In urban areas of Central and Northern regions of Italy, Aedes albopictus finds favourable conditions for its development, and a rapid spreading of the populations. Among the small peridomestic containers that are largely colonized by the species, underpots in gardens and balconies are very difficult to control with the conventional anti-larval campaigns. The toxic effect of copper is well known in agricultural field. Recent American and Italian studies have pointed out the toxic effect of metallic copper on Ae. albopictus larvae. In this experience we have studied the effect of metallic copper on the development of Ae. albopictus in order to ascertain its possible use as control agent in small artificial breeding sites. Tests have been carried out in a climatic chamber at 28+1 0C, 90% RII and with photoperiod of L:D 16:8, from Dec. 2nd, 94 to Apr. 28th, 95, using plastic underpots containing 500 ml of water and earthenware pot filed with peat. Evaporation of water was compensated daily. Two doses of metallic copper (multi-wire electric cable) were used: 4(A) and 8(B) g/l. For each dose 8 underpots were used plus 4 underpots as control. Forty 48 h old eggs, obtained from a colony, were placed into each underpot, larvae were fed with cat biscuit. Each unit was held in a gauze bag to prevent adult dispersion. Every 48h dead larvae were removed and larval stage checked; every 24h adults were collected. The experience has been replicated 3 times continuously using the same units to verify the persistence of toxic action. Every week 50 ml of water were sampled for chemical and microbiological analysis. Copper ion concentration increased during the first four weeks up to 424 mg/l and 565 mg/l for dose A and B respectively, then it fluctuated with a slight tendency to increase. Metallic copper had a strong inhibitory effect on the algal growth, though with no evident impact on the number of bacterial colonies. The average adults emergence obtained was 62.3% in the control, 14.0% in dose A, 3.96% in dose B. Linear relation between average copper concentration and adults production during single test was highly significative with R2 = 10.66, P<.00000. In the test with higher average copper concentration (647 mg/l) no adult was produced. Larval development, from egg immersion to adult emergence, was delayed by copper to 22.89 days in A; 26.51 days in B as compared to 13.6 days in control. Larval mortality was higher in the first and second stage. All the adults produced in the second test were dried at 50 0C for 24h and weighed. Adults weight was affected by copper concentration with a R2 = 0.77, P<.00000. The experience conducted in conditions that can be considered as a common situation shows a strong toxic effect of metallic copper on Ae. albopictus larval development. Considering the good persistence of its action, its practical use, its large availability, the low risk for human beings, metallic copper can be considered as an alternative agent for the control of Ae. albopictus in small artificial containers.
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After the first indication of September 1990, Aedes albopictus rapidly spread in Italy involving at the end of 1994 13 provinces in 9 regions. As no surveillance program has been organised on a national level usually the detection of new focuses results from complaints of the citizens; therefore it is very likely the actual number of infested areas has been undervalued. Although the role of used tyres trade in the diffusion of the species is well recognized both on international and national levels, tyres regulations have been adopted only locally and always after the arrival of the species. This mosquito shows high plasticity as it adapts very rapidly to new environment and climate conditions. After arriving in the Northern Italy regions Ae. albopictus exploited a variety of artificial containers, overwintered in the egg stage and the population grew very rapidly. Given the trend of diffusion, it seems unlikely we can succeed in stopping the spreading of the species without extraordinary effort. What is difficult to explain is the apparent restriction of Ae. albopictus to Italy and Albany despite the trade of used tyres between most of the Mediterranean countries. The Health Bureau of Emilia-Romagna Regional Administration in cooperation with the Institute of Entomology of the University of Bologna and the Center of Agriculture & Environment of Crevalcore started in 1995 an active surveillance program in accordance with the Istituto Superiore di Sanità. Local Health Units were required to organize during the winter 1994-95 a census of all the tyre trade companies and other activities potentially considered at risk of introduction. About 55 risky situations were surveyed and submitted to monitoring using ovitraps from May 15 to October 15. Secondary uses of old tyres such as safety barriers at motordromes, ballast for silo plastic cover in livestock farms represent another potential way of diffusion of the species and must be taken into consideration with appropriate measures. Control programs aimed at the maximum reduction of the infestation have been undertaken in three infested areas: Desenzano del Garda, Calderara di Reno-Bologna, 5. Giovanni in Persiceto. Data on 1995 activities will be presented.
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The nematode Dirofilaria immitis is widespread in vast areas of Northern Italy, where dogs constitute the main host. The diffusion of the parasite need the presence of a competent vector in which part of the larval cycle must be accomplished. Mosquitoes are considered the principal vectors but the role of different species in its epidemiology need to be clarified as well as the seasonal dynamic transmission. Considering that recent laboratory evidence seems to show the vector potentiality of Culex pipiens we organized this experience to collect field information on the seasonal development of D. immitis in the mosquito. In the dog-pound of the University of Modena, situated in the centre of town, 9 Beagle dogs were hosted, two of which were infected at a high microfilaremia level. The facility is normally infested by natural population of Cx. pipiens. Mosquito females were collected by means of a portable aspirator from June to December 1993 at weekly or biweekly intervals (in September a 4 week interval has been maintained). A total of 27 samples have been taken. Collected mosquitoes were kept separated according to the location of capture: A in the rooms of the infested dogs; B in the rooms of healthy dogs. Mosquitoes were left free to move inside and outside the dog-pound. When possible, samples of 50 females were collected. Mosquitoes were preserved at -20 0C and then observed under microscope for the presence of the parasite. Mosquitoes were disposed on the slide with a drop of physiological solution and squeezed under the cover slides. 2224 Cx. pipiens and 8 An. maculipennis were examined. 446 Cx. pipiens (20,05%) were found positive; out of these, 440 (98,65%) were infested with microfilariae, 3 (0.67%) with L1 larvae, 3 (0,67%) with L2 larvae, 0 with L3 larvae. 1 An. maculipennis was found with microfllariae. 346 positive mosquitoes were collected in location A, 101 in location B. Infested mosquitoes were found starting at the beginning of the study (June 10), its prevalence increased during July and remained high during August and September. The last infested mosquitoes were collected on October 27. A possible reason why no L3 larvae were found in mosquito females may have been the removal of blood-fed mosquitoes from the regular sampling activity before heartworm had time to reach L3 stage. This work received financial support from MURST 60% and Regione Emilia-Romagna.
