Evaluation of the effectiveness of three sticky traps to monitor four species of cockroaches (Hexapoda: Blattaria) with simulated use tests

Background

Cockroaches are the pest of major concern for the disinfestation programs of the sanitary system in Italy. Hygienic-sanitary interest is linked to the role of mechanical vectors of pathogens and to their allergological potential. Sticky traps are the best tool to monitor the presence of these insects and several types of them are available on the market. In most of the cases the traps are not indicated for a given species, but, instead, generically for cockroaches. Domestic cockroaches differ in morphology, size and habits. Consequently, the effectiveness of the trap can change in relation to the target species.

Materials and methods

In this study three of the most employed traps in Italy were compared: the INDIA trap with and without its attractant tablet (hereafter mentioned as INDIA-A and INDIA-E, respectively), the ZAPI Simply trap and the CATCHMASTER Spider & Insect Glue trap. We chose the four most common species of cockroach (Blattodea) in Italy, Blatta orientalis (L.), Periplaneta americana (L.) (Blattidae), Blattella germanica (L.) and Supella longipalpa (F.) (Blattellidae). Each species of cockroach was tested separately inside arenas containing one of the traps. Each test (one species with one kind of trap) was replicated five times.

Results and discussion

The INDIA-A trap collected more cockroaches of every species, followed by the INDIA-E. The ZAPI trap caught less specimens of each species in respect to the INDIA traps, with the only exception of B. orientalis, for which the ZAPI trap caught more than the INDIA-E. The CATCHMASTER trap performed significantly less for all the species. B. orientalis was the species most abundantly caught by all traps, followed by B. germanica, S. longipalpa and P. americana. No significant difference was observed in the catch according to the developmental stage. In general, there was no particular predisposition of any trap to catch a particular species.

Conclusions

It is not possible to indicate a model of trap for each species of cockroach, but it is clear that different traps have different performances in terms of attractiveness and capture. Therefore, the choice of the trap affects the results of the monitoring, and as consequence, the evaluation of the infesting population of the pest.

Indoor and outdoor winter activity of Culicoides biting midges, vectors of bluetongue virus, in Italy

Indoor and outdoor winter activity of Culicoides spp. (Diptera: Ceratopogonidae) in central Italy was investigated in order to evaluate whether indoor activity might account for the overwintering of bluetongue virus, as has been hypothesized by some authors. Weekly Culicoides collections were performed at three farms over three consecutive winter seasons. At each farm, two black-light traps were operated simultaneously, indoors and outdoors. Culicoides were identified using both morphological and molecular means. The Culicoides obsoletus group accounted for 98.2% of sampled specimens. Within this group, C. obsoletus s.s. accounted for 56.8% and Culicoides scoticus for 43.2% of samples. Nulliparous, parous and engorged females were caught throughout the entire winter, both indoors and outdoors. At times, indoor catch sizes outnumbered outdoor collections. A significant inverse correlation was found between minimum temperature and the proportion of indoor Culicoides of the total midge catch, thus indicating that lower outdoor temperatures drive Culicoides midges indoors. High rates of engorged females were recorded indoors, possibly as the result of the propensity of C. obsoletus females to feed indoors. Higher proportions of parous females were found in indoor than in outdoor catches, indicating higher survival rates indoors and, consequently, higher vectorial capacities of midges sheltering indoors compared with those remaining outdoors.

A 2-yr Mosquito Survey Focusing on Aedes koreicus (Diptera: Culicidae) in Northern Italy and Implications for Adult Trapping

Aedes koreicus (Edwards) is an invasive mosquito species, like Aedes albopictus (Skuse) and Aedes japonicus japonicus (Theobald), that has already colonized a large part of northeastern Italy and other European countries. Despite its rapid expansion, information about adult distribution and trapping is lacking. Here, we conducted a 2-yr longitudinal survey using adult traps to investigate the spatiotemporal distribution of Ae. koreicus and evaluated the effectiveness of three trapping devices in Latin square experiments conducted in an urban site and a forested site. The following three different traps were compared: a CO2-baited Biogents (BG) Sentinel trap, a CO2-baited Centers for Disease Control and Prevention light trap (CDC trap), and a grass infusion-baited gravid trap.In northern Italy, Ae. koreicus was collected from late April to early November, with peak of abundance observed in August. Aedes koreicus was more abundant in 2015 than in 2014 because of higher temperatures during summer. Unlike Ae. albopictus, the abundance of Ae. koreicus was not related to the altitude of the sampling locations in the range 241-660 m above sea level. The BG Sentinel and gravid traps collected significantly more Ae. koreicus than the CDC trap in the urban site, whereas there was no significant difference between the three traps in the forested site. In the urban site, the BG Sentinel trap and the gravid trap were the most effective for collecting Ae. albopictus and Culex pipiens L., respectively. In the forested site, Cx. pipiens was primarily collected by the CDC trap.

