A laboratory-based study on interspecific interactions between two stored-grain insect pests

Our recent work on applications of near infrared spectroscopy (NIRS) to entomological problems is reviewed. Using an automated NIRS system to scan individual wheat kernels at the rate of 15 per minute, we were able to differentiate between uninfested kernels and kernels infested with late instar larvae of Rhyzopertha dominica, Sitophilus oryzae, or Sitotroga cerealella. The ability to rapidly scan individual kernels indicates potential for automated segregation of infested kernels from bulk grain. The automated NIRS system was used to differentiate uninfested wheat kernels, kernels infested with rice weevils, and kernels that contained rice weevils that were parasitized by Anisopteromalus calandrae. Being able to distinguish kernels containing parasitoids would be useful for quality control in commercial insectaries that rear biological control agents, and would be useful for research on natural enemies. The NIRS system was used to segregate samples of transgenic maize that contain low and high levels of the protein avidin. Avidin is toxic to a number of insect pests, and transgenic maize that contains a level of avidin that is toxic to insect pests of stored grain has been developed. A manual NIRS system was used to quantify insect fragments in flour. Although the sensitivity is not sufficient to detect insect fragments at the US Food and Drug Administration defect action level (75 fragments per 50 grams of flour), the technique is accurate at an action level of 130 fragments per 50 grams of flour and could be useful for prescreening large numbers of flour samples to select samples for more expensive and labour intensive chemical analyses. A manual NIRS system was used to identify stored product insect pests to species level. We were able to identify insects to genus with greater than 95% accuracy and to identify insects as being primary or secondary pests with greater than 99% accuracy. Ability to identify insects to species depended on the genus. This technology could be useful to pest managers who may not be familiar with insect taxonomy. The manual NIRS system was used to determine chronological age of two primary pests and one secondary pest of stored products.

Sulfuryl fluoride (SF), an effective structural fumigant, is registered recently as Profume™ for controlling insect pests of stored grains and processed commodities. Information on its effectiveness in disinfestation of bulk grain, however, is limited. The ongoing problem with the strong level of resistance to phosphine has been addressed recently through deployment of SF as a ‘resistance breaker’ in bulk storages in Australia. This paper discusses important results on the efficacy of SF against key phosphine- resistant insect pests, lesser grain borer, Rhyzopertha dominca, red flour beetle, Tribolium castaneum, rice weevil, Sitophilus oryzae and the rusty grain beetle, Cryptolestes ferrugineus. We have established CT (g-hm3) profiles for SF against these insect pests at two temperature regimes 25 and 30°C, that showed that both temperature and exposure period (t) has significant influence on the effectiveness of SF than the concentration. Over a seven days fumigation period, CTs of 800 and 400 g-hm3 achieved complete control of all the target pests, including the most strongly phosphine - resistant species, C. ferrugineus at 25 and 30°C, respectively. Results from four industry scale field trials involving currently registered rate of SF (1500 g-hm3) over 2–14 d exposure period, confirmed its effectiveness in achieving complete control of the target pest species. The assessment of postfumigation grain samples across all the test storages indicated that the reinfestation occurs after three months. Monitoring resistance to phosphine in C. ferrugineus over a six year period (2009–2015), showed a significant reduction in resistant populations after the introduction of SF into the fumigation strategy at problematic storage sites. Overall our research concludes that SF is a good candidate to be used as a ‘resistance breaker’ where phosphine resistance is prevalent.

Stored grain pest prevalence and insecticide resistance in Egyptian populations of the red flour beetle Tribolium castaneum (Herbst) and the rice weevil Sitophilus oryzae (L.)

