The Effect Of Alpha-terthienyl On Aedes Albopictus Larvae

Objective:To study the toxicity and histomorphological changes of Aedes albopictus larvae by alpha-terthienyl.Methods:1. To identify the relationship between different treating time in dark and the toxicity of alpha-terthienyl under UVA to Aedes albopictus larvae.2. To determine the toxicity of alpha-terthienyl to different instars of Aedes albopictus larvae under UVA.3. To determine the effect of alpha-terthienyl on the growth of Aedes albopictus larvae under UVA.4. To investigate the toxicity of alpha-terthienyl to Aedes albopictus larvae under sunlight.5. To observe the histopathological changes of Aedes albopictus larvae by light microscope.6. To observe the ultrastructure changes of Aedes albopictus larvae in midgut microvilli, midgut cell, malpighian tubule with electron microscopes(SEM and TEM).Results:1.The most effective toxicity of alpha-terthienyl to mosquito larvae occurred as the treating time in dark was 3 hours.2. Under UVA and alpha-terthienyl, median lethal concentration (LC50 ) to Aedes albopictus larvae of 4th instar was 2.37#g/L; the smaller the larvae instar were , the more suspectibility larvae were.3. Alpha-terthienyl could reduce the pupation and emergence, prolonged the averagetime of pupation and emergence.4. Mosquito larvae could be quickly killed under strong sunlight radiation; the effect of administing alpha-terthienyl at Sam was better than that at 10am and 1pm.5. The observation with light microscope showed that the targets of alpha-terthienyl to Aedes albopictus larvae were midgut, malpighian tubule and fat body.6. The observation with scanning electron microscope showed that microvilli became fewer and fallen disordered partly absent from the cells.7. The observation with transmission electron microscope approved that the decreased cytoplasm density and swelled mitochondria and endoplasmic reticulum in midintestine cells; the smaller concretions in the cytoplasms of malpighian tubules increased , the black substance in the concretions increased.Conclusion:1. Alpha-terthienyl had light-activated, high effect to kill Aedes albopictus larvae, It could inhibit the growth of mosquito.2. The results of histology study showed that the tissular targets of alpha-terthienyl were midgut malpighian tubule fat body and the cellular targets were biological membrane system; contact action and stomach action were the important insecticidal modes of alpha-terthienyl.