Comparative field study to evaluate the performance of three different traps for collecting sand flies in northeastern Italy

Three standard methods for collecting sand flies (sticky trap, CDC light trap, and CO2 trap) were compared in a field study conducted from June to October, 2012, at a site located in the center of a newly established autochthonous focus of canine leishmaniasis in northeastern Italy. Six traps (two sticky traps, two CDC light traps, and two CO2 traps) were activated at the same time for a single night every two weeks during the season of sand fly activity. A total of 5,667 sand flies were collected and 2,213 identified, of which 82.1% were Phlebotomus perniciosus, 17.4% P. neglectus, 0.3% Sergentomya minuta, and 0.2% P. mascitti. The performances of all traps were influenced by their position inside the site, increasing with proximity to the animal shelters. CO2 traps were more attractive for females of P. perniciosus and P. neglectus. CDC light traps showed an intermediate efficiency and were more attractive for P. neglectus, compared to other two traps. Results suggest that in northern Italy the CO2 trap is a suitable sampling method for sand fly monitoring programs that include transmitted pathogen surveillance.

Schmallenberg virus in Italy: a retrospective survey in Culicoides stored during the bluetongue Italian surveillance program

Following the first case of Schmallenberg (SBV) in northern Italy in February 2012, virus detection was conducted on midges collected during the national entomological surveillance program for bluetongue (BT). Six cattle farms, within a radius of 50 km from the SBV case, were selected for a 12 month study, aiming to determine when the virus entered the area, if it was capable of overwintering, and the possible role played by each species of the Obsoletus complex in disseminating the infection. A total of 33,724 Culicoides were collected at the six sites between June 2011 and June 2012. Species belonging to the Obsoletus Complex were the most abundant (94.44%) and, within the complex, Culicoides obsoletus was the most prevalent species in the studying area (65.4%). Nearly 7000 Culicoides midges were screened, either in pools or individually, for SBV by real-time RT-PCR. Viral genome was detected in six pools of the Obsoletus complex, collected at three sites between September and November 2011, and in a single parous female of C. obsoletus, collected in May 2012. As a result of the BT surveillance program in Italy it was possible to demonstrate, retrospectively, that SBV has circulated in at least three Italian provinces since early September 2011, nearly 5 months prior and as far as 40 km away from the first detected case. Similarly, the survey confirmed the presence of SBV in the vector population 3 months after the outbreak, following a cold winter during which the blacklight traps failed to catch active adult midges.

Saturation deficit and deer density affect questing activity and local abundance of Ixodes ricinus (Acari, Ixodidae) in Italy

The wood tick Ixodes ricinus, one of the most common arthropod-borne disease vectors, is of increasing relevance for human and animal health in Europe. The aim of this study was to determine the relative contribution of several abiotic and biotic factors potentially affecting questing activity and local abundance of I. ricinus in Italy, considering the scale at which these factors interact with the host-seeking ticks. Within EDEN, a large-scale EU collaborative project on eco-epidemiology of vector-borne diseases, we collected questing ticks for three consecutive years using a standard protocol at eleven sites in the Italian Alps and Apennines. A total of 25 447 I. ricinus were collected. All sites showed the same annual pattern of tick activity (bimodal for nymphs and unimodal for larvae and adults), although the abundance of nymphs was statistically different between sites and years. A Generalized Linear Mixed Model and a Linear Mixed Model fitted to data for nymphs, showed that while the principal variables affecting the local abundance of questing ticks were saturation deficit (an index combining temperature and relative humidity) and red deer density, the most important variable affecting questing nymph activity was saturation deficit. As for the timing of seasonal emergence, we confirmed that the threshold temperature at this latitude for larvae is 10°C (mean maximum) while that for nymphs is 8°C.