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Weevil infestations cause post-harvest losses and have become important constraints to storage entomology and food security in Nigeria. The present study is aimed at assessing the efficacy of Azadirachta indica-treated storage materials against Sitophilus zeamais and Sitophilus oryzae. Storage materials such as bagco bags, calico bags, and plastic containers were treated with different concentrations (0.5, 1.0, and 1.5mg/ml) of A. indica oil. Untreated storage materials served as the control. These treatments were replicated three times following a completely randomized design in the laboratory and monitored for 100 days. The results showed a significant decrease (p<0.05) in weight loss of infested maize and rice grains with different concentrations of the extract and with the different storage materials compared to the control. The highest weight loss among the treatment concentrations across all the storage materials treated with Azadirachta indica was recorded for rice grains stored in calico bags at 0.5mg/ml with mean value of 10.61±0.37 and7.12±1.41 for maize grains, while the least value of 1.14±0.09 was recorded for rice grains stored in plastic containers at 1.5mg/ml and 0.75±0.21 was recorded for maize grains stored in plastic containers at 1.5mg/ml. there was a significant increase (p<0.05) in mortality of S. zeamais and S. oryzae with increased concentrations of the extracts compared to the control. There was no significant increase in mortality of S. zeamais and S. oryzae compared with the storage materials. The highest mortality for S. oryzae 8.00±0.58 was seen in rice grains stored in plastic containers at 0.5mg/ml concentration and least mortality 4.00±0.58 was seen in those stored in bagco bag at 1.0mg/ml concentration. For S. zeamais, there was no significant increase on the mortality of S. oryzae between 0.5mg/ml and 1.0mg/ml concentrations in A. indica treated bagco bags and between 1.0mg/ml and 1.5mg/ml concentrations in A. indica treated plastic containers. S. oryzae in maize grains stored in plastic containers at 1.0mg/ml had the highest mortality 9.00±1.53 and the least mortality (3.00±0.00) was recorded for S. zeamais in maize grains stored in calico bag at 0.5mg/ml of A. indica treated materials. Results of the storage materials (Bagco bag, Calico bag, and Plastic container) treated with Azadirachta indica leaves extract showed significant decrease (p<0.05) in adult emergence of S. zeamais and S. oryzae in the different concentrations of extracts compared to the control. There was no significant decrease among the A. indica treated storage materials for S. zeamais and S. oryzae emergence. The highest S.oryzae emergence in A. indica treated bags was recorded for S. oryzae stored in Bagco bag at 1.0mg/ml with mean value of 177.67±9.21 and the least value of 107.33±3.76 was recorded for S. oryzae infesting rice grains stored in plastic containers at 1.5mg/ml. There was a significant decrease (p<0.05) in the number of holes bored by S. zeamais and S. oryzae in maize and rice grains treated with Azadirachta indica leaf extract compared to control across various concentrations and storage materials. The highest number of holes bored by S oryzae 390.00±28.22 in infested rice grains was recorded in Calico bag at 0.5mg/ml concentration and the least was recorded in plastic containers at 1.5mg/ml concentration (134.67±11.26). Similar trends were observed with Weevil perforative index and percentage damage. The study concludes that bagco bags treated with A. indica at 1.5mg/ml are more effective for protection of maize and rice grains in storage. [ABSTRACT FROM AUTHOR]

Compounds with insecticidal properties from plant essential oils are an alternative to manage Sitophilus zeamais. However, these compounds can affect physiological processes such as seed germination and plant growth. The objective was to evaluate the toxicity of the Cymbopogon flexuosus essential oil by fumigation to S. zeamais and its phytotoxic to Zea mays. The mortality of S. zeamais was 100% with the doses of 20, 30, 40 and 50 µL of the C. flexuosus essential oil per 20 g of grains. The lethal dose (LD50) of this essential oil was 9.3 µL and its lethal time (LT50) greater with the 10 µL (18.8 h) and lowest with that of 50 µL (0.02 h), respectively. The doses of 10 and 20 µL of the C. flexuosus essential oil did not reduce the seed germination and growth of corn plants. The essential oil of C. flexuosus is an alternative for the control of S. zeamais. [ABSTRACT FROM AUTHOR]

