Stored Grain Research Articles

Comparative study on the repellency and chemical profiles of different chilli peppers formulations against Sitophilus oryzae L. (Coleoptera: Curculionidae) in stored wheat

The weevil Sitophilus oryzae L. (Coleoptera: Curculionidae) is the major insect pest of stored grains, including wheat. This study tested the repellency effectiveness of three formulations, including chilli dry powder (CDP), chilli ethanol extract (CEE), and chilli crude extract (CCE), from different chilli peppers of Capsicum annuum L. and Capsicum chinense Jacquin varieties (Solanaceae), against S. oryzae using a modified cup bioassay arena. Repellency responses varied significantly (P ≤ 0.001) within the three different formulations, where the CEE formulation at the concentration of 5 g (w/w) demonstrated the highest effectiveness, effectively deterring the highest number of insects (mean number of repelled insects ± SE) after 24 h of treatment across tested chilli varieties such as Guntur Sannam chilli (GSC) (15.0 ± 0.6), Kashmiri chilli (KC) (16.0 ± 0.0), and Bhut Jolokia chilli (BJC) (18.0 ± 0.6). CDP formulation closely followed, displaying notable repellency activity against the same varieties. Conversely, the CCE formulation exhibited the least effectiveness in repelling the adult weevils. Thus, the repellency activity observed was time-, concentration-, and formulation-dependent. Further, the percentage repellency (PR) assay conducted by following the area preference method demonstrated that the Bhut Jolokia chilli exhibited the highest repellency percentage (61.2%) at a concentration of 0.251 μg/cm2, by categorizing it as a class IV repellent. Gas chromatography-mass spectrometry (GC-MS) analysis detected the presence of capsaicinoids like capsaicin and dihydrocapsaicin, alongside various non-capsaicinoids such as n-hexadecanoic acid and n-pentadecylacetamide, etc., in the ethanolic fraction of chilli pepper varieties, suggesting that the observed differences in the repellency activity might be attributed to varying chemical compositions, warranting further detailed exploration in this domain. These findings provide valuable primary insights into the prospective application of chilli pepper formulations from different varieties as a repellent against S. oryzae.

Evaluation of five medicinal plants for the management of Sitophilus oryzae in stored rice and identification of insecticidal compound

Sitophilus oryzae is a kind of stored grain pest. This is controlled by using natural pesticides, which are more reliable, cost-effective, biodegradable, and eco-friendly than synthetic pesticides. Several plants show different insecticidal activities against various pests on their different parts (leaves, seeds, etc.). In this study, methanolic extracts of Lantana camara (leaves), Carica papaya (seeds), Ricinus communis (leaves), Calotropis gigantea (flowers), and Gliciridia sepium (leaves) were used to identify the best insecticidal activity against the rice weevil by doing mortality tests for one week with four replications under laboratory conditions. Gliciridia sepium leaves showed the highest insecticidal activity (100 ± 0) after seven days, and its extract was fractionated by using column chromatography and yielded 12 fractions. A contact bioassay of each fraction was performed, and fraction-11 showed the highest insecticidal activity against Sitophilus oryzae with a 100 % mortality after four days. Fraction-11 was analyzed by using GC-MS and FT-IR. Results revealed that the major constituent identified in fraction-11 was 4-C-methyl-myo-inositol. Therefore, 4-C-methyl-myo-inositol acts as a natural insecticide against rice weevils.

Bi-objective model for tactical planning in corn supply chain considering CO2 balance

This paper addresses the Brazilian corn production logistic supply chain with an optimisation model considering carbon emission from transportation and carbon sequestration from corn production. The focus is on the higher-level decision planning, which includes the best regions for corn cultivation, location and sizing of silos to store grains, transportation modes with intermodality, considering several resource constraints to meet the demands of domestic market and export. Two conflicting objectives are considered: the logistics costs of the supply chain and the balance of CO 2 . Accurate data are used to evaluate the model and the Pareto optimal solutions are produced in scenarios potentially feasible in practice. The solutions showed relevant information to guide decisions about investment in logistic infrastructure. We demonstrated that cleaner transportation routes lead to solutions that have larger carbon stocks with 3–5% increase in costs by only choosing more suitable regions for corn cultivation and transportation modes.

