Effect of light intensity and photoperiod on the biological characteristics of pea aphid (Acyrthosiphon pisum) offspring

The present study was conducted to examine the influence of light intensity and photoperiods on the offspring of two color morphs (i.e., red and green) of pea aphid (Acyrthosiphon pisum), and to explore the role of the light intensity and photoperiods in the color morphs of aphids. Under the artificial bioclimatic condition, the adult pea aphids of red and green morphs were treated with different light intensities low (5 722 lx), medium (11 778 lx), and high (17 389 lx) and photoperiods (10 h L/14 h D, 16 h L/8 h D, 22 h L/2 h D). The impacts were subsequently measured based on developmental duration, weight difference, mean relative growth rate (MRGR), the alate rate, and nymphal survival rate of the 1^st generation aphid’s offspring. The results indicated that, in the low light intensity, the nymphal survival rate and alate rate were increased, and the relative growth rate was decreased by 10.26% (P < 0.05) for the red morph compared to the green morph at the 10 h L/14 h D photoperiod. Meanwhile, the MRGR was decreased by 13.95% (P < 0.05) and alate rate was increased for green morph compared to red morph at the 16 h L/8 h D photoperiod. Furthermore, development duration was prolonged by 0.53 d (P < 0.05) f and alate rate was increased for green morph compared red morph at the 22 h L/2 h D. At medium light intensity, development duration was prolonged by 0.30 d (P < 0.05), and alate rate was increased for green morph compared to red morph at 10 hL/14 hD. Nymphal survival rate was decreased and MRGR increased by 13.04% (P < 0.05) for red morph compared to green morph at 16 h L/8 h D. Nymphal survival rate and alate rate were increased for red morph compared to green morph at 22 h L/2 h D. At high light intensity, nymphal survival rate was increased and the alate rate decreased for red morph compared to green morph at 10 h L/14 h D. The nymphal survival rate was increased, development duration was delayed by 1.93 d (P < 0.05), and the alate rate was decreased for red morph compared to green morph at 16 h L/8 h D. Nymphal survival rate and alate rate were increased for red than morph compared to green morph at 22 h L/2 h D. Therefore, with light intensity (17 389 lx), the offspring of pea aphids of two color morphs had significantly longer development duration and less relative daily growth rate with the shortening of light time. Furthermore, the environment of light intensity was not suitable for the growth of pea aphids, and the red pea aphids were more sensitive compared to the green morph.