Aim: To assess the status of the insect pests of stored wheat grains in Cheha destrict of Gurage Zone of Southern Ethiopia.
 Study Design: Peasant associations were selected purposefully based on intensity of wheat production, such that those peasant association growing wheat predominantly were selected for the survey, while villages, representative farmers and their storage systems were selected randomly using a nested design.
 Place and Duration of Study: Survey was conducted between 1, July to 30, December 2019 with the interval of one month in major wheat growing peasant associations of Cheha district of south central Ethiopia.
 Methodology: The assessment on abundance was made from of half kilogram of wheat grain sample taken from 135 randomly selected farmer’s storages of three peasant associations using taxonomic keys of books related to stored product insects.
 Results: Eight major species of insect pests consisting of four primary pests and four secondary pests belonging to five families with in two insect orders were documented. Of these pests recorded, Sitophilus oryzae, Sitophilus zeamais, Sitotroga cereallella, Tribolium castaneum and Tribolium confusum, respectively were the most prevalent and frequently occurring as they appeared between 12.74 and 33.78 individuals per 100 g of grain and as they occurred in the range between 77.78 and 92.26% per 100 g of sample wheat grain collected from the survey sites, respectively. These were followed by Cryptolestes ferrugineus, Cryptolestes pusillus and Rhyzopertha dominica which occurred between 7.26 and 10.74 individuals per 100 g of grain and in ranges between 51.85 and 66.67% per 100 g of sample wheat grain collected.
 Conclusion: The traditional methods and practices used by farmers were inefficient for sufficient wheat grains protection against insect pests in storages; this implies for the urgent need for designing management strategies for more effective and sustainable methods of control.

Resistance to phosphine (PH3) in key insect pests of stored grain is increasing, with a requirement for maintaining a dose as high as 1 mg l-1 for 14 d for effective fumigation, which is difficult to achieve under most commercial storage conditions. There is no suitable replacement for PH3, as most of the available alternatives suffer from specific weaknesses, creating an urgent need to increase the efficacy of this fumigant. One such possibility is co-fumigation of PH3 with another fumigant, sulfuryl fluoride (SO2F2-SF), with the goal of decreasing the time required for a successful fumigation. In this study, adult of two PH3-resistant strains in each of four key grain insect pests, Rhyzopertha dominica, (F.) (Coleoptera: Bostrichidae) Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), Sitophilus oryzae (L.) (Coleoptera: Curculionidae), and Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) were fumigated with PH3 and SF individually as well as in combinations at 25°C over 48 h. Mortality responses in each species were subjected to probit analysis to determine the LC50 and LC99.9 of PH3, SF, and PH3 + SF. Co-fumigation of PH3 with SF resulted in a 50% reduction of the PH3 concentration required to achieve 99.9% mortality in two pest species. For example, the PH3 + SF mixture, reduced the amount of PH3 required from 14.2-14.5 to 5.6-6.36 mg l-1 and from 2.71-5.03 to 0.93-1.2 mg l-1, respectively, for C. ferrugineus and S. oryzae. The overall mortality response to the PH3 + SF mixture followed an "additive model" suggesting that mutual enhancement in toxicity can be achieved with this mixture specifically to control PH3-resistant insects.

The present study has documented, for the first time in Egypt, the natural occurrence of four entomopathogenic protozoans (EPP) among five of the most abundant and damaging insect pests of stored grains or their products. These insect pests (Laemophloeus (Cryptolestes) turcicus (Grouvelle), Rhyzopertha dominica (Fabricius), Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst), and Plodia interpunctella (Hobner) were infesting lots of crushed-maize grains, wheat grains, and wheat flour, brought, in 2015, from El-Behera Governorate, Egypt. The morphological characteristics, including spore size, of the entomopathogen infective units, spores, of the isolated entomopathogenic protozoans, were closely fit with the description to the following genera: Mattesia, Farinocystis, Adelina, and Nosema. The prevalence of these entomopathogens ranged between 9 and 89%. This study seems to be the first report of Mattesia sp. on S. zeamais; Adelina sp. on L. turcicus or R. dominica, and the second report of Nosema sp. on R. dominica. The rate of natural infection by the neogregarine, Mattesia sp. (tentatively, M. dispora), was the highest in L. turcicus beetles (89%) followed by that in P. interpunctella moths (48%), larvae (40%), and pupae (32%) and then in S. zeamais weevils (42%) and R. dominica beetles with a low rate of infection (9%). The microsporidian entomopathogen, Nosema sp., (tentatively, N. whitei) was naturally occurred in 11% of the examined adult cadavers of R. dominica. The coccidian entomopathogen, Adelina sp., was found, respectively, in 60% and 27% of larval and adult cadavers of T.castaneum, while the Adelina-natural infection rates in R. dominica and L. turcicus adult cadavers were 34% and 14%, respectively. A high rate of natural infection with another neogregarine, Farinocystis sp. (tentatively, F. tribolii), has also been recorded in T. castaneum adult (50%) or larval cadavers (36%).

