scholarly journals Contact Toxicity Effects of Selected Organic Leaf Extracts of Tithonia diversifolia (Hemsl.) A. Gray and Vernonia lasiopus (O. Hoffman) against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Stephen Maina Gitahi ◽  
Mathew Piero Ngugi ◽  
David Nganga Mburu ◽  
Alex Kingori Machocho

Maize weevil (Sitophilus zeamais) infestation results in a substantial reduction in the quantity and deterioration of the quality of stored maize. Most farmers control weevils using conventional pesticides which are usually associated with several human health risks as well as intoxication of the fauna and flora. However, bioinsecticides form an alternative intervention since they possess fewer side effects on human health, are ecofriendly, and are readily available. This study sought to validate and document, in a systematic way, the pesticidal properties of the species Tithonia diversifolia and Vernonia lasiopus used for many years by many people of the world on S. zeamais. The plant leaf samples were obtained from Embu County, Kenya. Dichloromethane and ethyl acetate solvents were used to extract active phytochemicals from the dried plant sample powder. The GC-MS analysis of the obtained extracts was performed at ICIPE laboratories to identify their phytochemical compositions. Twenty grams of maize grains were put in 50 ml plastic vials and admixed with different treatments. The positive control group was treated with Actellic Super™, while the negative control was treated with the respective extracting solvent only. The experimental groups were separately treated with the plant leaf extracts at doses of 25, 50, 75, and 100%. After treatment, each of the six groups was infested with 10 male S. zeamais and weevil mortality as a result of contact toxicity of the treatments was assessed at 6, 24, 48, 72, and 96 hours after the insects were exposed to the extracts. Results of the study indicate that the selected organic leaf extracts of T. diversifolia and V. lasiopus possessed significant contact insecticidal effects that ranged between 1.67 to 99.98%. Furthermore, the GC-MS analysis revealed several active biocompounds in T. diversifolia and V. lasiopus extracts, which are known for their considerable insecticidal effects. Our data suggest that the organic leaf extracts of T. diversifolia and V. lasiopus have considerable insecticidal properties and would, therefore, be a valuable bioprotective agent for stored maize grains against S. zeamais.

Author(s):  
Julián Hernández-Cruz ◽  
Alfonso Luna-Cruz ◽  
Esperanza Loera-Alvarado ◽  
Evert Villanueva-Sánchez ◽  
Nadia Landero-Valenzuela ◽  
...  

Abstract The insecticidal and repellent effect of essential oil isolated from fresh leaves of Porophyllum linaria on maize weevil was evaluated, as well as the effect on the grain germination after treated. In total, 28 constituents were identified by gas chromatography coupled with mass spectrometry accounting for 99.86% of whole essential oil. The main majority compounds were β-myrcene (41.94%), D-limonene (20.29%), and estragole (20.03%). Contact toxicity significantly increased with dose and time after treatment. With the 800 ppm (highest concentration), the mortality (%) obtained for the tenth and fifteenth day was 43 and 82%, respectively, whereas with 50 ppm (lowest concentration) 30% mortality was obtained at the end of the experiment (fifteenth day). At 15 d (end of the experiment), the LC50 y LC90 were obtained with values of 329.01 ± 44.35 y 1058.86 ± 117.76 ppm, respectively. For a concentration of 800 ppm, a selection index of zero was obtained, indicating the preference of the pest to the untreated maize (control). The maize grains germination test showed a significant reduction both in the length of hypocotyl and radicle of maize grain. So, in the highest dose, the hypocotyl and radicle length was 1.40 ± 0.34 and 9.14 ± 0.55 cm, respectively, whereas the control group registered 3.28 ± 0.39 and 13.02 ± 0.97 cm, respectively. This finding is promising since as it could result in the identification of botanical substances capable of suppressing maize weevil, Sitophilus zeamais development.


Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 532
Author(s):  
William R. Patiño-Bayona ◽  
Leidy J. Nagles Galeano ◽  
Jenifer J. Bustos Cortes ◽  
Wilman A. Delgado Ávila ◽  
Eddy Herrera Daza ◽  
...  