Adult food and species type influence the nutritional physiology and tolerance of two flour beetles to the extract of Dennettia tripetala (G. Baker)

AbstractTribolium castaneum (Herbst) and Tribolium confusum (Jacquelin du Val) are common and damaging pests of stored grain flours in several homes and flour mill industries worldwide. This study examines how food, species, concentration, and exposure time affect the susceptibility and nutritional physiology of T. castaneum and T. confusum when exposed to partially purified methanolic fruit extract of Dennettia tripetala (G. Baker) and two of its major active compounds (linalool and 2‐phenylnitroethane). Gas chromatography–mass spectrometry was used to evaluate the chemical profile of the partially purified plant extract. Thirty‐two compounds were found in the plant, including established insecticidal and insectifuge compounds such as linalool, cis‐vaccenic acid, 2‐phenylnitroethane, and linoleic acid, among others. The interactions among the factors have a differential impact on the susceptibility and nutritional indices of both Tribolium species to D. tripetala, linalool and 2‐phenylnitroethane. According to LC50 values, linalool and 2‐phenylnitroethane were the most and least toxic to both beetles, respectively. With increasing extract concentrations, all nutritional indices except feeding deterrence decreased. Relative to controls, linalool and 2‐phenylnitroethane evoked the highest and least reduction, respectively, in beetles' nutritional indices. Treated corn discs deterred both species over treated wheat discs, regardless of insecticide type. T. castaneum had a higher overall food consumption than T. confusum. Regardless of insecticide type, the relative growth rate was higher in T. confusum and T. castaneum fed with treated corn and wheat discs, respectively. D. tripetala extract, linalool, and 2‐phenylnitroethane showed higher post‐ingestion toxicity to T. castaneum than T. confusum. This study emphasises the importance of certain intrinsic factors, like beetles' species and cereal food types, when managing Tribolium species with plant‐based insecticides. The various data obtained from this study will help researchers and pesticide manufacturers formulate effective biopesticides from linalool and 2‐phenylnitroethane to control Tribolium species on corn and wheat flours.

Impact of storage time on microbial communities and flavor profiles in highland barley grains

Microbial activity and the resulting flavor changes in stored highland barley grains may reduce the product quality and pose potential risks to food safety with economic losses. This study aims to elucidate the association between microbial load and flavor compounds during the preservation of highland barley. High-throughput sequencing (HTS) was used to investigate the microbial composition in stored highland barley. The volatile flavor components of the latter were identified via the headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Moreover, the study examined the correlation between the types of microorganisms and volatile flavor molecules. The results indicated that the dominant phyla in highland barley were Ascomycota and Basidiomycota, with the dominant genera being Cladosporium, Vishniacozyma, Filobasidium, Udeniomyces, Cystofilobasidium, Aspergillus, Alternaria, Monographella, Didymella, and Neoascochyta. Inside，Cystofilobasidium, Itersonilia, Sarocladium, Ustilago, Penicillium and Pyrenophora served as effective biomarkers to distinguish highland barley grains stored at different times. Further, the highland barley samples contained 192 volatile organic compounds (VOCs), such as alcohols, ketones, esters, alkanes, aldehydes, etc. The top 20 volatile flavor compounds with differences were selected based on the variable importance of projection (VIP) > 1. Based on the correlation analysis findings, it was found that the genera Cystofilobasidium, Aspergillus, and Cladosporium hold promise in contributing volatile flavor compounds to highland barley. This study examined a pattern of changes in safety and quality across varying storage durations, providing crucial insights to enhance the flavor profile and texture of highland barley products.

