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Abstract The objective of this work was to study the toxic effect of acetone and petroleum ether extracts as well as dusts of the african chillies (Capsicum frutescens) fruits, the leaves ofClerodendron (Clerodendron inerme), Eucalyptus (Eucalyptus globulus) and Duranta iDuranta plumieri) on mortality, reduction in F} progeny, and repellency effect on some stored products insects, namely the rice weevil (Sitophilus oryzae L.)~ the lesser grain borer (Rhizopertha dominica F.), and the red flour beetle (Tribolium castaneum Herbst). Tests were conducted at the stored product pests laboratory of the plant protection Department, Faculty of Agriculture Moshtohor, Zagazig University. The obtained results could be summarized as follows: 1- Toxicity and effect of acetone extract of the various plants: Results concerning the toxic effects of acetone extracts of the different plants on mortalities and reduction in Fj progeny of S. oryzae, R. dominica and T. castaneum showed the following: S. oryzae: Mortalties increased with increasing concentration and time of exposure. After 15 days from the initial treatment, mortality percentages were 1000/0 at all tested concentrations (1 0, 5, 2.5, 1.25 and 0.625%) w/v with Capsicum fruit extract. Mortality percentages resulted from the other plant extracts were considerably lower.,td ranged from 25-880/0, 10--60% and 18-320/0 at various concentations for the leaves extract of Duranta, - ------------------- 65 Clerodendron, and Eucalyptus, respectively. Reduction in F1 progeny ranged from 99-1000/0, 20-700/0, 66-86% and 56-950/0 at various concentrations with Capsicum, Clerodendron, Eucalyptus and Duranta acetone extract, respectively. Results of R. dominica indicated that mortalities were increased with rising concentration and exposure period. After 15 days following treatment, mortalities were between 4-23%, 47- 680/0, 10-19%, and 13-250/0 at various concentrations for Capsicum, Clerodendron, Eucalyptus and Duranta acetone extract, respectively. Higher reduction in F1 Progeny was achieved in range from 74-940/0, 72-92%, 58-780/0 and 63-880/0 at all concentrations with the extracts of Capsicum, Clerodendron, Eucalyptus and Duranta, respectively. In case of T. castaneum, very low mortality percentages were recorded after 15 days from treatment at all concentrations of the various plant extracts. Mortalities ranged from 3-120/0, 8-170/0, 0-15% and 2-70/0 for Capsicum, Clerodendron, Eucalyptus and Duranta acetone extract, respectively. Contrarly, higher reduction in Fl progeny was obtained for the various plant extracts and it was between 57-83%, 87-99%, 74-84% and 68-79% for Capsicum, ’Clerodendron, Eucalyptus and Duranta acetone extract, respectively. ----------- ---- -------~---~- ---------- 66 2- Toxicity and effect of petroleum ether extract of the various plants: Results concerning the toxic effect of petroleum ether extracts of the various plants on mortalities and reduction in F1 progeny of three insect species under investigations showed that mortalities were increased with increasing concentration and time of exposure. s. oryzae: After.15 days following treatment, complete mortalities were achieved at various concentrations of Capsicum extract. Also, 100% reduction in F1 progeny was recorded at all concentrations of this plant extract. Meanwhile, mortalities of the other plant extracts ranged from 5-980/0,80-980/0and 80-1000/0 for Clerodendron, Eucalyptus and Duranta extract, respectively. Reduction in Fj progeny was between 32-1000/0, 88-1000/0 and 83- 100% for the petroleum ether extract of the mentioned plants, respectively. Results of R. dominica indicated that after 15 days from initial treatment, mortalities were in range from 3-320/0,73-1000/0, 5-42% and 15-850/0 at the various concentrations of Capsicum, Clerodendron, Eucalyptus and Duranta extract, respectively. Reduction ’in F 1 p•.•• ny was relatively higher than mortality and ranged from 82-1ocJYo, 78-1000/0,60-84% and 68-92% at various . concentrations of ~um, Clerodendron, Eucalyptus and Duranta extract, resj;ctively. - --- ._... -~--- ------ ------ ----- ------_.