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Maize is the mainstay of food and animal feed globally. Maize weevil, Sitophilus zeamais, accounts for a significant global loss of stored maize annually. Twenty-one maize genotypes were evaluated for their reaction to attack by maize weevil during storage and the influence of nutritional contents on their response to the weevil attack. Fifty grams of whole grains of each genotype were infested in three replications with 20 unsexed weevils in a 250 ml test tube and kept under ambient conditions for 36 days. The nutritional attributes of the maize genotypes were determined. Genotype TZB-SR-A had the thickest (7.32 mm) grains, while TZEE-WSTR had the thinnest grains (3.46 mm). Crude protein ranged from 8.43 to 12.78% for NG/SA/07/029 and TZB-SR-B, respectively. Beta-carotene ranged from 38.91 to 51.22% for Igbogbo Local and EVDT-Y2000-STR, respectively. Genotypes TZM-212, TZM-1296, TZB-SR-B, and TZM-1311 showed no appreciable loss in grain weight, while EVDT-Y2000-STR, which had the highest beta-carotene content, showed the highest weight loss of 2 g. These indicate sufficient differences among the maize genotypes for improvement for weevil resistance. Furthermore, the findings of the present study suggest a potential role of beta-carotene in influencing the feeding preference of S. zeamais on maize grains. Genotypes TB87/97/15, TZB-SR-A, TZB-SR-B, TZM-1311, and TZM-144 should be targeted for future improvement of the trait. [ABSTRACT FROM AUTHOR]

The thrust of the study was to determine the chemical composition of the essential oils extracted from Thymus pallescens de Noé and Cymbogon citratus Stapf. as well as to evaluate their efficacy in controlling Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) in either single or combined populations. Carvacrol (56.04%) and geraniol (20.86%) were identified as the major constituents of T. pallescens and C. citratus respectively. The tested essential oils showed pronounced insecticidal activity against the pest species in relation with the applied doses. T. pallescens EO had the highest efficacy and S. zeamais was found to be more susceptible to both individual and combined treatments. With reference to the contact and fumigation assessments, T. pallescens EO effectuated corrected mortality rates ranging from 42.5–100% to 25–100% in S. zeamais with corresponding lethal concentration (LC50) values of 17.7 µl/ml and 15µL/L air respectively. Whereas, the T. pallescens EO exhibited corrected mortality rates of 42.5–100% and 20–100% with corresponding LC50 values of 18.1 µl/ml and 15.5 µL/L air against T. castaneum in contact and fumigation assessments, respectively. The corrected mortality rates increased for both insect species when using combination treatments, with significant increases in the LC50 values, ranging from 8.59 to 49.9% for both pest species. Analysis of energy biomarkers in the treated insects indicate significantly increased protein and carbohydrate contents and decreased lipids levels. The study therefore demonstrated the bio-insecticidal toxicity of the EOs from T. pallescens and C. citratus against two important maize post-harvest pests, concurrently revealing significant positive and negative insecticidal activity gradients in relation to single or combined populations. [ABSTRACT FROM AUTHOR]

Maize is a staple grain cereal that is consumed worldwide for the supply of daily energy requirements. However, its infestation by the weevil, Sitophilus zeamais often results in both qualitative and quantitative losses, which must be managed effectively. The health hazards that are associated with the application of synthetic insecticides for the management of pest infestations of stored products have necessitated the continual sourcing of safer and affordable alternatives. Hence, a laboratory experiment was conducted to assess the effects of morphological, biophysical and some intrinsic factors in fifteen improved maize varieties on their susceptibility or otherwise resistance to infestation by the maize weevil, S. zeamais. Firstly, the morphological and biophysical characteristics of the maize varieties were determined. Copulating pairs of adult S. zeamais were placed in containers that contained undamaged maize grains for seven days to allow for oviposition, after which the adults were removed. Thereafter, the number of eggs laid and adults that emerged were counted. The susceptibility index of each maize variety was calculated from the data obtained from oviposition and adult emergence. Also, the proximate, elemental, and antinutrient compositions of the maize varieties were determined. There was no significant difference (p > 0.05) in the size and hardness of seeds among the varieties with the size range of 0.78–0.95 cm3 while the hardness ranged from 17.43 N in SAMMAZ-15 F to 19.08 N in SAMMAZ-35. The maize varieties differed significantly with respect to proximate, elemental, and antinutrient compositions. The susceptibility of the seeds to infestations by S. zeamais differed significantly among the varieties and across the generations, with the potential for loss of resistant property during later generations. The data from the susceptibility index revealed that TZL COMP4, TZEE W POP and SAMMAZ-29 were the most resistant to infestations by S. zeamais. Although, several factors could have been responsible for the susceptibility or resistance of maize seed varieties to infestations by S. zeamais, however oviposition hardness and moisture were the most important factors in the present study. [ABSTRACT FROM AUTHOR]

