Potential of monoterpenes, phenylpropenes, and sesquiterpenes for the management Bemisia tabaci (Gennadius) biotype B (Hemiptera: Aleyrodidae)

The insecticidal, repellent, and oviposition-deterrent activities of 13 phytochemicals belonging to the monoterpene, phenylpropene, and sesquiterpene classes against Bemisia tabaci adults were evaluated on plants of tomato in laboratories and greenhouses. In the fumigant toxicity assay, p-cymene, α-terpinene, and α-pinene exhibited the highest fumigant toxicity with LC₅₀ values of 9.64, 11.74, and 14.35 μl/L air, respectively. In the contact toxicity assay, trans-cinnamaldehyde caused the highest insecticidal activity (LC₅₀ = 1.36 mg/L) followed by eugenol (1.42 mg/L). In contrast, farnesol, (Z, E)-nerolidol, α-pinene, α-terpinene, and p-cymene displayed a weak contact toxicity (LC₅₀ > 10 mg/L). The highest contact toxicity in the greenhouse experiment was also observed with the trans-cinnamaldehyde (83.45%), followed by eugenol (80.62%), compared with thiamethoxam (87.75%) at 10 mg/L and 72h post-treatment. The maximum repellency was observed with trans-cinnamaldehyde (80.45%), eugenol (79.64%), (−)-citronellal (78.93%), (1R,2S,5R)-menthol (78.17%), and (−)-carvone (73.52%) at concentration of 10 mg/L after 24h compared to thiamethoxam (89.26%). Moreover, the greatest oviposition deterrence percentage was observed after 24 h for trans-cinnamaldehyde (52.30%), and eugenol (48.56%) at 10 mg/L compared to thiamethoxam (46.68%). The results indicate that these compounds may be employed as bioinsecticides for the control of B. tabaci.