广聚萤叶甲和豚草卷蛾对广西来宾豚草的联合控制作用

【背景】豚草已成功入侵广西来宾,对当地生物多样性、农业生产和居民健康造成了严重影响。广聚萤叶甲和豚草卷蛾均为豚草的重要专一性天敌,在湖南等地已有效抑制了豚草的扩散蔓延。【方法】为考查2种天敌在广西对豚草的联合控制作用,于2009年5月24日在广西来宾豚草入侵地区同时释放广聚萤叶甲和豚草卷蛾(2种天敌释放密度均为1170头.hm-2)。【结果】至2009年8月29日释放区内豚草植株死亡率达98%以上,且天敌迅速向邻近豚草发生区扩散,2种天敌对扩散区豚草的控制率可达50%～60%。【结论与意义】2种天敌对豚草具有显著的控制效果,建议在广西大面积推广应用。     

广聚萤叶甲成虫的繁殖习性和活动规律初步观察

广聚萤叶甲Ophraella communa是豚草Ambrosia artemisiifoliaL.的一种重要专一性天敌昆虫,对豚草抑制作用显著。本文在室内对广聚萤叶甲成虫交配和产卵活动进行观察,结果表明广聚萤叶甲成虫一生多次交配多次产卵,雄虫交配前期为2.7d,明显长于雌虫的0.9d。交配雌虫有产卵前期,然后开始产卵。成虫交配活动主要在8:00-21:00,一般产卵高峰在12:00-16:00,在交配后的前16天,雌虫产卵处在高峰期,随后产卵逐渐减少。本论文为进一步开展广聚萤叶甲繁殖生物学研究和大量繁殖提供基础。     

广聚萤叶甲成虫产卵行为及其产卵部位的选择性

【目的】明确广聚萤叶甲成虫产卵行为及其产卵部位的选择性。【方法】在室内条件下,对广聚萤叶甲成虫交配及产卵的系列行为、产卵场所选择、不同部位豚草植株叶片叶绿素b的含量进行了观察和测定:(1)将1对成虫放到养虫笼内的一株豚草上,观察交配时间,记录产卵数量、前后2粒卵之间的产卵时间间隔;(2)在均匀分为5部分(0～10、11～20、21～30、31～40和41～50 cm)的豚草植株上,随机放置10对成虫,观察雌虫对于产卵场所的选择。(3)将上述5个部位的豚草叶片通过丙酮匀浆法处理,用紫外分光光度计测定其在645和663 nm的吸光值,计算叶绿素b含量。【结果】广聚萤叶甲成虫完成一次成功交配平均需96.09 min。雌虫一般需45 min的时间来寻找其适应的产卵场所,在产卵过程中,成虫习惯将卵产于叶片背面,雌虫喜欢用口器来清理刚产下的卵粒。在一株50 cm高的豚草植株上,雌虫喜欢将卵产在植株中部21～30 cm和中上部31～40cm的叶片上(从下往上划分)。卵块数量和豚草不同部位叶片叶绿素b含量呈显著的正相关性。【结论】广聚萤叶甲成虫喜欢产卵在叶绿素b含量较高的叶片背面,可能以视觉识别叶片颜色来选择和定位产卵场所。     