The insecticidal effect of four crude olive pomace oils extracted from pomace collected from four localities of Kabylia, refined olive pomace oil and extra virgin olive oil were assessed under laboratory conditions for the control of adults of Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrychidae)) and Sitophilus oryzae (Linnaeus, 1763) (Coleoptera: Curculionidae). The doses used ranged from 0.1 to 0.4 ml/25 g of durum and soft wheat seeds. In addition, the quality indices and the fatty acid composition of these oils were evaluated. The results show that the legal quality indices were well within the legal limits for crude olive-pomace oil (COP), refined pomace oil (ROP) and extra-virgin olive oil (EVO) categories. The effectiveness of these vegetable oils is highly dependent on the insect species, the dose rate, the exposure time and the type of oil tested The main fatty acids from all samples tested, were oleic (61.89–79.25%), palmitic (8.34–15.71%) and linoleic (8.17–16.52%) acids. For both species and substrates tested, mortality is dose and time of exposure dependent. The highest dose (0.4 ml/25 g) causes ≥ 63.75% mortality, after 24 h of exposure. Comparison of LD50 (ml/25 g) indicates that olive oil was generally more toxic than crude and refined pomace oils, for both insects and substrates, values varies from 0.005 to 0.189. The most sensitive insect was S. oryzae for most vegetable oils tested. Likewise, oils significantly reduced the F1 offspring of both insects and seed weight losses. No progeny were observed in the two pests at the highest dose, and therefore no weight loss was recorded. The results also revealed that the six oils affect the germination capacity of durum and soft wheat seeds when the dosage is increased. The results collected remain encouraging for the recommendation of natural substances as part of integrated pest management programmes against insect pests of stored grains.

Wheat, Yam, Cassava and Corn flour obtained during fortnightly interval for three months in Benin City, Edo State, were investigated for the occurrence and relative abundance of various insect pests. Six species of insect pests were recorded. They includes, Tribolium castaneum, sitophilus oryzae, Dinoderus porcellus, Oryzaephilus surinamensis, Araecerus fasciaculatus and tenebrioides mauritanicus. The infestation survey shows Trilobolium castaneun as a major pest of wheat flour. Other insect pests found are Tenebrioides mauritanicus and Dinoderus porcellus as indicated by their mean number and Percentage abundance of individual species in this study but Sitophilus oryzae does not thrive in wheat flour. Araecerus fasciaculatus is the major pest of yam and cassava flours while infestation of Tribolium castanuen in Corn flour was the highest. Oryzaephilus surinamensis and Sitophilus oryzae occur sporadically in flours. © JASEM

Insect pests impose considerable damage on stored grains and food products globally, leading to a decrease in their weight, quality, and market value. Historically, various herbs and spices, including turmeric, garlic, and cloves, have been utilized to control storage pests. The biological effects of essential oils were determined by various bioassays to measure their contact and fumigant toxicities, as well as their repellent properties. This study expected to determine the efficacy of essential oils from selected plants, such as Nigella sativa (black cumin), Syzygium aromaticum (clove oil), and Zingiber officinale (ginger), in repelling and killing two major insect pests of stored grains: the cowpea weevil (Callosobruchus maculatus) and the rice weevil (Sitophilus oryzae). The essential oils were extracted by decoction method, and ethylene was used as a solvent. The oils were applied individually to small pieces of Whatman No. 1 filter paper at dosages of 5, 10, 15, and 20µl/L of oil. Twenty insect pests were placed in Petri dishes, and the mortality rate for each treatment was recorded, with LC50 values calculated. Each experiment was replicated three times. The results directed that S. aromaticum exhibited a high mortality rate against both the cowpea weevil (300) and the rice weevil (300), with repellent effects observed at various concentrations (1, 5, and 10µl), which helps to prevent weevil invasion in stored grains and legumes. The mortality rate of the pests was directly related to the concentration of the essential oil. Essential oil extracts from Nigella sativa were important in controlling rice weevils (Sitophilus oryzae), while Syzygium aromaticum is active against cowpea weevils (Callosobruchus maculatus) due to the varied chemical components in their essential oils. Zingiber officinale showed reasonable insecticidal activity, but Syzygium aromaticum displayed greater repellent potential against both S. oryzae and C. maculatus.

