Biology Of Corythucha Ciliata And Its Impact On The Host Plants

The sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae) is a relatively new invasive pest infesting Platanus trees that was first found in China in 2002, and since has spread rapidly to nine provinces in these years. The species originated from North America and now widely distributed in Europe and eastern Asia. Both C. ciliata adults and nymphs feed on the underside of leaves and produce small chlorotic stippling on the upper leaf surface. Leaf undersides appear characteristically black or dark brown varnish spotted due to lace bug excrement. Their injury reduces photosynthesis and respiration and also causes aesthetically displeasing injured leaves. As a result, foliage becomes bronzed and leaves may drop early in late summer. Several consecutive years of severe C. ciliata damage, combined with other stress factors, may kill the trees. Based on stuying on the biology and occurrence of this pest, this paper furtherly studied spatial distribution pattern and sampling technique of the pest. In addition, the effect of low and high temperature on the survival rate of C. ciliata was also investigated. Finnally, we tested the range of host plants and studied the effect on physiologic index of P. acerifolia eventually.The main conclusions are as followed:1. The life history and habits of Corythucha ciliata (Say) was observed, and the occurrence was investigated in Shanghai. There were five generations each year and overwintering adults could survive on trunks and branches in middle until to late October in Shanghai. Adults began to damage in early April and lay eggs in late April. The first generation nymphae were seen at the beginning of May, the nymph period was 17 to 18 d, and the whole generation duration was about 30 d. The generations overlap was obvious between July and August. The host range of C. ciliata was narrow and only Platanus genera plants were its hosts.2. The dispersion patterns, which were generated by Taylor's power law and Iwao's patchiness regression, were compared for two stages of Corythucha ciliata (Say) in different sampling units of the plane tree Platanus acerifolia Willd. Both indices indicated that the values of Iwao's aggregation index were in a narrower range (from 1.02 to 22.87) than Taylor's (from 1.01 to 45.57), but both indices indicated a clumped distribution pattern in all sampling units (b>1,β>1). There was no significant difference of the densities of insects on twigs between the upper and lower layer of the canopy in the east, south, west and north of the tree. Trunks are recommended to be the target in the sampling of the overwintering adults. The adults on the twigs on the 2nd, 3rd and 4th leaves from the top in the tree were chosen as the sampling targets to represent the population of C. ciliata in pest management for the wandering stage.3. Sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae) is an important invasive pest of Platanus trees in China. The objective of this study is to determine supercooling capacity, of C. ciliate female adults was signicicantly lower than that of male adults, with an average of -11.49℃and -9.54℃, respectively. When laboratory reared females were transferred and maintained from the rearing temperature of 26℃to -12℃for 2 h there was 78% mortality, whereas exposure to 0℃for 4 h prior to transfer to -12℃reduces mortality to 32%. Comparison of NACC,ACC,RCH,ACC+RCH, the cold shock of RCH was the best.4. The study of heat tolerance of Corythucha ciliata (Say) was showed that the mortality of larvas and adults increased with the improvement of stress temperature. The heat tolerance of larvas and adults was no difference at the same condition when they were exposured. The mortality of male was a little higher than that of female. The mortality of larvas and adults increased prominently after exposuring 1h under non-lethal high temperature, especially the acclimation effect was optimal at 37℃after preheating 1 h.5. The paper studied photosynthesis and physiological indices of damaged leaves of platanus acerifolia by corythucha ciliate. With the increase grade, the content of the photosynthetic rate (Pn), stomatal conductance (Cond), transpiration rate (Tr), chlorophyll, soluble sμgar and proline in platanus acerifolia generally decreased, and intercellular CO2 concentration (Ci) increased. With the increasing leaf damage, no consistent patterns of free proline content in leaves were observed.