Identification And Biological Charecteristics Of A Pathogenic Bacterium From Heortia Vitessoides And Its Effect On The Physiological Indicators

Heortia vitessoides Moore is the most harmful leaf-eating pest in the growth of Aquilaria sinensis(Lour.)Gilg.The larvae can cause the leaves of Aquilaria sinensis to be incomplete.In the area where the larvae erupt,the leaves of Aquilaria sinensis will be completely consumed,and the tree of Aquilaria sinensis will be reduced and even die.A lethal parasitic Aspergillus strain was isolated and identified during rearing the larvae of Heortia vitessoides.The paper is about the studies of the biological characteristics of Aspergillus nomius and the effects on the physiological and biochemical characteristics of the larvae.The results are as follows:1.Isolation and identification of Q527 was isolated from the dead larvae of Heortia vitessoides.The strain Q527 was identified as Aspergillus nomius by morphological observation and molecular identification.The pathogenicity of the larvae of Aspergillus nomius was determined by the spore suspension with the concentration of 108·mL-1.The corrected pathogenicity rate was 83.3%after 7 days.2.Biological characteristics of pathogens.The optimum medium for the growth of Aspergillus nomius Q527 was PDA medium,followed by SDAY and PSA medium.The colony color on PDA was white at the early stage and yellow-green at the later stage.It could grow in the range of pH 5.0 to 12.0,and the growth rate was the fastest at pH 8.The mycelia and spores of Aspergillus rubra stopped growing and germinating after being bathed in water at 65?.Lactose as a carbon source effectively promoted the mycelial growth of Aspergillus nomius Q527,soluble starch as a carbon source effectively promoted sporulation,peptone as a nitrogen source could promote the mycelial growth and sporulation of Aspergillus nomius Q527.Aspergillus nomius Q527 vegetative reproduction prefers darkness.The mycelial growth rate was the fastest when the culture temperature was 28 ??3.After the infection of the larvae of Heortia vitessoides,the glucose content of the larvae of the Heortia vitessoides larvae decreased,the protein content reacted first and then slowed down,and the content of free amino acids showed a wavy change trend.The activity of SOD and CAT in larvae changes from high to low,and the activity of POD changes wavy.The activity of GST increases first.After decreasing and then rising,the activity of AChE increased first and then decreased.The activity of PPO increased sharply from the next day,reached the peak on the third day,and then decreased below the CK on the fourth day.