BACKGROUND: The application of allyl isothiocyanate (AITC) has been proposed as an alternative to control stored‐grain insects. However, AITC is a compound with a low diffusion coefficient, making its distribution throughout the grain mass difficult. Therefore, the objective of the present study was to evaluate the effectiveness of AITC applied in systems with or without recirculation for controlling Sitophilus zeamais (Mots. 1855) (Coleoptera: Curculionidae), Rhyzopertha dominica (Fabr.) (Coleoptera: Bostrichidae), and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) infesting a corn grain mass. The assays used a polyvinyl chloride (PVC) prototype, dimensioned 1.60 m in length, 0.30 m in diameter, and a static capacity of 60 kg of grains. AITC toxicity to insects was evaluated at the base, 0.5 m from the base, and top of the grain column (1.0 m). Different concentrations of AITC were tested for an exposure period of 48 h. RESULTS: In the system without AITC recirculation, insect mortality was verified only at the base of the grain column. However, insect mortality was considered uniform at the different positions of the column when the AITC recirculation system was adopted. In this system, there was also a marked reduction in the instantaneous population growth rate of S. zeamais, T. castaneum, and R. dominica, and a decrease in the dry matter loss of the grains, when the AITC concentrations were increased. CONCLUSION: AITC recirculation proved to be a viable strategy for protecting grains against the species S. zeamais, R. dominica, and T. castaneum. AITC fumigation ultimately did not cause changes in grain quality. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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In this paper, Sitophilus oryzae, Sitophilus zeamais, and Sitophilus granarius, three economically significant grain pests are thoroughly analyzed in terms of their morphological and molecular differences. The work provides critical insights into species identification, genetic differentiation, and adaptation by contrasting conventional morphological features and genetic approaches. The samples were collected from eight talukas of district Khairpur: Kingri, Kot Deji, Khairpur, Gamabat, Mirwah, Sobhodero, Nara, and Faizganj during the year 2018-2022. The samples were identified on the basis of morphology and extraction of DNA was done. The samples were sent for sequencing. The findings provide important evolutionary insights and aid in pest management. Additionally, the text describes the distinguishing physical characteristics of mature Sitophilus granarius, maize weevils, and rice weevils, emphasising size, colour, markings, and anatomical aspects. Understanding the differences among various weevil species is made easier by this information. [ABSTRACT FROM AUTHOR]

Discussion The tested aqueous extracts from plants I S. terebinthifolius i , I L. sericea i , I L. tomentosa i , I L. nervosa i , and I L. longifolia i , proved to be effective against I S. zeamais i in stored maize grains, with regard to their repellency. Keywords: bioinsecticide; aqueous extract; maize weevil; stored grains EN bioinsecticide aqueous extract maize weevil stored grains N.PAG N.PAG 11 09/27/22 20220901 NES 220901 1. This study aimed to determine the effects of botanical extracts of five plant species I Schinus terebinthifolius i , I Ludwigia sericea i , I L. tomentosa i , I L. nervosa i , and I L. longifolia i in reducing offspring emergence and repellency potential of adult insects. The plant species were deposited at the Herbarium of the Federal University of Grande Dourados-UFGD, with the following registration numbers: 6391 I L. tomentosa i , 6389 I L. longifolia i , 6388 I L. sericea i and 6390 I L. nervosa i , 6473 I S. terebinthifolius i . [Extracted from the article]

