Effect of Zinc Sulfate against the Red Palm Weevil Rhynchophorus ferrugineus with Reference to Their Histological Changes on the Larval Midgut and Adult Reproductive System

The red palm weevil Rhynchophorusferrugineus is the most important insect pest for the date palm trees in the Middle East and Gulf states. Zinc sulfate （ZnSOa＇H20） was toxicologically, biologically and physiologically evaluated as insect development disruptors against the RPW. LCs0 of Zinc sulfate against 10 days old larvae was 0.566%, 3% concentration inhibited the larvae from feeding. LCs0 concentration of zinc sulfate solution was capable to disrupting growth, development and reproduction of R. ferrugineus. Growth and development disruptions are resulted from larval feeding on the treated diet that causing percentage of mortality rate, retardation in larval and pupal duration, percentage of pupation, adults emergence, reduction in deposited eggs that laid by the resulting adults and in the egg fertility. The study further reveals that Zinc sulfate effects on histological structure of epithelial cells of the larval midgut including separation and elongation of their cells, rupture in the peritrophic membrane and in some microvilli and some degeneration of the surrounding muscles. Histological changes also was observed on the adults ovary, in this way, disrupt female gamete production through their action on the accumulation of yolk granules （vitellogenesis） and follicular epithelial cells. Disruption of male gamete production was detected by disorganized of testicular cysts and depopulation of these cysts in addition to degeneration in germ cells. Zinc sulfate may be used among other control methods by injection into the tree trunk or as fertilizer around the tree roots which in turn may have an indirect effect for controlling the RPW.

Red Palm Weevil, Rhynchophorus ferrugineus （Olivier）： Economic Importance, Biology, Biogeography and Integrated Pest Management

The Red Palm Weevil （RPW）, Rhynchophorus ferrugineus （Olivier）, （Coleoptera, Curculionidae, Rhynchophorinae）, is an invasive species that is originated from Southeast Asia. It has.invaded Middle East and several countries of the Mediterranean Basin during the last three decades where it attacks palm trees. During the last three decades, multiple introductions of RPW to the Middle East, Europe and Caribbean （Island of Curacao, Netherland Antilles）, Lebanon and United States of America （Laguna Beach, Orange County, California） （USA） have occurred and the RPW is now a serious pest of many palm species. Duration of all life parameters varies significantly where the entire life cycle takes about 45 to 298 days. Different artificial diets were developed and were tested for mass rearing of RPW. Control of RPW is difficult due to the concealed nature of the life cycle of the pest. Integrated Pest Management （IPM） strategy has been applied successfully to deal with RPW problem. The IPM strategy consists of various preventive and curative methods; those methods were categorized in nine categories in this review. The main objective of this work was to review the existing knowledge on RPW＇s different aspects, with an ultimate aim of revealing the actual situation of the research on RPW.

Genetic Comparison among Rhynchophorus ferrugineus and Four Rhynchophorus Species

Genetic comparison between Rhynchophorus ferrugineus （Coleoptera： Curculionidae： Rhynchophorinae） and other four Rhynchophorus spp. such as R. bilineatus, R. phoenicis, R. cruentatus and R. palmarum was investigated using partial sequences of Cytochrome c oxidase subunit I （COl） mitochondrial gene. The number ofpolymorphic sites ranged from 79 to 102 while the genetic distances ranged from 0.058 to 0.095. The number of polymorphic sites, genetic distances and phylogenetic relationships among R. ferrugineus and the other four tested species revealed that R.ferrugineus was more closely related to R. bilineatus while it was distantly related to R. palmarum. It is possible to rank the five tested species as follows： R.ferrugineus, R. bilineatus, R. phoenicis, R. cruentatus and R. palmarum. The result of this study is the first step of the revision of the uncertain taxonomic status and phylogenetic relationships among the Rhynchophorus genus. Further analysis should be performed using other Rhynchophorus species as well as other molecular markers.

