Sitophilus Zeamais Research Articles

Effects of PICS bags on insect pests of sorghum during long-term storage in Burkina Faso

The PICS bags, originally developed for cowpea storage, were evaluated for sorghum (Sorghum bicolor) preservation. Batches of 25 kg of sorghum grain were stored in 50 kg PICS or polypropylene (PP) bags under ambient conditions for 12 months and assessed for the presence of insect pests and their damage, seed viability and, oxygen and carbon dioxide variations. The grain was incubated for 35 days to assess whether any insects would emerge. After six months of storage, oxygen levels decreased in the PICS bags compared to polypropylene bags. After 12 months of storage, only two pests, Rhyzopertha dominica and Sitophilus zeamais were found in the PICS bags. However, in PP bags there were additional pests including Tribolium castaneum and Oryzeaphilus mercator and Xylocoris flavipes. Grain weight loss and damage caused by these insects in the PP bags were significantly higher compared to those stored in PICS bags. Germination rates of sorghum grains stored in PP bags decreased significantly while no changes were observed in grains stored in PICS bags when compared to the initial germination. After the incubation post storage period, there was a resurgence of R. dominica in sorghum grains from PICS bags but the population levels were significantly lower compared to polypropylene bags. PICS bags preserved the quality and viability of stored sorghum grains and protected it from key insect pests. The PICS technology is effective for long-term sorghum storage but the potential resurgence of insects in low-oxygen environment calls for further research.

The Insecticide Toxicity and Repelling Ability of Jeruk Purut (Citrus hystrix D.C) Leaf Extract on Maize Weevil (Sitophilus zeamais Motsch)

Sitophilus zeamais Motsch. is a primary storage insect pest damaging maize grains.
 Control of S. zeamais can be done by applying biopesticide. This study was aimed at assessing the
 ability of Jeruk Purut leaf extract, as biopesticide, to kill and repel Sitophilus zeamais Motsch. The
 study was conducted at Entomology Laboratory, Seameo Biotrop in March to August 2018. A
 completely randomized design with three replicates in each rate of Jeruk Purut leaf extract was
 used. In preliminary pesticide toxicity experiment, five rates of Jeruk Purut leaf extract, namely
 0%, 2%, 4%, 6%, and 8% were applied. In preliminary repelling ability experiment, five rates of
 Jeruk Purut leaf extract, namely 1%, 2%, 4%, 6%, and 8% were applied. In the main pesticide
 toxicity and repelling ability trial, five rates of Jeruk Purut leaf extract, namely 3%, 6%, 9%, 12%,
 and 15% were applied. Results showed that in 24 hour after treating (HAT) no significant effects
 were found. Significant effects of Jeruk Purut leaf extract as insecticide on S. zeamais were found
 in 48 and 72 HAT. The highest mortality rate (82.2%) of S. zeamais was found in 15% rate of Jeruk
 Purut leaf extract in 72 HAT. The application of Jeruk Purut leaf extract was not found to give
 significant effects on repelling S. zeamais in 24, 48, and 72 HAT as indicated in their sharply
 fluctuating repellent values. The highest repelling ability (95%) was found in the application of
 9% Jeruk Purut leaf extract in 24 HAT. It was concluded that Jeruk Purut leaf extract was more
 potential as insecticide repellent for Sitophilus zeamais Motsch.
 Key words: biopesticide, repellent, insecticide, maize, primary storage insect pest

Evaluation of Purdue Improved Crop Storage Triple Layer Hermetic Storage Bag against Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae).

Hermetic technologies are being promoted in Africa as safer and more effective methods of grain storage on smallholder farms. However, farmers and policy makers lack knowledge of their efficacy in controlling major stored grain pests. An on-station study was conducted to evaluate the triple layer Purdue Improved Crop Storage (PICS) airtight bags against two major storage insect pests. Two sets each of PICS, jute and polypropylene bags were filled with 50 kg maize grain per bag. Each set was replicated four times. One set of PICS bags was each infested with 50 insects each of the larger grain borer P. truncatus and the maize weevil S. zeamais; while the other set was not. One set of jute and polypropylene woven bags was treated with a cocktail of 1.6% Pirimiphos methyl and 0.3% Permethrin, serving as positive controls; while the remaining sets with untreated maize grain formed negative controls. Gas analysis in the PICS bags followed the expected trend with oxygen levels falling sharply below 10% and carbon dioxide increasing to almost 10% after 12 weeks hence resulting in insect death. After 16 weeks, increase in oxygen levels may be attributed to perforation of the bags from outside by the P. truncatus. Results showed that PICS bags were significantly (P < 0.05) superior to treated and untreated controls of polypropylene and jute bags in suppressing insect development, maize grain damage and weight loss during storage. Weight loss in polypropylene and jute bags reached 40% and 41%, respectively, at 24 weeks after storage compared to PICS (2.4–2.9%). These results demonstrate that PICS bags can be used to store maize against P. truncatus and S. zeamais attack.