Sitophilus zeamais (Coleoptera: Curculionidae) is a common pest in stored corn grains [Zea mays (Poaceae)]. Synthetic insecticides are effective to control S. zeamais; however, they can develop resistant insects and are toxic to humans and animals. Compounds with insecticidal potential from plants are alternatives for pest control. This study identified the chemical composition of Cymbopogon flexuosus (Poaceae) essential oil, its insecticidal and repellency activity against S. zeamais. The major chemical constituent found in the essential oil of C. flexuosus was citral (88%). The data showed that the essential oil of C. flexuosus and citral showed better insecticidal and repellent activity than the commercial insecticide Actellic used as positive control. The 100% mortality of S. zeamais was obtained at doses of 50 and 44 µL of essential oil and citral, respectively. The highest repellent activity was obtained with 40 and 50 µL of essential oil and 35.2 and 44 µL of citral, respectively, and the lowest with commercial insecticide Actellic. The lethal dose (LD50) was 18.10 and 18.95 µL for essential oil and citral, respectively. The lethal time was lower at doses of 44 and 50 µL essential oil and citral, respectively, and higher with the commercial insecticide. The insecticidal and repellent action of the essential C. flexuosus and its major compound confirms the potential of producing new biopesticide for the control of S. zeamais in Integrated Pest Management (IPM) programs in stored grains. [ABSTRACT FROM AUTHOR]

Maize (Zeamays) and beans (Phaseolus species) are staple food, feed and sources of income for millions of people in developing countries and most especially for the people of the North West Region (NWR) of Cameroon. Production and storage of these grains is greatly hampered by inappropriate storage practices and pest infestation. This study determined the storage practices and insect pests associated with these grains in theNWR of Cameroon. A structured questionnaire designed to document the indigenous methods of storingmaize and beans against post-harvest insect pests with particular emphasis on plants and plant-derived materials used was administered to 29 farmers selected from Babungo, Kom and Oku villages in the NWR of Cameroon. Samples of maize and beans were also collected from the stores of respondents to collect and identify the insect species. The 29 respondents used more than one method to protect their grains against damage by insects in storage. The different methods implored were conventional methods, local plants and wood ash with independent counts (percentages) of 18 (62.1 %), 18 (62.1 %) and 7 (24.1 %), respectively. Sitophilus zeamais, Tribolium casterneum, T. confusum and Brachymeria spp. were recorded in maize while only Acanthoscelides obtectus was recorded in beans. There were no significant differences in the number of insects recorded across the study sites. Therefore, post-harvest insectpests are a common problem in the NWR of Cameroon. Farmers within this region also use different methods of post-harvest storage practices to combat these pests. Integrated methods of post-harvest management should receive high priority to prevent damage and losses incurred. Management practices should focus on further developing plants used in post-harvest storage. There is equally a strong need for training farmers on aspects of post-harvest storage practices and management in the NWR of Cameroon. [ABSTRACT FROM AUTHOR]

The efficacy of Diatomaceous Earth (Protect IT ®) was tested for the control of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in a metallic silo of Matanzas province, Cuba. A random design was arranged and three groups were evaluated: Protect IT (90% of diatomaceous earth), a positive control (Actellic CE 50) and an untreated control. The diatomaceous earth and Actellic were evaluated at 9.0 kg PC. ton - 1 and 12.0 ml. ton - 1, respectively. The dose of Diatomaceous Earth tested showed insecticide activity with 100% mortality percentage during the first 60 days, without statistical differences with the Actellic insecticide. After three months, the insect mortality was 60%, with statistical differences with the chemical insecticide. The results suggest the potentialities of Diatomaceous Earth (Protect IT ®) as an alternative for management of S. zeamais in metallic silos and for reducing the use of chemicals in corn grain storage. [ABSTRACT FROM AUTHOR]

