How do they cope with the situation when the caterpillars of beet armyworms, Spodoptera exigua, attack their host plant under different fertilization conditions?
Fertilizer with different ration of nitrogen (N) to phosphorus (P) could influence performance of plants including crops and vegetables. Spodoptera exigua is an important agriculture pest that has caused serious economic loss especially recent decades. In the present study, we explored that the response of host plants and S. exigua after S. exigua caterpillars damaged on the way of different level intensity and frequency under five fertilizer treatments with different ratio of N to P. The
... f N to P. The results indicated that fertilizer can significantly influence the interaction between host plants and caterpillars. Compensatory growth was detected under definite fertilizer with N : P = 3 : 1. Higher N proportion in fertilizer appears to contribute to maintain similar stem biomass in defoliated seedlings to control ones. Root biomass had almost no significant difference between defoliation and control, but it can not compensate under definite fertilizer. Higher proportion of N in fertilizer also contributed to enhance antioxidant enzymes activities: antioxidase catalase (CAT), superoxide dismutase (SOD), at low-level intensity caterpillars on host plants.However, when the herbivorous intensity was increasing, higher proportion of P in fertilizer seemed to play more important role on increase the activities of CAT and SOD. Higher phosphorus likely contributes to enhance acetylcholin esterase (AChE) activity at lower degree of defoliation, but higher nitrogen proportion could result in higher AChE activity at higher degree of defoliation. Higher content of nitrogen in definite range contributed to reduce the carboxylesterase (CarE) activity at high intensity within short-term defoliation. However, when defoliation intensity enhanced, the difference of CarE activity between fertilizer categories was small.