Seasonal prevalence and host-seeking of mosquitoes in southeastern Republic of Korea

Adult mosquito surveillance was conducted at two sites at Gijang-gun, Busan southeastern area of the Korean peninsula, in 2004. The most frequently collected species at cow sheds were Anopheles sinensis sensu lato (s.l.) (83.4%), followed by Culex tritaeniorhynchus Giles (8.2%), Culex pipiens Coquillett (5.6%) and Aedes albopictus (Skuse) (2.4%). Adult populations of An. sinensis s.l. peaked during July (Trap Index, TI 1043.1), declining in August (TI 659.4) and September (TI 462.9) in 2004, while Cx. tritaeniorhynchus populations increased in August (TI 77.5) and September (TI 35.9). Adult Cx. tritaeniorhynchus was first collected in the second week of May (TI 4.0) and increased through August with two population peaks in the third week of July (TI 98.0) and the second week of August (TI 99.5). Armigeres subalbatus (Coquillett) was the most frequently collected mosquito at human-landing collections (30.4%) followed by An. sinensis s.l. (28.6%) and members of the Cx. pipiens complex (19.3%). Anopheles sinensis s.l. demonstrated two peaks of host-seeking activity at 22.00–23.00 hours and 02.00–03.00 hours in July, while in August the host-seeking peaks appeared at 22.00–23.00 hours and 03.00–04.00 hours. The black light trap collections of An. sinensis and Cx. tritaeniorhynchus demonstrated significant correlations to the ambient temperatures.     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea, 2007

Adult mosquito surveillance was conducted using New Jersey light traps from 1 May to 15 October during 2007 at 14 US Army and three Air Force installations and two US Army training sites located in six provinces in the Republic of Korea to determine threshold levels to initiate pesticide applications based on trap indices. A total of 24 013 adult mosquitoes (19 763 [82.3%] females and 4250 [17.1%] males) comprising 16 species (including five members of the Anopheles Hyrcanus Group) and belonging to seven genera were collected. Females of the most commonly collected species were members of the Anopheles Hyrcanus Group (52.1%), followed by, Culex tritaeniorhynchus Giles (20.6%), Culex pipiens Coquillett (13.8%), and Aedes vexans nipponii (Theobald) (11.6%). Trap indices varied widely for species over their range, due in part, to geographical distribution and degree of association with urban or rural communities.     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea, 2006

Adult mosquito surveillance was conducted during 2006 at 22 US Army and Air Force installations and two training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps from 1 May through 15 October 2006 to determine threshold levels to initiate pesticide applications based on trap indices. In total 16 217 adult mosquitoes [13 612 (83.9%) females and 2605 (16.1%) males] comprising 16 species (including five members of the Anopheles sinensis Group) belonging to eight genera were collected. Females of the most commonly collected species were members of the Anopheles sinensis Wiedemann Group (58.9%), followed by Aedes vexans nipponii (Theobald) (21.3%), Culex tritaeniorhynchus Giles (11.8%) and Culex pipiens Coquillett (5.2%). Trap indices varied widely for species over their range, due in part, to their geographical distribution and degree of association with urban or rural communities.     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea, 2005

Adult mosquito surveillance was conducted during 2005 at 22 US military installations and two training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps from 1 May to 15 October to determine threshold levels to initiate pesticide applications based on trap indices. A total of 27 363 adult mosquitoes (22 368 [81.7%] females and 4995 [18.3%] males) comprising 15 species (including five members of the Anopheles sinensis group) belonging to seven genera were collected. The most common species collected were members of the Anopheles sinensis Wiedemann group (50.2%), followed by Culex tritaeniorhynchus Giles (30.6%), Aedes vexans nipponii (Theobald) (11.8%), and Culex pipiens Coquillett (6.3%) females. Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban or rural communities.     