Sitophilus zeamais is a pest of global significance and it is difficult to control due to the high indices of resistance to insecticides showed by the populations. As an alternative to the management of S. zeamais populations, in the present study, we evaluated the toxicity of essential oil (EO) of Lippia sidoides , its major compound (thymol − 68.5%) and prototypes of nanoformulations (NF) (18%) based on these compounds on S. zeamais populations (N = 5) from different regions of Brazil. Toxicity bioassays were performed to determine lethal and chronic toxicity doses and times to test the efficiency of prototypes in the treatment of stored grains. Additionally, we study the efficiency and stability of stored NFs. The lethal doses of EO of L. sidoides and thymol required to kill 50% of S. zeamais populations ranged from 7.1 to 19.9 μg/ mg −1 and 17.1 to 25.7 μg/ mg −1 , respectively. The populations of Jacarezinho-PR and Maracaju-MS were, respectively, the most tolerant and susceptible to the EO of L. sidoides . EO of L. sidoides , thymol and its NFs acted fast on the populations of S. zeamais . Increasing of NF concentrations led to reduced grain consumption and total population mortality. NFs stored for up to seven months maintained high mortalities on S. zeamais . This work indicates that the prototypes of NFs based on the EO of L. sidoides and its major compound are promising for the management of S. zeamais populations. [ABSTRACT FROM AUTHOR]

Cereals constitute a relevant part of human and domestic animal diet. Under storage conditions, one of the most significant problems of these crops is insect pests as the maize weevil (Sitophilus zeamais Motschulsky). This insect species is usually controlled by means of synthetic insecticides but problems as toxic residues and resistance has led to the search for more friendly control alternatives such as botanical insecticides. The aim of this research was to evaluate, under laboratory conditions, the insecticidal properties of the powder and the essential oil of peumo (Cryptocarya alba [Molina] Looser; Lauraceae) leaves against S. zeamais. The variables assessed were toxicity by contact and fumigant activity, adult emergence (F1), repellent effect, and impact on wheat (Triticum aestivum L.) seed germination. A completely randomized design was used with five treatments and 10 replicates. The higher mortality levels were obtained at 80 g powder kg-1 grain and 40 mL essential oil kg-1 grain of C. alba; in both cases, the mortality of adult S. zeamais surpassed 80%. The emergence of adults S. zeamais (F1) was reduced by 100% at 80 g powder kg-1 grain and 40 mL essential oil kg-1 grain. Germination of wheat seeds treated with C. alba powder and essential oil was not affected. Both, the powder and the oil treatments showed repellent effect, but not fumigant activity. [ABSTRACT FROM AUTHOR]

The maize weevil (Sitophilus zeamais Motschulsky) is one of most important pest of stored seeds worldwide, but its current control method is based on the use of synthetic insecticides, usually leading to undesirable problems such as insecticide residues on treated food, human intoxications, and insect resistance development. Therefore the search of friendly alternative methods is required. The aim of this study was to assess, under laboratory conditions, the insecticidal properties of Peumus boldus Molina, Laurelia sempervirens (Ruiz & Pav.) Tul., and Laureliopsis philippiana (Looser) Schodde essential oils against S. zeamais. The phytochemical analysis of the three essential oils showed 1,8-cineole, safrole and methyleugenol as the common components; all of them documented with insecticidal activity from essential oils from other plant species. The highest toxicity (100% mortality) of these three oils acting as a contact insecticide was observed at 24 h exposure at 4% concentration. The estimated LC50 values for P. boldus, L. sempervirens, and L. philippiana were 0.37, 1.02, and 0.28 μL g-1, respectively. Peumus boldus exhibited the highest fumigant activity with 100% adult mortality at 30 μL oil L-1 air. At ≥ 0.5% (v/w) concentration, all essential oils showed repellent activity. These three essential oils showed a promissory insecticidal activity against the maize weevil. [ABSTRACT FROM AUTHOR]

