The Potency of Six Medicinal Plant Extracts Against the Stored Grain Insect Pest Sitophilus granarius L.

Jawalkar, N.B., S.P. Zambare and M.I. Al Ghannoum. 2021. The Potency of Six Medicinal Plant Extracts Against the Stored Grain Insect Pest Sitophilus granarius L. Arab Journal of Plant Protection, 39(4): 323-328. https://doi.org/10.22268/AJPP-039.4.323328 This study was conducted on six medicinal plants viz., Vitex negundo (leaves), Xanthium strumarium, Caesalpinia bonduc, Mucuna pruriens, Moringa oleifera (seed kernels), Tagetes erecta (petals) for their bio-insecticidal activity. The powders of various parts of plants were extracted using the MARS6 microwave acid digestion system. Three different concentrations (20, 30, and 40%) of plant extracts were tested against granary weevil, Sitophilus granarius L. (Coleoptera: Curculionidae) for their bio-insecticidal activities under laboratory conditions. The results of statistical analysis showed a good performance of all plant extracts, especially at the high concentrations of the extracts, where they showed different levels of insect mortality and their developmental rate was also reduced leading to significant reduction in insect numbers. The mortality rate ranged was 0-100% with S. granarius adults (p < 0.01). There was significant correlation (R=1) between mortality rate and the concentration of plant extracts. However, the extract of Mucuna pruriens with solvents (Acetone + Petroleum Ether) showed the highest mortality rate of 100% at the three concentrations used (p < 0.01), whereas, the lowest average mortality of 43.3% (p < 0.01) was observed with Xanthium strumarium and Vitex negundo extracts with solvents (Methanol + n-Hexane) compared with 0% mortality in the control. All plant extracts have revealed insecticidal as well as propitious protective effect on grains, and it can be selected as effective control treatment after proper dose formulation to prevent weevil infestation in stored grains. Keywords: Bioinsecticide, stored grains, Sitophilus granarius, mortality, medicinal plants, MARS 6.

Toxicity and repellent activities of Thymus pallescens Noë. and Cymbopogon citratus Stapf. essential oils against Sitophylus granarius L.

This study evaluated the toxicity and repellent activities of essential oils (EOs) against Sitophilus granarius (Linnaeus, 1758), both in vitro and in vivo conditions. The EOs obtained from Thymus pallescens Noë. (Lamiaceae) and Cymbopogon citratus Stapf. (Poaceae) were analyzed by GC-MS, and revealed that carvacrol (56.64%) and geraniol (20.8%) as the respective major components. T. pallescens EO was found to be a more effective toxicant, with LC₅₀ and LC₉₀ values of 9.3 and 34.6 µL/mL, respectively, in the contact test vs 8.2 and 25.3 µL/mL in the fumigation test. T. pallescens EO showed also a stronger repellent effect with values ranging from 83.4% to 100%. In the in vivo test, the survival probability decreased from 99.9 to 2.48% among insects exposed to T. pallescens EO. These data demonstrated that EOs could be considered effective alternatives to chemical insecticides, providing pest control for stored products in an ecologically sustainable manner.

Fatty Acids Present in Wheat Kernels Influence the Development of the Grain Weevil (Sitophilus granarius L.)

Sitophilus granarius (L.) is considered to be one of the major pests causing damage to cereal grain stored in silos and granaries. Using traditional methods (synthetic insecticides, mechanical, or physical methods) to control this pest is either ineffective or dangerous to people and nature. It is, therefore, necessary to develop new cultivars of cereals that will be distinguished by a high natural tolerance of the foraging by S. granarius. The aim of this study is expressed in the set research hypothesis, stating that the number of offspring of the grain weevil on stored wheat kernels can depend on the content of fatty acids in the kernels. Thus, the qualitative and quantitative composition of fatty acids was determined in kernels of 10 winter wheat cultivars, and the abundance of the beetle’s offspring generation of S. granarius that developed on the wheat grain, as well as the mass of produced dust and loss in the mass of wheat grain were determined. By applying statistical analyses (GLM, ANOVA, Pearson’s linear correlation coefficient, and analysis of redundancy), the presence and character of the dependence between the determined content of fatty acids in wheat grain and the factors describing the development of S. granarius were established. The research results indicate that fatty acids from the groups C 18:1 and C 20:1 probably play an important role as substances stimulating the increase in the number of the tested pest progeny. In contrast, fatty acids C 15:0, C 16:1, and C 18:3, which were determined in large amounts in the grain of wheat cultivars Speedway, KWS Livius, and Julius, can reduce the number of offspring of pest insect.