Seasonal prevalence of third-stage larvae of Dirofilaria immitis in mosquitoes from Florida and Louisiana

Heads of 109,597 mosquitoes collected during 1996 and 1997 from Gainesville, Florida (1996, n = 39,131; 1997, = 34,209), Bartow, Florida (1996, n = 12,000; 1997, n = 12,000), and Baton Rouge, Louisiana (1996, n = 12,257) were tested by a polymerase chain reaction and Southern hybridization-based test for the presence of third-stage larvae of the canine heartworm Dirofilaria immitis. Mosquito heads were pooled (1-200 heads) by month, locality, and species for testing. The test used was species specific for D. immitis and was capable of detecting DNA from a single larva in a pool of 200 mosquito heads. Specificity for the third larval stage was achieved by probing only mosquito heads. One or more D. immitis-infected mosquito heads were detected in each month of the year from Barrow in both 1996 and 1997. No infected mosquito heads were detected from Gainesville or Baton Rouge in December, January, February, or March. These results are in general agreement with previous sentinel dog and model prediction studies that showed heartworm transmission in the warm temperate Gulf coast region of the United States to be seasonal rather than continuous as previously believed.     

Seasonal prevalence of mosquitoes, including vectors of Brugian filariasis, in southern islands of the Republic of Korea

A survey of mosquitoes, including the vector status of Brugia malayi filariasis and their relative larval density, was conducted from 2002 to 2005 at several southern remote islands of Jeollanam-do (province), Gyeongsangnam-do, and Jeju-do, Korea, where filariasis was previously endemic. Overall, a total of 9 species belonging to 7 genera were collected. Ochlerotatus togoi (formerly known as Aedes togoi), Anopheles (Hyrcanus) group, and Culex pipiens were the predominant species captured at all areas. Oc. togoi larvae were most frequently collected at salinity levels <0.5% during June and July, with densities decreasing sharply during the rainy season in August. The most likely explanation for the eradication of filariasis in these areas is suggested to be an aggressive treatment program executed during the 1970s and the 1990s. However, high prevalence of the vector mosquitoes may constitute a potential risk for reemerging of brugian filariasis in these areas.     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea in 2003

Surveillance of adult mosquitoes was conducted at 29 US military installations and training sites in six provinces in the Republic of Korea during 2003. Adult mosquitoes were collected in New Jersey light traps and dry ice‐baited New Jersey light traps from 1 May to 15 October. Mosquito surveillance was conducted to determine threshold levels to initiate pesticide applications and identify malaria infection rates at selected army installations and training sites. A total of 42 024 adult mosquitoes (32 594 females [77.6%] and 9430 males [22. 4%]) comprising 14 species and Anopheles sinensis s.l. (a complex of five species), representing seven genera, were collected. The most common species were members of the Anopheles sinensis Wiedemann complex (54.9%), followed by Aedes vexans nipponii (Theobald) (19.0%), Culex pipiens Coquillett (14.3%) and Culex tritaeniorhynchus Giles (10.6%). Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban communities.     

Seasonal prevalence of mosquitoes collected from light traps with notes on malaria in the Republic of Korea, 2004

Adult mosquito surveillance was conducted during 2004 at 29 US military installations and training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps and Magnet traps from 1 May through 15 October to determine threshold levels to initiate pesticide applications and to identify malaria infection rates at selected army installations and training sites. A total of 89 206 adults (78 454 [87.9%] females and 10 752 [12.1%] males) comprising 20 species (including five members of the Anopheles Hyrcanus Group) and belonging to seven genera were collected. The most common species collected were members of Culex tritaeniorhynchus Giles (49.4%) and Anopheles sinensis Wiedemann complex (39.1%), followed by Culex pipiens Coquillett (6.1%) and Aedes vexans nipponii (Theobald) (4.2%). Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban communities.     

Isolation of Sindbis (alphavirus) and Leanyer viruses from mosquitoes collected in the Northern Territory of Australia, 1974.

Mosquitoes collected near Darwin, Northern Territory, in 1974 yielded two virus strains. One was identified as Sindbis virus, not previously isolated from the Northern Territory. The other is antigenically distinct from viruses previously isolated from arthropods in Australia, and the name "Leanyer" is proposed for it. Its properties suggest that it may be a togavirus serologically unrelated to available alphaviruses and flaviviruses.     