The maize weevil poses significant global concerns as it causes huge economic losses to stored grains. The chemical control methods are popular among farmers but raise serious concerns regarding human and environmental safety, highlighting the urgent need for novel and safe strategies. Plant extracts are seen as safe substitutes to toxic chemicals. Therefore, this study investigated the efficacy of methanolic plant extracts prepared from Azadirachta indica (seeds), Caralluma tuberculata (succulent fruits), Allium sativum (rhizomes), Curcuma longa (rhizomes), Citrullus colocynthis (succulent fruits) and Calotropis procera (leaves) against maize weevil under constant conditions of 27 ± 2 0C, 65% R.H). The experiments were carried out using a CRD design having five replications in the laboratory of the Entomology department, Gomal University, Dera Ismail Khan, Pakistan. The methanolic plant extracts were tested at 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% (v /w), concentrations, respectively. The parameters investigated, included, the number of days to F1 generation, emergence of F1 progenies, percent infestation and weight loss of grains, adult life span and sex ratio (male/female). Each methanolic plant extract was mixed with 20 g maize grains. Among the treatments, the A. indica and C. longa extracts showed greater effectiveness at the maximum concentration (3.0%), significantly delaying the emergence of F1 adults to 40.20 and 38.80 days, respectively, compared to the control group which emerged in 26.20 days. Least number of F1 adult emergence (11.60) was observed in A. indica extracts followed by C. longa having (18.00) while the highest number (45.80) was observed in C. procera treated grains at the maximum concentration of 3.0% compared to 81.20 in the untreated grains. The A. indica extracts showed the least infestation rate (2.14%) followed by C. longa (3.15%). Conversely, higher infestation rates were noted in C. tuberculata (8.38%) and C. procera (9.20%) treated grains at the maximum concentration of 3% compared to 35.20% in the control group. The minimum (1.10%) weight loss was observed in A. indica extracts treated grains whereas; maximum weight loss was observed in C. procera (5.11%) treated grains at the maximum concentration compared with control (27.50%). The minimum adult life span of 32.40 days was observed in maize grains treated with A. indica extracts followed by C. longa (34.20 days) and maximum adult life span was documented in C. procera (37.60 days) and C. tuberculata (37.00 days) treated grains at the maximum concentration compared with control (46.00 days). All the tested methanolic plant extracts had no significant effect on the sex ratio of the weevil adults. It is concluded from the results that the methanolic extracts of A. indica and C. longa could be used as allele-chemicals to control maize weevil under storage conditions. [ABSTRACT FROM AUTHOR]

Control of the M LE: Please check if the authors' affiliations are presented/captured appropriately. aize weevil (Sitophilus zeamais) often relies on synthetic insecticides, which, although effective, can leave toxic residues in grains and promote the development of resistant insect populations. Certain essential oils (EOs), including Cinnamomum cassia EO, present a natural alternative recognized for their insecticidal and repellent properties. However, their effectiveness is constrained by high volatility and limited solubility. To address these limitations, controlled release technologies, such as microencapsulation, offer a promising solution. This study aimed to evaluate the chemical composition, insecticidal, and repellent efficacy of free and microencapsulated C. cassia EO against S. zeamais and the persistence and reuse potential of the microencapsulated EO in maize grains. GC–MS analysis identified trans-cinnamaldehyde (86.4%) as the major compound, followed by methyl cinnamate (9.92%). The EO was microencapsulated via spray drying with a 10% gum arabic-maltodextrin solution. Insecticidal activity showed LD₅₀ values of 8.90 μL/cm3 for free EO and 24.76 mg/cm3 for microencapsulated EO. The persistence of insecticidal activity reached 45% on the 15th day and remained nearly stable for 65 days. Moreover, the microcapsules showed effectiveness across five cycles, maintaining 70% mortality. This study highlights C. cassia EO as a sustainable solution for maize weevil management, with prolonged efficacy achieved through microencapsulation. [ABSTRACT FROM AUTHOR]