Bioactivity of Cereal- and Legume-Based Macaroni Pasta Volatiles to Adult Sitophilus granarius (L.)

The attractiveness of ten commercially available Italian macaroni pastas made from different cereals [Triticum durum; Triticum durum (whole wheat); Triticum dicoccum; mixture of five cereals; Triticum turgidum; Triticum turanicum] or legumes (Cicer arietinum; Lens culinaris; Pisum sativum; Vicia faba) to Sitophilus granarius, was compared. S. granarius adults were more attracted to cereal pastas than legume pastas, but the differences in attractiveness were not always significant. Consistent with the results of behavioural bioassays, the mortality of adults over 20 days exposed to pasta samples was 100% with the legume pasta samples and only 8% with the T. turanicum pasta. GC-MS analysis of HS-SPME extracts from the different pasta samples highlighted marked qualitative and quantitative differences, with aliphatic aldehydes and aliphatic alcohols being the most abundant volatile components of cereal- and legume-pastas, respectively. In two-choice behavioural bioassays, insect attraction to a 1:1 combination of T. turanicum and C. arietinum pastas (80%) was even higher than that observed in T. turanicum pasta alone (64%) and in C. arietinum pasta alone (20%). This strongly suggested that the low attractiveness of legume pasta is mainly due to the lack of attractant stimuli rather than emission of repellent compounds.

Insecticidal Effect of Eucalyptus Essential Oils on Mortalities of Storage Pests of Grains Sitophilus oryzae and Sitophilus granarius in the Region of Tissemsilet Algeria

Background: Stored cereals are attacked by pests including Sitophilus, a primary insectpestthat kthe whole grain and destroys the germ. The usual control methods are less efficient and more expensive. The use of essential oils of aromatic plants is more interesting. Eucalyptus is a plant of great medicinal value due to the presence of secondary metabolites. Methods: In this experimentation that took place during the year 2017, extraction of oils by hydro distillation of eucalyptus was used on insects at different doses by two methods with are ingestion and inhalation. Two species of Sitophylus are morphologically different as they may be different with regard to the use of biopesticide (eucalyptus essential oil), regarding the mortality rate in relation to the duration of treatment Result: Sitophilus oryzae was more sensitive to this bio-pesticide since it was only after eight (08) hours of treatment that mortality exceeded 50% by the ingestion method whereas only 6.6% of mortality was recorded on Sitophilus granarius. Same observation by the inhalation method, 90% mortality on the third day for Sitophilus oryzae while only 20% mortality on Sitophilus granarius. So the ingestion method requires fewer products plus a speed in the mortality time.

Controversial impact of experimental soil inoculant containing Beauveria bassiana and Metarhizium anisopliae on Sitophilus granarius

The insecticidal efficacy of the experimental bioinoculants (Natur Nova, Natur Agro Hungary Ltd., Hungary) containing Beauveria bassiana (Bals.-Criv). Vuill. and Metarhizium anisopliae Metschnikoff against stored product pests modelled by granary weevil, Sitophilus granarius L. was evaluated on wheat in laboratory tests. In order to comparability, two applications were also set up: one purely ash-treated grain treatment against wireworms and a soil-injected one. Our results confirmed that some biopesticides can exert unexpected effect on non-target arthropods. However, the examined biopesticides were as empirically effected against the target arthropods regarding wireworms. Nevertheless, the application exempt from ash of the examined bioinoculants Natur Nova containing B. bassiana and M. anisopliae were not suitable for the elimination of the stored product pests modelled by S. granarius. In contrast, the putative plant protection effect of these biopesticides was observed in the course of applying the agents in the recommended environment and pest species as well as when applying them with ash carrier.