Host Volatiles Potentially Drive Two Evolutionarily Related Weevils to Select Different Grains

The Sitophilus zeamais (maize weevil) and Sitophilus oryzae (rice weevil) are two insect pests that have caused huge economic losses to stored grains worldwide. It is urgent to develop an environmentally friendly strategy for the control of these destructive pests. Here, the olfactory-mediated selection preference of the two weevil species to three stored grains was analyzed, which should help establish a pull–push system in managing them. Bioassays showed that maize weevil adults prefer to select maize, followed by paddy and wheat, while rice weevil adults mainly migrate towards wheat. Volatile analyses revealed that 2-ethylhexanol, piperitone, and (+)-Δ-cadiene are the major components in volatiles from both maize and wheat, but the abundance of these chemicals is much lower in maize than that in wheat. The volatile limonene was only detected in paddy. Y-tube bioassays suggest that 2-ethylhexanol, piperitone, and (+)-Δ-cadiene were all attractive to both weevils, whereas limonene was attractive only to rice weevils. Overall, maize weevil appeared more sensitive to the tested volatiles based on having much lower effective concentrations of these volatiles needed to attract them. The differences in volatile profiles among the grains and the sensitivity of the two species towards these volatiles may explain the behavioral differences between maize and rice weevils in selecting host grains. The differences in sensitivity of maize and rice weevils towards host volatile components with abundance differences are likely determinants driving the two insect species to migrate towards different host grains.

Physicochemical characterization of seeds and aril of Renealmia aromatica (Aubl.) Griseb

The Amazon has great biodiversity, being inhabited by indigenous peoples since time immemorial, as well as being home to traditional farmers, settlers, riverine dwellers, people responsible, in large part, for the conservation of biodiversity through the cultivation and storage of grains, tubers, roots and seeds. Among the numerous species cultivated and managed by the Amazonian peoples, we approach, in this work, the species Renealmia aromatica (Aubl.) Griseb., belonging to the Zingiberaceae family. The objective of this article is to present physicochemical aspects of the fruits of Renealmia aromatica (Aubl.) Griseb. aiming to emphasize its alimentary potential and nutritional value.This work consisted of harvesting the fruits of mother plants located in the experimental garden of the Universidade Federal do Acre – UFAC. The analyzes were carried out at the Unidade de Tecnologia de Alimentos – Utal of UFAC – Campus Rio Branco. The variables analyzed were protein, ascorbic acid (vitamin C), titratable acidity, moisture and ash (fixed mineral residue) according to the methods for physicochemical analysis of foods from the Instituto Adolfo Lutz. In the aril and in the seed, protein contents of 7.97% and 6.67% were found, respectively. As for lipids, the highest concentration was observed in the seeds, with a content of 6.76%. The aril showed a satisfactory level of vitamin C (182,81 mg/100g). With a high concentration of lipid, the seeds had a total caloric value of 335,56 kcal/100g. Thus, the seeds and arils of R. aromatica have alimentary and nutritional potential, being the seeds used for the production of edible oil or condiment, and the aril, rich in vitamin C, used in alimentation. This, although already used in food, is still restricted to indigenous peoples and traditional communities.

Investigation of the control of Sitophilus granarius in stored grain using vacuum packaging and the creation of an anaerobic atmospheric environment

The efficacy of vacuum and oxygen absorption-based treatments for controlling Sitophilus granarius L. damage in wheat grains was compared under laboratory conditions. The efficacy of the treatments was evaluated at different temperature ranges (−5, 26, 42 °C) and exposure times (0.5, 1, 3, 6, 24, 48, 72 h). Treatment-survived adult progeny were measured on day 45. Our studies demonstrated that the efficacy of the controlled atmosphere methods (CAs) we tested varied significantly as a function of time. While the mortality curve induced by the different temperature-controlled low-pressure vacuum packaging treatments is logarithmic, the mortality trend induced by the absorber's low oxygen levels follows an exponential slope. The hypoxia induced by low oxygen levels has a much longer duration of action. We have shown that vacuum packaging at lower and higher pessimum temperature ranges other than the thermal optimum of the insect induced significant mortality of S. granarius. The method was particularly effective when vacuum-packed items were kept at a higher pessimum temperature range. Our results confirm that vacuum packaging based on atmospheric modification, especially at elevated temperatures, can be a sustainable solution for pest control of small volume, valuable seed samples.

