Effects of LdNPV on growth, development and biochemical enzymatic activities of Lymantria dispar under CO₂ concentration stress

ObjectiveIn this study, the forest pest Lymantria dispar was used to study the effects of LdNPV on the development, detoxifying enzymes and protective enzymes of Lymantria dispar larvae under CO₂ concentration stress.

MethodThe effects of LdNPV on the growth and development of L. dispar larvae under different CO₂ concentrations (397, 550 and 750 μL/L) reared into the closed CO₂ artificial climate chamber, and in vivo detoxifying enzymes and protective enzyme activities of L. dispar larvae were also determined by spectrophotometry.

Result The cumulative growth rate of fresh mass of the 3rd instar larvae of L. dispar decreased under high CO₂ concentration stress. The cumulative increase rates of fresh mass of the 3rd instar L. dispar larvae infected by LdNPV were higher than the control by 81.27%, 71.63% and 68.41%, respectively. The mortality rate increased with increasing CO₂ concentration, and the cumulative mortality rate of 750 μL/L CO₂ treatment was 27.09%. Under the high CO₂ concentration stress, the activities of detoxifying enzymes CarE and AChE in the 3rd instar larvae of L. dispar were induced with the increase of CO₂ concentration, and the ALP activity was inhibited with the increase of CO₂ concentration; the activity of protective enzyme CAT was induced with the increase of CO₂ concentration while SOD activity was inhibited with increasing CO₂ concentration. However, the activities of CarE, ALP, AChE and CAT in 3rd instar larvae of L. dispar infected by LdNPV were inhibited with the increase of CO₂ concentration, and the activity of SOD was induced with the increase of CO₂ concentration.

ConclusionThe duration and cumulative mortality rate of L. dispar larvae infected by LdNPV increased while cumulative growth rate decreased after different CO₂ concentraion treatments. The activities of CarE, AChE, ALP and CAT in 3rd instar larvae of L. dispar decreased with the increase of both the treatment time and CO₂ concentration, and the activities of SOD were increased. Therefore, elevated concentration of CO₂ may increase the virulence of LdNPV to the L. dispar larvae by affecting the growth, development and biochemical enzymes.