In order to evaluate the insecticidal activity of a formulation of the mixture made of ammoides verticillata essential oil with diatomaceous earth on Sitophilus zeamais, the Sitophilus were exposed to diatomaceous earth at 1 mg/cm on filter paper in petri dishes, and to different concentrations of the essential oil (00 µl, 01 µl, 02 µl, 04 µl and 8 µl). We checked their mortality rate after 24 h and 48 h. After having positive results for diatomaceous earth as well as the essential oil, we tested the effectiveness of our formulation (1 mg of diatomaceous earth/8 µl essential oil/cm2) in petri dishes, and in boxes which contain 20 corn seeds and 20 individuals of Sitophilus (1 mg of diatomaceous earth/8 µl essential oil/cm3). The repellent activity of the essential oil gives us a repellency rate of 52.5% to 75.5% according to the doses. The insecticidal activity of the essential oil on Sitophilus showed significant results as a function of dose and time. We obtained an LC50 of 1.99 mg/cm3. After 24 h of exposure of Sitophilus to diatomaceous earth, we noticed that the average mortality is 40%, and 80% after 48 h. While the average mortality of Sitophilus after 24 h of exposure to the formulation is 80%, and 90% after 48 h. For the population treated with the mixture in the boxes, we noticed an average mortality of 100% and no seeds attacked by insects. [ABSTRACT FROM AUTHOR]

Our aim was to perform a qualitative review and a meta-analysis with 57 scientific articles (108 assays) published from 1 January 2000 to 31 June 2021 dealing with fumigant toxicity of essential oils (EOs) against Sitophilus zeamais. The studies were obtained from four electronic databases: Web of Science, SCOPUS, PubMed, and Google Scholar. The survey comprised 107 plant species belonging to 26 different families. Lethal concentration values (LC50) of EOs were included in a random-effect model, and two subgroups were defined: "until 24 h" and "more than 24 h". The EOs more frequently evaluated were those belonging to Lamiaceae (20.18%), Asteraceae (17.43%), Apiaceae (9.17%), and Rutaceae (6.42%). The global mean value was 21.37 (CI95 16.84–27.12), while the summary mean values of the subgroups were 41.45 (CI95 31.10–55.26) for "until 24 h" and 8.45 (CI95 5.72–12.48) for "more than 24 h". Most species belonging to Apiaceae, Lamiaceae, Asteraceae, and Schisandraceae reported the highest insecticidal effects with mean values that ranged from 1.31 to 27.39 for "until 24 h" and from 0.57 to 5.31 for "more than 24 h". Additionally, the toxicity of the most effective EOs was discussed by addressing their chemical composition and their major pure compounds chemical features. [ABSTRACT FROM AUTHOR]

It has been planned to minimize the yield and quality impairment of the seed corn, which is strategically important in the world, by pests under storage conditions with a biological product produced with a biotechnological approach. In this context, the present study aimed to control the maize weevil Sitophilus zeamais, known as a warehouse pest, using a nanoformulation. In the study, the chitinase enzyme from Lactobacillus coryniformis was purified first using ammonium sulfate precipitation and then by using the HiTrap Capto DEAE column, and the molecular mass of the purified enzyme was determined to be ~ 33 kDa, and the optimum pH and the values as pH 6.0 and 65–75 °C, respectively. Five different doses of nanoformulation (2, 4, 6, 8 and 10 mg/L) were applied to corn grains by the spraying method with three repetitions so that the insect can ingest the formulation through feeding. The effects of the applications on the death rate and mean time of death of Sitophilus zeamais were determined. According to these findings, it was concluded that the best practice was nanoformulation with 6 mg/L, considering both the mortality rate (100%) and the average death time (2.4 days). Chitinase from L. coryniformis is a promising candidate for corn lice control and management. [ABSTRACT FROM AUTHOR]

The aim of the current study was to investigate the entomopathogenic capacity of the mold Fusarium verticillioides and the effect of its mycotoxins fumonisins, on the grain beetle Sitophilus zeamais. We evaluated the capacity of this fungus to infect live insects, the antifungal activity of constituents of the insect's epicuticle, and the effect of a fumonisin extract on the fitness of the insects. We found that F. verticillioides could not penetrate the cuticle of S. zeamais and that the fumonisin extract had no negative effects on the fitness of the insects. However, the progeny of the insects increased, and the fumonisin extract had repellent effects. This is the first report about the effects of fumonisins on the relationship between F. verticillioides and S. zeamais, which may provide useful information about interactions between pathogenic microorganisms and insects, especially on stored product pests. [ABSTRACT FROM AUTHOR]