Chemical control of the maize weevil (Sitophilus zeamais) has been ineffective and presents serious collateral damage. Among plant-derived insecticides, essential oils (EOs) are suitable candidates to control this stored products pest. In this work, the insecticidal activities of 45 natural EOs against S. zeamais adults were screened, and the most promising ones (24 EOs) were characterized by GC–MS. The repellent and toxic effects (contact and fumigant) of these 24 EOs were determined, and by a cluster analysis they were classified into two groups considering its fumigant activity and contact toxicity. For the EOs with the highest fumigant potential (14 oils) and their main active constituents (17 compounds), lethal concentrations were determined. The most active EOs were those obtained from L. stoechas and L. alba, with LC50 values of 303.4 and 254.1 µL/L air and characterized by a high content of monoterpenes. Regarding the major compounds, the oxygenated monoterpenes R-(+)-pulegone (LC50 = 0.580 mg/L air), S-(-)-pulegone (LC50 = 0.971 mg/L air) and R-(-)-carvone (LC50 = 1.423 mg/L air) were the most active, as few variations in their concentrations significantly increased insect mortality.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
A.G.W.U. Perera ◽  
M.M.S.C. Karunaratne ◽  
S.D.M. Chinthaka

Neem (Azadirachta indica A. juss), is known to possess a wide range of pharmacological properties and is thus commercially exploitable. Apart from its medicinal potential, a considerable progress has been achieved regarding biological potential and chemical composition of the leaves which is an ever-increasing interest to the scientific community. During this study, biological phenomena and secondary metabolite composition of A. indica leaves were examined in the management of Sitophilus zeamais on stored maize. Insecticidal and repellent potential of A. indica leaf powders were evaluated in both contact and fumigant forms. Phytochemical screening of 11 phyto constituents was performed following the standard procedures for n-hexane, dichloromethane, ethyl acetate, methanol and aqueous leaf extracts. Volatile profile of A. indica leaves was characterized by employing headspace-solid-phase micro extraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Over 60% weevil repellency was recorded at doses above 23.33%, whereas 100% and 67% contact and fumigation mortalities were observed respectively, 9 days after treatment at the dose of 33.33% and the respected LD50 values were 1.56 g and 4.48 g. Thirty two volatile compounds were identified in three distinct chemical classes (Monoterpenoid, sesquiterpenoid and purine nucleosides). γ-Elemene (24.06%), 3,7 (11)-eudesmadiene (6.83%), caryophyllene (6.40%), and 10s,11s-himachala-3(12),4-diene (6.36%) were the major constituents of neem leaf volatiles, followed by other compounds present in less than 4% which might be responsible for varied biological activities observed. Thus the odour impact of the bioassayguided study clearly implies that A. indica leaves can be harnessed against S. zeamais infestations.Keywords: Azadirachta indica, Sitophilus zeamais, headspace-solid-phase micro-extraction, insecticidal activity, repellency


2014 ◽  
Vol 6 (3) ◽  
pp. 83-88 ◽  
Author(s):  
Awoke Yohannes ◽  
Genet Asayew ◽  
Getachew Melaku ◽  
Mulugeta Derbew ◽  
Sirgota Kedir ◽  
...  

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Stephen Maina Gitahi ◽  
Mathew Ngugi Piero ◽  
David Nganga Mburu ◽  
Alex Kingori Machocho

Introduction. Sitophilus zeamais infestation is among the major setbacks to sustainable maize farming and availability. It causes an estimated annual loss of 5–10% and 20–30% of the total maize grains loss in the temperate and tropical zones, respectively. Although synthetic pesticides are quick and effective in managing crop pests, their overuse and misuse is discouraged due to their detrimental effects on human and environment. Natural pesticidal products that are extracted from plants are particularly gaining importance as an alternative to synthetic pesticides. They are available, easily biodegraded and have low toxicity to nontarget organisms. Most botanical pesticides act on insects by repelling them away from the crops in the field or in the stores. Therefore, this study aimed to determine repellency potential of organic leaf extracts of Tithonia diversifolia and Vernonia lasiopus on S. zeamais. Materials and methods. The phytochemical profile of T. diversifolia and V. lasiopus was determined using GC-MS. Laboratory-based experiments were carried out using area preference method to assess the efficacy of the extracts against weevils for a test period of 5 h. Six groups of experiments were set up with ten S. zeamais in each test: positive control (Actellic), negative control (solvent only), and four different experimental extract concentrations (25, 50, 75, and 100%). Results. The results indicated that T. diversifolia and V. lasiopus leaf extracts possess potent repellency effect on weevils. All the extracts simply discouraged S. zeamais from the treated areas recording significantly good levels of repellent activities between 26 and 96%. Furthermore, the GC-MS analysis manifested the presence of bioactive compound in the extracts which are associated with the repellency effects. Conclusion. The study scientifically confirms the traditional use of the T. diversifolia and V. lasiopus and provides important platform for further study on the extracts as bioresource of botanical repellent.