低温条件下广聚萤叶甲成虫的耐饥饿能力

【背景】广聚萤叶甲是恶性入侵杂草豚草的一种重要专一性天敌,在冬季低温且缺乏食物的条件下,广聚萤叶甲的耐饥饿能力直接关系到其越冬种群的虫源基数。【方法】在室内观察广聚萤叶甲成虫在10℃低温条件下的存活率和死亡率,研究了水分(有水、无水)、不同密度(一雌一雄、二雌二雄、五雌五雄)、加入泥土枯枝对广聚萤叶甲耐饥饿能力的影响。【结果】无水、有水条件下,广聚萤叶甲成虫的平均存活时间分别为(15.23±1.01)、(13.33±0.88)d,水分对广聚萤叶甲的耐饥力的影响不显著;随着密度的增加,广聚萤叶甲的耐饥饿能力增强,一雌一雄、二雌二雄和五雌五雄的平均存活时间依次为(11.96±0.57)、(13.78±0.60)、(14.81±0.42)d;加入泥土和豚草枯枝后,广聚萤叶甲的耐饥饿能力明显提高,其平均存活时间为(15.97±1.05)d。【结论与意义】低温条件下广聚萤叶甲的耐饥饿能力较强,可保证部分广聚萤叶甲的自然种群在野外安全越冬,研究低温条件下广聚萤叶甲的耐饥饿能力对豚草的生物防治具有重要意义。     

短时低温胁迫对广聚萤叶甲发育和生殖的影响

广聚萤叶甲Ophraella commnuna 是入侵性杂草豚草Ambrosia artemisiifolia的一种重要专一性天敌.为探明短时低温胁迫对广聚萤叶甲发育和生殖的影响,将广聚萤叶甲置于2,5,8,11和14°C人工气候箱内(RH 70%±5%,14L:10D)处理2 h,测定卵、幼虫、蛹存活率、发育历期及成...     

TESTS OF INBREEDING EFFECTS ON HOST-SHIFT POTENTIAL IN THE PHYTOPHAGOUS BEETLE OPHRAELLA COMMUNA

Although inbreeding, on average, decreases additive genetic variance, some inbred populations may show an increase in phenotypic variance for some characters. In those populations with increased phenotypic variance, character changes by peak shifts may occur because of the effects of the higher variance on the adaptive landscape. A population's increased phenotypic variance may place it in the domain of attraction of a new adaptive peak or increase the likelihood of a selection-driven peak shift as the landscape of mean fitness flattens. The focus of this study was to test for increased variance, in inbred populations, in a behavioral character involved in adaptive diversification and probably speciation. We examined the effect of inbreeding on feeding responses of the leaf beetle Ophraella communa in a series of inbred lineages across a range of levels of inbreeding (f = 0.25, 0.375, 0.5). We measured the feeding response of inbred lineages of O. communa on its normal host, Ambrosia artemisiifolia, and on two novel plants, Chrysopsis villosa and Iva frutescens, that are the hosts of other Ophraella species. The results show that feeding responses on the different plants are not correlated, indicating that the feeding responses to the different plants are to some degree genetically independent. Despite apparent genetic variation in lineage feeding responses, we could not statistically demonstrate increases in phenotypic variance within the lineages. Thus, the experimental results do not support the idea that host shifts in this beetle evolved by peak shifts in bottlenecked populations.     