The efficacy of green silica nanoparticles synthesized from rice straw in the management of Callosobruchus maculatus (Col., Bruchidae).

Rice straw, a byproduct of harvesting rice, must be disposed of by farmers in a variety of ways, including burning, which is hazardous for the environment. To address this issue, the straw needs to be utilized and turned into valuable products. One such product is nano-silica (SNPs), which will be synthesized and investigated in our study as a safe alternative to chemical insecticides. Rice straw-derived SNPs were synthesized using the Sol-Gel method. The contact toxicity of SNPs on Callosobruchus maculatus, a major pest of cowpea seeds, has been assessed. The size of synthesized SNPs was determined by transmission electron microscopy to be ~ 4 nm. The SNPs estimated LC50 on C. maculatus adults was 88.170 ppm after 48h exposure. By raising the tested concentration, SNPs treatment increased the mortality%, which reached 100% at 200 ppm exposures. Additionally, SNPs at LC50 treatment decreased adult longevity and the average number of emerged adults. The findings also verified that SNPs had no phytotoxic effects on the cowpea seeds germination. Rather, their application improved seed germination efficacy. This study proposed that rice straw can be utilized to manufacture highly efficient SNPs which can be efficiently employed to preserve stored grains from C. maculatus infestation.

Plant-Based Insecticides for Control of Aedes aegypti, Sitophilus zeamais and Nasutitermes corniger: A Review and Bibliometric Analysis

Insect pests can transmit diseases or affect the economy and their uncontrolled growth is intensified by human activity, which has affected ecosystems and interfered with trophic chains. Aedes aegypti L. transmits dengue, chikungunya, zika and yellow fever, while Sitophilus zeamais Motsch is a stored grain pest, and Nasutitermes corniger Motsch attacks trees and urban buildings. This work provides a review of the state of art and current trends, as well as a bibliometric analysis on the insecticidal activity of plant-based products against Ae. aegypti, S. zeamais and N. corniger. The review of literature data showed that plant insecticides comprise secondary metabolites and proteins that can impair the viability of embryos, larvae, pupae, and adults, as well as fertility and oviposition or feeding behavior of insects. Also, they tend to be more biodegradable and less harmful to non-target organisms compared to synthetic insecticides. The bibliometric analysis revealed the concentration of publications in tropical regions worldwide, where there is a strong occurrence of diseases transmitted by Ae. aegypti. These reports were far more numerous than those on N. corniger and S. zeamais. Furthermore, the synthesis of metallic nanoparticles from plant products has strongly emerged as a current trend.

Biosynthesis of Copper Nanoparticles from Acacia cornigera and Annona purpurea and Their Insecticidal Effect against Tribolium castaneum

Diverse studies have showed that the pesticides can cause important damages in ecosystem. Therefore, the development of bio pesticides through nanotechnology can increase efficacy and limit the negative impacts in the environmental that traditionally seen through the use of chemical pesticides. Nanoparticles obtained from plants’ extracts can be used for effective pest management as a combined formulation of metal and some other organic material present in the plants. In the present study, our evaluated biosynthesis of nanoparticles of copper used two plant extracts (Acacia cornigera and Annona purpurea), and the Taguchi method was adopted for the synthesis optimization of the following variables of biosynthesis: temperature, pH, extract concentration, and reaction times to maximize the insecticidal activity on Tribolium castaneum. Our results showed that the nanoparticles were successfully synthesized using Acacia cornigera and Anona purpurea extract under optimum conditions under Taguchi L 9 orthogonal design, where copper nanoparticles were obtained with a size of 63–153 nm for using A. cornigera extract, 87–193 nm for A. purpurea extract, and a zeta potential of 9.6 mV and −32.7 mV, respectively. The nanoparticles of copper from A. cornigera showed effective insecticidal activity against Tribolium castaneum, and 90% mortality compared to the 76.6% obtained from nanoparticles of copper from A. purpurea. The results suggest that Cu-nanoparticles derived from both plants could be used as a biocontrol agent of Tribolium castaneum, a pest of stored grain with great economic importance.