Our understanding and prevention of postharvest losses are critical if we are to feed a growing global population. Insect infestation-related losses of stored commodities are typically considered only in terms of quantitative, physical weight loss. Insect infestation affects the nutritional value and some nutritional components are impacted more severely than others. We infested maize and cowpea grain with commonly occurring stored product insect pests, and mapped infestation levels against nutritional composition over a 4-to-6 month storage period to analyse how insect infestation relates to different macro- and micro-nutrient contents. Insect infestation decreased the carbohydrate content of the stored grains, causing a relative increase in the proportion of protein and fibre in the remaining grain, and moisture content also increased. Sitophilus zeamais preferentially fed in the floury endosperm of maize, resulting in more carbohydrate loss relative to protein loss. Conversely, Prostephanus truncatus consumed the germ and endosperm, disproportionately reducing the fat, protein, iron and zinc grain contents. Nutrients are distributed more homogenously within cowpea than in maize grains, but Callosobruchus maculatus infestation increased the relative protein, fat, iron and zinc to carbohydrate ratios. This indicates how the nutrient content of insect-infested stored grain depends upon the grain type, the infesting insect, and the infestation level. Insect infestation therefore has consequences for human nutrition beyond those of grain weight loss. Using data collected on the changing nutritional composition of grain over time, with and without insect infestation, we modelled the associations between infestation and nutritional quality to predict estimated nutritional losses that could be associated with consumption of insect-infested stored maize and cowpea. [ABSTRACT FROM AUTHOR]

Plant defensins are divided into 18 groups and are multifunctional proteins. The Zea mays defensin 1 (ZmDEF1) gene encodes the defensin 1 protein, which can inhibit alpha-amylase in the insect gut. In this study, the ZmDEF1 gene was transferred into two maize cultivars, LC1 and LVN99, to improve weevil resistance in maize. The recombinant ZmDEF1 protein was assessed for its ability to inhibit alpha-amylase in the gut of the larvae of the maize weevil (Sitophilus zeamais Motsch.). ZmDEF1 was cloned into a pBetaPhaso-dest vector, which harbours phaseolin, a seed-specific promoter, and the Agrobacterium tumefaciens strain C58 harbouring the pBetaPhaso-ZmDEF1 vector was used to transfer the ZmDEF1 gene into two maize cultivars using immature embryos. Transformed calluses were selected on selection media containing kanamycin. The stable integration of the ZmDEF1 transgene into the transgenic maize plant genome was confirmed using Southern blotting. The recombinant ZmDEF1 protein of approximately 10 kDa was expressed in three transgenic maize lines from the LC1 cultivar (C1, C3, and C5) and two transgenic maize lines from the LVN99 cultivar (L1 and L3). The ZmDEF1 transgenic efficiency based on the results of PCR, as well as Southern and Western blotting, was 1.32% and 0.82%, respectively, which depends on the genotypes of LC1 and LVN99. The recombinant ZmDEF1 protein inhibited the alpha-amylase activity of the maize weevil larvae, and its ability to inhibit alpha-amylase is 54.52–63.09% greater than the ZmDEF1 protein extracted from non-transgenic plants. [ABSTRACT FROM AUTHOR]

There is a dearth of comprehensive data regarding the performance of large-scale hermetic maize storage in sub-Saharan Africa (SSA) as an alternative to the sole and widely used phosphine fumigant. Trials were therefore conducted at three sites in Zimbabwe for up to 12 months to evaluate the performance of 20 tonne-capacity GrainPro Cocoons™ compared with conventional phosphine fumigation practice. A split-plot experimental design was used consisting of two main plots, namely: the cocoon and fumigated stack with three sub-plots being depth positions: top, middle and bottom. At each site, sampling was conducted at setting-up and at termination. Samples were assessed for insect population, grain damage, weight loss, germination and moisture content. There were no significant differences between the main plots for grain damage, weight loss, insect pest population/kg and germination after 4 months of storage. Hermetic storage was significantly more effective than fumigation practice in preserving germination after 8 and 12 months; and in reducing grain damage, weight loss, and insect population after 12 months of storage (P < 0.05). An economic analysis using the cocoon instead of conventional fumigation, based on an incremental benefit-cost ratio (BCR), showed no benefit of the alternative when considering the local retail price. However, the alternative was beneficial with a BCR of 1.11 when import tariffs were removed from the initial cost. These findings show that with supporting national policies, cocoons can be a cost-effective alternative to phosphine fumigation. Other environmental and human safety gains of using cocoons are priceless. [ABSTRACT FROM AUTHOR]