Efficacy of Modified Atmospheres on Trogoderma granarium (Coleoptera: Dermestidae) and Sitophilus zeamais (Coleoptera: Curculionidae).

We investigated the efficacy of two types of modified atmospheres (MA) against adults of the khapra beetle, Trogoderma granarium Everts, and the maize weevil, Sitophilus zeamais Motschulsky, under laboratory conditions. Adults of the above species on wheat were exposed to a carbon dioxide (CO2) concentration of 70% or a low oxygen (O2) concentration of 0.1% for durations of 0.67 (16 h), 1, 2, 4, and 6 d and stored in an environmental chamber set at 28 ± 2°C, 70 ± 5% RH, and a photoperiod of 16:8 (L:D) h. After each exposure interval, immediate mortality and knockdown were recorded, and the surviving or knocked down individuals were transferred to normal atmospheres and returned to the environmental chamber, where survival was recorded 7 d later. In addition, after the immediate and delayed mortality counts, all adults were removed from the substrate, and the number of progeny produced was recorded 60 d later. Both MA conditions totally controlled (100% mortality) the adults of T. granarium and S. zeamais immediately after a 6-d exposure or after a 4-d exposure when delayed mortality was taken into account, showing the postexposure effect of the MA. Moreover, high CO2 was more effective than low O2 for S. zeamais, whereas the reverse was true for T. granarium. The 4-d exposure period was crucial for the production of progeny of both species because after that period surviving insects did not produce offspring. Our results show that both MA conditions can be used with success to control these species.

New insecticide delivery method for the control of Sitophilus zeamais in stored maize

Maize kernel deterioration caused by the action of insects has led to an urgent need to develop new control methods against the maize weevil, Sitophilus zeamais, one of the major pests found in silo bags during the storage of maize. Here, we evaluated the insecticidal efficiency of plasticized and unplasticized cotton matrices (deliveries), loaded with R-(+)-pulegone, (−)-carvone, 2-decanone and trans-2-hexenol against S. zeamais. R-(+)- pulegone was the only compound that produced weevil mortality. Plasticized delivery loaded with R-(+)-pulegone achieved a 90% mortality on the 12th day, with mortality values recorded of above 96% over the course of 30 days. R-(+)-pulegone from plasticized delivery was released more slowly compared to unplasticized delivery. Moreover, delivery loaded with R-(+)-pulegone did not show phytotoxicity in maize kernels. Hence, due to its effectiveness against the weevil and the lack of phytotoxic activity against maize kernels, plasticized delivery loaded with R-(+)-pulegone represents a promising material for S. zeamais control. However, large-scale studies are needed in order to evaluate its potential use in grain storage systems.

Non-destructive screening method for detecting the presence of insects in sorghum grains using near infrared spectroscopy and discriminant analysis

The potential of near-infrared spectroscopy (NIRS) combined with partial least squares discriminant analysis (PLS-DA) to develop a screening method for distinguishing uninfested from infested sorghum (Sorghum bicolour (L.) Moench) grains was for the first time investigated. A total of 108 sorghum grain samples from thirty-six different genotypes were infested with seventy Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) unsexed adult insects during seventy days. More 101 uninfested sorghum grain samples from these same genotypes were used to build models. Principal components analysis (PCA) allowed slightly discriminating between the two classes along principal component two. A PLS-DA model presented perfect classification rates, with sensitivity and specificity equal to 100% for the test set. In addition, the model showed high accuracy, and accordance and concordance (precision) both equal to 100%. These results showed that the combination of NIRS with PLS-DA provided a rapid, cost-effective and non-invasive way to detect insect infestation in sorghum grains.