2017 ◽  
Vol 6 (3) ◽  
pp. 174-177
Author(s):  
◽  
S Vinotha ◽  
A Vijayan ◽  
Anand Gideon V ◽  
◽  
...  

The investigation was carried out to determine the possible phytochemical constituents from aqueous, methanol and chloroform extracts of Turnera subulata leaf extracts. Among the phytochemical screening of these extracts, Methanolic extract showed that the leaf was rich in alkaloids, flavonoids, glycosides, phenols, saponins and quinones. The chemical composition of the plant leaf extract of T. subulata was investigated using Gas Chromatography – Mass Spectroscopy (Agilent-7890A GC instrument coupled with MS-5975) and NIST-MS library. GC-MS analysis of T. subulata plant leaf extract, revealed the existence of the GC-MS chromatogram of the major peaks presented in methanolic extract like Methyl 8,11,14-heptadecatrienoate (23.244%), Pentadecanoic acid, 14-methyl-,methyl ester (8.654%), n-Hexadecanoic acid (8.654%), 4H-Pyran4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl (6.598%), 1b,4a-Epoxy-2H-cyclopenta[3,4] cyclopropa[8,9]cycloundec[1,2-b] oxiren-5(1aH)-one(5.400%), 3,7,11,15-Tetramethyl-2-hexadecen-1- ol(5.400%), etc. From this study it is obvious that T. subulata leaf extract contains many biologically active compounds and also it gives a detailed insight about the phytochemical profile which could be exploited for the development of plant based drug.


Author(s):  
C. P. O. Emeka ◽  
F. K. Ewete ◽  
S. T. Ebeniro

Annually, Nigeria loses 20–40% of maize grain due to insect pests attack. However, insect pest control in stored products relied heavily on the use of gaseous fumigants and residual contact insecticides. The control method is limited as it is toxic to beneficials and humans. Efforts have now shifted to the use of edible plant materials as protectants of which the tropics are well endowed with. Therefore, a study was conducted in laboratory in order to evaluate the effectiveness of powders of eucalyptus leaf (Eucalyptus camaldulensis Schlecht,) moringa seed (Moringa oleifera Lam.) and Pirimiphos-methyl against maize weevil (Sitophilus zeamais) on stored maize (Zea mays L.). camaldulensis leaf powder showed 100% repellence effect at a concentration of 2.0 g / 20 g maize seeds while M. oleifera seed powder had 75% repellence effect against S. zeamais. Contact toxicity of E. camaldulensis leaf powder on S. zeamais was 65% at 1.0 g/20 g maize seeds after 96 hours of exposure. Contact toxicity of M. oleifera seed powder on S. zeamais was 60% at 96 hours of exposure at a concentration of 1.0 g/20 g maize seeds. The powders of E. camaldulensis leaf and M. oleifera seed showed promising effects against S. zeamais in stored maize, hence could be incorporated in an integrated approach as alternative to synthetic pesticides when used in reducing weevil infestation in stored maize seeds.


