Graphene oxide causes delayed toxicity and reduces reproductive output in Frankliniella occidentalis (Thysanoptera: Thripidae)

Graphene oxide (GO) is increasingly considered for agricultural applications, but its effects on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), remain poorly defined. We evaluated the acute toxicity of GO to second-instar nymphs and demographic responses of surviving thrips exposed to 0.4 mg/mL GO under laboratory conditions. In a bean pod–dip bioassay, mortality increased with concentration and exposure time, ranging from 1.1% in the control to 38.9% at 1.6 mg/mL after 24 h and from 1.1% to 88.9% after 48 h. The 24-h response did not reach 50% mortality at the highest concentration, whereas the 48-h LC50 and LC90 values were 0.76 and 1.75 mg/mL, respectively. Demographic effects were then evaluated using the age-stage, two-sex life-table approach. GO exposure shortened egg duration from 5.66 to 5.37 d, second-instar duration from 10.99 to 9.06 d, and the preadult period from 27.35 to 25.49 d, but prolonged pupal duration from 5.88 to 6.27 d. GO also reduced the oviposition period from 42.42 to 32.32 d and fecundity from 146.00 to 71.76 eggs per female. Net reproductive rate declined from 43.80 to 28.23 offspring per individual, and gross reproductive rate declined from 73.00 to 45.40 offspring per individual, although intrinsic and finite rates of increase were not significantly affected. These findings indicate that GO caused delayed acute toxicity and partial demographic suppression, mainly through reduced reproductive output, suggesting possible value as a supporting component or formulation aid within integrated pest management programs rather than as a fast-acting stand-alone toxicant against F. occidentalis.