Insecticidal activity of Jatropha extracts against the azalea lace bug, Stephanitis pyrioides (Hemiptera: Tingidae)

Authors: Sampson, Blair; Tabanca, Nurhayat; Werle, Christopher; Stringer, Stephen; Wedge, David; MORALES, RITA - Santa Martha Agro

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/4/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: We assessed the insecticidal activity of essential oil (EO) extracts from the leaves, roots and stems of bellyache bushes (Jatropha) against an ornamental plant pest, the azalea lace bug. Five species of bellyache bushes were found to have levels of insecticidal activity equal to or greater than that of a commercial EO-based insecticide, azadirachtin in neem oil. Compared with our control solutions, all 35 bellyache bush extracts were insecticidal and possessed active ingredients that could be be processed into a new biologically-based insecticide.

Technical Abstract: We assessed bioactivity of ethanolic extracts from 35 species of Jatropha against an ornamental plant pest, the azalea lace bug, Stephanitis pyrioides (Scott). Jatropha extracts were prepared by air-drying stem, root, or whole plant material, grinding the tissue into a fine powder, adding 70% ethanol, and then vacuum filtering the contents. Emulsions included the extract diluted to a desired concentration in de-ionized water and 10% dimethyl sulfoxide (DMSO). Treatments involved pipetting 20µl of emulsion onto three adult lace bugs in each well of a 96-well microtiter plate. Treated wells served as replicates for each of six extract concentrations and were arranged according to a RCBD. Extracts of Jatropha clavuligera Müll. Arg. and J. ribifolia (Pohl) Ballion from 0.06% – 0.50% were the most acutely bioactive with bug mortality exceeding that of the positive control – azadirachtin, a terpenoid and chief active ingredient in neem oil. At 1.00 %, extracts of J. clavuligera, J. ribifolia and azadirachtin killed 100% of bugs within 3 h. Jatropha clavuligera induced the lowest LC50 and ranked first in insecticidal potency based on =98% of bugs dying within 3 h. Extracts of J. curcas L., J. gossypiifolia L., J. excisa Griseb and azadirachtin were equally bioactive; although after 3 h, the three Jatropha species killed bugs faster. When compared with DMSO, all extract emulsions were bioactive against adult bugs. Thus, active ingredients in a new biopesticide could be sourced from the stem, root, or whole plant extracts of at least five Jatropha species.