Seasonal abundance of Culex annulirostris and other mosquitoes at Kowanyama, north Queensland, and Charleville, south west Queensland.

At Kowanyama, 104,006 adult female mosquitoes of a probable 47 species were collected on twelve occasions from April, 1972, to April, 1976. At Charleville, 71,791 adult females of 20 taxa were taken during thirteen periods from February, 1974, to February, 1976. Culex annulirostris was predominant at Kowanyama and especially at Charleville where it comprised up to 99% of dry season collections. Culex fatigans, Ae normanensis, An annulipes and, at Kowanyama only, An bancroftii were the other major species collected. Several bait trapping methods were suitable for monitoring densities of Cx annulirostris and other species but mammalian baits were best. Because Cx annulirostris activity continued throughout winter even at Charleville, continuous cycles of arbovirus transmission are possible, although the potential of dormant Aedes eggs also bears investigation as a method of arbovirus survival.     

Whale Shark (Rhincodon typus) Seasonal Presence,Residence Time and Habitat Use at Darwin Island,Galapagos Marine Reserve

The life history of the whale shark (Rhincodon typus), including its reproductive ecology, still remains largely unknown. Here, we present results from the first whale shark population study around Darwin Island, Galapagos Marine Reserve. Following a diversified approach we characterized seasonal occurrence, population structure and size, and described habitat use of whale sharks based on fine scale movements around the island. Whale shark presence at Darwin Island was negatively correlated with Sea Surface Temperature (SST), with highest abundance corresponding to a cool season between July and December over six years of monitoring. From 2011 to 2013 we photo-identified 82 whale sharks ranging from 4 to 13.1 m Total Length (TL). Size distribution was bimodal, with a great majority (91.5%) of adult female individuals averaging 11.35 m±0.12 m (TL±SE), all but one showing signs of a potential pregnancy. Population dynamics models for apparently pregnant sharks estimated the presence of 3.76±0.90 (mean ± SE) sharks in the study area per day with an individual residence time of 2.09±0.51 (mean ± SE) days. Movement patterns analysis of four apparently pregnant individuals tracked with acoustic tags at Darwin Island revealed an intense use of Darwin''s Arch, where no feeding or specific behavior has been recorded, together with periodic excursions around the island''s vicinity. Sharks showed a preference for intermediate depths (20–30 m) with occasional dives mostly to mid-water, remaining the majority of their time at water temperatures between 24–25°C. All of our results point to Darwin Island as an important stopover in a migration, possibly with reproductive purposes, rather than an aggregation site. Current studies carried out in this area to investigate regional scale movement patterns may provide essential information about possible pupping grounds for this enigmatic species.     

Seasonal distribution and species composition of daytime biting mosquitoes

Adults and immatures of Aedes mosquito populations were collected at temperatures between 40 and 44°C (summer), while larvae were collected at 0°C (winter). Major mosquito activities were observed from February to mid-December at various collection sites that yielded high populations of Aedes spp. from May to September, and high populations of Culex spp. and Anopheles spp. from March to September. In June to July, mosquito activity was suspended because the relative humidity was high (70%); a result of the monsoon rains. In August, with temperature ranging from 38 to 42°C, the populations of Culex , Anopheles and Aedes began to increase (36.8, 32.1 and 26.3%, respectively). Population estimates (through standard prototype Centers for Disease Control (CDC) and Biogents (BG)-sentinel) and species composition of Aedes in forest habitats indicated a rapid increase in the populations of Ae. albopictus (52.3%), Ae. aegypti (19.1%) and Ae. vittatus (28.5%) following the rainy season in July. Areas positive for Ae. albopictus had identical population levels and distribution ranges of Ae. vittatus , however, there were no Ae. aegypti in Ae. albopictus areas from August to September. The population level, seasonal distribution, habitat and areas of adult activity marked by global positioning system (GPS) coordinates are being used for reference and for species composition data of Anopheles spp. (2), Culex spp. (10) and Aedes spp. (5) in addition to associated temperature, relative humidity and physico-chemical factors of larval habitat. Global meteorological changes have caused an expansion of the active period, leading to the mosquito's possibility of being a vector of disease increasing, resulting in the spread of dengue fever.     