The maize weevil Sitophilus zeamais Motschulsky is a worldwide key pest of stored products. Usually contact insecticides or fumigants are used against it, but problems as toxic residues, human intoxications, and resistance have triggered the search for alternative control methods as the use of essential oils. The objective of this research was to assess under laboratory conditions, the insecticidal properties of Laurelia sempervirens (Ruiz & Pav.) Tul. essential oil against S. zeamais. In contact toxicity bioassay assessed treatments were 0 (control), 1.25, 2.5, 5.0, 10, 20, and 40 mL essential oil kg-1 grain and 0 (control), 25, 50, 75, 100, 125,150, and 175 µL essential oil L-1 air in fumigant toxicity tests. The highest toxicity by contact activity was reached by concentrations higher than 10 mL essential oil kg-1 grain (100% mortality). The same treatments totally inhibit F1. The dose of 175 µL essential oil L-1 air showed a significant toxicity by fumigant activity causing 72.5% of dead insects. The other treatments did not surpass 5% mortality. In offspring effect (F1) bioassay, all treatments had an insect emergence significantly lower than the control but concentrations equal or higher than 10 mL essential oil kg-1 grain prevented the emergence of F1 during the 7 wk of bioassay. The residual effect of contact toxicity remained by 15 d. The treatments based on essential oil lead to a weight grain loss lower than control and germination was not affected. All assessed treatments showed repellent effect. The essential oil of L. sempervirens has promissory perspectives to maize weevil control. [ABSTRACT FROM AUTHOR]

The maize weevil (Sitophilus zeamais Motschulsky) is one of the most widespread pests and causes heavy losses of stored grain throughout the world. Control of this insect is primarily dependent upon continued applications of organophosphorus and pyrethroid insecticides and fumigants as phosphine but the increasing problems with current insecticides drive the need for research and to develop new control methods. The insecticidal effect of leaf powder of tepa, Laureliopsis philippiana (Looser) Shodde, was evaluated against maize weevil under laboratory conditions. The parameters evaluated were adult mortality and emergence, grain weight loss and germination, and residual, repellent and fumigant effect. The highest levels of insect mortality were registered with treatments at 1, 2, and 4%, with values from 94.7 to 100%. Also, it was obtained 0% of adult insect emergence with these concentrations. In all treatments grain weight was less than 5.8 g. Seed germination was not affected. The powder of L. philippiana exhibited repellent effect in all concentrations and did not show fumigant effect. Insecticidal effect of powder remained for 14 d. Finally, we concluded that powder of L. philippiana has great potential for controlling S. zeamais. [ABSTRACT FROM AUTHOR]

Essential oils are promising substitute for chemical pesticides with the inherent resistance by pests, environmental and health effects on humans. In this study, the chemical composition of essential oil extracted from Citrus sinensis peel was characterized, the insecticidal activities of the oil and its constituents against Callosobrunchus maculatus (Cowpea weevil) and Sitophilus zeamais (maize weevil) were investigated and the underlying insecticidal mechanism were elucidated. The essential oil was extracted by hydro-distillation and characterized using gas chromatography–mass spectrometry (GC–MS). Insecticidal activity was determined by contact and fumigant toxicity assay. The inhibitory effect of the oil and its constituents on acetylcholinesterase (AChE) , Na+/K+-ATPase and glutathione-S- transferase (GST) activity were assayed using standard protocols. The total number of volatile compounds detected in C. sinensis essential oil was eighteen (18). d -limonene (59.3%), terpineol (8.31%) and linalool (6.88%) were the major compounds present in the essential oil. Among the tested essential oil compounds, terpineol showed highest contact toxicity against C. maculatus (LD 50 =17.05 μg/adult) while 3-carene showed highest contact toxicity against S. zeamais (LD 50 =26.01 μg/adult) at 24 h exposure time. Citral exhibited the highest fumigant toxicity against C. maculatus and S. zeamais with LC 50 value 0.19 and 2.02 μL/L air at 24 h respectively. Acetylcholinesterase and Na+/K+-ATPase activities were significantly inhibited by C. sinensis oil and its constituents in both C. maculatus and S. zeamais as compared to control. This study indicates that C. sinensis essential oil and its constituents have potential to be developed into botanical pesticides. Unlabelled Image • C. sinensis essential oil (EO) toxicity was studied on C. maculatus and S. zeamais. • The main compounds of C. sinensis EO were limonene, terpineol and linalool. • EO and its compounds showed potent insecticidal activity on both insects. • AChE and Na+/ K+-ATPase activity was inhibited in both C. maculatus and S. zeamais. [ABSTRACT FROM AUTHOR]