----- -------- - --- 67 T. Castaneum: Mortalities recorded after 15 days from treatment were very low for the various plant extracts and ranged from 5- 130/0) 5-15%, 5-80/0 and 0-7% at the various concentrations of Capsicum, Cler~dendron, Eucalyptus and Duranta extract, respectively. Reduction in Fl progeny was significantly higher than mortality and was in range from 5-69%), 30-880/0,44-770/0 and 11-57% for the various plant extracts) respectively. Data revealed also that S. oryzae adults were the most susceptible insect species followed by R. dominica and T. castaneum adults to acetone and petroleum ether extracts of the different plants under study. 3- Toxicity and effect of the various plant dusts: Results of the toxic effect of the various plant dusts at 4, 2 and 1% concentrations on mortalities and reduction in F1 progeny of S. oryzae, R. dominica and T. castaneum revealed the following: s. oryzae: After 15 days from treatment) mortalities ranged from 7-25%) 25-50%, 8-18% and 10-200/0at various concentrations for Caps icurn, Clerodendron, Eucalyptus and Duranta powder) respectively. Reduction in Fj progeny were between 6-230/0, 16- 56%,.3-21 % and 12-530/0for the various plant dusts, respectively. R. dominica: Recorded mortalities after 15 days from treatment were in range from 11-35%, 50-60°/0) 25-450/0 and 50-65% for Capsicum fruit dust, Clerodendron, Eucalyptus and Duranta leaves ----------” -_ ... ’---- ._.- 68 dust, respectively. Reduction in F} progeny ranged from 5-640/0, 57-79%, t4-64% and 57-86% at various concentrations of the various plant dusts, respectively. T. castaneum: After 15 days following treatment, mortalities ranged ,from 12-IS%, 25-35%, 10-250/0 and 18-38% at all concentrations of Capsicum fruit powder, Clerodendron, Eucalyptus and Duranta leaves powder, respectively. Reduction in Fl progeny was between 32-52%, 50-68%,2- 370/0 and 3•.31%for the various plant powders, respectively. At the highest concentration of 4%, results indicated clearly that the reduction in FI progeny was considerably greater than mortal ity of the various insect species with all tested plant dusts. Also, R. dominica was themost.sensitive species’ to the various plant dusts than S. oryzae andT. eastaneum. Dusts were less effects than the extracts. 4.RepeileDcyeffeet4;f~”tone exUKtsoftile variolas plants: Results ..of the·.~ effect of acetone extract of the various plants againlt -$1 oryzae, R. dolIti1tica and T. castaneum revealed the followiq: Relatively hirj.,jI1ues of average repellency during the .observation period’1~~ys were recorded for S. oryzae with the various plant ~ valueswere·ranged from 4>64%, 33- t’!.’’•’.’..::’’>:, ..--:. -~:’::,’.; ’-~’’’’_. 69 780/0, 14-61 %, and 21-51 % at all concentrations for Capsicum, Clerodendron, Eucalyptus and Duranta acetone extract, respectively. These values were also relatively high for T. castaneum and were in range from 30-56%, 45-710/0, 20-52% and 32-590/0 with the various plant extracts, respectively. In case of R. dominica, repellency values were lower and ranged from ,3-14%, 14-57%, 1-23% and 5-330/0 for the different plant extracts, respectively. 5- Repellency effect of petroleum ether extracts of the various plants: S. oryzae: Mean repellency was from 26-610/0, 22-600/0, 20- 530/0 and 18-530/0 at various concentrations for Capsicum, Clerodendron, Eucalyptus and Duranta petroleum ether extract, respectively. Lower values were obtained with R. dominica in range from 2-240/0, 8-180/0, 6-240/0 and 9-180/0 for the extracts of the different plants, respectively. The repellency vaules of T. castaneum ranged between 26- 490/0, 20-52%, 31-58% and 17-38% with petroleum ether extract of Capsicum fruits, Clerodendron, Eucalyptus and Duranta leaves, respectively. -----_.- ... _- -”- ---- -_._. - ------------ ---------------- 70 Conclusion: The obtained results indicated clearly that the powders of the various tested plants were obviously less effective against S. oryzae, R. dominica and T. castaneum than aceton and petroleum ether extract. Reduction in F 1 progeny was generally much higher . than mortality percentages at all tested concentartions and plants. The susceptibility ’ofthe insects under study varied from species to another. The, extracts of the various plants under investigation especially at the highest concentrations of 5 and 10% proved to be effective against the various insect species and could be recommended for use in frame of an integrated pest management programme for protection of stored grains against postharvest pests. |