Seasonal distribution of pollen in the atmosphere of Darwin,tropical Australia: Preliminary results

Pollen loads in the atmosphere of Darwin, a city located in the wet‐dry tropics of Australia, have been monitored for the period March 2004 to November 2005 as part of a large research program looking at atmospheric particles and human health. Seven pollen types dominate the pollen spectrum, the herbaceous families of Poaceae (grasses) and Cyperaceae (sedges), as well as several native tree and shrub taxa, Acacia, Callitris, Casuarina, Arecaceae and Myrtaceae. The pollen loads were found to have a strong seasonal component associated with the alternating wet (November to March) and dry (April to October) seasons of the region. Seventy percent of the yearly pollen load is captured during the dry season, with the peak pollen period occurring at the onset of the dry season (April–May) when most grasses are in flower. The daily pollen concentration decreases as the dry season progresses, accompanied by a change in composition; fewer herbaceous but increasing woody taxa. Preliminary health outcomes reveal a positive association between hay fever, Poaceae and Acacia pollen, as well as a significant association between total fungal spore concentrations and asthma. The Darwin record contrasts significantly with surveys conducted in the subtropical and temperate cities of Australia where temperature as opposed to rainfall and the prevalence of northern hemisphere exotic tree species have a greater influence over the seasonality and composition of the pollen loads.     

福建东山短枝木麻黄小枝氮磷含量及其再吸收率季节动态

对福建东山赤山林场短枝木麻黄纯林小枝中的N和P含量、N ∶ P比、养分再吸收率的季节动态进行研究.结果表明,随着小枝的成熟和衰老,各季节N和P的含量依次降低,其中衰老小枝中N和P含量分别为(3.97±0.21)～(8.64±0.58) mg · g~(-1)和(0.04±0.03)～(0.10±0.03) mg · g~(-1),基本上表现为N和P的完全再吸收.成熟小枝N ∶ P比的季节动态介于(18.67±3.24)～(37.98±1.32)之间,均高于16,表明木麻黄的生长受到不同程度的P限制.N、P再吸收率的季节变化分别为(51.02±4.66)%～(63.00±8.61)%和(81.24 ±5.08)%～(91.78±5.84)%,P再吸收率显著高于N.N和P的再吸收率之间以及成熟叶中N、P含量与二者再吸收率之间没有显著相关性,但在衰老叶中存在显著负相关,表明养分再吸收程度越高,其再吸收率就越高.因此,木麻黄通过小枝衰老过程中的养分再吸收,减少养分的损失,从而适应贫瘠的立地条件.     

A comparison of adult mosquito trapping regimes across seasons and ecosystems in Darwin,Australia

Mosquitoes are problematic as vectors and pests in many tropical cities, including Darwin, the principal city in the Northern Territory of Australia. To monitor peaks in mosquito populations, the Medical Entomology unit of the Health Department sets overnight CO₂‐baited traps weekly. Trap setting and retrieving, followed by mosquito counting and identification, are labor intensive. Aiming to reduce this workload, we tested the hypothesis that fortnightly trapping is as effective as weekly trapping across seasons and ecologically distinct systems in Darwin. We applied cross‐sectional negative binomial mixed effects models, which adjusted for rain and calendar month, to existing historical data. Culex annulirostris peaks were effectively identified using fortnightly trapping across all three ecological systems, during wet/dry and build‐up seasonal patterns. For Aedes vigilax, fortnightly trapping was adequate in identifying peaks during wet and dry season months, but inadequate during build‐up months across all three ecological systems. Therefore, weekly trapping should continue during build‐up months, but trapping could be reduced to fortnightly for wet and dry season months for all ecological systems. Trapping for Cx. annulirostris monitoring could be reduced to fortnightly in all areas and seasons. Evaluation of programs can maximize staff efficiency and improve service delivery by reducing the need for unnecessary tasks.     

