Biochemical characteristics of sorghum cultivars affect life table parameters, feeding performance, and digestive enzyme activities of Helicoverpa armigera

Abstract

The cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a major insect pest of various agricultural crops worldwide. In this study, the effects of eight sorghum [Sorghum bicolor (L.) Moench, Poaceae] cultivars (Payam, Pegah, Sepideh, Spidfid, Kimia, KGS₂₃, KFS₂, and KFS₁₈) on life table parameters, feeding performance, and activities of digestive enzymes in H. armigera were assessed under laboratory conditions. The insects were fed grains of the eight cultivars. Furthermore, the phytochemicals starch, proteins, flavonoids, and phenolic compounds in the grains were quantified to investigate their relationship with ecological and physiological parameters in H. armigera. Our results revealed that H. armigera had the shortest development time when reared on cv. Sepideh and the longest development time when reared on cv. Payam. The insects reached the highest and lowest intrinsic rate of increase (r) on cv. Sepideh and Payam, respectively. The relative growth rate (RGR) and efficiency of conversion of digested food (ECD) of larvae were highest and lowest on cv. Sepideh and Payam, respectively. Larval proteolytic activity was highest on cv. KFS₁₈ and lowest on cv. Sepideh. Concerning phytochemicals, protein content was highest in cv. KFS₁₈ and lowest in cv. Payam and KGS 23. Total phenolic levels were highest in cv. Payam and lowest in cv. Sepideh. According to the correlation analysis, overall, plant protein content was negatively correlated with insect development time, but positively correlated with pupal weight and r. Total phenolic content was positively correlated with insect development time, and negatively correlated with r and RGR. Cluster analysis indicated that cv. Sepideh was the most susceptible host, whereas cv. Payam was the most resistant. Therefore, cv. Payam may be a candidate for use in integrated pest management (IPM) against H. armigera.