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Plants produce secondary metabolites for defense against herbivorous insects. In this study, the effects of different concentrations of quinine, nicotine, and tannic acid on food consumption and pupal parameters of the larva of a severe pest, Malacosoma neustria L. (Lepidoptera: Lasiocampidae), were investigated in 2007. Artificial diets containing 0.125%, 0.25%, and 0.5% concentrations of quinine or nicotine were prepared. In addition, diets containing 1.25%, 2.5%, and 5% tannin and a control diet without secondary metabolite were prepared. The feeding experiments revealed that the food consumption and pupal parameters of male and female larvae were different, and all parameters of female individuals were higher than those of male larvae. It has been determined that tannins cause more reductions in food consumption and pupal parameters than alkaloids in male and female individuals. We observed an increase in male larvae's pupal mass with increased concentration of nicotine to 0.5%. Nicotine did not cause a decrease in pupal parameters of larvae compared to quinine. In addition, all parameters of female individuals decreased with the addition of secondary metabolite. Although food consumption in alkaloid-containing diets was less than in the control group, there was a positive relationship between food consumption and pupal lipid and protein content. However, quinine had a more significant effect on triggering protein storage than nicotine. In diets containing tannins, more lipids were stored. A decrease was observed in the food consumption and pupal parameters of all individuals in the tannin-containing diets compared to the other diets.

Thaumetopoea pityocampa (Denis & Schiffermüller, 1775) (Lepidoptera:Notodontidae ) is the most important defoliating insect for several pine species and cedars. In this study, body nutrient composition of T. pityocampa larvae were analyzed under feeding inhibition caused by natural chemical agents. In no-choice assays, larvae were fed ponderosa pine needles treated with oleic acid and chlorogenic acid solutions, respectively, at each of four concentrations, 0%, 25%, 50% and 75%. The neetles were as given to separate test groups. At the end of feeding experiments, antifeedant index (AFI) was calculated for each solutions with different concentrations. Then, rates of protein, lipid, glycogen and water of larvae were calculated for control and test groups. It was determined that there had been a strong relation between concentrations of solution and AFI values regarding oleic acid (r= 0.998, P < 0.05). However, there was no significant relationship between concentrations of solution and AFI values regarding chlorogenic acid (r= 0.663, P > 0.5). The most remarkable finding was a sharp decline in the level of larval glycogen during starvation period in accordance with rising concentrations of both oleic and chlorogenic acid in its food. The glycogen level of the larvae was also affected by both chemical applications

In this study, the effects of secondary metabolites on the feeding preference and growth of generalist caterpillars, Agelastica alni L., were investigated. Feeding experiment has been applied with a total of 11 diet; 6 of which were prepared by adding different concentrations of gallic acid (1, 3, 5 %) and quinine (0.125, 0.25, 0.5 %) to the control diet, 3 diet of which prepared by adding different concentrations of gallic acid and quinine. According to the results, the amount of gallic acid consumed did not affect the food consumption and the amount of pupa lipids. However, the amount of gallic acid consumed positively affects the pupal mass and the pupal crude protein. In addition, the amount of quinine consumed negatively affected the developmental performance of larvae except for the food consumption. As the count of secondary metabolites in the diet increases, the pupal mass and the pupal crude protein decrease. Overall, during the co-evolution processs, A. alni larvae may be able to adapt to gallotannins. However, quinine, an alkaloid, is a feeding deterrence and growth suppressor for larvae.