The essential oil from the aerial parts of Lobularia maritima was investigated for its chemical composition, and its repellent and insecticidal efficacy against the grain pests Callosobruchus maculatus, Tribolium castaneum and Sitophilus oryzae. A number of 41 compounds were identified by GC-MS from which azeleonitrile (39.7%), trans-3-pentenenitrile (36.3%) and 4-isothiocyanato-1-butene (10.9%) were the most abundant. A fumigant bioassay-guided fractionation of the essential oil constituents led to the isolation of trans-3-pentenenitrile. Its structure was confirmed by EI-MS and NMR techniques. Fumigant effect of the essential oil was strong (LC50 = 7.48 μL/L) on C. maculatum and moderate on S. oryzae and T. castaneum (LC50 = 35.37 and 59.94 μL/L, respectively). trans-3-pentenenitrile showed strong fumigant effect on the three pest species (LC50 = 6.62–8.36 μL/L). Both the oil and trans-3-pentenenitrile showed strong contact effect with LD50 values in the range 4.84–7.81 µg/adult. The oil showed a repellency of 100% on C. maculatus and S. oryzae at concentrations higher than 0.05 and 0.1 nL/cm2, respectively, and 93% against T. castaneum yet at 0.2 nL/cm2. trans-3-pentenenitrile also showed 100% repellency against C. maculatus (≥ 0.05 nL/cm2), S. oryzae (≥ 0.15 nL/cm2) and T. castaneum (0.2 nL/cm2). The results in this study indicated that the essential oil of L. maritima is an important source of trans-3-pentenenitrile which can be used in the development of insecticidal agents against the three grain pests.

Sunflower seed hulls waste as a novel source of insecticidal product: Pyrolysis bio-oil bioactivity on insect pests of stored grains and products

The susceptibility of t'ef (Eragrostis abyssinica Schard.) to infestation by some insect pests of stored grain

Monitoring and early detection of stored-grain insect infestation is essential to implement timely and effective pest management decisions to protect stored grains. We report a reliable analytical procedure based on headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) to assess stored-grain infestation through the detection of volatile compounds emitted by insects. Four different fibre coatings were assessed; 85 µm CAR/PDMS had optimal efficiency in the extraction of analytes from wheat. The headspace profiles of volatile compounds produced by Tribolium castaneum (Herbst), Rhyzopertha dominica (Fabricius), and Sitophilus granarius (Linnaeus), either alone or with wheat, were compared with those of non-infested wheat grains. Qualitative analysis of chromatograms showed the presence of different volatile compound profiles in wheat with pest infestation compared with the wheat controls. Wheat-specific and insect-specific volatile compounds were identified, including the aggregation pheromones, dominicalure-1 and dominicalure-2, from R. dominica, and benzoquinones homologs from T. castaneum. For the first time, the presence of 3-hydroxy-2-butanone was reported from S. granarius, which might function as an alarm pheromone. These identified candidate biomarker compounds can be utilized in insect surveillance and monitoring in stored grain to safeguard our grain products in future.

The quality and quantity of rice as a source of food for most of Indonesian people are closely connected with the activity of insect pests in Warehouse. This study aims to determine the species and insect pests populations on Rice at Traditional and Modern Warehouse in Province of Gorontalo. The study used a survey method shelter/rice warehouse in Mootilango district, Boliohuto District, and Tolangohula district, Gorontalo province. Sampling was conducted in a purposive sampling is to take a sample of the suspected rice pests. Sampling was carried out 4 times with a time interval of 2 weeks. The research found six species of insect pests on rice commodities in Gorontalo regency consisting of 5 species of the order Coleoptera and 1 type of the order Lepidoptera. The results show that the identification of insect pests found are Sitophilus oryzae (Coleoptera; Curculionidae), Tribolium castaneum (Coleoptera: Tenebrionidae), Carpophilus hemipterus (Coleoptera: Nitidulidae) Oryzaephilus sp. (Coleoptera; Silvanidae), Ahasverus sp. (Coleoptera; Cucujidae), Corcyra cephalonica (Lepidoptera; Pyralidae). Average highest pest insect populations, respectively S. oryzae (54.60 individuals), Tribolium sp. (13.85 individuals), Oryzaephilus sp. (4.52 individuals), Ahasverus sp. (3.42 individuals), Corcyra sp. (2.42 individuals) and C. hemipterus (6.94 individuals), while the highest populations of insect pests found in traditional 16.40 modern warehouses 12.34 individual Keywords : insect pests, rice, traditional and modern werehouse

