Effect Of Host Plants On Yeast-like Symbionts And Feeding Behavior In Laodelphax Striatellus

The smaller brown planthopper (SBPH), Laodelphax striatellus, iswidespread in China. SBPH has a lot of host plants, and main of them belong to thegrass family, such as barley, wheat and rice. The different generation of SBPH cantransfer between different host plants. The type of host plants and rice varietiesinfluence survival rate, sex ratio, developmental duration and egg number of SBPH.The virulence variation, feeding behavior and the number, type and shape ofyeast-like symbiotes (YLS) in the fat bodies can be influenced by different hostplants or rice varieties. In order to determine virulence variation mechanism of SBPHand the change of YLS in the type of host plants or rice varieties, we have studied theeffect of different rice cultivars on feeding behaviour and different host plants on thenumber and shape of YLS in SBPH.The results are as followings:1. In order to get different species of SBPH, it was cultivated in different host plants.It was mainly fusiform and oval forms to constitute the YLS in SBPH, and usingbudding reproduction to asexual propagation. Its size and quantity are compared, theresult is that the type of host plants influence the size and quantity of YLS.5.8S-ITSrDNA sequences of YLS were amplified, identity among YLS from SBPH ofdifferent species were compared. The result is that YLS of barley population has704bp, wheat population has703bp, rice population has702bp. YLS of barleypopulation has variation of2bp, wheat population has variation of1bp, ricepopulation has variation of1bp. Similar rate of different species is99.72%. It alsoverify that ITS sequences are easy variation. Phylogenetic analysis based onITS-5.8S rDNA showed that YLS from three rice planthoppers showed no obviousidentity to other known fungi. It was suggested that insect YLS have a closeevolutionary relationship with insects and form a specific group from other fungi.2. Studied the effect of various rice cultivars on the SBPH feeding behaviour byElectrical Penetration Graph (EPG), the results showed that there were four basictypes of EPG waveforms performed by SBPH, that is A, B, C, D. Non-feeding waveof TN1is less than other rice varieties, and passively feeding wave in phloem of it is longer than other rice varieties. There were no significant differences in xylembetween rice varieties. It was suggested that EPG can detect the resistance of hostplants.