2017 ◽  
Vol 52 (4) ◽  
pp. 337-342
Author(s):  
SA Babarinde ◽  
MO Petinrin ◽  
AD Adeleye ◽  
BS Ajani

Toxicity of Sclerocarya birrea A. Rich. (Anacardiaceae) leaf and bark and Azadirachta indica A. Juss (Meliaceae) leaf extracts against Sitophilus zeamais Motchulsky (Coleoptera: Curculionidae) was evaluated under the laboratory conditions (77±4% relative humidity and 27±3°C temperature). When extracted doses were compared, mortality was dose- and exposure period-dependent. At 1 DAT, A. indica leaf extract had significantly (p<0.05) higher mortality (12.50-15.00%) than that of S. birrea bark extract (5.00-15.50%). However at 5 DAT, when 0.45 ml/33 cm2 was applied, mortality was not significantly (p>0.05) different and ranged from 91.25 to 97.5% for all the botanicals. When the extracting solvents were compared, mortality was exposure period-dependent with highest percentage mortality (99.17%) recorded at 5 DAT in S. birrea petroleum ether leaf extract, which was significantly higher than that of mortality observed in filter paper treated with the petroleum ether extracts of other botanicals. However, there was no significant difference in the effect of the two studied solvents. The results highlight the insecticidal potentials of the selected Nigerian-grown botanicals against maize weevil and recommend them as component of weevil Integrated Pest Management, in the areas where the botanicals are abundant.Bangladesh J. Sci. Ind. Res. 52(4), 337-342, 2017


2018 ◽  
Vol 87 (1) ◽  
pp. 85-99 ◽  
Author(s):  
Mohammed Suleiman ◽  
Costancia P. Rugumamu ◽  
Nasiru D. Ibrahim

Abstract Repellency of Euphorbia balsamifera, Lawsonia inermis, Mitracarpus hirtus and Senna obtusifolia along with permethrin powder against Sitophilus zeamais was evaluated in the laboratory at 28-32°C and 60-75% RH. The botanicals were applied as powders, methanolic, ethanolic and aqueous extracts at the rate of 2.5, 5.0 and 10.0 x 104 ppm per 20 g of sorghum grains, while the permethrin powder was applied at 0.056 x 104 ppm. Percentage repellency was recorded at 1, 6, 12 and 24 hours after exposure (HAE). All the botanicals were found to have a repellent effect against Sitopholus zeamais at all three concentrations. The highest (82.22 ± 2.22%) repellency among the botanical powders was exhibited by 10.0 x 104 ppm of Euphorbia balsamifera within 24 HAE. Methanolic leaf extracts were found to be more effective than the other formulations, causing total repellency against the weevils at 10.0 x 104 ppm of all the botanicals, while the activities of the aqueous extracts were the least repellent (41.37 ± 7.39 to 60.14 ± 1.64%) after 24 hours of exposure. The repellent activities of the botanicals decreased with increasing exposure periods for powders and aqueous extracts, and increased with increasing duration for methanolic and ethanolic extracts. The results showed that the botanicals were good repellents against Sitopholus zeamais and could serve as stored sorghum protectants against maize weevil infestation. Grains protected with these botanicals could be used as seeds for planting. Meanwhile, studies on the toxicity of these botanicals against higher animals are recommended.


2021 ◽  
Vol 38 (1) ◽  
pp. 38-49
Author(s):  
Mukesh K Chaubey

Inappropriate use of synthetic insecticides in pest management programs contribute in ozone depletion, neurotoxicity, carcinogenicity, teratogenicity, mutagenesis and resistance. These negative outcomes have diverted attention towards the use of plant products in insect’s population management. In this study, dill (Anethum graveolens) and star anise (Ilicium verum) essential oils were isolated by hydrodistillation method using clevenger apparatus, and evaluated for repellent, toxic and oviposition inhibitory potential against maize weevil Sitophilus zeamais (Coleoptera: Curculionidae) by fumigation and contact methods. In toxicity assay by fumigation method, median lethal concentrations (LC50) recorded were 0.316 and 0.243 μlcm-3 air; 0.362 and 0.284 μlcm-3; and 0.497 and 0.418 μlcm-3 of A. graveolens and I. verum oils and pure limonene after 24 and 48h exposure to S. zeamais adults, respectively. In contact toxicity assay, LC50 were 0.219 and 0.159 μlcm-2 area; 0.269 and 0.226 μlcm-2; and 0.567 and 0.386 μlcm-2 of A. graveolens and I. verum oils and pure limonene after 24 and 48 h exposure to S. zeamais adults, respectively. Both A. graveolens and I. verum oils and limonene reduced progeny production and acetylcholinesterase activity in S. zeamais adults when fumigated with sub-lethal concentrations. The outcomes of this study will help in preparation of essential oil based formulations for stored grain insect pest management.


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