scholarly journals Could biorational insecticides be used in the management of aflatoxigenic Aspergillus spp. and their insect vectors in stored wheat?

Author(s):  
Tiyyabah Khan ◽  
Ahmad Ali Shahid ◽  
Hafiz Azhar Ali Khan

Insect pests in stored wheat cause significant losses and play an important role in the dispersal of viable fungal spores of various species including aflatoxin producing Aspergillus spp. The problems of insecticide resistance in stored insects and environmental hazards associated with fumigants and conventional grain protectants underscore the need to explore reduced risk insecticides to control stored insects and the ultimate effect on fungal infection inhibition. The purpose of this study was to investigate the insecticidal potential of four biorational insecticides: spinosad, thiamethoxam, imidacloprid and indoxacarb on wheat against Rhyzopertha dominica and Sitophilus oryzae and the subsequent effect of insects’ mortality on Aspergillus flavus and A. parasiticus infection in grains. Spinosad and thiamethoxam were the most effective insecticides against R. dominica compared to S. oryzae followed by imidacloprid. Spinosad applied at 0.25, 0.5 and 1ppm and thiamethoxam at 2 and 4ppm concentrations resulted in complete mortality of R. dominica and >90% infection inhibition of A. flavus and A. parasiticus. However, indoxacarb was more toxic against S. oryzae compared to R. dominica. The mortality of R. dominica was directly related to the percent infection inhibition of A. flavus and A. parasiticus in all the treatments. Whereas, mortality of S. oryzae was only related to the percent infection inhibition of A. parasiticus in all the treatments. The results show that although both spinosad and thiamethoxam can provide protection against R. dominica and fungal infections in stored grains, more potent reduced risk insecticides and/or their combinations would be needed than either of these to provide broad spectrum protection of stored grains. In conclusion, the results of the present study provide baseline data for the management of aflatoxigenic fungi by controlling stored insects using biorational insecticides .

2015 ◽  
Author(s):  
Tiyyabah Khan ◽  
Ahmad Ali Shahid ◽  
Hafiz Azhar Ali Khan

Insect pests in stored wheat cause significant losses and play an important role in the dispersal of viable fungal spores of various species including aflatoxin producing Aspergillus spp. The problems of insecticide resistance in stored insects and environmental hazards associated with fumigants and conventional grain protectants underscore the need to explore reduced risk insecticides to control stored insects and the ultimate effect on fungal infection inhibition. The purpose of this study was to investigate the insecticidal potential of four biorational insecticides: spinosad, thiamethoxam, imidacloprid and indoxacarb on wheat against Rhyzopertha dominica and Sitophilus oryzae and the subsequent effect of insects’ mortality on Aspergillus flavus and A. parasiticus infection in grains. Spinosad and thiamethoxam were the most effective insecticides against R. dominica compared to S. oryzae followed by imidacloprid. Spinosad applied at 0.25, 0.5 and 1ppm and thiamethoxam at 2 and 4ppm concentrations resulted in complete mortality of R. dominica and >90% infection inhibition of A. flavus and A. parasiticus. However, indoxacarb was more toxic against S. oryzae compared to R. dominica. The mortality of R. dominica was directly related to the percent infection inhibition of A. flavus and A. parasiticus in all the treatments. Whereas, mortality of S. oryzae was only related to the percent infection inhibition of A. parasiticus in all the treatments. The results show that although both spinosad and thiamethoxam can provide protection against R. dominica and fungal infections in stored grains, more potent reduced risk insecticides and/or their combinations would be needed than either of these to provide broad spectrum protection of stored grains. In conclusion, the results of the present study provide baseline data for the management of aflatoxigenic fungi by controlling stored insects using biorational insecticides .


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1665 ◽  
Author(s):  
Tiyyabah Khan ◽  
Ahmad Ali Shahid ◽  
Hafiz Azhar Ali Khan

Insect pests in stored wheat cause significant losses and play an important role in the dispersal of viable fungal spores of various species including aflatoxin producingAspergillus parasiticus. The problem of insecticide resistance in stored insects and environmental hazards associated with fumigants and conventional grain protectants underscore the need to explore reduced risk insecticides to control stored insects with the ultimate effect on aflatoxin production. The purpose of this study was to investigate the insecticidal potential of four biorational insecticides: spinosad, thiamethoxam, imidacloprid and indoxacarb, on wheat grains artificially infested withRhyzopertha dominica/Sitophilus oryzaeand/orA. parasiticusspores, and the subsequent effect on aflatoxin production. Spinosad and thiamethoxam were the most effective insecticides againstR. dominicacompared toS. oryzaefollowed by imidacloprid. Spinosad applied at 0.25–1 ppm and thiamethoxam at 2 and 4 ppm concentrations resulted in complete mortality ofR. dominica. However, indoxacarb was more toxic againstS. oryzaecompared toR. dominica. Wheat grains inoculated withR. dominica/S. oryzae+spores elicited higher aflatoxin levels than wheat grains inoculated with or without insecticide+spores. In all the treatment combinations containing insects, aflatoxin production was dependent on insects’ survival rate. In addition, thiamethoxam and imidacloprid had also a significant direct effect on reducing aflatoxin production. Aflatoxin levels were lower in the treatment combinations with any concentration of thiamethoxam/imidacloprid+spores as compared to wheat grains inoculated with spores only. Correlation analyses revealed highly significant and positive association between moisture contents/insect survival rate and production of aflatoxin levels, and insect survival rate and moisture contents of the wheat grains. In conclusion, the results of the present study provide baseline data on the use of biorational insecticides againstR. dominicaandS. oryzaeand subsequent effect on aflatoxin production.


