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保山市科学技术协会

联合推出

第4期

The 4th Phase

节肢动物.三突伊氏蛛Ebrechtella tricuspidata

节肢动物，蛛形纲，蜘蛛目，蟹蛛科。三突伊氏蛛（也叫三突花蛛）广泛分布于我国各省的农田、果园及森林，是农林害虫的重要天敌。图片摄于云南保山青华海国家湿地公园。

很多人以为蜘蛛是昆虫，其实不然。昆虫一般分为头、胸、腹三个部分，而蜘蛛身体分为头胸部和腹部两个部分，大部分有8只眼睛，全部为单眼。眼的排列，不同种之间差异很大。昆虫有3对足而蜘蛛有4对足。而且蜘蛛和昆虫几乎是死对头，蜘蛛的主要食物来源就是昆虫（绝大多数是农林的主要害虫）。

三突伊氏蛛属于蟹蛛科的蜘蛛，这一类蜘蛛的多数身体短宽，8只步足能够左右伸展，可以横行或后退，就像螃蟹那样，所以叫蟹蛛。三突伊氏蛛是小型蜘蛛，雌蛛长5毫米左右，而雄蛛则要更小一些。头胸部通常绿色，8眼排成2行，前、后侧眼显著大于中眼，眼区黄白色，前两对步足显著长于后两对。腹部梨形，前窄后宽。背面黄白色，或金黄色，并有红棕色斑纹。

蜘蛛可分为结网型和游猎型两大类。三突伊氏蛛属于不结网游猎型选手，常静静守候在花草丛中等候， 当猎物靠近时，就迅速跳出将食物逮住。每年3月中旬，三突伊氏蛛开始出来活动，上树捕食各种野虫，冬天则在树干翘皮裂缝及地面土石缝中越冬。繁殖期的时候，雌蛛会将叶子卷起来，把卵产在里面。产卵后的雌蛛在旁进行守护，期间很少远离卵袋进行觅食，直到幼蛛孵出。

三突伊氏蛛是稻田、棉田、果园、菜地等作物害虫的一种重要捕食性天敌。它能捕食蔬菜害虫小菜蛾、果树害虫苹果黄蚜、桃粉蚜、桃小叶蝉和山楂叶螨、棉田害虫棉铃虫和棉蚜等。

你们见过不结网的蜘蛛吗？

The 4th Phase

Ebrechtella tricuspidata

Arthropoda, Arachnida, Araneae, Thomisidae. Ebrechtella tricuspidata is the important natural enemies of agricultural and forestry pests and widely distributed in farmland, orchards and forests in all provinces of China. The photo is taken in The Qinghuahai National Wetland Park in Baoshan city, Yunnan proince.

Many people think spiders are insects, but they are not. Insects generally contain three parts: head, chest and abdomen, while spiders contain two parts: cephalothorax and abdomen. Most spiders have eight eyes, all of which are ocellus. The arrangement of eyes varies greatly from species to species. Insects have three pairs of feet while spiders have four. Moreover, spiders and insects are almost enemies, and the main food source for spiders is insects (most of which are major pests in agriculture and forests).

Ebrechtella tricuspidata is belong to the Thomisidae. This kind of spiders are short and wide, with eight feet stretching from side to side, which can run sideways or backward, just like crabs. It is the reason why they are called crab spiders. Ebrechtella tricuspidata are the smaller spiders, and females are about 5 millimeters long but males are smaller. Their cephalothorax are usually green, 8 eyes are arranged in 2 rows, the anterior lateral eyes and posterior lateral eyes are significantly larger than the middle eyes. The ocular area are yellow-white, and the former two pairs of feet are obviously longer than the latter two pairs. The abdomen is pear-shaped, narrow in front and broad in back. The back is yellow-white, or golden, with red brown markings.

Spiders can be divided into two groups: the web-weaving type and the hunting type. Ebrechtella tricuspidata belong to the non-net hunting type, and they often quietly waiting among the flowers and plants, then jump out quickly to catch food when the prey is approaching. In the middle of March every year, Ebrechtella tricuspidata begin to come out and climb trees to hunt various wild insects. They spend their winter in the cracks of the tree trunk, cracks of soil and stone on the ground. During breeding season, females roll up the leaves and lay their eggs in them. After laying eggs, the female guards nearby, and rarely leave the egg bag to forage until the baby spider hatches.

Ebrechtella tricuspidata is an important predatory natural enemy of crop pests in paddy field, cotton field, orchard and vegetable plot. They can prey vegetable pests such as Plutella xylostella, fruit pests such as Aphis citricola, Hyaloptera amygdali, Erythroneura sudra and Tetranychus viennensis, cotton field pests such as Heliothis armigera and Aphis gossypii, etc.

Have you ever seen a spider that doesn't net？

文字整理：黄木娇

海报设计：黄木娇

英文翻译：何雪、黄木娇

Text: Mujiao Huang

Poster design: Mujiao Huang

English translation: He Xue, Mujiao Huang