Detection of Leishmania amazonensis and Leishmania braziliensis in Culicoides (Diptera,Ceratopogonidae) in an endemic area of cutaneous leishmaniasis in the Brazilian Amazonia

Biting midges in the genus Culicoides act as vectors of arboviruses throughout the world and as vectors of filariasis in Latin America, the Caribbean, and parts of Africa. Although Culicoides spp. are currently not considered to be vectors of Leishmania protozoa, the high abundance of biting midges in areas with active cutaneous leishmaniasis transmission points to the possibility of Culicoides infection by these pathogens. We used PCR to test captured Culicoides species for natural infection with Leishmania spp. We tested 450 Culicoides females, divided into 30 pools of 15 individuals each, as follows: nine pools of C. foxi (135 specimens), seven pools of C. filariferus (105), seven pools of C. insignis (105), five pools of C. ignacioi (75), and two pools of C. flavivenula (30). PCR confirmed the presence of Leishmania braziliensis DNA in C. ignacioi (0.14%), C. insignis (0.14%), and C. foxi (0.11); and Le. amazonensis DNA in C. filariferus (0.14%) and C. flavivenula (0.50%). We conclude that these Culicoides species can be naturally infected, but vector competence and transmission capability must be confirmed in future studies. Our results warrant further investigation into the role of these biting midge species in the leishmaniasis epidemiological cycle.     

Exposure to stable flies reduces spatial learning in mice: involvement of endogenous opioid systems

Abstract. Biting flies influence both the physiology and behaviour of domestic and wild animals. This study demonstrates that relatively brief (60min) exposure to stable flies, Stomoxys calcitrans (L.), affects the spatial abilities of male mice. Stable fly exposure resulted in poorer subsequent performance in a water maze task in which individual mice had to learn the spatial location of a submerged hidden platform using extramaze visual cues. Determinations of spatial acquisition and retention were made with mice that had been previously exposed for 60min to either stable flies or house flies, Musca domestica (L.). Mice exposed to stable flies displayed over one day of testing (six blocks or sets of four trials) significantly poorer acquisition and retention of the water maze task than either mice that had been exposed to house flies or fly-naive mice. This attenuation of spatial learning occurred in the absence of any evident sensorimotor or motivational impairments. The reduction in spatial abilites involved endogenous opioid systems, as the decreased performance resulting from stable fly exposure was blocked by pre-treatment with the prototypic opiate antagonist, naltrexone. These results indicate that relatively brief exposure to biting flies can lead to a decrease in spatial abilities which is associated with enhanced endogenous opioid activity. These results support the involvement of endogenous opioid systems in the mediation of the behavioural and physiological effects of biting fly exposure. They further suggest that decreases in spatial abilities and performance may be part of the behavioural consequences of biting fly exposure in domestic and wild animals.     

Two new species of Torymus Dalman, 1820 (Hymenoptera: Torymidae) parasitizing Celticecis japonica Yukawa and Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan

Torymus celticolus Matsuo sp. nov. and Torymus celtidigalla Matsuo sp. nov. (Hymenoptera: Torymidae) are described as parasitoids of larvae of Celticecis japonica Yukawa & Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan. A key to species of the genus Torymus known in Japan is provided.     

Seasonal and diel patterns of biting midges (Ceratopogonidae) and mosquitoes (Culicidae) on the Parris Island Marine Corps Recruit Depot

The Marine Corps Recruit Depot on Parris Island, SC, is surrounded by tidal salt marshes, which are breeding habitats for many pestiferous biting flies. Knowledge of biting fly behavior patterns is needed to develop effective pest management strategies in urban areas adjacent to salt marshes. We measured biting midge (Ceratopogonidae) and mosquito (Culicidae) seasonal abundance and diel activity patterns on Parris Island using CO₂‐baited suction traps from November 2001 – November 2004. Of the three biting midge species collected, Culicoides furens was most abundant (86.2% of total) and was present in high numbers from late March to November. Culicoides hollensis (12.0% of total) was present during spring and fall but absent in summer and winter; and Culicoides melleus (1.7% of total) was present in spring through fall but absent in winter. Abundance of C. furens had a positive linear correlation with air temperature and rainfall. There were nonlinear correlations between air temperature and C. hollensis and C. melleus numbers, which were most abundant at moderate temperatures. Of 18 mosquito species collected, the most abundant were Aedes taeniorhynchus (42.7% of total), Aedes sollicitans (26.3% of total), Culex salinarius (15.6% of total), Culex quinquefasciatus (7.3% of total), and Aedes vexans (5.7% of total); other species comprised <5% of collections. Aedes taeniorhynchus numbers were positively correlated with temperature and rainfall, and Cx. salinarius was correlated with soil moisture. Activity of most biting midges and mosquitoes were highest the first two hours following sunset. Species of biting flies were present in all months, suggesting that year‐round control measures are necessary to reduce exposure to potential disease vectors and nuisance biting.     

