稻田及其毗邻杂草地寄生蜂群落结构与特征

通过在稻田及其毗邻杂草地的系统调查、采集和室内标本鉴定,获知稻田中有67种寄生蜂,隶属16科;毗邻杂草地中有96种寄生蜂,隶属19科。稻田生境中的寄生蜂物种数占稻田天敌总物种数的45．89％,杂草生境中的寄生蜂物种数占杂草地天敌总物种数的46．60％。对稻田及其毗邻杂草地寄生蜂群落的各种属性指标进行比较研究,结果表明：杂草地寄生蜂群落的丰富度、多样性、优势集中度指数均比稻田高,而均匀性指数值比稻田低。对杂草生境和稻田生境寄生蜂群落的优势种动态比较可知,寄生蜂优势种在水稻的不同生育期是不相同的,在稻田生境中,优势种稻虱缨小蜂(Anagrus sp．)出现在水稻生育前期和中后期,等腹黑卵蜂(Telenomus dignus)出现在水稻生育后期,稻苞虫黑卵蜂(Telenomus sp．)在水稻生育前中期及后期出现。然而在杂草地中,作为优势种,稻虱缨小蜂出现在水稻生育前期和中期,等腹黑卵蜂出现在水稻生育前中期和后期,稻苞虫黑卵蜂在水稻整个生育期均有出现。两种锤角细蜂(Monelata sp．1和Acropiesta sp．2)是稻田的重要优势种,但不是杂草地的优势种;相反,稻蝽小黑卵蜂(Telenomus gifuensis)是杂草地的重要优势种,但不是稻田的优势种。由此可见,杂草地生境是稻田寄生蜂的种库之一,对稻田节肢动物群落的重建和种群保存有重要影响,因而适当保留田埂杂草和稻田周围的杂草地,减少对天敌的损害,提高天敌对害虫的自然控制作用,是水稻害虫持续控制的途径之一。

Structure and characteristics of parasitoid communities in a rice field and adjacent weed habitat

Based on outdoor surveys and suction device-based collections in a rice field as well as adja- cent weed habitat from June to September 2001 and laboratory identifications of specimens obtained from the field investigations, 67 species of parasitoids were collected and identified in the rice field, and 96 in the weed habitat. The species number of parasitoids accounted for 45. 9% of the total species number of natural enemies in the rice field, and 46. 6% in the weed habitat. For a comparative study of community diversity, species richness (S), Shannon-Wiener's diversity index (H'), Simpson's index of dominant centralization (C) and Pielou's evenness (E) were calculated. The results showed that the numerical values of S, H' and C of the parasitoids in the weed habitat were higher than those in the rice field, and the value of E was lower in the weed habitat. Temporal variation of dominant species was also different between the two habitats. In both habitats, Telenomus dignus and Anagrus sp. were dominant, but each habitat also had its unique dominant species, e. g., Monelata sp. 1 and Acropiesta sp. 2 were common in the rice field but not in weed habitat, while Telenomus gifuensis was only common in the weed habitat. The dominant species of the parasitoids tended to colonize the weed habitat in the seedling-transplanted stage of rice, immigrate into the field in the growing stage of rice, and emigrate from the fields to live in the weed habitat again in the mature stage of rice. This clearly indicates that the weed habitat can serve as a "species pool" of natural enemies, which provides the enemies with opportunities for natural dispers- al, host alternation and refuge-seeking when there is lack of suitable food or disturbances caused by culti- vation in the rice field. This is favorable for ecologically-based integrated pest management in rice ecosys- tems.