U
NIVERSITÀ DI
P
ISA
DIPARTIMENTO DI SCIENZE AGRARIE, ALIMENTARI E
AGRO-AMBIENTALI
CORSO DI LAUREA IN PRODUZIONI AGROALIMENTARI E GESTIONE
DEGLI AGROECOSISTEMI
Curriculum Agricoltura Biologica e Multifunzionale
TESI DI LAUREA MAGISTRALE
Behavioral ecology of selected ticks and flies of veterinary importance
Relatori: Candidata: Prof. Angelo CANALE Alice CASELLI Dott. Giovanni BENELLI
Correlatore:
Prof. Marcello MELE
Contents: Abstract... .pag. 1 1. Introduction...pag. 3 1.1. Calliphora vomitoria...pag. 4 1.2. Ixodes ricinus………...pag. 6 1.3. Lucilia sericata...pag. 7 1.4. Mallophaga...pag. 10 1.4.1 Mallophaga as vector of filariasis and fowl cholera………...pag. 13 1.5 Aim………....pag. 14 2. Materials and Methods...pag. 16 Ethics statement………..pag. 16 2.1 Calliphora vomitoria...pag. 16 2.1.1. C. vomitoria rearing and general observations………..pag. 16 2.1.2. Innate color preferences……….pag. 17 2.2. Ixodes ricinus………pag. 18 2.2.1 Ixodes ricinus rearing and general observations ………....pag. 18 2.2.2. Lateralized questing………...pag. 18 2.3 Lucilia sericata...pag. 20 2.3.1. L. sericata rearing and general observations ……….……...pag. 20 2.3.2. Courtship and mating behavior………..pag. 21 Data analysis………...pag. 22 3. Results and Discussion...pag. 22 3.1. Color preferences in blowflies...pag. 22 3.2. Lateralized behavioral traits in ticks and flies………..pag. 24 3.2.1. Ixodes ricinus……….pag. 24 3.2.2. Lucilia sericata...pag. 26 3.2.3. Discussion………..pag. 28 3.3. Control of Mallophaga...pag. 29 3.3.1. Cattle...pag. 29 3.3.2. Goats and sheep...pag. 38 3.3.3. Dogs...pag. 39 3.3.4. Resistance to chemical insecticides...pag. 40
3.3.5. Eco-friendly control of Mallophaga...pag. 40 3.3.6 Bacillus thuringensis...pag. 41 3.3.7. Entomopathogenic fungi...pag. 43 3.3.8. Herbal formulations...pag. 43 3.3.9. Azadirachta indica extracts...pag. 44 3.3.10. Carapa guianensis extracts………....pag. 45 3.3.11. Conclusions………....pag. 46 4. Conclusions………....pag. 47 Acknowledgments………..pag. 48 References………..pag. 48
Abstract
Pest infestations are one of the most influential problems of livestock worldwide. Their successful control is strictly connected to a proper management of husbandry. Furthermore, climate changing trends can be very influential, routing the seasonal presence of the ectoparasites. In this thesis, we focused on behavioral ecology of ticks and two species of calliphorid flies. Additionally, we critically examined and discussed current knowledge on Mallophaga control strategies.
Ticks are very dangerous vectors of several pathogens, including Borrelia burgdorferi and Coxiella
brunetii that cause the Lyme disease and the Q fever, respectively. However, these ones are only
two of the several etiological agent that ticks can transmit. Here, lateralization (i.e. functional and/or structural specialization of one brain hemisphere than the other) of questing behavior in Ixodes
ricinus was investigated. Ticks exhibited lateralization at both individual- and population level.