Protection 94 focusing on plant-derived materials as potential sources of commercial insect control agents and found the usefulness of several aromatic plant extracts and their active compounds or constituents.In spite of widespread public concern for the side effects of synthetic pesticides, the market share of biopesticides including botanical and microbial pesticides is less than 2.2% of the global pesticides market.However, the potential in market growth of botanical pesticides is very high because the use of many conventional insecticides has been restricted by lots of countries and these botanical pesticides as alternatives are likely to occupy the needs.This chapter briefly describes resistance to insecticides used for control economically important stored products insect pests, and the insecticidal and antifeeding activities of several plant extracts obtained by lots of laboratory studies.Although promising activities of various aromatic plant extracts could be presented, mainly discussed plants in this review are Acorus gramineus including several oriental medicinal plants, Cocholearia armoracia, and Origanum vulgare and targeted insects are S. zeamais, Callosobruchus chinensis, Lasioderma serricorne, and Attagenus unicolor japonicus.Based on these results, these plant extracts including essential oils and their active components could be potential candidates to be used in management programmes as naturally occurring insect-control agents. Resistance to insecticidesChemical insecticides to manage stored products insect pests have been used extensively in grain storage facilities.Methyl bromide, phosphine, and sulfuryl fluoride as fumigants showing rapidly killing effect have been being used in a food stuff or a storage house.In addition, malathion, chlorpyriphos-methyl, dichlorvos, diazinon and deltamethrin plus piperonyl butoxide as contact poisoners have been sprayed directly on contaminated grains or structures and provided protection from the infestation of insect pests for several months (Hargreaves et al., 2000).Why are people looking for alternatives to these effective chemicals?Among many reasons, the most important issue will be responsible for the widely developed resistance in a target insect population.Fumigation plays an important role in insect pest management in various stored products and currently, phosphine and methyl bromide are the two common fumigants used for protection world-widely (Rajendran & Sriranjini, 2008).Due to the internationally limited use of methyl bromide, the importance of phosphine in controlling coleopteran stored insects has relatively grown (Zettler & Arthur, 2000).This situation increased the frequency of its applications and resulted in higher selection pressure for phosphine resistance (Benhalima et al., 2004;Collins et al., 2002).Consequently, since FAO (Food and Agriculture Organization) carried out globally phosphine resistance between 1972 and 1973 years, there is a general increase in the frequency of resistant strains to phosphine over time (Table 1, Mills, 2001).Although the resistant level of these coleopteran insect pests to phosphine is different depending on both surveyed regions and targeted insect species, all the reports focusing on resistant problems showed that the resistant development is increasing.This indicates that the management strategies of resistance to phosphine must be developed.Most of all, we have to understand the phosphine resistance mechanism in these coleopteran insects to achieve the aim.Price (1984) suggested that the mechanism is the reduced uptake of phosphine and it is likely to be accepted because respiration is a good factor observing a physiological response of an www.intechopen.comToxicity of Aromatic Plants and Their Constituents Against Coleopteran Stored Products Insect Pests 95 insect to the environmental changes (Chaudhry et al., 2004).Pimentel et al. (2008) also reported that phosphine resistance in four coleopteran insect pests (T.castaneum, R. dominica, S. zeamais, and O. surinamensis) collected from 36 locations over seven Brazilian states is related to the reduced production of carbon dioxide.Comparing with the respiration rates between the most resistant and the most susceptible populations to the fumigant, the carbon dioxide production of the former is significantly (P < 0.05) lower than that of the latter.Similar results were obtained using R. dominica (Price, 1984), L. serricorne (Chaudhry et al., 2004), and some populations consisted of R. dominica, S. oryzae, and T. castaneum (Benhalima et al., 2004).Interestingly, uptake of a susceptible strain of T. castaneum exposed to 0.7 g/m 3 of phosphine for 5 hours at 25 ℃ was seven times more gas per gram than a resistant strain.These results strongly suggest that the lower phosphine uptake in resistant populations of coleopteran insects may be occurred and it may have been derived from the reduced respiration rate.However, to understand the fuller genetics of the resistance, it is important to study the most resistance strains available and also to develop and refine rapid resistance tests.These approaches are very useful for identifying resistance and allowing recognition of a problem or failure with a fumigation method.