of stored food and feed products. Sensitivity of red flour beetle Tribolium castaneum to RFP has been investigated using an irradiation applicator system with the two types of inert gases, argon (Ar) and helium (He), at 100 W for five exposure time levels of 0, 20, 40, 60 and 90 s, respectively. We demonstrated that He RFP was more efficient against T. castaneum than Ar RFP. In addition, a positive correlation was observed between mortality percentages of treated insect stages and exposure times for both He and Ar RFP. The adult stage showed the highest tolerance to RFP irradiation followed by larvae and pupae; however, it was more susceptible than larvae within 24 h after He RFP treatments. The optimum exposure time was 90 s with He RFP, where a full mortality at all tested stages was accomplished, while mortalities of 71.4, 65.3 and 36.7% were recorded for pupae, larvae and adult stage, respectively, after an Ar RFP treatment of 90 s. In case of treated adults, the reproduction rate was higher than treated larvae and pupae. Our findings indicated that He RFP was an effective method for inhibiting T. castaneum development and impacting the insect life cycle and could be considered a promising tool for pest control of stored food.

Purpose Objective of this study is the valorisation of mass rearing waste of fruit flies from sterile insect technique facilities by black soldier flies into high quality and quantity products as a sustainable utilisation concept. Methods Different ratios of medfly rearing waste in hen feed were used for rearing black solder fly (BSF) larvae. The growth rate and insect survival were determined. Moreover, the mass gains were determined and bioconversion rates were assessed. Furthermore, the nutritional compositions of BSF pupae were analysed to evaluate the product quality. Results The omnivorous BSF larvae were highly efficient at converting digested waste into body mass as compared to the control treatment (hen feed). High weight of pre-pupae was recorded for all experimental diets. The efficacy of larvae to reach pupae ranged from 92.5 to 98.5%, while the efficacy of pupae to reach adults ranged from 81.7 to 89.0%. All experimental diets exhibited high rates of prepupal weight, metabolism and efficiency of conversion of digested food. A nutritional analysis revealed that the protein and fat contents were high, while the bioaccumulation of heavy metals was low, Conclusion Medfly rearing waste is a potential feed ingredient for the production of BSF pre-pupae and could be applied to valorise this rearing waste into high-value feed. Graphical Abstract

SummaryThe cowpea beetle, Callosobruchus maculatus (Fabricius), is recognized as a common insect pest of cowpea worldwide. The present study aimed to evaluate the insecticidal activity of ozone gas against all life stages (egg, larva, pupa and adult) of C. maculatus at a concentration of 600 ppm (1.2 g/ m3) after 6 exposure times of 0.5, 1, 2, 3, 4 and 5 h under laboratory conditions. The mortality percentages of all life stages were significantly increased with increasing exposure time. Similarly, longer exposure time to ozone caused higher reduction of adult emergence from eggs, larvae and pupae. Treatment with ozone for 5 h caused egg mortality of 72.3%. Total mortality of adults was observed 5 days after treatment with ozone for 0.5 h. Moreover, treatment with ozone for 5 h resulted in 75, 100 and 94.1% reductions in adult emergence from eggs, larvae and pupae, respectively. The results also indicated that the larvae and adults were more susceptible to ozone gas than the eggs and pupae. Based on the findings, ozone showed promising insecticidal activity against all stages of C. maculatus and could be used as potential fumigant for management of this insect.

Fumigant activities for three essential oils; Garlic oil (Allium sativum L); Chili pepper (Capsicum annuum L.) and Nigella (Nigella sativa L.) were assessed at different concentrations against the adult and 20-days old larval stages of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in the laboratory. The accumulative mortality was observed at different exposure periods (3, 5 and 7 days). The residual effect of garlic oil that was the effective oil, on the treated wheat grains was evaluated with respect to histological changes in the liver, kidney, and stomach of rat fed on this treated wheat. The results showed that the mortality rates of treated stages increased with increasing the time of fumigation treatment. Moreover the highest essential oils toxicity at the Median lethal concentration (LC50) values for exposure periods (3, 5 and 7 days) to fumigation were (126, 53, and 47 mg/L air) for adult stage and were (79, 62, and 41 mg/L air) for larval stage, respectively in the case of Garlic oil treatment. While, the lowest essential oils effective was Nigella oil at the Median lethal concentration (LC50) values for exposure periods (3, 5 and 7 days) to fumigation were (3594, 629, and 335 mg/L air) for adult stage and were (1040, 416, and 227 mg/L air) for larval stage, respectively. The toxicity effect of various essential oils against adults and larvae of T. castaneum at the LC50at 7 days fumigation could be arranged in descending order as follows: Garlic oil, Chili pepper oil, and Nigella oil. The histological changes showed that the organs slightly affected at the fumigation for 3 days. It may be concluded that the garlic essential oil is the good effective fumigant to control T. castaneum in the stored products and it recommended that the fumigation period does not exceed 3 days. The garlic essential oil has the potential for applications in IPM programs for stored-grain pests because of its high volatility and fumigant activity and its safety.

This study was designed to characterize the combination of gamma-irradiation and food grade diatomaceous earth(Wolf Creek ranch, California, USA) as diatomaceous earth formulation (DE) treatment against three of stored product insect pests [Sitophilusgranarius(L), Triboliumcastaneum(Herbst.) and Rhyzoperthadominica,(F)]in the laboratory. The study was assessed the killing effect of γ-irradiation at 0,50,100 and 250 Gray against these pests. As well as 0, 0.5, 1.0 and 1.5 g/kg (w/w) concentrations of DE formulation alone or in combination with irradiation were assessed. The obtained results indicated that the mixing between two insect control methods had the combined advantages of quick speed of killing and a high level of safety. Where, the LT 50 have a wide range of values and the combined treatments of γ-irradiation and treatment with DE maybe were the most influencing factors reducing lifespan after treatments. In this laboratory study the combination between DE (1g/kg) and irradiated the tested pests with (100 Gy) of gamma ray produced a potentiation and additive interactions in the case of T. castaneumandR.dominica F adults, while the same combination produced an antagonistic interactionin the case of S. granariusadults. Our finding stated that the use of 'control method' γ-irradiation in conjunction with DE could be a feasible strategic component in Insect Pest Management; IPM in operational modality might be 'sequential' against the tested pests. That is to apply irradiation to eliminate existing census personnel. This is then followed by the addition of DE to the grain to prevent the re-infestation.