Lateralization was also studied in the green-bottle fly, Lucilia sericata, both during mating behavior (pre-copula and copula). L. sericata is well known as one of the first myiasis-fly all over the world. This species can be a vector of the Mycobacterium avium complex and Clostridium botulinum type C toxin. Lateralization at individual-level was recorded. During these experiments, several
reproductive traits were also studied, such as pre-copula and copula duration, the number of foreleg tapping acts and head butting deeds. Calliphora vomitoria is another threating livestock pest that may be a vector of several microbial contaminants, for example C. botulinum type C toxin, as L.
sericata. In this last part of the thesis, we investigated the innate color preferences of C. vomitoria
adults using two-choice assays, tested combinations included: (i) black vs. white, (ii) black vs. yellow, (iii) black vs. red, and (iv) black vs. blue. Result suggested that C. vomitoria has an innate preference to the black color and that could be interesting to develop cheap chromotropic traps for blowfly monitoring. Concerning chewing-lice, Mallophaga, our knowledge about their vector activity and control is extremely patchy. Mallophaga control methods still relied on the employ of chemical pesticides, while the development of eco-friendly control tool is scarce. That situation
reflects the control management of the entire pests mentioned above. Behavioral studies are very limited and the analysis of pest ethological traits can become very difficult. The scientific
1. Introduction
Arthropod ectoparasites are important vectors of many etiological agents, which may cause infections and epidemics in humans and animals (Bonizzoni et al., 2013; Mehlhorn, 2015;
Mehlhorn et al., 2012a; Benelli et al., 2016c). Among them, mosquitoes are undoubtedly one of the most dangerous parasites, representing a serious problem for millions of people worldwide. With their feeding activity, mosquitoes transmit many deadly pathogens such as malaria, yellow fever, dengue fever, filariasis and Zika virus (Jensen and Mehlhorn, 2009; Benelli and Mehlhorn, 2016; Pastula et al., 2016; Saxena et al., 2016). Furthermore, mosquitoes can also harm animals’ health. Dogs and horses are very susceptible hosts for many agents that are transmitted by Culicidae, for example the dog heartworm, the West Nile virus and the Eastern equine encephalitis (WHO, 2012; Mehlhorn, 2015). However, the highest competence among arthropods in transmitting disease agents belongs to ticks (Benelli et al. 2016a; Bissinger and Roe, 2010: Sonenshine et al., 2002). In Europe and North America, ticks are vectors of many human and animals’ diseases, such as anaplasmosis, babesiosis, borreliosis, tularemia, rickettsiosis, and encephalitis (Benelli et al., 2016a). Tick-borne encephalitis can arouse an influenza-like illness that in about 30% of cases is followed by high fever and disorder of nervous system (Benelli et al., 2016a).
Many other arthropods cause pain in vertebrates. For example, blowflies (Diptera:
Calliphoridae) are commonly considered threating ectoparasites because of their capacity to cause human and animal myiasis (Zumpt, 1965; Urquhart et al., 1987). Additionally, they can also be vectors of several pathogens, such as Clostridium botulinim type C toxin, which is transmits both by
Lucilia sericata Meigen and Calliphora vomitoria Linnaeus (Hubálek and Halouzka, 1991). The
seriousness of problems caused by arthropods does not decrease with the dimensions of the pest. It is well known that lice, fleas and Mallophaga can be causes of many human and animal diseases. For example, Pediculus humanus capitis De Geer is considered as a potential vector of Rickettsia
(Robinson et al., 2003). The flea Xenopsylla cheopis Rotshild is the first vector of Yersinia pestis Lehmann and Neumann, the etiological agent of bubonic plague in humans, while Ceratophyllus
gallinae Shrank causes irritation and even anemia in domestic poultry (Urquhart et al., 1987). Later
on, among the order of Mallophaga can be found the vectors of the filarial heartworm, Sarconema
eurycerca Wehr and the fowl cholera, Pseudomenopon pilosum Scopoli (Bartlett and Anderson,
1987; Seegar et al., 1976).
1.1. Calliphora vomitoria
Calliphora vomitoria is a pest fly characterized by the capacity of his larvae to live and
develop in vertebrate flash, as all the species belonging to Calliphoridae family. If the vertebrate is living, this kind of parasitism is called myiasis (Stevens, 2003). Generally, Calliphora genus includes primarily carrion feeders (Aak et al., 2011) however, several species can be classified as secondary or tertiary agents of myiasis, as in the case of C. vomitoria (Zumpt, 1965). Myasis have been firstly described by Hope (1840) and since then several cases of this condition were reported both in animals and in humans (Edwards et al., 1984; Erzinlioglu, 1987; Ferrar, 1987; Zeltser and Lustman, 1988; Rawlins, 1988; Gursel and al., 2002). Generally, myiasis are infrequent in humans, however, they might occur if the hygienic conditions are inadequate and if the health state of the person is compromised (Gursel et al., 2002). For example, an uncommon case study has been conducted by Rodman Wood and Rigby Slight (1970) about a destructive orbital myiasis due to C.
