Evaluation of spinetoram and spinosad for control of Prostephanus truncatus, Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum on stored grains under laboratory tests

Spinetoram and spinosad have been evaluated against certain stored-product insect pests with success but there are no data available on the comparison of the efficacy of these two novel compounds in stored grains. Thus, laboratory bioassays were conducted to compare spinetoram and spinosad as grain protectants against Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) adults, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) adults and larvae. Factors such as treatment (1 ppm spinetoram, 1 ppm spinosad, 0.1 ppm spinetoram + 0.9 ppm spinosad, 0.5 ppm spinetoram + 0.5 ppm spinosad, and 0.9 ppm spinetoram + 0.1 ppm spinosad), exposure interval (1, 2, 7, and 14 days), temperature (20, 25, and 30 A degrees C), and commodity (barley, maize, rye, and wheat) were evaluated. Progeny production was assessed after 60 days of exposure. Concerning temperatures, for P. truncatus adults, after 14 days of exposure, all adults were dead in treatments except of the case of spinosad alone at 20 A degrees C. Offspring emergence was completely suppressed in all treatments at 20 and 25 A degrees C. For R. dominica adults, after 7 days of exposure, the overall mortality ranged from 92.8 to 100 %. After 14 days of exposure, all adults were dead in all treatments of the combined use of spinetoram and spinosad at 25 and 30 A degrees C. Progeny production was completely suppressed in all treatments at 30 A degrees C. For S. oryzae adults, after 7 days of exposure, all S. oryzae were died at 25 and 30 A degrees C in all treatments except in the case of spinosad alone. Offspring emergence was very low in all treatments and temperatures except in the case of spinosad alone at 30 A degrees C. For T. confusum adults, after 1, 2, and 7 days of exposure, the overall mortality was low in all treatments and temperatures. Concerning commodities, for R. dominica adults, after 7 and 14 days of exposure, the overall mortality was > 97 %. Offspring emergence was very low in all commodities. For S. oryzae adults, after 7 and 14 days of exposure, the overall mortality was increased exceeding 91 % except in the case of spinosad alone 7 days after exposure in barley. Progeny production was high in barley and rye in all treatments. For T. confusum adults, after 7 and 14 days, the overall mortality was low in barley, rye, and wheat. No offspring emergence was recorded in all treatments and commodities. For T. confusum larvae, after 14 days of exposure mortality was further increased, but did not reach 100 % for any of the combinations tested. The results of the present study suggest that the simultaneous application of spinetoram and spinosad was generally equally effective with the use of either spinosad or spinetoram alone. Furthermore, the increase of dose of either compound resulted in the same mortality levels. Thus, no benefits were achieved when spinetoram and spinosad were used simultaneously on grains, regardless of the proportion of each ingredient. These issues should be seriously considered when control measures against stored-product insects are designed

Efficacy of spinetoram as a contact insecticide on different surfaces against stored-product beetle species

Contact toxicity of spinetoram was evaluated in laboratory bioassays on concrete, ceramic tile, galvanized steel, and plywood. The efficacy of spinetoram was assessed at dose rates of 0.025 mg (AI)/cm(2), 0.05 mg (AI)/cm(2), and 0.1 mg (AI)/cm(2) in two series of bioassays. The first series was conducted on concrete surfaces, with adults of Rhyzopertha dominica (F.), Sitophilus oryzae (L.), S. granarius (L.), Tribolium confusum Jacquelin du Val, Oryzaephilus surinamensis (L.), and Cryptolestes ferrugineus (Stephens). The second series was conducted at the same dose rates on all surfaces against adults of R. dominica, S. oryzae, and T. confusum. An equal number of dishes with and without food were used in both bioassay series. Mortality was assessed daily for 7 days for T. confusum and after this interval all live adults were removed and transferred to untreated surfaces with food and held under the same conditions. After the first week of daily evaluation, delayed mortality was evaluated 7 days later. For all the other species, mortality was measured after 5 days of exposure. The results of the first series of bioassays showed that T. confusum was the least susceptible to spinetoram-treated concrete surfaces. In contrast, all the other species were found susceptible, regardless of the dose and the presence of food. Regarding the comparison of different surfaces, our results illustrate that, with the exception of T. confusum, there were no significant differences among surfaces. The results of the present study indicate that spinetoram was effective against various species on several types of surfaces, and the presence of food did not influence its efficacy in most cases

Toxicity Of Some Terpenoids Of Essential Oils Of Xylopia Aethiopica From Cameroon Against Sitophilus Zeamais Motschulsky

The acute toxicity of essential oils from the whole fruit (EF) or from the fibres of the fruit (FF) of the local aromatic plants Xylopiα αethiopicα Dunal (Annonaceae) collected in north Cameroon was evaluated on Sitophilus zeαmαis adults. A concentration of 1 ml of essential oil per 100 g of maize seeds was tested to determine weevil mortality after 24 h of exposure. Under these conditions, the essential oil derived from both EF and FF of X. αethiopicα led to 100% mortality. In a second step, proportions of active compounds present in the oil of both EF and FF of X. αethiopicα were quantified. The toxicity of the four main compounds was tested against S. zeαmαis: α-pinene, β-pinene, -3-carene and terpinen-4-ol according to their proportion in the essential oil of the concerned plant part. β-pinene and terpinen-4-ol were responsible for 50% of the mortality at the proportion found in EF and FF essential oils respectively. When mixed, a synergic effect of the compounds was observed that restored the mortality percentage observed for the crude oil. It appears that X. αethiopicα essential oil could be a potential source of natural and low-cost insecticide to control storage pests

Insect Pest Management in Stored Grain

Once cereal grain is harvested and put into storage, it provides a resource for a range of insect pests of stored grain. With few exceptions, these insects rarely attack grain in the field before harvest, but once the grain is in storage there is a degree of inevitability that insect infestation will occur. This means that methods are needed to either disinfest grain or to protect it from infestation during storage. The aim of this chapter is to review recent advances in insect pest management in stored grain, ranging from methods that are well established to those that are still being evaluated. This topic has been the subject of considerable laboratory and field research as evidenced by the large and growing body of published studies. Resistance to phosphine resistance and various insecticides, as well as the phase-out of methyl bromide as an ozone-depleting substance, continue to be major drivers for research on management of insects in stored products. Other research has focussed on improving the basic understanding of various methods or ways of improving methods currently in use. Despite extensive research on a wide variety of chemical and non-chemical treatments, very few have been commercialised. Two examples are spinosad, which has been registered as a grain protectant, and sulfuryl fluoride, which is now available as a grain fumigant. The interest in non-chemical treatments, especially aeration cooling, is encouraging. In general, integrated pest management is seen as the goal of entomologists, requiring the strategic integration of multiple methods to provide maximum effect with minimal health and environmental risks. Some of the chemical and non-chemical treatments reviewed in this chapter have great potential to be used as part of an integrated approach