Atmospheric cold plasma-induced mortality in Sitophilus oryzae (L.)

The rice weevil, Sitophilus oryzae, is a common pest in grain storage and agriculture, causing considerable damage to stored grains. Increasing resistance of rice weevils to current fumigation methods continues to occur, necessitating the development of alternative control strategies. In this study, we investigated the impact of atmospheric cold plasma (ACP) on the mortality of rice weevils. ACP generates non-thermal ionized gas at or near room temperature and has been effective in inactivating microorganisms and pests, including rice weevils. We hypothesized that ACP treatment would have detrimental effects on the weevils, leading to a high mortality rate. To evaluate this hypothesis, we applied a treatment voltage of 80 kV and treatment times of 0, 3, 5, 8, and 10 min across all life stages of rice weevils, including the egg, larval (1st – 4th instars), pupal, and adult phases. Additionally, we examined post-treatment retention times of 0, 24, 48, and 72 h to assess how long the treated weevils survived after exposure. We observed that both treatment time and post-treatment retention time impacted, especially for weevils treated with shorter durations. Higher treatment times (5,8, and 10 min) showed that eggs failed to hatch, larvae and pupae were unable to emerge, and adults either died immediately after treatment (depending on the treatment duration) or within 24–48 h post-treatment. Based on these findings, we can conclude that ACP has detrimental effects on rice weevils, providing valuable insights into the potential use of ACP as an integrated pest management strategy.

Insecticidal activity of essential oils derived from lavender, laurel and peppermint against lesser grain borer, Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrichidae)

Fumigant effects of the essential oils from Laurus nobilis L., 1753 (Laurales: Lauraceae), Mentha piperita L., 1753 and Lavandula x intermedia Emeric ex Loisel, 1828 (Lamiales: Lamiaceae) were determined using the lesser grain borer [Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrychidae)], an important pest species of stored grains. The experiments were conducted in the 2021 in the Department of Crop Protection, Faculty of Agriculture, Malatya Turgut Özal University. The experiments were conducted in a controlled-climate chamber at 27 ± 1°C, 50 ± 10% RH and in the dark. The fumigant effects of essential oils were determined at five concentrations (1, 5, 20, 50 and 200 μl/L air) with larva, pupa and adult stages of R. dominica. The highest fumigant effect was with R. dominica larvae was complete mortality with 200 μl/L L. nobilis essential oil and for the adults, 200μl/L of either L. nobilis and M. piperita essential oil also caused complete mortality. However, the complete mortality of pupal stage was not obtained and the highest mortality was 49% with L. nobilis. As a result, it is considered that both L. nobilis and M. piperita essential oils have the potential to be used as effective biofumigants for stored product pests.

Development and verification of a graphical detection system for multi-field interactions in stored grain based on LF-NMR

Stored grain is a complex ecosystem in which intricate multi-field interactions exist among abiotic and biotic factors, as well as the surrounding environment. Clearly understanding these interactions is crucial for ensuring grain storage security. This study developed a graphical detection system based on low-field nuclear magnetic resonance (LF-NMR) technology, which consists of an LF-NMR imaging analyzer, a small grain container, and dedicated software. This system can simultaneously detect the temperature, moisture, and humidity of a grain sample stored in the grain container and visually present the cloud maps of these fields through the dedicated software. To verify the system's performance, two laboratory storage experiments with paddy rice samples were conducted for 15 d. The results indicated that the measured cloud maps could accurately depict the variations in the temperature, moisture, and humidity fields within the stored paddy rice samples during the storage period. The areas with potential risks of fungal growth, grain sprouting, and moisture condensation due to the multi-field interactions could also be identified through the cloud maps, which demonstrated the credible performance of the system. This system could provide a new technical means to uncover the complex coupling relationships within grain storage ecosystems.