Avaliação da diversidade genética de Sitophilus zeamais, Motschulsky, 1855 (Coleoptera: Curculionidae) utilizando isoenzimas em amostras de diversas regiões do Brasil e do Paraguai

O manejo das principais pragas de grãos armazenados tem sido feito, preferencialmente, com o uso de inseticida o que representa um enorme risco no desenvolvimento de resistência. Há muitos estudos com o Sitophilus zeamais visando seu controle, porém poucos analisando a variabilidade genética desta espécie. Este trabalho teve como objetivo estimar a variabilidade genética de S. zeamais em 10 amostras de diferentes localidades, destas, oito são do Brasil: Tunápolis (SC), Iguatemi (PR), Piracicaba (SP), Coimbra (MG), Maracaju (MS), Canarana (MT), Jataí (GO), Picos (PI) e duas são do Paraguai: Amambay e Pedro Juan Caballero. Para tal, foi utilizada a técnica de eletroforese de isozimas, em gel de amido para analisar seis sistemas enzimáticos (AAT, ACP, GPI, IDH, MDH e ME) e em gel de poliacrilamida que permitiu analisar uma enzima (EST). Concluiu-se que a espécie apresenta alta variabilidade genética (He), diferenciação moderada entre as amostras e as amostras foram agrupadas em três grupos.

Methyl Benzoate as a Putative Alternative, Environmentally Friendly Fumigant for the Control of Stored Product Insects.

Historically, stored product insect pest management has been based around the use of methyl bromide and phosphine as fumigants. However, methyl bromide has been phased out for structural fumigations, and there is increasing worldwide insecticide resistance to phosphine. One potential alternative, environmentally friendly option is the use of methyl benzoate (MBe), which is considered a food safe compound. In this study, we evaluated the direct and sublethal effects of MBe exposure on the survivorship and mobility of four stored product species with diverse life histories, including Rhyzopertha dominica, Tribolium castaneum, Sitophilus zeamais, and Trogoderma variabile. Sets of insects were exposed to a control, low, or high MBe concentrations in flasks with or without food for 24 or 72 h in the laboratory. Furthermore, we assessed phosphine exposure under similar conditions. Overall, R. dominica was the most susceptible to MBe exposure, followed by T. castaneum. By contrast, S. zeamais and T. variabile were relatively unaffected by MBe exposure. Exposure to MBe induced multiple-fold decreases in the total distance moved and velocity of adults still considered alive or affected after assays. By comparison, phosphine effectively killed all individuals of all species. Our data suggest that while MBe was effective for R. dominica, it was not competitive in comparison to phosphine for controlling susceptible strains of these species at the specified experimental conditions.

Sensilla on the Antennal Funiculus of the Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae): A Morphological Investigation

Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) has a great capacity to destroy stored grain worldwide. We report on the sensilla on the antennal funiculus of S. zeamais, using classical anatomical methods and scanning electron microscopy to obtain a detailed database of the antennal sensilla for each sex. The antenna is composed of eight antennomeres. Average antennal length is 781.58±20.64 µm for males and 808.91±11.80 µmfor females. Six types and subtypes of sensilla were identified on the funiculus: squamiform, basiconic (2 subtypes), chaetic (2 subtypes), and coeloconic. Sensilla squamiformia are distributed evenly but in few numbers on male and female antennomeres. Sensilla basiconica can be divided into subtypes, SB1 and SB2, according to the shape of the cone. Both subtypes occur on the last antennomere of the flagellum and there are fewer SB2 than SB1. Sensilla chaetica appear in the same position as sensilla basiconica and have two subtypes, SC1 and SC2. Significant differences were not found in the types of sensilla on the antennae of the two sexes, but a difference was found in the number of sensilla.

Efeitos do extrato supercrítico de Melia azedarach (Meliaceae) no controle de Sitophilus zeamais Motschulsky, 1855 (Coleoptera, Curculionidae)

O presente estudo teve como objetivo testar a eficiência do extrato supercrítico de Melia azedarach no controle de Sitophilus zeamais por meio do contato tarsal. Observou-se a sobrevivência dos insetos a cada 24 h após o início do experimento. Constatou-se que houve maior mortalidade de insetos nas primeiras 72 h. O tratamento que teve melhor desempenho considerando-se a relação tempo de ação e número de insetos mortos foi o de concentração 200 μL mL-1. A concentração letal média que mata 50% da população (CL50) obtida após 96 h do tratamento foi de 165,52 μL mL-1, indicando que a maior dose pode ser reduzida com resultados satisfatórios para as condições empregadas no estudo. O extrato de M. azedarach revelou-se efetivo no controle de S. zeamais em condições de laboratório.

