Survival of boll weevil （Coleoptera： Curculionidae） adults after feeding on pollens from various sources

The survival of overwintering boll weevil, Anthonomus grandis grandis （Boheman）, adults on non-cotton hosts in the Lower Rio Grande Valley （LRGV） of Texas was examined from 2001 to 2006. The success of the Boll Weevil Eradication Program, which was reintroduced into the LRGV in 2005, depends on controlling overwintering boll weevil populations. Laboratory studies were conducted using boll weevil adults that were captured in pheromone traps from September through March. The number of adults captured per trap declined significantly in the field from fall to the beginning of spring （3.5-7.0-fold）. The proportion of trapped males and females did not differ significantly. The mean weight of boll weevil adults captured in September was 13.3 mg, while those of captured adults from November to February were significantly lower and ranged from 6.7 to 7.8 mg. Our results show that boll weevil adults can feed on different plant pollens. The highest longevity occurred when adults were fed almond pollen or mixed pollens （72.6 days and 69.2 days, respectively） and the lowest when they fed on citrus pollen or a non-food source （9.7 days or 7.4 days, respectively）. The highest adult survival occurred on almond and mixed pollens [88.0%-97. 6% after 1st feeding period （10 days）, 78.0%-90.8% after 3rd feeding period （10 days）, 55. 0%-83.6% after 5th feeding period （10 days）, and 15.2%-32.4% after lOth feeding period （10 days）]. The lowest adult survival occurred on citrus pollen [52.0%-56.0% after 1st feeding period （10 days）, 13.3% after 3rd and 5th feeding periods （10 days）, and 0 after 6th feeding period （10 days）]. Pollen feeding is not a behavior restricted to adult boll weevils of a specific sex or physiological state. Understanding how boll weevil adults survive in the absence of cotton is important to ensure ultimate success of eradicating this pest in the subtropics.     

不同扰动生境中动物对酸苔菜种子的捕食和散布

有效的种子散布是木本植物形成入侵种需要经历的过程之一,但在预测入侵种时却常常被忽略.紫金牛科东方紫金牛(Ardisia elliptica)原产热带亚洲而在北美成为入侵植物,分布在云南南部的其同属种酸苔菜(A.solariacea)与之具有相似的生物学特征.本文以酸苔菜为研究对象,于2004年12月至次年2月分别在人为干扰轻的野象谷和人为干扰重的植物园进行酸苔菜的种子散布及捕食研究,试图了解生境变化对其种子散布和种子捕食的影响.结果表明,酸苔菜在两地的种子散布者均为白喉冠鹎(Alophoixus pallidus)、黑冠黄鹎(Pycnonotus melanicterus)和灰眼短脚鹎(Iole propinqua),但3种食果实鸟类的组成比例、拜访行为、频率及种子捕食者的影响在两地均不相同.人为干扰轻的野象谷生境中白喉冠鹎、黑冠黄鹎与灰眼短脚鹎的拜访频率分别为25%、32%和26%.取食后的第一次停栖地点有4%在10 m以外;人为干扰重的植物园生境中3种鸟的拜访频率分别为67%、8%、5%,取食后的第一次停栖地点有26%在10 m以外.人工摆放种子试验表明,地面上种子捕食者主要是啮齿类;在两生境中种子捕食率均较低(2-6%),但野象谷生境中种子捕食率仍显著高于植物园生境.野象谷生境中种子还受到象鼻虫幼虫的危害,危害率为17.9±3.5%(n=512);而植物园生境中未发现种子被象鼻虫危害(n=489).干扰对生境中的动物组成及行为造成了明显影响,并可能通过种子散布与捕食的改变而间接影响与其有密切关系植物的种群动态.     