2021 ◽  
Vol 90 (3 - Ahead of print) ◽  
pp. 119-129
Author(s):  
James Adebayo Ojo ◽  
Adebayo Amos Omoloye

Detailed information on insect pests of stored grains in Nigeria is lacking. A two-year survey was conducted to determine the species composition and abundance of insects associated with maize, millet, rice, sorghum and tamarind in eighteen locations across five agro-ecological zones in Nigeria. Sixteen coleopteran, lepidopteran and hymenopteran species were associated with stored products, with high species richness on cereal grains but low species richness on tamarind. Most of these insects are polyphagous on cereal grains, whereas the tamarind weevil Sitophilus linearis (Herbst, 1797) (Curculionidae), and Caryedon serratus (Oliver, 1790) (Chrysomelidae) were found only on tamarind in this study. The maize weevil Sitophilus zeamais (Motschulsky, 1758), rice weevil Sitophilus oryzae (Linneaus, 1763), lesser grain borer Rhyzopertha dominica (Fabricius, 1792) (Bostrichidae), rusty grain beetle Cryptolestes ferrugineus (Stephens, 1831) (Laemophloeidae) and red flour beetle Tribolium castaneum (Herbst, 1797) (Tenebrionidae) were most abundant on stored grains. The tamarind weevil, C. serratus and the sawtoothed grain beetle Oryzaephilus surinamensis (Linneaus, 1758) (Silvanidae) were most abundant on tamarind. The hymenopterans Theocolax elegans (Westwood, 1874) (Pteromalidae), Anisopteromalus calandrae (Howard, 1881) (Pteromalidae) and Cephalonomia waterstoni (Gahan, 1931) (Bethylidae) were the dominant parasitoids of larvae and pupae of the storage pests. Simpson index of diversity of insect species across locations ranged from low (0.63) to high (0.89).


Author(s):  
Tsehaynew Wubetu ◽  
Berhanu Hiruy

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.


Author(s):  
Dayami Laguna Ávila ◽  
Carlos Pupo Feria ◽  
Gladia González Ramírez ◽  
Alina Espeek González

Insects pest of stored grains. Impact on food security of Las Tunas municipality, Cuba Resumen Con el objetivo de determinar las especies de insectos plaga en granos almacenados para la obtención de información que contribuyan al manejo de sus poblaciones y minimizar las pérdidas que influyen en la seguridad alimentaria de la población, se realizó un estudio en la Unidad 639 de la Empresa Mayorista de Productos Alimenticios del municipio Las Tunas, Cuba, en el período de enero del año 2011 hasta diciembre del año 2013. En el estudio se colectaron e identificaron 26 especies de insectos plaga en las naves, distribuidas en 19 géneros y 12 familias, pertenecientes a tres órdenes, de ellas, 23 especies cosmopolitas y de amplia distribución en Cuba. Las principales especies de insectos plaga encontradas fueron Tribolium castaneum; Ahasverus advena; Bruchus pisorum; Sitophilus oryzae; Ephestia sp. y Liposcelis sp. El hospedante con mayor frecuencia de aparición de las especies de insectos plaga fue el arroz, seguido por el frijol y el chícharo. Palabras clave: almacenes; cereal; plagas Abstract In order to determine the species of insect pests in stored grains to obtain information that contribute to the management of their populations and minimize losses that influence the food security of the population, a study was carried out in Unit 639 of the Company Wholesaler of Food Products of the municipality Las Tunas, Cuba, in the period from January 2011 until December 2013. The study collected and identified 26 species of insect pests in the ships, distributed in 19 genera and 12 families, belonging to three orders, of which 23 species are cosmopolitan and widely distributed in Cuba. The main species of pest insects found were Tribolium castaneum; Ahasverus advena; Bruchus pisorum; Sitophilus oryzae; Ephestia sp. and Liposcelis sp. The host with the highest frequency of appearance of insect pests was rice, followed by beans and peas. Keywords:  Insect pests; storage; food safety.