Andean Flora as a Source of New Repellents against Insect Pests: Behavioral, Morphological and Electrophysiological Studies on Sitophilus zeamais (Coleoptera: Curculionidae).

Sitophilus zeamais (Motschulsky) is considered as one of the most destructive foodstuff pests. Due to their efficiency, low toxicity for mammalians and low environmental impact, plant-derived essential oils (EOs) are promising tools for pest control. In particular, the OEs extracted from Lamiaceae are considered among the most bioactive in terms of repellent and/or insecticidal effect. Here, we investigated the repellence of the EOs extracted from two aromatic plant species typical of the flora of the Ecuadorian Andes, Clinopodium tomentosum and C. nubigeum, against adults of S. zeamais. The behavioral assays carried out at concentrations ranging from 0.7 to 23.9 μL L−1 air in a two-way static olfactometer showed a significant repellent effect starting from the concentration of 8.4 mL L−1 air both for the EO of C. nubigenum and C. tomentosum. We also carried out a complete structural analysis of the antenna of S. zeamais using scanning (SEM) and transmission electron microscopy (TEM), in order to characterize the olfactory sensilla equipment. In this species, there is no sexual dimorphism also as regards to the antennal morphology and the sensilla type and distribution. We identified six type of sensilla, among which at least three types (Sensillum Trichoideum 1, Sensillum Trichoideum 2 and Grooved Peg Sensillum) can be considered as olfactory. Electroantennography (EAG) recordings carried out on S. zeamais revealed a positive dose-response to both EOs, without differences between the two sexes.

Does Prior Feeding Behavior by Previous Generations of the Maize Weevil (Coleoptera: Curculionidae) Determine Future Descendants Feeding Preference and Ovipositional Suitability?

The maize weevil Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) is an important pest of stored grains, predominantly corn (Zea mays), wheat (Triticum spp.), rice (Oryza spp.), and sorghum (Sorghum bicolor) (all Poaceae). In Africa, post-harvest grain losses of maize amounts to about US $4 billion annually, with an estimate of 10 to 88% loss of maize due to stored grain pests (FAO 2010; Ojo & Omoloye 2012). Current control methods are the application of an insecticide, cultural practices, and the development of resistant grain. Unfortunately, there is no effective trapping system for control of the maize weevil. Previous studies have indicated that the odors associated with the grains upon which the weevils feed, mate, and oviposit are known to be attractive. To better understand this behavior, a study was developed to investigate the weevil's attraction to dry grains with and without the presence of the commercial pheromone lure. The weevil's ability to develop on specific grains also was investigated. The weevils were reared on 4 types of grain to determine, if presented a choice, whether they would prefer the grain upon which their parents and they themselves fed as larvae. This research demonstrates that previous feeding did not influence the weevil's attraction to a certain grain. The isolation of key corn semiochemicals should be the focus in the development of an attractant for S. zeamais. These findings eliminate the need to develop individualized attractants that would have to be tailored to weevils feeding upon specific hosts.

Susceptibility of Six Corn Varieties (Zea mays L.) to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

Agricultural produce is commonly stored in warehouses after the harvest period, before being utilized and fulfilling the crop stock. However, crop threats are not only present during cultivation and harvest, but crops can also be infected during storage, which leads to agricultural loss. This research aimed to observe the resistance level of corn varieties of Bisma, Bisi 18, Bisi 19, Pioneer 21, Pioneer 29, and Pertiwi 3 to the Sitophilus zeamais pest of stored product insects. This resistance was based on the mechanism of non-preference (antixenosis) resistance, measured with the Free Choice Test Method (FCTM), and antibiosis resistance mechanism, measured with the No Choice Test Method (NCTM). The results showed that based on the susceptibility index (Dobie, 1974), corn varieties of Pertiwi 3 were categorized as resistant to S. zeamais pests, while the varieties of Bisi 19, Bisma, Bisi 18, Pioneer 21 and Pioneer 29 were moderately resistant.