Predicting early mycotoxin contamination in stored wheat using machine learning

With continued global population growth and current rate of climate change, grain loss during storage remains a major contributor to postharvest losses of wheat (Triticum aestivum L.). Infection with mycotoxin leads to degradation or even discarding of stored grain, causing economic losses and risks to food security. Deep learning models have been used in the agricultural domain for detecting prevalent diseases or contamination; however, data scarcity remains a critical bottleneck for rapid implementation of computer vision in this field. Herein, a compact convolutional transformer (CCT)–based model was applied to classify contaminated wheat by deoxynivalenol (DON) and aflatoxins (AFB1, AFB2, AFG1, and AFG2), which was divided into three main classes: healthy, incipient, and contaminated. The classification was performed based on elevated CO2 respiration rate (≥31.20 ± 0.62 mg CO2 kg−1 h−1) and visual appearance of mold formation in initial and severe stage since the start the storage experiment. The proposed CCT model achieved an accuracy of 83.33%, with the contaminated class demonstrating the highest performance metrics, including precision (1.0), recall (0.90), and F1-score (0.95), followed by the healthy and incipient classes. At the same time, explicit classification between the healthy and incipient classes deserves further improvement because it is highly relevant for the timely detection of spoilage and prevention of proliferation of mycotoxins in stored wheat.

Biopesticidal Potential of Indigenous Plant Extracts against Rice Weevil in Stored Wheat

Stored products are significantly affected by certain well-known stored grain pests, with Sitophilus oryzae L. (Coleoptera: Curculionidae) being one of the most destructive pests of stored products. It is a primary pest that causes substantial quantitative and qualitative losses. The present study was conducted to investigate the insecticidal efficacy of different plant extracts from four commonly grown plants in Pakistan: ginger (Zingiber officinale), neem (Azadirachta indica), clove (Syzygium aromaticum), and tobacco (Nicotiana tabacum) against S. oryzae infesting stored wheat. Crude extracts from these plants were applied to stored wheat at various dose rates (20, 40, 60, 80 mg). Adults of S. oryzae were introduced to the treated wheat and observed for mortality, repellency, and grain damage. The results of the study indicated that the maximum mortality of S. oryzae (99.17%) was recorded due to the application of crude extract of Z. officinale, while the minimum mortality of S. oryzae (67.50%) was recorded due to the crude extract of N. tabacum at an 80 mg dose rate after a 10-day exposure interval. The maximum grain damage due to S. oryzae (0.19%) was observed in N. tabacum treated crude extract at an 80 mg dose rate, while the minimum grain damage due to S. oryzae (0.04%) was observed in Z. officinale treated crude extract at an 80 mg dose rate. Z. officinale also exhibited the maximum repellent effect on S. oryzae (95.77%). This study concluded that Z. officinale emerged as a potent, readily available biopesticide against S. oryzae, surpassing current alternatives with near-eradication efficacy, minimal grain damage, and a proactive repellent effect, paving the way for sustainable and eco-friendly pest management. Further research is needed to optimize extraction methods, dosage recommendations, and assess long-term effects on grain quality and storage stability.

SPECIES DIVERSITY OF PULSE BEETLE IN FOUR MAJOR GRAIN LEGUMES IN ANDHRA PRADESH

Studies were carried in kharif, 2022 to know the species diversity of pulse beetles infesting  stored grain legumes in Krishna zone of Andhra Pradesh.The pulse beetles were identified as Callosobruchus maculatus and C. chinensis based on their morphological characters. A total of 1391 adults of C. maculatus were observed in blackgram. About 737 and 473 individuals of C. maculatus were recorded in greengram and chickpea, respectively. A total of 566 individuals of C. maculatus and 241 individuals of C. chinensis were found in pigeonpea grains collected from the different storage godowns. The diversity indices for pulse beetle species in pigeonpea were calculated. The Shannon- Wiener index was 2.712, indicating moderate diversity.The species evenness was 0.6273 suggesting that the evenness among the species was zero and the Margalef index was 3.436 indicating relatively high species richness.

