Location: Southern Horticultural ResearchTitle: Insecticidal Activity of Jatropha Extracts against the Azalea Lace Bug, Stephanitis pyrioides (Hemiptera: Tingidae)
|MORAES, RITA - University Of Mississippi|
|DEHGAN, BIJAN - University Of Florida|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2022
Publication Date: N/A
Interpretive Summary: We assessed the extracts from the roots, stems, and whole plants of 35 species of bellyache tree for their use as insecticides targeting against an ornamental plant pest, the azalea lace bug. Fresh shoots and roots were harvested, air-dried, processed to a fine powder, and extracts made using ethyl alcohol as the solvent. All 35 species showed some insecticidal activity against adult lace bugs. However, five species of bellyache plants, one of which (Jatropha curcas) is in wide scale production (~90 million acres globally), produced compounds as toxic or more toxic than the quintessential natural insecticide, neem oil. These results show that bark and root extracts from five species of Jatropha are particularly promising sources of new biologically based pesticides targeting small armored horticultural pests. Hence, the processing of dead or senescing bellyache trees for insecticide production could provide a secondary revenue stream to Jatropha farmers and a new potent product for plant protection.
Technical Abstract: We assessed insecticidal activity of ethanolic extracts from 35 species of Jatropha against an ornamental plant pest, the azalea lace bug, Stephanitis pyrioides (Scott). Fresh shoots and roots were harvested, air-dried, and processed to a fine powder. Ethanolic extracts were then prepared, emulsified in aqueous dimethyl sulfoxide (DMSO), and applied to adult bugs at 0.06, 0.13, 0.25, 0.50, and 1.00% concentration in accordance with a randomized complete block design (RCBD). From 0.06 to 0.50 % concentration, Jatropha clavuligera Müll. Arg. and J. giffordiana Dehgan &Webster, sp. nov. extracts were more toxic than the neem (azadirachtin) positive control. At 1.00 %, J. clavuligera, J. giffordiana and neem killed all bugs within 3 h of exposure. Extracts from J. curcas L., J. gossypiifolia L. and J. excisa Griseb equaled the toxicity of the neem positive control. The three Jatropha species, interestingly, exhibited a faster knockdown. Extracts of J. clavuligera at its lowest concentration (0.06% or 600 ppm) was unique in its ability to kill 98% to 100% of lace bugs within 3 hours. All extracts tested showed some level of contact insecticidal activity against adult azalea lace bugs when compared with 10% DMSO, our negative control and non-toxic emulsifier. The results together demonstrate that bark and root extracts from five species of Jatropha are particularly promising sources of biopesticides targeting small, armor-plated insect pests.