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Aedes albopictus (Skuse), a medically significant mosquito, has originated in Southeast Asia (Smith, 1956) and has spread to the West: Madagascar, Hawaii, Mauritius, South Pacific (Hawley, 1988; Rai, 1991) and to the East through Indomalayan and Oriental regions, China and Japan (Ho et al., 1973; Tanaka et al., 1979). Ae. albopictus was introduced in 1980 in the United States and Brazil (Forattini, 1986; Sprenger and Wuithiranyagool, 1986). This species has a wide distribution in U.S., covering about 23 southern, southeastern and midwestern states. In Europe, only Albany and Italy are reported as infested countries. In Albany this species was discovered in 1987 (Adhami and Murati, 1987). In Italy Ae. albopictus was first detected in Genoa (Sabatini et al., 1990). Since then, other foci have been found. The National Institute of Health confirmed that in 1994 the presently established populations concern 7 regions, 6 in northern Italy and 1 in central Italy (Romi, 1994). We have studied the population genetics of Ae. albopictus collected in various Italian regions, using 17 genetic markers. The results obtained indicate that the samples are genetically quite similar. In fact, the mean genetic distance value (Nei, 1972) is D=0.022, although the range of Nei's D values varies from 0.004 (between Bologna and Vicenza) to 0.047 (between Pisa and Vicenza). The contribution of population partitioning to deviation from Hardy-Weinberg equilibrium, as revealed by F-statistics, resulted to be due to differences existing among samples more than to differences within the samples. The loci which mainly contributed to interpopulation diversity were Mdhp-1, Idh-1, 6Pgdh, Pgm, Acon-i and Gpi, because their allele frequencies were significantly different among the samples. Accordingly, it appears a limited gene exchange takes place among Italian populations, as evidenced by the Nm value: 1.50. Previous studies on colonising populations from U.S.A. and on populations from Southeast Asian native habitat of Ae. albopictus revealed an amount of local differentiation strictly related to the natural breeding structure of this species and not to the colonization event. Our data indicate that the genetic variability of Italian populations is comparable to that of Japanese, Indian, and Indonesian populations, and would confirm the above hypothesis. Further studies are needed in order to clarify the genetic structure of this species, that has recently colonized some Mediterranean countries. Such data, compared to those dealing with the colonizing populations of America and Brazil, may allow to better understand the microevolu­tionary processes occurring in Ae. albopictus (e.g. the role of selection, genetic drift, etc.) and to improve the control strategies of this mosquito.
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Aedes albopictus is recognized as an important potential vector of several arboviruses of medical importance in the originating areas as well as in the areas of new colonization. Studies conducted in different regions and on different strains have shown the species to be highly susceptible to the infection with a number of viruses in the families Togaviridae, Flaviviridae, Bunyaviridae. Hepatitis C Virus (HCV) is a single stranded RNA virus distantly related to flavivirus and pestivirus considered to be mainly transmitted with blood and its derivatives or parenterally in drug users. This preliminary study has been undertaken on the basis of the recent evidenee regarding possible implication of mosquitoes in HBV transmission and of the lack of explanation about the transmission route in some cases of IICV infected humans. Mosquito adults were obtained from a colony started in 1993 from eggs collected in Desenzano del Garda (Northern Italy). Four to five day old females were fed on HCV RNA positive blood (titre of 5x105 copies RNAIml) previously mechanically defibrinated. About 3 ml of blood were placed in a unit feeding device thermostated to maintain blood temperature at 37+1 0C. After 1 h exposure non engorged females were removed from the cage and engorged females held in the cage at 27+1 0C and 90% RII. Pool mosquitoes of 2-4 individuals were withdrawn at interval time after feeding (TO: immediately after feeding; T1: 24 h after; T2: 48 h after; T3: 72 h after; T4: 120 h after) and placed in liquid nitrogen. Frozen pool mosquitoes were triturated in sterile Buffer using cold mortar and pestel. Supernatant was centrifugated at 14,000 rpm for 5 mm. Two Polymerase Chain Reaction (PCR) methods were used: reverse transcription-nested PCR to detect an HCV 5' non coding viral RNA sequence using primers described by Okamoto and Amplicor HCV (Roche). HCV RNA in supernatant samples were positive at T0 and T1 in all the pools tested and negative at T2, T3, T4 using both methods. Preliminary results indicate that Ae. albopictus maintains detectable IICV RNA only within 24 h after ingestion of infected blood. This result suggests that the virus is destroyed during digestion process.
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