The labial gland system of larvae of the imported fire ant,Solenopsis invicta Buren

Summary The authors describe the ultrastructure of the labial gland system in imported fire ant larvae, Solenopsis invicta Buren and present an enzyme analysis of enzymes in labial-gland secretions and midgut contents. The tubes of the labial gland produce and secrete a proteinaceous substance rich in digestive enzymes. The narrow cells of the reservoir of the gland have little or no secretory function but the lumen stores the proteinaceous secretion. The labial-gland enzymes include proteases and amylases, which function in extraintestinal digestion of solid food placed on the anteroventral body region of 4th-instar larvae by adult workers. The midgut contains proteases, amylases, and upases. Lipids appear to be predigested by the workers before being fed to the larvae.Approved as TA 15262 by the Director of the Texas Agricultural Experiment Station in cooperation with ARS/USDA. Supported by the Texas Department of Agriculure interagency agreement IAC-0487 (78-79)We would like to thank Rosemary Kamas, Dr. John Mirenda, and Mike Strand for their help in dissections of larvae and Dr. Howard Williams for his advice and suggestions     

Culture-independent identification of gut bacteria in fourth-instar red imported fire ant, Solenopsis invicta Buren, larvae

Red imported fire ants (RIFA), Solenopsis invicta Buren, are medical, urban, and agricultural pests from South America. They are successful invaders due to their preference for disturbed habitats, high reproductive rates, and the ability to feed on a wide variety of food items (omnivorous). Fourth-instar larvae are used by the colony to digest solid food and then regurgitate it for consumption by workers and queens. Larvae are an ideal source of investigations of endosymbiotic bacteria possibly involved in nutrient distributions. Our study utilized 16S rDNA sequencing to describe the composition of the bacterial community in fourth-instar ant larvae in order to identify possible endosymbiotic bacteria present therein. The 16S rRNA gene was directly amplified from mixed-population DNA of whole fire ant larval guts and cloned into Escherichia coli. Bacterial communities from three geographically separated RIFA colonies were examined. Sequenced bacterial clones from guts were determined to be predominantly from the phylum Proteobacteria and the family Enterobacteriaceae. Our results did not detect the presence of endosymbiotic bacteria in the guts of RIFA larvae among the colonies. In addition, minimal species overlap was found when bacterial inventories were compared among colonies. Thus, bacteria coadapted with red imported fire ant larvae were not detected. Identified bacteria were not closely affiliated with endosymbiotic bacteria common in other insect species. Bacteria communities appeared to be unique to each geographical location and were determined by the foods consumed by the ants.     

Genome complexity and organization in the red imported fire ant Solenopsis invicta Buren

The red imported fire ant Solenopsis invicta is the most destructive invading arthropod in the southern United States, yet little is known about its genome complexity and organization. Here we report the size, organization and GC content of S. invicta genome. DNA reassociation kinetics using S1 nuclease assay and a modified second-order kinetics model indicated that the S. invicta genome is approximately 0.62 picograms or 5.91 x 10(8) base pairs, composed of 36% unique, 41% moderately repetitive and 23% highly repetitive/foldback sequences. Comparison of the reassociation kinetics of short and long DNA fragments revealed that the sequence arrangement follows a pattern of short period interspersion, as in most organisms with relatively large genomes. Melting-temperature analysis showed that the GC content of the fire ant genomic DNA is 34.8%, similar to that of most eukaryotic organisms. The results reveal that the fire ant genome is much larger and more complex than those of a number of hymenopteran insects studied to date. Our study provides a foundation for further analysis and genetic manipulation of the S. invicta genome.     

Revisiting the trail pheromone components of the red imported fire ant,Solenopsis invicta Buren

Ants use species-specific trail pheromones to coordinate their sophisticated foraging behavior. During the past decades, many trail pheromone components with various structures have been identified in ants, including the red imported fire ant, Solenopsis invicta, a notorious invasive species worldwide. Four compounds, Z,E- (ZEF) and E,E-α-farnesene (EEF), Z,E- (ZEHF) and E,E-α-homofarnesene (EEHF), have been reported as components of S. invicta trail pheromone. However, another study reported an analog of α-farnesene, Z,Z,Z-allofarnesene, as a key trail pheromone component. These contrasting results caused some uncertainty about the trail pheromone composition in S. invicta. In this study, we synthesized ZEF and EEF, ZEHF and EEHF, and reanalyzed the chemicals in the Dufour gland extract and in the trail pheromone fraction of S. invicta worker body extract. The reported isomers of farnesene and homofarnesene were detected and showed trail-following activity, with ZEF as the major compound, while no allofarnesene was found, neither in the Dufour gland extract nor in the whole-body extract. Our results confirm ZEF and EEF, ZEHF and EEHF as trail pheromone components of S. invicta.     