豌豆来源的毒性抗虫白蛋白cDNA在毕赤酵母中异源表达及抗虫毒性分析

一种来源于豌豆的白蛋白 (PA)对多种昆虫具有明显的毒性作用 .为了进一步研究其抗虫机理 ,采用基因工程的方法富集蛋白质 .将该白蛋白基因克隆到毕赤酵母分泌型表达载体pPICZαA .并导入毕赤酵母菌GS115中表达 .通过PCR和Northern印迹法分析基因的整合及转录 ,对工程菌进行发酵 ,采用两步培养 :第一步富集菌体 ,第二步甲醇诱导工程菌表达重组蛋白 ,并分泌到培养基中 .经过超滤和HPLC分离 ,重组抗虫白蛋白得率约 10mg L .重组蛋白对象鼻虫敏感株表现出很强的毒力 ,半致死剂量LC50 为 4 7,与直接纯化于豌豆种子的白蛋白毒力一致 ,而对象鼻虫抗性株无明显毒力 .     

Circadian rhythms of feeding, oviposition, and emergence of the boll weevil （Coleoptera： Curculionidae）

Circadian rhythm of feeding, oviposition, and emergence of boll weevil adults were determined at five different photophases （24, 14, 12, 10, and 0 hours） and a constant 27℃ temperature, 65% RH in the laboratory. Squares from Petri dishes, where they were exposed to boll weevil females, were removed and examined for feeding and oviposition punctures every 4 hours during daylight （0700-1900 h） and every 12 h at night （1900-0700 h） over eight consecutive days. Cohorts of randomly selected egg-punctured squares were sampled from ovipositing females at 0700, 1100, 1500, and 1900 during 24 hours and under different photophase treatments, and maintained in Petri dishes at 27 ＋ I℃, 65% RH. Dishes were observed twice daily （1900 and 0700 h） for adults emerging at day or night. Circadian rhythm of oviposition was not affected by the length of the photophase. The boll weevil has round-the-clock circadian rhythm of oviposition, with a daytime preference. We observed that 82.4%-86.0% of the boll weevil eggs were deposited between 0700 and 1900 h, and 14.0%-17.6% between 1900 and 0700 h during a 24-h period. Feeding of boll weevil females in photoperiods 24：0 h （complete light） and 0：24 h （complete darkness） did not significantly change between 0700-1900 h versus 1900-0700 h, while the d .ally cycle of light and darkness in other photoperiods significantly increased the feeding punctures from 0700-1900 compared with 1900-0700 h. The circadian rhythm of emergence depended significantly on the time of oviposition and the length of the photophase. Investigation of boll weevil circadian rhythm provides a better understanding of boll weevil ecology and reveals potential weak links for improving control technologies targeting their reproductive strategies.     

竹象鼻虫生活史的观察

竹象鼻虫主要分布于竹产区,是我国主要的竹类害虫。通过野外观察和实验室培养探究竹象鼻虫的生活史。竹象鼻虫的发育过程经历卵、幼虫、蛹、成虫4个时期,幼虫蛀食竹笋,使竹笋枯死,成虫土茧内越冬,次年4月底至5月初出笋旺盛期出土蛀食竹笋。幼虫的形态结构和习性与成虫显著不同,属于典型的变态发育。     

Distribution of the related weevil species Sitophilus oryzae and S. zeamais in Brazil

The genus Sitophilus （Coleoptera： Curculionidae） encompasses species of great economic importance as stored grain pests worldwide. Among these species, the maize and the rice weevils （Sitophilus zeamais and Sitophilus oryzae, respectively） are partic- ularly important in warmer climates. These two weevils exhibit closely morphological and ecological resemblance making difficult their proper identification and recognition of their distribution in grain-producing regions. Both species are recorded in South America and particularly in Brazil, but their respective distribution and prevalence were not yet assessed in the region. Therefore, several insect samples throughout Brazil were collected and subjected to morphological identification using male genitalia and also using molec- ular identification with species-specific primers designed for clear recognition of both the species. The primers were designed for the specific amplification of a gene fragment of the cytochrome oxidase subunit I, which exhibited high specificity during our prelimi- nary experiments with insects from six populations of known species （either S. zeamais or S. oryzae）. Both identification strategies provided the same results indicating preva- lence of the maize weevil S. zeamais throughout the country. Two hypotheses may explain such prevalence： （i） the likely host preference ofS. zeamais for maize because this is the most cultivated cereal in Brazil, and （ii） the prevalence ofS. zeamais in tropical regions as compared with S. oryzae, which is more disseminated in subtropical and temperate regions.