vomitoria maggots. The patient died few days after the admission to the hospital. It was the first
situation of a human lethal myiasis in North America (Rodman Wood and Rigby Slight, 1970). Additionally, a rare case of gingival myiasis due to a direct infestation with Calliphora spp. eggs was described by Gursel et al., (2002) in a report study. The patient was a 26-years old farmer having a not acceptable oral hygiene. The diagnosis was based on the visual presence of the blowfly larvae. One week later, a flap operation was done and the healing was uneventful (Gursel et al.,
2002). However, myiasis occurs more frequently in animals, particularly in sheep and goats
(Sotiraki and Hall, 2012). C. vomitoria is well known for his capacity to arouse the ovine cutaneous myiasis, also called sheep strike, a worldwide problem of livestock (Hall, 1997; Morris and
Titchener, 1997). Furthermore, Hubálek and Halouzka (1991) demonstrated first the capacity of C.
vomitoria to transmit Clostridium botulinim type C toxin in birds. The first vehicle of intoxication is
represented by bird carcasses that can be used by other fowls and invertebrates as feeding sources (Duncan and Jensen, 1976; Hubálek and Halouzka, 1991). If C. vomitoria larvae feed on an infected carcass could become infected themselves. The cycle closes when birds ingest infected larvae receiving a lethal dose of C. botulinum type C toxin (Hubálek and Halouzka, 1991). Later on, Van der Wolf and Van der Zouwen (2010) demonstrated that C. vomitoria can be a potential vector of the etiological agent of crucifer black rot, the pathogen Xanthomonas campestris pv. campestris (Xcc). In their study, the colonization of Brassica oleracea by Xcc via blue-bottle fly was
investigated (Van Der Wolf and Van Der Zouwen, 2010). However, detailed studies concerning the role of pollinator insects in the dissemination of Xcc are still needed.
Historically, Calliphoridae control was based on the use of chemicals, such as
organophosphates and pyrethroids (Hall and Wall, 1995).Additionally, the use of insect growth regulators (IGRs) has shown efficient results (Graf, 1993). Strong (1989) focused on the efficacy of ivermectin at a dose of 0-3 µg applied topically to last instar larvae of the C. vomitoria. Results suggested that a significant number of adult flies did not come out from their puparia. Furthermore, females that manage to emerge were not able to develop mature oocytes (Strong, 1989). However, the massive use of pesticides can arouse resistance problems and potential detrimental effects on non-target species. In this scenario, alternatives to chemical insecticides are urgently needed (Aak, 2010). Mass trapping and lure-and-kill techniques seem to be efficient in blowfly’s control (Hall and Wall, 1995). However, they maximize their efficiency only if sheep congregate and are not very appropriate over large areas of land (Tellam and Bowles, 1997). Recently, Bedini et al., (2017) investigated the efficacy of the essential oils of two aromatic plants, Artemisia annua and A.
dracunculus against C. vomitoria. However, limited knowledge on these topics have been exploited
to develop effective and reliable control tools “in the real world”, this has been also linked with the fact that C. vomitoria is also not considered as a first myiasis agent and little is known about its vector activity.
1.2. Ixodes ricinus
Ticks are considered among the most dangerous arthropod vectors of diseases agents to both humans and animals worldwide (Colwell et al. 2011; Jongejan and Uilenberg 2004), holding a vector competence surpassed only by mosquitoes (Benelli et al., 2016a; Bissinger and Roe 2010; Soneshine et al., 2002). They include approximately 900 species described, which are distributed in two main families Argasidae and Ixodidae and the Nutalliellidae family including only a species (Nuttalliella namaqua, Bredford) (Pfäffle et al., 2013; Guglielmone et al., 2014).
