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The effects of sublethal concentrations of three insecticides namely monocrotophos, dimethoate and quinalphos on the life table parameters were studied in a harpactorine reduviid predator Rhynocoris marginatus (Fabricius) in the laboratory (temp. 32 ± 2°C, Rh 75 - 80%, photoperiod 11-13 hrs). Normal R. marginatus were multiplied 59.20 times per generation in a mean generation time of 110.37 days. The insecticides reduced the capacity of multiplication and enhanced the mean generation time. The intrinsic rate of natural increase (rm) and finite rate of increase in control R. marginatus were 0.043 and 1.044, respectively, which decreased to 0.031 and 1.03, 0.035 and 1.036 and 0.038 and 1.038 in monocrotophos, dimethoate and quinalphos treated categories. Maximum reductions of weekly multiplications rate and annual rate of increase were observed in monocrotophos treated R. marginatus., Učinak subletalnih koncentracija tri insekticida: monokrotofos, dimetoat i kvinalfos na biotički potencijal stjenice predatora Rhynocoris marginatus (Fabricius), istraživan je u laboratorijskim uvjetima (temperatura 32 ± 2°C, relativna vlaga 75 - 80%, fotoperiod 11:13 sati). Redovito se R. marginatus umnožava 59.20 puta po generaciji uz prosječno trajanje generacije od 110.37 dana. Insekticidi su skratili kapacitet umnožavanja i povećali dužinu razvoja generacije. Prava stopa prirodnog povećanja (rm) i konačna stopa povećanja u kontroli R. marginatus bila je 0.043 i 1.044, odnosno, smanjena je na 0.031 i 1.031; 0.035 i 1.036 i 0.038 i 1.038 kod monokrotofosa, dimetoata i kvinalfosa u tretiranim kategorijama. Maksimalno smanjenje stope umnožavanja i godišnje stope porasta zapaženo je kod R. marginatus tretiranih monokrotofosom.