Analysis of reproductive traits and laying egg rhythm of maize weevil sitophilus zeamais (motschulsky)

The maize weevil, Sitophilus zeamais (Motschulsky), is a serious pest affecting a wide range of cereal crops, such as maize, rice, beans and other stored dried grains. As a S. zeamais female can keep laying eggs for a long time throughout its life after chewing its way into the grains, most development stages of the maize weevil, such as eggs, larvae and pupae, can always be found in stored maize grains. Our experiment with S. zeamais on long grain rice showed that 10 days after eclosion and mating, maize weevil females started laying eggs for a period of 145 days. On average, a S. zeamais female laid 38.67 eggs, of which, up to 62.81% were laid in the first 7–8 weeks (with the remaining 37.19% in the latter half of the 145 day period), and 55.07% were laid within day 55–95. The egg laying pattern of S. zeamais was modeled using cubic polynomials, which described the maximum percentages of eggs laid at day 15, 35, 75, 95 and 105.

Effectiveness of the solar biomass hybrid dryer for drying and disinfestation of maize

The Solar Biomass Hybrid Dryer (SBHD) is a new technology developed in Ghana for grain drying and utilizes biomass (agro-residues, timber scraps, etc.) along with solar drying, and is especially useful for drying during rainy periods of the year when solar drying cannot be relied on. This study assessed the effectiveness of a 5.0-MT SBHD comprising a solar tent and a furnace for thermal drying and disinfestation of maize. Mortalities of adults of Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst) and Cryptolestes ferrugineus Stephens were assessed. Additionally, mortalities of immatures of these three species were assessed. Internal and cage temperatures (°C) in the SBHD, sun drying (SD) and laboratory (control) were monitored, as were moisture content (MC) and thermally (stress) damaged kernels (TDK) (%). During the 7-h experiment, mean internal temperatures in the SBHD, SD and laboratory were 52.3 ± 1.0 °C, 41.4 ± 0.8 °C and 30.3 ± 0.2 °C, respectively. Similarly, temperatures in cages in the SBHD (49.5 ± 1.0 °C) were higher than those for cages in the laboratory (29.9 ± 0.2 °C) and SD (38.2 ± 0.6 °C). Reduction in the moisture content of maize dried using SBHD, SD and under laboratory conditions were 7.7, 5.2 and 2.9%, respectively. This corresponded to grain MC reduction rates of 1.1%, 0.74% and 0.4% per hour. There was 100% mortality of S. zeamais and C. ferrugineus adults achieved in only the SBHD; some immatures of all three species survived in all three treatments. However, survival of immatures was highest in the laboratory, followed by SD and lowest in the SBHD for all three species. Percent TDK was higher in the SBHD (6.7 ± 0.9) than SD (3.3 ± 0.3) and laboratory (2.7 ± 0.3). These data show that the SBHD is effective for both drying and disinfestation of grain.

The Compared Efficiency of the Traditional Method, Radiography without Contrast and Radiography with Contrast in the Determination of Infestation by Weevil (Sitophilus zeamais) in Maize Seeds.

Technologies that increase safety and efficiency, while facilitating and streamlining the work of seed analysts, are increasingly required by the seed industry. X-ray image analysis is a technique that has been used in the analysis of grain and seeds because it is fast, accurate and non-destructive. The traditional method to verify the presence of insect damage in seeds involves manual cutting of the seeds, which endangers the safety of the analyst and is time-consuming and repetitive work that leads to visual fatigue. The objective of this study was to compared the efficiency of radiographic analysis with and without contrast in the determination of infestation by Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), at different stages of development, in maize seeds, compared to the traditional method required by seed legislation, which consists of cutting and visual evaluation. Seeds were evaluated regarding the presence of eggs/oviposition signs, larvae, pupae, adult insects, insect damage in five infestation periods (5, 18, 33 and 35 days after infestation), while evaluating the total number of seeds infested, comparing the three methods. For characterization of the oviposition stage, the use of contrast was best at all times of infestation. For the larval stage, there was no difference between the evaluation methods; however, at 18 days, larger infestations were observed by the traditional method. At 5 days, the identification of pupae was better by the traditional method and radiography without contrast, while for the identification of adult insects the best method was the use of radiography without contrast. The characterization of the level of infestation with maize weevil damage was best verified using contrast radiography. Radiographic analysis is efficient in the detection of damage caused by S. zeamais in maize seeds. This method of radiographic analysis (with or without contrast) is thus an auxiliary tool to assess the damage and presence of S. zeamais in maize seeds.