GENETIC CONSTRAINTS ON MACROEVOLUTION: THE EVOLUTION OF HOST AFFILIATION IN THE LEAF BEETLE GENUS OPHRAELLA

We hypothesize that the evolution of an ecologically important character, the host associations of specialized phytophagous insects, has been influenced by limitations on genetic variation. Using as a historical framework a phylogenetic reconstruction of the history of host associations in the beetle genus Ophraella (Chrysomelidae), we have employed quantitative-genetic methods to screen four species for genetic variation in larval survival, oviposition (in one species only), and feeding responses to their congeners' host plants, in the Asteraceae. We here report results of studies of one species and evaluate the results from all four. Analysis of half-sib/full-sib families and of progenies of wild females of O. notulata, a specialist on Iva (Ambrosiinae), provided evidence of genetic variation in larval consumption of five of six test plants and in adult consumption of four of six. Larval mortality was complete on five plants; only on Ambrosia, a close relative of the natural host, was there appreciable, and genetically variable, survival. Oviposition on Ambrosia showed marginally significant evidence of genetic variation; a more distantly related plant elicited no oviposition at all. In compiling results from four Ophraella species, reported in this and two other papers, we found no evidence of genetic variation in 18 of 39 tests of feeding responses and 14 of 16 tests of larval survival on congeners' hosts. This result is consistent with the hypothesis that absence or paucity of genetic variation may constrain or at least bias the evolution of host associations. The lower incidence of genetic variation in survival than in feeding behavior may imply, according to recent models, that avoidance is a more common evolutionary response to novel plants than adaptation. The usually great disparity between mean performance on congeners' hosts and the species' natural hosts, and an almost complete lack of evidence for negative genetic correlations, argue against the likelihood that speciation has occurred by sympatric host shift. The presence versus apparent absence of genetic variation in consumption was correlated with the propinquity of relationship between the beetle species tested and the species that normally feeds on the test plant, suggesting that the history of host shifts in Ophraella has been guided in part by restrictions on genetic variation. It was also correlated with the propinquity of relationship between a test plant and the beetle's natural host. The contributions of plant relationships and insect relationships, themselves correlated in part, to the pattern of genetic variation, are not readily distinguishable, but together accord with phylogenetic evidence that these and other phytophagous insects adapt most readily to related plants. In this instance, therefore, the macroevolution of an ecologically important character appears to have been influenced by genetic constraints. We hypothesize that absence of the structural prerequisites for genetic variation in complex characters may affect genetic variation and the trajectory of evolution.     

广聚萤叶甲对广东佛冈豚草的控制作用

广聚萤叶甲Ophraella communa是恶性入侵杂草豚草Ambrosia artemisiifolia的一种重要专一性天敌。为了评价其对广东省豚草的野外控制效果,2009和2010年分别在佛冈进行释放,试验调查了释放后的种群动态及其对豚草的控制效果。结果表明:广聚萤叶甲在广东省佛冈县可成功建立自然种群。广聚萤叶甲释放后,其虫口密度不断增加,豚草植株的死亡率也不断上升,2009年豚草死亡率低于20%,2010年叶甲对豚草的控制作用较好,豚草死亡率可达到95%以上,而大量豚草死亡后,广聚萤叶甲的虫口密度又急剧下降。广聚萤叶甲种群扩张与气象因子有密切关系,温度偏低是5～6月广聚萤叶甲的种群数量难以扩增的主要因素,大雨频繁和光照偏少也一定程度上限制了其种群增长,7～8月是广聚萤叶甲种群激增的关键时期,此时其种群数量急剧增加。     

Reevaluation of biosecurity of Ophraella communa against sunflower (Helianthus annuus)

Ophraella communa (Coleoptera: Chrysomelidae), originally from North America, has been used for biological control of common ragweed, Ambrosia artemisiifolia, in China since 2007. However, there is still a debate on whether O. communa can attack sunflowers under field conditions. To re-evaluate the biosecurity of O. communa against sunflower (Helianthus annuus), we investigated the population density of O. communa on three sunflower varieties that were intercropped with or planted in circumambience of A. artemisiifolia under field conditions. Our results showed that only very few O. communa eggs (<0.5 eggs/plant) were found on sunflower plants at the last two surveys when sunflowers were planted in circumambience of common ragweed. O. communa eggs were not found on sunflower plants at each survey when sunflowers were intercropped with common ragweed. The first–second instar larvae, third instar larvae, pupae and adults of O. communa were occasionally found on sunflower plants, but their densities were very low under either case of planting patterns. Based on these results, we conclude that sunflower is not a potential host plant for O. communa and the beetle is an effective host-specific biological control agent of common ragweed.     

野外条件下广聚萤叶甲对豚草的产卵选择

为探究影响广聚萤叶甲Ophraella communa LeSage选择豚草广卵的环境因素,在南京城郊于2009年6月23日至9月1日豚草生长季节,跟踪调查了60个豚草斑块上落卵数量动态,运用跨栏模型分析了影响叶甲产卵以及产卵数量的因素.结果表明:(1)产卵发生随季节延长、豚草被取食程度增大、株高增长、暴露环境中斑块增...