Ixodidae, commonly known as hard ticks, are the responsible for most of the cases of human parasitization, although also Argasidae (e.g. soft ticks), sporadically bite human (Estrada-Penã and Jongejan 1999; Dantas-Torres et al., 2012).
Human parasitization is caused by a number of tick species that are different from region to region and generally infest animals representing a reservoir host of several pathogen
micro-organisms (Estrada-Penã and Jongejan 1999; Dantas-Torres et al., 2012; Colwell et al. 2011; Piesman and Eisen 2008).
Interestingly, both biotic (e.g., host density) and abiotic (e.g., weather) variables play an important role in affecting the host-seeking activity of the ticks, which is directly correlated with the host risk of contracting tick-borne diseases (Loye and Lane 1988; Schulze et al., 2001; Hubálek et al., 2003). However, also ticks cognitive endogenous factors are worth to be investigated in the host seeking/contacting behavior. Lateralization has a crucial role for the development of several
Rogers 2005; Rogers et al., 2013a,b; Frasnelli 2013; Benelli et al., 2015a,b,c, 2016b; Romano 2016a,b). With a particular reference to arthropods, concerning insects, asymmetrical traits were recently found in the courtship and mating behavior of three product-stored beetle species (Benelli et al., 2016b, 2017c; Romano et al., 2016b), an encyrtid parasitic wasp (Romano et al., 2016a), and a tephritid (Benelli et al., 2015a). Lateralization during aggressive interactions were observed in tephritids (Benelli et al., 2015a,c), blowflies (Romano et al., 2015), and mosquitoes (Benelli et al., 2015b). In the Arachnida class, asymmetries were reported only in a spitting spider (Ades and Ramires, 2002). However no findings are available concerning lateralization in ticks and more generally in the subclass of Acari. Lateralization contributes significantly to biological fitness in many animals, conferring many functional advantages (Frasnelli 2013; Vallortigara and Rogers, 2005) and its involvement in tick cognition/perception would critically improve our knowledge in their host-seeking behavior. Since Ixodidae climb on top of the vegetation assuming a questing posture in order to intercept a host (Norval et al., 1987), we investigated if ticks have any lateral bias in the use of the forelegs when a host was presented to a lurking tick.
1.3 Lucilia sericata
The family of Calliphoridae, commonly known with the name of blowflies, is composed of many species that threaten human and animal health worldwide (Zumpt, 1965; Urquhart et al., 1987). Lucilia sericata (syn. Phaenicia sericata), also called the green-bottle fly, is one of the major pest belonging to this family (MacLeod, 1943; Urquhart et al., 1987; Hall and Wall, 1995; Morgan, 1995). This fly is well known for his capacity to arouse myiasis in several animal species, including man. In the majority of cases, L. sericata is found on cutaneous myiasis of sheep (Ovis aries
Linnaeus) (Urquhart et al., 1987; Hall and Wall, 1995). Myiasis occurs when dipteran larvae infest living animals (Urquhart et al., 1987; Wall and Wall, 1995; Stevens and Wall, 1997). Usually, L.
of living animals as oviposition substrata (Morgan, 1995; Talari et al., 2004; Boulay et al., 2013). As soon as the eggs hatching, larvae start feeding on the substratum with their oral hooks,
provoking laceration of the skin and liquefaction of the tissues due to proteolytic enzymes that are produce by flies themselves (Urquhart et al., 1987; Morgan, 1995). The feeding activity generally causes itch, pain, irritation and erythema in strike animals (Talari et al., 2004).
The green-bottle fly was firstly recorded as ectoparasite in the 15th century, in England (Stevens and Wall, 1997). Approximately, 80% of farms in England and Wales, nowadays, are subjected to sheep strike due to L. sericata each year. Among this value, the 1.5% of ewes and 2.8% of lambs are included (French et al., 1992; Bisdorff et al., 2006). In the Netherlands, 52.4% of farmers has recorded, at least, one case of blowfly infestation per year, with the average of 2.9% of strike sheep per livestock (Snoep et al., 2002). However, not only European animal farms are subjected to L. sericata myiasis. This fly is very important also in the southern hemisphere. It was introduced in Australia more than 100 years ago and at once, it became the primary myiasis fly (Miller, 1939). The green-bottle fly is very influential also in New Zealand, even though another calliphorid species, Lucilia cuprina Wiedemann has almost replaced it (Heat and Bishop, 1996). L.
sericata and L. cuprina have many ethological common traits. They are classified as primary
facultative parasites (Stevens and Wall, 1997) because of their double behavior, both as ectoparasites arousing myiasis, and as facultative saprophages (Hall and Wall, 1995).