Searching new sources of resistance to the maize weevil are critical in a successful breeding program to address grain damage by postharvest pests. This study was undertaken to evaluate resistance in 28 quality protein maize (QPM) inbred lines against Sitophilus zeamais infestation and their important agronomic attributes, and consequently their value for use in breeding programs to develop resistant QPM hybrids. Susceptibility index (SI), which considers the progeny number in the F generation and the time the insects take to mature from egg to adult, was used to measure the susceptibility. Out of the 28 inbred lines tested, one inbred line (CML-142) was resistant, three (CML-144/144-7-b (F2)-4-2-1-1-1-1-1, POOL 15QPFS-693-B-2-B-#-B-B-B-# and CML-149) were moderately resistant and the remaining 24 inbred lines were categorized as susceptible to highly susceptible. Importantly, those inbred lines that are resistant and moderately resistant had better yield and other agronomic performances as compared to the susceptible ones. These resistant and moderately resistant inbred lines showed considerable reduction in grain damage and losses for S. zeamais, suggesting that they contained genes that confer resistance to the pest. Correlations between kernel size, breadth and texture with some important susceptibility parameters were found to be significant, indicating possible influence of these factors together with others in determining the susceptibility of the QPM inbred lines to S. zeamais. Identification of QPM lines resistant to S. zeamais in the present study offers an opportunity to breed for resistance to maize weevil in developing QPM hybrid with enhanced resistance to S. zeamais. [ABSTRACT FROM AUTHOR]

The possibility that Sitophilus zeamais Motschulsky prefers a particular grain side and a grain side area for feeding, and the implications and value in maize programmes' breeding for resistance were investigated in the laboratory at ambient temperature (32.7 °C) and relative humidity (70.4%) using standard techniques. A total of 20 elite maize varieties were used: TZBRCOMP.2C1F1, TZBRELD3C5, PVASYN-3F2, PVASYN-6F2, DTSYN-11-W, BR9943DMRSR, IWDC3SNY-W, WHITEDTSTRSYN, 2008DTMA-YSTR and 2000SYNEE-WSTR, obtained from the Maize Breeding Unit of International Institute for Tropical Agriculture (IITA), Ibadan, Nigeria, and ILE-1-OB, IFEMAIZEHYBRID-1, IFEMAIZEHYBRID-2, IFEMAIZEHYBRID-5, IFEMAIZEHYBRID-6, ARTCOMPOSITE-A-Y, ARTCOMPOSITE-B-Y, ART/98/SW1-OB, ART/98/SW4-OB and ART/98/SW5-OB, obtained from the Institute of Agricultural Research and Training (IAR&T), Moor Plantation, Ibadan, Nigeria. The flat side of a maize grain at the point of penetration was significantly preferred (P≤ 0.05), possibly because it provided much needed space for anchorage and feeding. The South locus of the flattened side of a maize grain was also significantly preferred (P≤ 0.05), possibly because of its soft nature and proximity to the nutrient-rich embryo. The findings of the study have implications for seed viability and can be considered in breeding for resistance to infestation by S. zeamais in stored maize. [ABSTRACT FROM AUTHOR]

Essential oils obtained from fifteen different plant species (Achillea biserrata M. Bieb., Achillea coarctata Poir., Achillea gypsicola Hub-Mor., Achillea wilhemsii C. Koch, Artemisia santonicum L., Hypericum perforatum L., Melilotus officinalis (L.) Lam., Origanum acutidens (Hand.-Mazz), Origanum onites L., Origanum rotundifolium L., Origanum syriacum L., Satureja hortensis L., Satureja spicigera (C. Koch)., Salvia nemorosa L., and Tanacetum agrophyllum (L.) C. Koch were tested against adults of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Obtained results showed that the tested essential oils isolated from all plant species, except that from S. nemorosa had significant insecticidal effects against S. zeamais adults, compared with the control. Mortality rate of S. zeamais adults increased significantly (p < 0.01), as the concentration (μl/L air) level and/or exposure time increased. Treatments with the essential oils of A. coarctata, A. gypsicola, O. onites, S. hortensis, and S. spicigera showed highest percentages of adult mortalities, when they were applied at the high concentrations (10 & 20 μl/L air) and at all the post treatment periods or at a moderate concentration (5 μl/L air) with long exposure periods (48 or 96 hs). The essential oil of S. nemorosa had lowest effect. After 96 h of exposure, at the maximum concentration (20 μl/L air essential oil) of A. biserrata, A. coarctata, A. gypsicola, A. santonicum, H. perforatum, M. officinalis, O. onites, O. rotundifolium, S. hortensis, S. spicigera, T. agrophyllum recorded 100% mortality, while O. syriacum, O. acutidens, A. wilhemsii, and S. nemorosa attained 99-76.77 mortality. After 96 h of treatment, 100% mortality was achieved at the concentration of 5 μl/L air essential oil of A. gypsicola. Essential oils of M. officinalis, H. perforatum, and O. rotundifolium possessed the most effective fumigant toxicity against S. zeamais adults, with LC50 values of 0.289, 0.526, and 0.573 μl/L air, respectively. [ABSTRACT FROM AUTHOR]