Protection of cowpea seeds and toxicity against cowpea weevils by the essential oils from Lippia alba (verbenaceae) and Schinus terebinthifolius (anacardiaceae)

Alternative methods have been widely studied to mitigate problems arising from the use of pesticides in agriculture. Among them is the use of essential oils to control stored grain pests. In this context, the aim of this study was to evaluate the effect of fumigation of cowpeas with 12 essential oils having different chemical profiles, derived from the germplasm collection of Schinus terebinthifolius and Lippia alba at Rio de Janeiro Federal Rural University. These oils were applied at various concentrations (0.1–1.0 mg/mL of air) against cowpea weevils (Callosobruchus maculatus). The chemotypes evaluated included citral, citral/limonene, carvone/limonene, and linalool from the essential oils of L. alba, as well as α-pinene, sabinene, α-phellandrene/α-pinene, β-pinene/α-pinene, δ-carene/α-pinene, limonene, α-phellandrene/sabinene, and myrcene from the essential oils of S. terebinthifolius. Various aspects of the insects' reproductive cycle were evaluated, including mortality, egg laying, emergence of new adults, emergence rate, and larval hatching, along with grain mass loss. The results indicated life cycle inhibition of all evaluated oils, with the essential oil from the UFRRJ ECB028 (linalool CT) genotype having the lowest LC50 (0.10 mg/mL of air), completely halting the insects’ life cycle and totally preventing seed mass loss. Overall, the results pointed to certain genotypes as promising for the development of technologies aimed at seed protection.

Efficacy of Botanical Oils on Adult Mortality, Egg Laying, Hatchability and Adult Emergence of Callosobruchus. Maculatus (F.) (Coleoptera: Chrysomelidae: Bruchidae)

The cowpea weevil Callosobruchus maculatus Fabricius, is the major insect pest that threatens effective legume storage. The laboratory experiment was conducted to assess the efficacy of four different botanical oils (Clove, Eucalyptus, Jojoba and Lemon) against the cowpea weevil, C. maculatus by using residual film technique. All the botanical oils were applied at two different concentration levels (0/50 and 0.75%). The results showed that all used oils significantly increased the mortality and reduced the mean number of eggs laying, hatchability and emergence percentages compared to the untreated control. The treatment of cowpea seeds with oils reduced slightly the germination but swelling percentage was higher in treated seeds than control. The results also indicated variation in the activity of botanical oils regarding the stage of the insect, the plant origin of the oils and concentration level. The present study suggested that botanical oils (Clove, Eucalyptus, Jojoba and Lemon) may be preferred option than conventional pesticides far the protecting stored pulse grains against stored products insect pests’ infestation, especially C. maculatus.

Potential fumigant toxicity of essential oils against Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and its egg parasitoid Trichogramma evanescens (Hymenoptera: Trichogrammatidae)

Sitotroga cerealella is a serious pest of a wide range of stored cereal grains. An essential element of an integrated pest control approach is the application of plant oils as a substitute for chemical insecticides. This study aimed to investigate the fumigant toxicity of Allium sativum and Mentha piperita essential oils against S. cerealella adult moths and the egg parasitoid Trichogramma evanescens. Gas chromatography–mass spectrometry analyses detected that Diallyl trisulfide (37.97%) and dl-Menthol (47.67%) as main compounds in A. sativum and M. piperita, respectively. The results showed that, A. sativum at 10.0, 5.0, and 2.5 µL/L air resulted in 100% insect mortality after 24 h exposure. The concentrations of 10.0 and 5.0 µL/L air of M. piperita oil resulted in 100 and 96% insect mortality, respectively. The parasitoid adult emergence in the F1 reduced when exposed to LC99 of A. sativum and M. piperita oils by 10.89 and 9.67%, respectively. Also, the parasitism of emerged parasitoid decreased by 9.25 and 5.84% (class I-harmless), respectively. Therefore A. sativum and M. piperita have the potential to be used as bio-fumigant for the management of S. cerealella and can be used alongside the T. evanescens in integrated pest management.