Furthermore, L. sericata is considered a threatening species also for his capacity to be a pathogens vector (Fischer et al., 2004; Kather et al., 2011; Banumathi et al., 2017). Hubálek and Halouzka, (1991) demonstrated the persistence of C. botulinum type C toxin in L. sericata larvae and pupae as a plausible cause of avian botulism. The toxin is spread by the feeding activity of birds. Few larvae are enough to give a lethal dose of the toxin to birds (Hubálek and Halouzka, 1991). An experiment conducted by Fischer et al., (2004) has demonstrated that L. sericata larvae can be vector of the paratuberculosis agents, the Mycobacterium avium complex. In this test, the
second-stage larvae were artificially feed with meat contaminated with Mycobacterium avium
avium (serotype 1, genotype IS901+ and IS1245+) and M. a. hominissuis (serotype 8, genotype
IS901- and IS1245+). After 4 days of the infection, M. a. avium was isolated from L. sericata larvae (Fischer et al., 2004).
In this scenario, monitoring and control methods take on great importance. Generally, for L.
sericata monitoring programs were used colored sticky target (Wall et al., 1992a; 1993). However,
this kind of traps can be subjected to several range of biases that provoke alterations of the data. Biases can be due to the weather and the stage in the reproductive cycle in which L. sericata is more or less attracted (Vogt et al., 1983; 1985; Vogt and Morton, 1991; Spradbery and Vogt, 1993: Wall, 1993). Another monitoring model was developed to predict the sheep-strike incidence due to L.
sericata and its seasonal changes in flight. Result suggested that the best moment to start blowflies
control by treating stock is early spring (Wall et al., 1993). However, more works about this monitoring tool are required, in order to determine the relationship between insects’ abundance, strike incidence and weather (French et al., 1994a). Historically, the control of dipteran pest was based on the massively use of insecticides such as organophoshates, synthetic pyrethroids and carbamates (French et al., 1994b; Srinivasan et al., 2008). Smith et al., (2000) investigated the effect of phenylpyrazole fipronil and β-cyfluthrin against L. sericata larvae. Both of them results very efficient if compared to acetone and water control (Smith et al., 2000). However, fipronil gave the best results. Its toxicity was approximately 10 times stronger compared to β-cyfluthrin. In this experiment, LC50 values were recordedat 0.14 ppm for fipronil and 1.56 ppm for β-cyfluthrin (Smith et al., 2000). Furthermore, the removal of faecally soiled wool and the regular sharing from around the breech can both arouse the elimination of suitable oviposition sites (Hall and Wall, 1995).
Nowadays, scientists are trying to replace the use of chemicals with new eco-friendly methods of control. Many studies were been conducted about the potential effect of plant extracts
against blowflies. Results are very encouraging and the development of insecticides resistance is strongly unlikely (Chandler et al., 2011). For example, Kather and Khater (2009) had successfully employed the extracts of Trigonella foenum-graecum (LC50 2.81%), Apium graveolens (LC50 4.60%), Raphanus sativus (LC50 6.93) and Brassica compestris (LC50 7.92%) against L. sericata larvae (Kather and Kather, 2009). Waliwitiya et al., (2010) studied the effect of an essential oil composed of thymol and eight other neuroactive chemicals on flight activity and wing beat frequency of L. sericata. Results suggested that the oil extract acts by mimicking or facilitating GABA action, interfering with flight muscles and central nervous function (Waliwitiya et al., 2010). Furthermore, the use of extract oils of Lactuca sativa, Matricaria chamomilla, Pimpinella anisum and Rosmarinus officinalus against the third larval stage of L. sericata were tested by Kather et al., (2011). Later on, the use of green-coated zinc oxide Lobelia leschenaultiana nanoparticles was successfully evaluated against the green-bottle fly by Banumathi et al., (2017) as an interesting control method both for the cost and for the eco-friendly aspects. To the best of our knowledge, this is the only experiment involving the use of nanomaterials against L. sericata (Banumathi et al., 2017). In this scenario, more research work is needed on this promising control strategy.