Maize weevil ( Sitophilus zeamais Motschulsky) is one of the major maize storage pests among smallholder farmers in eastern and southern Africa (ESA), thereby, reducing total on-farm maize harvests. Experiments were conducted in a controlled temperature and humidity (CTH) laboratory at CIMMYT-Zimbabwe to compare the resistance of new maize open pollinated varieties (OPVs) from regional trials undertaken in ESA to maize weevils. Twenty maize OPVs were shelled and cleaned before being placed in a deep freezer at −20 °C to kill any pests and eggs in the grain from the field. Fifty grams of grain from each OPV was measured after 3 weeks and placed in the CTH lab for conditioning. The samples were placed in 250-mL jars with brass-screened lids and then infested with 32 maize weevils aged between 10 and 14 days. Data were collected for kernel hardness prior to weevil infestation, as kernel hardness to confer resistance to weevils. The components of maize weevil resistance considered were: median development period, Dobie index of susceptibility, weevil emergence, weevil mortality, weevil fecundity, grain weight loss, kernel damage and germination. There were highly significant differences in maize kernel characteristics and median development period ( P < 0.001) among the maize OPVs. There were significant differences in the number of damaged kernels, grain weight loss ( P < 0.01), weevil mortality and germination ( P < 0.05) among the maize OPVs. There were no significant differences found for weevil progeny emergence (F), Dobie index of susceptibility and weevil fecundity, the last of which was positively and significantly correlated with kernel damage ( P < 0.001). The DIS was positively and significantly correlated with weight loss and F ( P < 0.001). The maize OPVs 07WEEVIL, Chitedze6, Strigoff126, Strigoff128 and ZM625 were found to be resistant; on the other hand, Strigoff140, Strigoff125, Strigoff133, VP05199 and VP074 varieties were highly susceptible. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is Kenya's most important staple crop with annual production fluctuating between 2.6 and 3.1 million tons in 2012 and 2011, respectively. However, frequent food shortages are still experienced in the country. These have been attributed to pests and diseases and post-harvest constraints. The dominant post-harvest pest of maize is Sitophilus zeamais (Motsch.), which causes losses between 10 and 20% of harvested grain. The objective of this study was to establish the repellent activity of essential oils extracted from selected eucalyptus species against S. zeamais. Essential oils were extracted from the fresh leaves of Eucalyptus saligna Sm., Eucalyptus globulus Labill., Eucalyptus camaldulensis Schlecht and Eucalyptus citriodora Hook by steam distillation using a Clevenger-type apparatus. A repellency bioassay, with varying concentrations (0.002, 0.02, 0.2 and 2 μl/μl) of the oils, was carried out against the maize weevils using a Y-shaped olfactometer. Repeated measures of analysis of variance were applied to test the different doses and repellents, and their interactions against S. zeamais. The essential oils of E. camaldulensis and E. citriodora presented better repellent activity at the 2 μl/μl concentration (74.35 and 69.15%, respectively) followed by those of E. globulus (53.68%) and E. saligna (40.5%). Gas chromatography (GC)–mass spectrometry and GC co-injections with authentic samples showed the presence of the following major constituents in: (i) E. camaldulensis oil: 1,8-cineole (18.9%), α-cardinol (6.4%) and β-phellandrene (2.6%); (ii) E. citriodora oil: 1,8-cineole (11.2%), β-pinene (3.2%) and 4-terpineol (3.1%); and (iii) E. globulus oil: 1,8-cineol (17.2%), α-pinene (7.1%) and spathulenol (6.5%). The results provide a scientific rationale for the use of eucalyptus oils in the protection of maize against weevils. [ABSTRACT FROM AUTHOR]

Extracts of Letharia vulpina (L.) Hue and Peltigera rufescens (Weiss) Humb. lichen species and two major lichen compounds (diffractaic and usnic acids), isolated from Usnea longissima Ach., were tested against adults of the maize weevil, Sitophilus zeamais Motschulsky under laboratory conditions at various concentrations (2.5, 5, 10, 20 mg.ml-1 for extracts and 1.25, 2.5, 5, 10 mg.ml-1 for major compounds) and at 24, 48, 72, and 96 h period. Results showed that both the extracts and the secondary metabolites of U. longissima had significant insecticidal effects on adults of S. zeamais. Mortality rate was the highest at 96 h period at the treatment of maximum concentration of extracts (20 mg.ml-1) and compounds (10 mg.ml-1). The mortality rates attained 96.97, 95.96, 96.97 and 76.77% for L. vulpine, P. rufescens, diffractaic and usnic acids, respectively. No mortality was found in the control. The present results suggest that the lichen extracts and the secondary metabolites can provide a good potential for the control of S. zeamais adults. [ABSTRACT FROM AUTHOR]

