Studies On The Adaptation Of Octodonta Nipae (Maulik) In Different Species Hosts

In this paper, the host plants of Octodonta nipae (Maulik,1921) were investigated in Fuzhou. The effects of the morphology, feeding capacity, development and fertility of O. nipae affected by different host plants were studied. Based on those, the adaptablity of O. nipae in different host plants was analysed. The relationship between the selectivity of O nipae to host waxiness content and crude extract in alcohol of interior leaves was analysed too. The selectivity mechanistic of this insect and the application of preventing Octodonta nipae harming the agriculture was discussed. The results were as follows:The plamae plants are the main host of O. nipae. It is reported that most of the plamae plants are their host, such as Cocos nucifera, Metroxy-lon sagu, Royston earegia, Trachycarpusfortunei, Caryota ochlandra and so on. The Cocos nucifera is the main host. But in Fuzhou, Phoenix dactylifera is the main host of O. nipae. O. nipae has not been found on other plants. However, in our investigation, Livistona chinensis which was near the Phoenix dactylifera hadn't been dangered.Studies on the morphological shows that: Under different hosts, little difference was acquitted in the head width and body length of the first instar larva. a significant difference was acquitted in the head width from the second instar larvae to the fourth instar larvae, wider on the Trachycarpusfortunei and Phoenix L, narrower on Livistona chinensis. The result of body length of larvae comparison showed that significant difference between the first instar larvae and the fourth instar larvae. Seven parts of the adult were measured and compared between the male and the female respectively. The results shows the body length, elytron width and antenna length of the female insect on the Phoenixsp were remarkable difference from others; the Trachycarpusfortunei and Phoenix. L also had significant difference; but the Phoenix L. was a little difference between Trachycarpusfortunei and Phoenix dactylifera. The effect of different hosts on male insect was much more complex, the body length, elytron and antenna length of male insect are longest on Phoenix dactylifera, which was a remarkable difference to other hosts. The female adult insects were much bigger than the male under the four hosts in 7 targets.In this paper, the selectiong of were studied in Lab, including selective experiments and non-selective experiments. The result showed that the Phoenix dactylifera and Trachycarpusfortunei were eaten by O. nipae mostly, and Phoenix L. and Livistona chinensis were the second. The selective experiments corresponded with non-selective experiments, and they were the same with the field surveys. In the same condition, the favourable host was selected by O. nipae. This conclusion was firstly suggested. On the fecundity ability selection, the results showed that the difference on the selectivity of Octodonta nipae to different hosts was increased as the time went on, it reached stable after 24 hours. The egg laying amount was the biggest on the Phoenix dactylifera (15.2±4.97) and had a little difference between the Phoenix L. and Trachycarpusfortunei, but had significant difference to Livistona chinensis. Therefore, the Livistona chinensis had a little difference between Phoenix L.and Trachycarpusfortunei. The insect amount and the feeding capacity had the same law with the egg-mass.A comparison experiment of the waxiness content to the interior leaf of the four hosts in the feeding capacity of O. nipae was conducted, the results showed that the waxiness content of Livistona chinensis interior leaf which was disliked by Octodonta nipae was the highest; however, the others were much lower. The results already showed that the waxiness content had a little effect if lower than a certain degree; but had a significant effect after exceed the point. After removing the waxiness of the host leaf, found that the feeding capacity had a significant difference on the four hosts, this results showed that the affect of waxiness removal to feeding capacity was significant.The experiment of O. nipae tempted by different concentrations of alcohol crude extract of four hosts showed that the Trachycarpusfortunei, Phoenix dactylifera and Phoenix L. all had the tempted effect to this insect. Trachycarpusfortunei, 0.05gDW/ml-0.1gDW/ml; Phoenix dactylifera 0.5gDW/ml; Phoenix L. 0.4gDW/ml, respectively; Livistona chinensis had many adult insects crowed both in <0.05 gDW/ml and CK. These results illustrated that distinguish to the alcohol crude extract by O. nipae was very important to the host choice from Trachycarpusfortunei, Phoenix L. and Phoenix dactylifera; it had no significant effect to the choice on Livistona chinensis.Based on the above study, this article presented the host selection mode of O. nipae and showed the feasibility of using palm plants which had high waxiness content as landscape trees. The extract of Phoenix dactylifera could be used in tempted pesticide.manufacture.