1.4 Mallophaga
The Mallophaga, commonly knew as chewing lice, constitute an order that includes around 2500 species of insects. The name Mallophaga comes from Greek mallos = wool, hair; phagein = feeding by gnawing (Mehlhorn et al., 2012b). They are ectoparasites of birds and, to a lesser extent, of mammals. Rarely, they can be found on stenothermic insects (Séguy, 1944; Saxena and Agarwal, 1983). The Mallophaga order is composed of three suborders, Amblycera, Ischnocera, and
Rhyncophthirina (Masutti and Zangheri, 2001). The species included in the two most representative suborders, Amblycera and Ischnocera, show opposite behaviors. Amblycera are nimble and agile, while Ischnocera are slow and sluggish, and rarely abandon their hosts. The chewing lice cannot
live more than 3–6 days without the host. Birds can harbor many Mallophaga genus, major ones include Lipeurus, Cuclotogaster and Menacanthus. All of them generally live on poultry, even if minor genera, such as Gonioides and Menopon, can live on pigeons, doves, ducks, game birds, and even birds of prey (Emerson, 1954; Ash, 1960; Clay, 1951, 1976; Hill and Tuff, 1978; Price and Clayton, 1983; Urquhart et al., 1987) (Fig. 1). One of the most common species, Menopon gallinae Linnaeus lives at the base of chicken feathers (Masutti and Zangheri, 2001). Young birds are generally the most suffering subjects. Otherwise, also adults can be very pained. They are not able to rest, often their weight goes down day by day. Often, depression in eggs production is recorded because of heavy infestations (Urquhart et al., 1987). Mallophaga are common on marine birds (Cheng, 1976). Generally, penguins host two genera of Ischnocera, Austrogonoides and Nesiotinus. They live in penguins’ feather coat that is water repellent and contains air around the body to prevent heat loss. Therefore, insects can live always in a terrestrial environment and they do not need adaptations for marine life (Cheng, 1976). Pelicans can harbor both Ischnocera and Amblycera species, with special reference to Pectinopygys spp. for the first suborder, Colpocephalum sp. and
Piagetiella sp. for the second one. The genus Pectinopygus can feed on cormorants. Shags usually
harbor also Amblycera, such as Eidmaniella sp. (Cheng, 1976). Similarly, gulls can be parasitized by Ischnocera (Quadraceps sp. and Saemundssonia sp.), as well as Amblycera (Actornithophilus sp. and Austromenopon sp.). Furthermore, many other marine birds usually host chewing lice, such as puffins, terns, albatrosses, and gannets (Cheng, 1976), while Mallophaga have been not reported on marine mammals (Cheng, 1976). The suborder Ischnocera includes several parasites of terrestrial mammals (Emerson and Price, 1983; Mey, 1988; Masutti and Zangheri, 2001). A good example is
Trichodectes canis Degeer, which causes cutaneous crust and hair loss in dogs. Especially, this
species can be found in dog breeds that possess long ears (e.g., basset and spaniel). The ears are a suitable habitat for the multiplication of the pest (Urquhart et al., 1987). In cats, the same symptoms are caused by Felicola subrostratus Burmeister. This pest is typical of longhaired breeds, because they have more difficulties in grooming than shorthairs (Urquhart et al., 1987). Damalinia
(Bovicola) bovis Linnaeus lives on ungulates, and arouses cutaneous irritations, itch, and hair removal in various parts of the body (Masutti and Zangheri, 2001). It prefers the top of the head, neck and shoulders because these places are very difficult to reach by cattle tooth. The intense pruritus can cause self-inflicted injury by scratching (Urquhart et al., 1987). Damalinia (Bovicola)
ovis Schrank is the cause of phthiriasis in sheep. It can infest the whole body of the animal and for
this reason it is called the “body louse” (Urquhart et al., 1987). D. ovis is not the only species that infest sheep. Linognathus pedalis Osborn, also called the “foot louse”, prefers the lower region of sheep hind legs. However, D. ovis is more active than this pest. Both are susceptible to high temperature and high percentage of humidity (Urquhart et al., 1987). Likewise, Damalinia (Bovicola) caprae Gurlt arouses phthiriasis and wool loss in goats. Equines are parasitized by
Werneckiella equi Linnaeus, which causes itch and dermatitis (Masutti and Zangheri,
2001). Generally, the typical habitat of Mallophaga is difficult to reach by birds’ beak and mammals’ tooth, making their removal extremely difficult for the selected host. For instance,
Tetrophthalamus sp. lives inside the membranous sac of the pelican’s lower jaw, while Neocolpocephalum flavescens Nitzsch penetrates inside the barrel of bird feathers (Grandi,
1951).