2020 ◽  
Vol 17 ◽  
pp. 39-46
Author(s):  
S.K. Ajao ◽  
K.O. Popoola ◽  
S Mande ◽  
A Togola

The need to screen new rice genotypes for resistance to stored product insect pests is important to boost production and availability of rice for food security. Therefore, thirteen rice genotypes and varieties included ten interspecific rice genotypes from two crossed parents Oryza sativa (WAB 56-104) and Oryza barthii (IRGC 106107), the two parents and NERICA8 variety were collected from Africa Rice Center, International Institute of Tropical Agriculture (IITA) Ibadan, to examine their resistance level to infestation by Sitophilus oryzae L. and Rhyzopertha dominica F. The resistance of the varieties were assessed by artificial infestation with 12 unsexed adults each in 10 g of the rice varieties in four replicates under laboratory conditions of 26 ± 2oC temperature and 75 ± 5% relative humidity in a completely randomized design. Number of adult insect emergent, per cent grain damage, percent weight loss of infested samples and index of susceptibility were determined. Correlation analysis between nutritional contents of the varieties and infestation variables were also obtained. Results indicate differential responses of the two insects on the rice genotypes/varieties. The O. barthii parent was resistant, while the O. sativa parent was moderately resistant using the susceptibility index. Of the ten rice genotypes, G4, G3, G1, G7, G2, G10 and G9 were resistant in descending order, while G5 and G6 were moderately resistant, whereas only G8 was susceptible. NERICA8 was also found to be susceptible to infestation. In addition, the resistant grains had lower ash content. Modification in genetic variations and nutritional contents of new rice varieties may be a critical factor in insect resistant genotype pro-grammes to reduce post-harvest losses incurred by farmers. Keywords: Rice resistant genotypes; Rhyzopertha dominica; Oryzae sativa; Oryzae barthii; Sitophilus oryzae; susceptibility index


1980 ◽  
Vol 58 (9) ◽  
pp. 1524-1534 ◽  
Author(s):  
N. D. G. White ◽  
R. N. Sinha

The consequences of infestation of bulk-stored wheat by multiple species of insects were determined for 60 weeks at 30 ± 2 °C. Eight 204-L drums containing wheat at 15.5% moisture content were used as three distinct systems: (I) Control system (two drums), insect free; (II) RST system (three drums), infested with the grouping of Rhyzopertha dominica F., Sitophilus oryzae (L.), and Tribolium castaneum (Herbst); and (III) COT system (three drums), infested with the grouping of Cryptolestes ferrugineus (Stephens), Oryzaephilus surinamensis (L.), and T. castaneum. At triweekly intervals carbon dioxide, oxygen, temperature, grain moisture, seed damage, grain weight, dust weight, fat acidity values (FAV), seed germination, microflora, and the numbers of insects and the mite Tarsonemus granarius Lindquist were measured. Seeds died by week 15 and bacterial infection on them increased in all systems. The seed FAVs in the RST system peaked by week 30 and then declined steadily while these values were increasing continuously in the Control and levelling off in the COT systems. Insects multiplied exponentially for 6–15 weeks and then declined sharply or maintained oscillating populations; Sitophilus and Oryzaephilus were unable to survive in the presence of the other insects.


2014 ◽  
Vol 19 ◽  
pp. 76-83
Author(s):  
D.M. Mailafiya ◽  
Z. Dauda ◽  
M.M. Degri ◽  
B.G.J. Kabir ◽  
Y.T. Maina

This study investigated insect pest infestation of maize, millet, sorghum, rice and wheat grains traded in the three main markets namely Monday, Baga-Road and Custom-Park markets in Maiduguri, Borno state, Nigeria. Sampling lasted from January to June 2012. Samples per grain type, each weighing one kilogram, were obtained every two weeks from ten randomly selected traders per market. Each sample was sieved in the laboratory to recover all adult insects present, both at sampling and also after one month stay (laid out in a completely randomized design). In each market, Sitophilus zeamais Motschulsky and Rhyzopertha dominica (F.) followed by Tribolium castaneum Herbst, Sitophilus oryzae (Linnaeus), Trogoderma granarium (Everts) or Cryptolestes sp. were the insect pests commonly found attacking more (between two to five) grain types. Observed highest and lowest mean insect numbers were respectively by S. zeamais in maize grains (12.13 individuals in Monday market) and T. granarium in wheat grains (0.13 individuals in Baga-Road market). Results unveil that among three markets, higher mean total numbers of insects were present in maize, rice or wheat (18-33). For all grain types, the mean numbers of damaged grains were significantly higher in Monday (53-357) and Custom-Park (46-302) than in Baga-Road (17-109) markets. Furthermore, the mean total number of damaged grains across markets was significantly higher maize, followed by rice and wheat (55-231) than in other grain types (37-41). The implications of all these results on insect infestation of different cereal grain types sold in these markets are discussed.


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