LEAF ESSENTIAL OIL FROM Croton pulegiodorus Baill SHOWS INSECTICIDAL ACTIVITY AGAINST Sitophilus zeamais Motschulsky

ABSTRACT The present study aimed to assess the effects of the essential oil of Croton pulegiodorus Baill on eight populations of Sitophilus zeamais Motschulsky with different patterns of susceptibility to synthetic insecticides. Populations of S. zeamais were obtained from Sete Lagoas-MG, Jacarezinho-PR, Bom Conselho-PE, Garanhuns-PE, Jupi-PE, Lajedo-PE, São João-PE and Serra Talhada-PE. To estimate the lethal concentrations (LC50 and LC90) of oil for each population, fumigation tests were performed. The susceptibility of S. zeamais to the essential oil varied among populations. Garanhuns and Bom Conselho was considered the susceptibility patterns, presenting the lowest LC50 (3.40 μL L-1 of air) and LC90 (9.60 μL L-1 of air) for the essential oil, respectively. The population from Jupi exhibited the highest LC50 (14.49 μL L-1 of air) and LC90 (19.60 μL L-1 of air) for C. pulegiodorus. The resistance ratio ranged from 1.84 for the São João to 4.26 for the Jupi population. Thus, the essential oil of C. pulegiodorus showed fumigant activity, causing mortality in all S. zeamais populations used.

CONTACT TOXICITY OF ESSENTIAL OIL OF Croton pulegiodorus BAILL ON Sitophilus zeamais MOTSCHULSKY

ABSTRACT The objective of this work was to evaluate the contact toxicity of essential oil of Croton pulegiodorus Baill on six populations of Sitophilus zeamais Motschulsky. The S. zeamais populations used were from Crixás-GO, Espírito Santo do Pinhal-SP, Juiz de Fora-MG, Picos-PI, Serra Talhada-PE, and Vicentina-MS, Brazil, and present different susceptibility to synthetic insecticides. The essential oil of C. pulegiodorus used was obtained from plants collected in Triunfo-PE, Brazil. The lethal concentrations (LC50 and LC90), toxicity ratio of the essential oil, and the resistance ratio of the populations were estimated. The S. zeamais population from Serra Talhada-PE presented the lowest LC50 (4.21 μL 20 g-1) and LC90 (6.67 μL 20 g-1) and was the reference for susceptibility to the essential oil of C. pulegiodorus. The S. zeamais population from Espírito Santo do Pinhal-SP presented the highest LC50 (6.02 μL 20 g-1) and LC90 (10.55 μL 20 g-1) and was the reference for tolerance to the essential oil of C. pulegiodorus. The toxicity ratio ranged from 1.01 (Picos-PI) to 1.43 (Serra Talhada-PE); and the resistance ratio ranged from 1.13 (Crixás-GO) to 1.43 (Espírito Santo do Pinhal-SP). The essential oil of C. pulegiodorus reduced the emergence of adult S. zemais and showed residual effect, with contact toxicity, after 30 and 60 days of application.

Inheritance and combining ability studies on grain yield and resistance to maize weevil (sitophilus zeamais, motschulsky) among extra early quality protein maize inbred lines

A Thesis Submitted to the Department of Crop and Soil Sciences, Faculty of Agriculture, College of Agriculture and Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana in Partial Fulfilment of the Requirements for the Award of Degree of Master of Philosophy in Plant Breeding, 2016.

Trans-2-hexen-1-ol as a tool for the control of Fusarium verticillioides in stored maize grains

Fusarium verticillioides infects stored maize grains. In the present study, we first evaluated the effects of ten volatile organic compounds on F. verticillioides growth in culture medium. Subsequently, based on the antifungal activity obtained in the present study and the insecticidal effect against Sitophilus zeamais reported previously, trans-2- hexen-1- ol was selected to analyzed its effect on the fungus in stored maize. All the compounds tested showed inhibitory activity on fungal development, being the most active compounds geraniol, nerol, isovaleraldehyde and linalool, followed by trans-2-hexen-1-ol, cis-3-hexen-1-ol, cis-2-hexen-1-ol and trans-3-hexen-1-ol. Besides its antifungal activity against F. verticillioides, trans-2-hexen-1-ol inhibited FB1 production. In this study it was also demonstrated that S. zeamais favors F. verticillioides dispersion, confirming the importance of these insects as mechanical vectors of fungal spores. These results reveal the ability of trans-2-hexen-1-ol as a potential tool to control F. verticillioides in a natural approach as an alternative to synthetic pesticides.