上海地区红棕象甲的耐寒性研究

红棕象甲Rhynchophorus ferrugineus(Olivier)是我国危害棕榈科植物的重要入侵害虫,为探明其越冬抗寒性,利用过冷却点测定仪测定了红棕象甲上海种群不同虫态的过冷却点,在低温箱内测定了该虫不同虫态的耐寒性,然后结合田间越冬模拟试验、气象资料和寄主分布情况,初步确定了红棕象甲在我国的越冬北界。结果表明:红棕象甲过冷却点随虫态的发育程度的升高而下降,卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫的平均过冷却点分别为-5.92,-6.42,-7.19,-7.43和-11.84℃,过冷却点由高到低的顺序依次为:卵>幼虫>成虫。在6,24,48和72h4个时间处理下,各虫态在低温与存活率之间呈显著或极显著的logistic回归,半致死温度(Ltemp50)均随处理时间的延长而上升,不同虫态在处理72h后,卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫之间的Ltemp50分别为1.61,-1.67,-2.39,-2.40和-0.40℃,各虫态耐寒性由弱到强的顺序依次为:卵<成虫<幼虫。红棕象甲不同发育阶段的过冷却点与其耐寒性并不完全相关,幼虫和成虫均可能是该虫的越冬虫态。连续两年的田间模拟越冬试验表明,在上海地区,红棕象甲的幼虫和成虫的越冬存活率均在60%以上,说明红棕象甲在上海地区是可以越冬的。根据这些结果,结合寄主分布情况,初步将红棕象甲在我国的越冬北界定于北纬35°附近,即1月份0℃等温线左右。

红棕象甲在中国的风险性分析

红棕象甲是我国林业检疫性害虫。运用国际植物检疫措施实施标准(ISPM)的有害生物风险分析(PRA)程序,建立红棕象甲传入风险分析评估模型,采用定性分析和多指标综合评估相结合的方法进行分析。结果显示,国内分布情况,风险值为2;潜在的经济危害性,风险值为2.4;寄主植物的经济重要性,风险值为3;传播扩散的可能性,风险值为1.89;风险管理难度,风险值为2.33。红棕象甲的综合风险性值为2.29,符合高风险检疫性害虫条件,在我国很多地区易定殖,对我国的棕榈科植物威胁很大。

红棕象甲生物防治研究进展

红棕象甲是我国棕榈科植物的重要外来入侵害虫,具有隐蔽钻蛀的危害特点,对其进行防治具有一定难度。在我国,对红棕象甲生物防治的研究还很少报道,为对我国红棕象甲的生物防治研究提供科学参考及建议,综述了昆虫病原线虫、昆虫病原真菌、昆虫病原细菌以及其他天敌对红棕象甲生物防治的研究进展。

入侵种红棕象甲棕榈种群的肠道菌及纤维素降解能力研究

新近发现重要检疫害虫红棕象甲转移为害本土棕榈树,严重威胁当地农林生态系统。“共生入侵”假说认为入侵害虫与其共生菌(尤其肠道微生物)存在共生关系,驱使着入侵扩散进程。据此,本次以红棕象甲棕榈种群肠道菌为研究对象,通过与原引入的加拿利海枣种群、人工饲料种群的肠道菌数量、组成对比,揭示红棕象甲新种群的肠道菌变化特征。并进一步以纤维素降解菌为检测对象,比较分析不同食源种群的纤维素降解菌功能群差异,及其降解能力。以营养琼脂培养基和羧甲基纤维素钠培养基培养,检查菌落生长,结果发现来自不同食源的红棕象甲肠道菌差异较大:(1)加拿利海枣种群肠道菌丰富度最高,而棕榈种群肠道菌丰富度相比下降了近50%;(2)棕榈种群肠道纤维素降解菌中,缺失一些强降解力菌株(如AM、BR、BS),导致其与加拿利海枣种群相比,降解能力明显下降。而通过形态、理化性状相似性比较,并基于16rDNA序列构建系统发育树,初步鉴定菌株AV(AM)、D(U)、BR分别为Bacillus cereus、Klebsiella variicola、Bacillus pumilus纤维素降解菌。除了食源外,红棕象甲肠道菌也因虫态不同而异,其中成虫肠道菌最丰富,其次为幼虫,而蛹期仅检测到少量菌株。以上结果说明,红棕象甲转移到本土棕榈树为害后,其定殖、建群可能需要经历一个比预期时间更长的适应期才可能稳定。预示红棕象甲侵入新区后,早期防控工作应重视跟踪监测与点上防治的结合,争取在其定殖瓶颈阶段将种群压到最低。