红火蚁雌蚁生殖发育的研究

通过解剖多后型红火蚁Solenopsis invicta Buren雌蛹、有翅雌蚁和脱翅雌蚁,观察了雌蚁内生殖系统的结构和发育进度。结果表明,多后型雌蚁内生殖系统形成于蛹期,其结构与单后型雌蚁存在一定差异。从发育进度来看,虽然雌蚁羽化后其卵巢大小和卵巢管数量仍有一定增长,但蛹期是卵巢大小、卵巢管数量快速增长的阶段;卵子发生始见于羽化后第4d,且卵量随个体发育而快速增加,直至脱翅后第10d达到高峰,随后开始下降;生殖系统的其它结构的变化较小。雌蛹、有翅雌蚁和脱翅雌蚁发育后期的卵巢平均大小分别为1149．23×712．42、1594．88×834．26和1975．60×1303．57μm;而卵巢管数量则分别为62．67、81．33和86．33条。至雌蚁脱翅后10d,卵巢中成熟卵和总卵量分别为20．00±4．62粒和34．00±2．31粒。     

中国红火蚁入侵扩散、防控及对策

红火蚁Solenopsis invicta Buren是全球百种最具危险性的外来入侵物种之一,被列为我国农业、林业和进境植物检疫性有害生物。红火蚁入侵我国初期,发生区域数量少、面积小,制定了相应的应急防控和根除策略。随着该蚁在我国呈现扩散加快、多区域多生境发生、多途径扩散等新态势新特点,其防控策略转向“老疫区常态治理、新疫区力争根除”。为了更好地防控红火蚁,未来工作应从部门协作、队伍建设、综合治理、检疫监管和宣传培训等多个方面加强。     

Characteristics of 11 polymorphic microsatellite markers in the red imported fire ant, Solenopsis invicta Buren

We have characterized 11 polymorphic microsatellite loci in the invasive ant Solenopsis invicta. Primer pairs were evaluated on fire ants collected from monogyne mounds in Lauderdale County, Mississippi. The observed and effective number of alleles ranged from two to six and from 1.31 to 2.64, respectively. The observed and expected heterozygosity values ranged from 0.1613 to 0.7826 and from 0.1491 to 0.6242, respectively. The polymorphism information content of the microsatellites ranged from 0.1482 to 0.6208. Probability tests indicated significant deviations from the Hardy-Weinberg equilibrium at three loci. Pairwise tests did not detect linkage disequilibrium between any pair of loci.     

四种毒饵对红火蚁的田间防治效果评价

采用工蚁诱测法和挖巢观察法评价了4种国产毒饵对红火蚁Solenopsis invicta的田间防治效果。结果表明,氟虫胺、胺菊酯、苯氧威、多杀霉素4种毒饵处理后,红火蚁工蚁诱集百分率均明显降低,处理5d后氟虫胺、胺菊酯的工蚁诱集率为0,而多杀霉素处理10d后诱集率为0。施药后25d4种毒饵处理活动蚁巢减退率分别为100％、100％、50％和71．4％,工蚁减退率分别为100％、100％、92．7％和100％。处理6周后蚁群级别分别降低了100％、100％、83．3％、73．0％。     

Flight energetics and dispersal capability of the fire ant, Solenopsis invicta Buren

Experiments were conducted to estimate the flight capabilities of fire ant (Solenopsis invicta Buren) alates. These experiments were designed to: (1) quantify energetic expenditure during fixed flight; (2) characterize metabolic substrates of male and female alates; (3) estimate flight speed of male and female alates; and (4) quantify wingbeat frequency and water loss of females during flight. Flying males (in closed-system respirometry) increased metabolic rate approximately 38.4-fold over resting rate. Females increased metabolic rate approximately 51-fold (closed-system respirometry) and 48-fold (flow-through respirometry) over resting rate. Female alates had a mean respiratory quotient (RQ) of 0.999, indicating reliance on carbohydrates. The mean RQ of males was significantly lower (0.867). The flight speed of females on a circular flight mill averaged approximately 0.7 m s(-1), and increased with temperature but decreased with increasing body mass. The flight speed of males was 43% greater (approximately 1.0 m s(-1)) and increased linearly with temperature and increasing body mass. Female alates lost an average of 1.8 mg water h(-1) during flight. A simple energetics model, combined with previous work on the nutrient content of S. invicta and patterns of CO(2) release observed in this study, indicate that the flight capability of S. invicta female alates is limited to <5 km in the absence of wind.     