The maize weevil, Sitophilus zeamais, is an economically important pest of stored grains in tropical and subtropical regions of the world. The behavioral responses of adult S. zeamais to volatile organic compounds (VOCs) from maize seeds, Zea mays, were studied to identify semiochemicals used in host location and provide potential tools for managing this pest. VOCs released directly from crude seed extracts, vacuum distilled extracts, hexane and diethyl ether fractions from silica gel chromatography of the vacuum distillates, air entrainment samples, and identified volatile compounds were assayed using a Perspex four-arm olfactometer. Weevils spent significantly more time, and made a higher number of visits, to the region of the olfactometer where Z. mays volatiles were present than in control regions comprising solvent only. When white and yellow Z. mays VOCs were compared in a choice test, the mean time spent in the two olfactometer treatment arms was significantly greater than the mean time spent in the control arms. However, weevils did not show any preference for either of the two treatments, thus demonstrating that both varieties of maize have similar activity. Gas chromatography (GC), coupled gas chromatography-mass spectrometry (GC-MS), GC peak enhancement and electroantennography (EAG) identified hexanal, ( E)-2-heptenal, and octanal as biologically active compounds in air entrainment samples and diethyl ether fractions of vacuum distillates. A 3-component synthetic blend of the identified compounds was significantly attractive to both sexes of the weevil. These host kairomones could be deployed in semiochemical based monitoring and management of S. zeamais in the tropics. [ABSTRACT FROM AUTHOR]

Background: Several species from Saussurea have been used in the traditional medicine, such as S. lappa, S. involucrate, and S. obvallata. There is no report on medicinal use of S. nivea. The aim of this research was to determine chemical composition and insecticidal activity of the essential oil of S. nivea Turcz (Asteraceae) aerial parts against maize weevils (Sitophilus zeamais Motschulsky) for the first time. Results: Essential oil of S. nivea flowering aerial parts was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 43 components of the essential oil of S. nivea were identified. The principal compounds in the essential oil were (+)-limonene (15.46%), caryophyllene oxide (7.62%), linalool (7.20%), β-pinene (6.43%), β-pinene (5.66%) and spathulenol (5.02%) followed by β-eudesmoll (4.64%) and eudesma-4,11-dien-2-ol (3.76%). The essential oil of S. nivea exhibited strong contact toxicity against S. zeamais with an LD50 value of 10.56 μg/adult. The essential oil also possessed fumigant toxicity against S. zeamais with an LC50 value of 8.89 mg/L. Conclusion: The study indicates that the essential oil of S. nivea flowering aerial parts has a potential for development into a natural insecticide/fumigant for control of insects in stored grains. [ABSTRACT FROM AUTHOR]

Powdered maize cobs were tested as an alternative for pesticide use in stored maize. Five doses (2, 4, 6, 8 and 10 g/250 g seed) of powdered maize cobs applied at particle sizes of 1.4 and 0.4 mm diameter were compared with actellic powder against Sitophilus zeamais Motschulsky for 120 days. Mortality and survival data showed that cob powders did not act as fumigant but exerted a potent inhibition of progeny on direct contact with S. zeamais adults. The particle size of powdered cobs had no effect on maize damage and losses. At doses equal to or higher than 6 g powdered maize cobs/250 g grain maize, i.e. 2.4% (w/w), damage to grain was < 5% and weight losses < 1%. The protection offered at the highest dose was comparable to the pesticide control. The use of powdered maize cobs is discussed as a natural alternative to synthetic pesticides for protection of maize against S. zeamais. [ABSTRACT FROM AUTHOR]