Genetic structure and population dynamics of the biting midges Culicoides obsoletus and Culicoides scoticus: implications for the transmission and maintenance of bluetongue

Culicoides species belonging to the Obsoletus complex (Diptera: Ceratopogonidae) have been indicated as primary bluetongue (BT) vectors in many European countries and their possible involvement in the maintenance and overwintering of BT viruses has been suggested, even in regions where Culicoides imicola Keiffer is the main vector. The Obsoletus complex includes two predominant taxa, Culicoides obsoletus (Meigen) and Culicoides scoticus Downes & Kettle. However, the role played by each species in the epidemiology of BT is still unknown. Taxonomic identification is mainly based on the morphology of male genitalia and the lack of other reliable diagnostic features makes the screening of trap‐collected vector populations, mainly females, particularly difficult. Although molecular markers have facilitated species identification, little information is yet available on the biology, abundance and population dynamics of the two taxa. The aim of this work was to investigate the genetic profile and temporal distribution of C. obsoletus and C. scoticus by using isozyme electrophoresis applied to adult midges, collected weekly at two selected farms in southern Sardinia. A total of nine enzyme loci were analysed and five of them provided diagnostic allozyme markers (Hk, Mdh, Pgi, Idh‐1 and Idh‐2). Nei's genetic distance between the two taxa was in the range of other well‐separated taxa (D = 1.792), supporting their status as true species. Culicoides scoticus represented almost 61% of the 562 specimens analysed; its genetic structure was characterized by a very low level of intra‐population variation (mean heterozygosity H_e = 0.019) and higher genetic divergence between populations (F_ST = 0.0016) than in C. obsoletus. The latter species had significantly more heterozygotes (H_e = 0.123), a higher percentage of polymorphic loci, and no inter‐population differentiation (F_ST?0). We suggest that different biological and ecological constraints, such as breeding habitat requirements, may contribute to shaping the genetic profiles of C. scoticus and C. obsoletus. However, enough gene flow was maintained between populations of each species as no spatial and temporal structuring was sustained by Fisher's exact probability test (P > 0.5). The seasonal distributions of C. scoticus and C. obsoletus only partially overlapped: both species were mainly found early in the year, when the main vector, C. imicola, was present in low numbers, and peaked in abundance in April and May. Culicoides scoticus was predominant until May, decreased rapidly in the following months and increased again in winter, whereas C. obsoletus decreased more slowly and was still present in early summer. Consequently, C. scoticus may be a good candidate for playing a role in the transmission and maintenance of BT virus in Sardinia, as well as in other Mediterranean countries, during the months of late winter and early spring when the seroconversion of sentinel animals is still occurring in the absence of the main vector.     

Biting of anthropophilic Culicoides fulvithorax (Diptera: Ceratopogonidae), a vector of Mansonella perstans in Nigeria

Anthropophilic Culicoides were investigated in a rural community endemic for Mansonella perstans in Ijebu North area of western Nigeria between December 2003 and October 2004. Three hundred and fifty-nine adults of Culicoides fulvithorax collected by human bait in the morning were dissected for Mansonella perstans larvae, and 1.95% of infection rate was found. Seasonal abundance of C. fulvithorax was investigated by monthly biting rates, and showed that higher prevalence was observed in rainy season, with peak in September. Culicoides prevalence was positively correlated with rainfall and relative humidity, but not temperature. Human perceptions on the behavior of these biting midges were determined by interviewing 854 self-selected villagers, of which 86.5% of the interviewees confessed having experienced Culicoides bites. Between 76.5 and 99.1% of the various age groups complained body reactions to Culicoides bites. Itching was the most frequent body reaction. No interviewees associated Culicoides with transmission of any parasitic infections. The results showed need to adequately control Culicoides in the community.     

Occurrence of immature Culicoides molestus (Skuse) (Diptera: Ceratopogonidae) in relation to habitat characteristics

Abstract Analysis of beach sites on the Gold Coast, Australia, found that 14 physical and chemical habitat characteristics differed significantly between sites where numerous immatures of the canal biting midge, Culicoides molestus (Skuse), were found and sites where no midge immatures occurred. Five of the chemical factors found to reliably distinguish C. molestus habitat are major components of seawater, while another, electrical conductivity, is related to the concentration of seawater components. Calcium was the only one of the six primary components of seawater that was not a statistically significant correlate of C. molestus habitation by sand analysis. It is likely that a causative variable in occurrence of immatures is the concentration of seawater present in canals, because larvae are found where seawater component concentration is low in relation to uninhabited sites of similar appearance.     

In situ occurrence of a gall midge (Insecta,Diptera, Cecidomyiidae) on fossilized angiosperm leaf cuticle fragments from the Pliocene sediments of eastern India

In situ preservation of fossil insect damage in plant fossils is an excellent tool to study the coevolution of flora and fauna through geological time, but finding both damage and the insect causing that damage in the same specimen is a very rare phenomenon. Galling is a common form of angiosperm leaf damage, which can be regarded as a kind of extended phenotype of the causal insects, essentially the gall midges, but galls usually lack remains of the insects themselves. Here we report the in situ occurrence of a gall midge (Insecta, Diptera, Cecidomyiidae) as well as its pupal exuviae on the abaxial cuticular surface of fossilized leaf cuticle fragments of Fabaceae leaves (cf. Albizia) that also bear galls, recovered from the latest Neogene (Rajdanda Formation, Pliocene) sediments of the Chotonagpur Plateau, Jharkhand, northeastern India. This Pliocene gall midge features well-preserved legs, segmented antenna with distinct and enlarged scape, elongate curved setae, and longer than broad terminal plate of the ovipositor lamellae. The in situ presence of a gall midge on a host fabaceous leaf cuticle indicates the existence of a host-ectoparasite relationship in the ancient warm and humid tropical monsoon-influenced forests of eastern India during the Pliocene. This is the first authentic fossil record of an in situ phytophagous insect of Cecidomyiidae from India, as well as southeast Asia. Although the identification of the recovered phytophagous insect associated with the fossil leaf cuticle is only possible to family level, this find reveals that such plant-insect relationships existed in the Pliocene of eastern India.