Infection characteristics of Solenopsis invicta virus 2 in the red imported fire ant, Solenopsis invicta

Solenopsis invicta virus 2 (SINV-2) is the second virus identified from the fire ant, S. invicta Buren. SINV-2 is unique among positive-strand RNA viruses from insects by possessing four cistrons in a monopartite genome. Fire ant colonies testing positive for SINV-2 by RT-PCR did not exhibit any discernable symptoms. RT-PCR-based surveys for SINV-2 among 688 fire ant mounds in Alachua County, Florida, sampled during the period January, 2006 through December, 2007 showed that the prevalence of SINV-2 among nests ranged from 1.6% to 16.4%. Unlike S. invicta virus 1, no seasonal-associated prevalence was observed with regard to SINV-2 infection among fire ant colonies. No social form specificity was evident; SINV-2 was found in both monogyne and polygyne S. invicta ants. Real-time quantitative PCR experiments showed that SINV-2 genome equivalents per individual ant ranged from 1.9 × 10⁷ in. pupae to 4.3 × 10¹¹ in. inseminated queens. The SINV-2 infection was detected in all ant stages examined (eggs, larvae, pupae, workers, and queens). Tissue tropism studies indicated that the alimentary canal (specifically the midgut) is most likely the susceptible tissue. SINV-2 was successfully transmitted to uninfected S. invicta ants by feeding a partially purified homogenate of SINV-2-infected ants. The SINV-2 transmission rate ranged from 30% to 80%, and both positive (genomic) and negative (replicative) SINV-2 RNA strands accumulated in recipient ants over the course of the experiment. These results indicated that SINV-2 replicates within S. invicta.     

寄生红火蚁的蚤蝇类群野外监测新技术

通过试验研究,设计出了3个适于监测、收集红火蚁Solenopsis invicta Buren天敌-蚤蝇Pseudacteon的诱集器,并提出了该诱集器的制作和野外设置的技术要求.测试了野外该诱集器对蚤蝇的监测、收集效果,证实该装置是可行的和实用的.     

我国大陆红火蚁入侵扩张趋势长期预测

红火蚁Solenopsis invicta Buren是一种严重危害农林业生产、生命健康、公共安全和生态环境的国际性重大外来入侵害虫。2004年9月中国大陆首次发现红火蚁,2021年12月该蚁已入侵了12个省区近500个县区。本研究根据中国大陆红火蚁入侵发生县区数量变化,结合潜在适生区域评价信息,建立了红火蚁入侵县区数量与入侵时间长度间关系模型,并对入侵县区数量变化趋势作出长期预测。当中国大陆红火蚁潜在入侵县区数量上限分别为1 400、1 500和1 600个时,入侵县区数量与入侵时间长度关系模型分别为N=1400/(1+e^{5.4048-0.1784T})、N=1500/(1+e^{5.4335-0.1757T})和N=1600/(1+e^{5.464-0.1734T})。基于以上模型的分析结果显示,我国红火蚁快速扩散传播从2009-2010年开始,快速扩张期可能持续26～28年,年平均新增县区41～52个/年,预测2035-2037年入侵县区数量增长速率将开始减缓,2...     

红火蚁不同品级个体的药剂敏感性研究

【目的】红火蚁Solenopsis invicta Buren不同品级的个体在群体生存中担负不同的功能。然而,红火蚁群体中不同品级个体的药剂敏感性还不清楚。【方法】本文采用点滴法测定了氟虫腈、高效氯氰菊酯和茚虫威三类不同药剂对红火蚁各品级个体的触杀毒力,以了解其药剂敏感性。【结果】研究结果显示,红火蚁对不同药剂的敏感性存在显著差异,对氟虫腈最为敏感,高效氯氰菊酯次之,而对茚虫威的敏感性最低,但不同品级个体的药剂敏感性规律却基本一致。有翅雌蚁、有翅雄蚁和蚁后的药剂敏感性最高,3个品级个体的药剂敏感性没有显著差异;除高效氯氰菊酯外,兵蚁的敏感性显著低于有翅蚁和蚁后,而工蚁又显著低于兵蚁。4龄幼蚁对供试的3种杀虫剂的敏感性非常低,致死中量分别为428.77 mg/kg、699.77 mg/kg和1 159.95 mg/kg,比对有翅雌蚁的致死中量高数百至数千倍。对毒力线斜率值的分析发现,同一品级内个体间对不同药剂的敏感性也存在显著差异,对氟虫腈的敏感性表现出品级内个体较大差异,特别是兵蚁和工蚁的敏感性差异最大,其斜率值分别为1.1和1.8,而对茚虫威的个体敏感性差异极小,其斜率值均≥4.7,且工蚁个体间表现出最高的同质性,其斜率值达7.8。【结论】同一品级的个体对不同药剂的敏感性差异没有一致规律,但基本上表现出个体差异较小的特点,特别是4龄幼蚁、有翅雄蚁和蚁后3个品级内个体的药剂敏感性差异较小,其斜率值均≥4.0。本研究的结果为田间防治红火蚁化学药剂的合理使用提供理论指导。     

溴甲烷对红火蚁的熏蒸效果研究

以广东口岸进口原木和废纸上携带的红火蚁Solenopsis invicta Buren为杀灭对象,测定了溴甲烷对其的熏蒸效果.在空箱内分别按6.01、12.01、22.52、25.53、28.53、31.53、34.53及37.54 g/m3的浓度投药;在实箱内分别按25.53、28.53及31.53 g/m3的浓度投...