Numbers,species richness and equitability of coastal birds at Darwin,Northern Territory

Studies of the species richness and equitability were made of coastal birds at Darwin, Northern Territory, following censusing. A general decrease in numbers and species richness of indigneous and palaearctic migrants occurred in the wet season. Equitability values were depressed at the beginning of the wet season indicating an ecologically disturbed situation Freshwater discharge and its complex mixing patterns in neritic and estuarine water may be responsible for such a disturbance through its effects on the bird's food supply.     

Humboldt,Darwin, and population

Conclusions I have attempted to clarify some of the pathways in the development of Darwin's thinking. The foregoing examples of influence by no means include all that can be found by comparing Darwin's writings with Humboldt's. However, the above examples seem adequate to show the nature and extent of this influence. It now seems clear that Humboldt not only, as had been previously known, inspired Darwin to make a voyage of exploration, but also provided him with his basic orientation concerning how and what to observe and how to write about it. An important part of what Darwin assimilated from Humboldt was an appreciation of population analysis as a tool for assessing the state of societies and of the benefits and hardships which these societies can expect to receive from the living world around them.Darwin exhibited in his Journal of Researches a casual interest in the economic and political conditions of the countries he visited, but these considerations were much less important to him than to Humboldt. Instead, Darwin, with the assistance of Lyell's Principles of Geology, shifted from Humboldt's largely economic framework to a biological one built around the species question. This shift led Darwin away from a consideration of how the population biology of animals was related to man's economy to focus instead upon how population biology fitted into the economy of nature.Humboldt's Personal Narrative served very well as a model for Darwin's Journal of Researches, thereby helping Darwin gain scientific eminence. The Journal of Researches, like virtually all of Humboldt's writings, was a contribution to scientific orthodoxy. But Darwin had, along the way, acquired an urge to do more than just add his building blocks to the orthodox scientific edifice. He decided to rearrange those blocks of knowledge into a different structure, and for that task neither Humboldt's Personal Narrative nor any other of his works could serve as a model. Humboldt had lacked the confidence which Darwin needed that biogeography and the origin of species could be understood. Humboldt had not explored very far the possible connections between biology and geology. Nor had he provided a general synthetic account of population biology. Had he done so, he might have been more explicit about the extent of his endorsement of Malthus. But even if he had, Humboldt's strong orientation toward cooperation would probably have inhibited his recognition of the importance of competition in nature.Lyell, who had also benefited from reading Humboldt, gave Darwin insights that were lacking in Humboldt's Personal Narrative. Lyell admirably demonstrated how stratigraphy, paleontology, biogeography, and population biology could be interrelated, and his reasons for doing so were essentially the same as Darwin's. Lyell's understanding of biogeography and ecology came from the writings of Augustin-Pyramus de Candolle as much as from Humboldt's, and from the former Lyell derived an appreciation for the importance of competition and also a confidence that the mysteries of biogeography could be explained.¹¹⁷ Furthermore, Lyell's discussion of all these subjects and also of evolution in his Principles of Geology is a good synthetic argument that was the ideal model for Darwin's greatest book.Darwin, having become convinced that species change through time, was able to synthesize in his mind the contributions which he had derived from the writings of Humboldt and Lyell as they applied to the species question. When Darwin wrote his Journal of Researches there were two large gaps in his thinking about evolution that bothered him—the mechanism of evolution and the causes of extinction. It was only after reading Malthus in 1838 that he realized, as Lyell had more or less pointed out, how important was competition in nature. He now had the general outlines for his theory, and in the 1845 abridged edition of his Journal, now retitled The Voyage of the Beagle, he inserted a fuller discussion of competition in nature which showed his awareness of its importance as an ecological factor.¹¹⁸ An abridged version of this paper was presented at the meeting of the History of Science Society in Washington, D.C., on 29 December 1969.