Study On Microstructure Of The Compound Eye And Phototactic Behavior Of Chrysoperla Sinica Tjeder And Chrysopa Formosa Brauer (Neuroptera: Chrysopidae)

The microstructure of the compound eye under light and dark adaptation, and spectral sensitivity and light intensity response of the dominant predatory enemies Chrysoperla sinica Tjeder and Chrysopa formosa Brauer in many farmlands and orchards was investigated by means of optics microscope, histology and phototactic behaviour measure. The main results were as follows:1 The compound eyes with a shape of half sphere, located on the lateral upside of the heads of C. sinica and C. formosa, were composed of 1400 and 2000 ommatidia in both sexes. There were some sensillae between the ommatidia on the exterior of compound eyes, the surface of ommatidium was hexagon, arranged closely just like beehive. These showed that the compound eyes of C. sinica and C. fomosa had square-built eyeshot, and high sensitivity.2 The organization of the compound eye of C. sinica and C. fomosa belonged to the type of superposition eye. Each ommatidium contained corneal lens, crystalline cone, 6 to 8 retinula cells and basement membrane where the pigment granules could be observed, which were encompassed by two primary iris pigment cells and six secondary iris pigment cells in periphery. The microstructure of compound eyes of C. sinica and C. fomosa were different in dark or light adaptation. In light adaptation, the 5-7 distal retinula cell nucleus and the most of pigment granules of secondary iris pigment cells moved to proximal end of retinula cells column. In dark adaptation, the distal retinula cell nucleus moved close to the crystalline cone, the pigment granules of secondary iris pigment cells surrounded the crystalline cone. No differences in the microstructure of compound eye were observed between male and female under the same light or dark adaptation respectively.The crystalline cone cell of the ommatidium of C. sinica showed circadian rhythm in one day: it opened at morning and closed at midnight; it opened at evening and closed in the light adaptation; it opened and closed in both of the two adaptations at midday.3 At 14 monochromatic light selected through 340nm to 605nm, the phototactic spectral sensitivity curve of C. sinica occured in 3-4 peaks, the primary peak was on 400 nm (17.83%), the others were on 460 nm (17.45%), 380 nm (16.23%) and 562 nm (16.19%) in order, that proved it was strong sensitive on ultraviolet, blue and green. That was so different between the two species of lacewing for that the sensitive phototactic response of C. fomosa were feeble, the highest response rate was on 605 nm (7.26%). There was no obviously photophobism response of C. sinica and C. fomosa to 14 monochromatic lights, such a reaction mostly probably derived from phototaxis or partly dued to some random actions, the all response rates were under 1.90% and 1.25%.4 The certain range of white light intensity (Log I = 4.5-0.0) of C. sinica caused phototactic behaviour response, and showed circadian rhythm in one day: as the stronger the luminance, the higher the phototactic behaviour rate at morning (6:00-8:00), the highest response rate was 22.29% on Log I = 0.5 and decreased on Log I = 0.0 (15.55%), so the whole curve appeared a near"S"shape; the photophobism response increased slow with the peak on Log I = 0.0 (6.06%). The phototactic response rate increased with the luminance at midday (12:00-14:00) which the primary peak was 13.22% (Log I = 0.0); the photophobism response increased slowly with the peak on Log I = 0.0 (4.70%). The line style phototactic response curve increased with luminance at evening (18:00-20:00), the highest response rate was 36.91% on Log I = 0.0; the photophobism response rate were all under 1.70%. The phototactic response curve was appeared a near"S"shape at midnight (0:00-2:00) with the highest rate (12.23%) on Log I = 1.0, and decreased on Log I = 0.0 (9.35%); the photophobism response increased slowly with the peak on Log I = 0.0 (5.18%). C. sinica has strong sensitivity on light, especially at morning and evening when the light was changing, and it could endure the stronger luminance of white light at midday and evening. These no obviously photophobism response probably derived from phototaxis or partly dued to some random actions.As the luminance stronger, the phototactic behaviour rate with C. fomosa bcame higher, which the biggest was 30.66% (Log I = 0.0); and the photophobism response rates were under 1.56%, showing no orderliness.This paper described the first observation of morphology and microstructure of compound eyes with C. sinica and C. fomosa, pronounced differences of spectral sensitivity response and similar light intensity behavioral responses between the two species of lacewing. C. sinica showed circadian rhythm with opened and closed crystalline cone cell and light intensity phototaxis behavioral responses. It indicated that the similarities and differences may be the premise to choose suitable habitat or action, and their sexual behavior and preferences phototaxis activity habits around dusk. Insect pest monitoring and prevention and control technologies would be developed based on the structural and physiological mechanisms.