Botanical insecticides are among the most promising alternatives to synthetic insecticides for stored product protection. Calneem oil from Ghana and local neem oils from two localities in northern Cameroon (Garoua and Maroua) were tested at 0 (untreated control), 2, 4, 6, 8 and 12 ml/kg, on the adult and immature stages of the maize weevil Sitophilus zeamais (Motschulsky), for mortality and reproduction inhibition. The neem oils from Cameroon were extracted using the traditional kneading method and a hydraulic press in the laboratory (refined). Maize grains were coated with the five neem seed oils (Calneem, Garoua traditional and refined, and Maroua traditional and refined, respectively) and adult mortality was recorded at 1, 3, 7 and 14 days after exposure. Within 1 day of exposure, the highest tested concentration (12 ml/kg) of Calneem, Garoua traditional, Garoua refined, Maroua traditional and Maroua refined oils caused similar weevil mortality of 86.3, 93.8, 93.8, 97.5 and 97.5%, respectively. The 24-h LC50values for the oils in the same order were 7.0, 6.0, 5.0, 5.0 and 4.8 ml/kg, respectively. The lowest (2 ml/kg) and highest (12 ml/kg) concentrations of the oils suppressed progeny production by over 80 and 98%, respectively. The oils arrested the development of the hidden eggs and immature stages in the maize grains. The results suggested that neem seed oils from different localities of northern Cameroon, irrespective of the method of extraction, were effective for the protection of stored maize against S. zeamais. The promotion of natural neem seed oils as stored grain protectants in Cameroon would boost food security, alleviate poverty and reduce environmental degradation. [ABSTRACT FROM PUBLISHER]

The efficacy of NeemAzal powder, two local neem ( Azadirachta indica ) products [neem seed powder (NSP) and neem seed oil (NSO)], as well as a local Lamiaceae, Plectranthus glandulosus leaf powder, applied at four different rates for the control of Sitophilus zeamais was determined . Mortality was recorded 1, 3, 7 and 14 days after S. zeamais infestation, followed by the determination of F progeny production. Grain damage, population increase and grain germination were assessed for treated grains that were stored for 4 months. Grains treated with P. glandulosus powder and NSP had relatively low mortality (5.0-22.5%) after 3 days whereas NeemAzal and NSO had higher mortality (55.0-98.8%). Maximum mortality of 99, 100, 96 and 74% were achieved for NeemAzal (12 g/kg after 14 days), NSO (4 ml/kg after 7 days), NSP (40 g/kg after 14 days) and P. glandulosus powder (40 g/kg, after 14 days), respectively. In the same order, 7-day LC values were 0.02 g/kg, 1.46 ml/kg, 12.44 g/kg and 28.9 g/kg. The three neem products greatly reduced progeny emergence, while P. glandulosus powder was less effective. NeemAzal protected the grains against S. zeamais damage better than the local neem products, which in turn provided far better grain protection against the weevil damage than P. glandulosus powder. NeemAzal was superior to the local neem products in grain protection against germination loss, with P. glandulosus being the least effective. NeemAzal and NSO had sufficient efficacy to be a component of an integrated management package for S. zeamais. [ABSTRACT FROM AUTHOR]

Insecticidal effects of different doses of the dust and methanol extracts of Garcinia kolae on Collosobruchus maculatus and Sitophilus zeamais were tested. The dust had no significant effect on the two insects; none of them died even at 3 d after treatment. The methanol extracts, however, had rapid lethal effects on both C. maculatus and S. zeamais. The mortality of C. maculatus by the lowest concentration of methanol extracts ranged from 95%∼100% whereas in S. zeamais, the mortality ranged from 87.5%∼100% and 70%∼100% in concentrations of 1 g extract+3 ml methanol and 1 g extract+5 ml methanol, respectively, from 24 to 48 h. The least concentration of 1 g extract+15 ml methanol had no significant lethal effect on Sitophilus zeamais. [ABSTRACT FROM AUTHOR]

Sitophilus zeamais Motschulsky is an important field-to-store pest of maize in several parts of Africa including Cameroon. Although synthetic insecticides are effective at controlling the pest, the environmental and health hazards of these chemicals are of increasing concern. This study assesses the efficacy of ashes of local plant material against S. zeamais in the western highlands of Cameroon as an alternative to synthetic insecticides. Laboratory studies on toxicity against F1 progeny of S. zeamais were conducted using leaf ashes of Cupressus arizonica, Eucalyptus grandis, Ocimum gratissimum and root ash of Vetiveria zizanioides at the rates of 0.1, 0.25, 0.5 and 1.0 g/25 g maize grains in Kilner jars. Toxicity of E. grandis ash extract was also evaluated. The ashes of E. grandis and 0. gratissimum at the rate of 0.25g/25g grains significantly reduced the number of emerged weevils. Eucalyptus grandis ash showed toxicity (1.0 F1 progeny emerging at 0.25 g/25 g grains compared with 16.5 for the control). Eucalyptus grandis ash at 20 g/2 kg grains significantly reduced grain weight loss and protected grains for 6 months without adversely affecting the germination of the seeds. Ethanolic E. grandis ash extracts at rates of 50,000 and 100,000 ppm significantly (P < 0.05) reduced the number of emerged F1 progeny of S. zeamais. [ABSTRACT FROM AUTHOR]