The Mallophaga diet is mainly composed by necrotic fragments, epidermal peeling, hairs, feathers, egg corion, exuviae and sebaceous secretions from their hosts (Grandi, 1951; Urquhart et al., 1987). The hematophagy is not typical for these insects, but sometimes it has been observed, particularly in the Amblycera species (Grandi, 1951; Urquhart et al., 1987). The reproduction can be sexual or thelytokous parthenogenesis, it depends on species. The eggs can be very large, reaching one third of the length of female body. They can hatch in mass or alone. Generally, the eggs, that are commonly called “nits”, are glued to host feathers or hairs (Grandi, 1951; Urquhart, 1987). During their life span, about one month, females lay among 200–300 operculate eggs (Urquhart et al., 1987). The postembryonic development takes place in three nymphal instars during a 2–3-week period, and with the third molting insects reach the adult stage. The time that occurs to have the
whole cycle from nit to adult is about 2–3 weeks (Grandi, 1951; Urquhart et al., 1987). Mallophaga do not result very dangerous for vertebrates in which they live. Otherwise, they can open entryways for many microorganisms, such as pathogenic bacteria and tapeworms. Infested animals try to get rid of these insects making dust bathing and brushing off ant’s nests (Grandi, 1951). Generally, heavily infested animals result subjected to anemia, and only heavy infestations can have strong economic impacts on livestock productions. Otherwise, the economic losses due to Mallophaga are often underestimated (Campbell et al., 2001). Animals’ diet can define the level of infestation. A low-protein alimentation breaks down cattle resistance to parasites (Campbell et al., 2001). The infestation level can be also determinate by the season. Intensive farming favors infection among animals and the situation gets worse in winter (Masutti and Zangheri, 2001) and spring and decreases in summer (Arundel and Sutherland, 1988). This fluctuation in Mallophaga populations may be due to high summer temperatures, solar radiation, heavy rainfall and to sharing effects for livestock animals (Arundel and Sutherland, 1988).
1.4.1. Mallophaga as vectors of filarasis and fowl cholera
The filarial heartworm Sarconema eurycerca Wehr, belongs to the Dipletalonematidae family, and parasitized waterfowls (Seegar et al., 1976). An intermediate host for the life cycle of this nematode is the chewing lice Trinoton anserinum Fabricius that plays the role of heartworm vector (Seegar et al., 1976). A dissection of 89 Mallophaga collected from different individuals of
Cygnus olor Gmelin, the mute swan, and Cygnus columbianus Ord, the whistling swan, showed that
in the midgut of the 66% of T. anserinum a fresh blood meal was found. This has been surprising since historically, it has been thought that chewing lice did not feed routinely on blood, but only occasionally. Therefore, they were not deeply considered as potential vectors of parasites and pathogens, leading to underestimated losses due to their feeding activity (Seegar et al., 1976). Furthermore, researchers found microfilariae larvae in 39 of the 89 T. anserinum above mentioned.
More than one developmental stage of S. eurycerca was found in the 62% of infected chewing lice examined. Microscopic analysis illustrated that infective nematode larvae were very active, moving back and forth between lice head and thorax (Seegar et al., 1976). These results highlight that T.
anserinum is a natural vector of the filarial heartworm. Later, Bartlett and Anderson (1987) studied
the development of Pelecitus fulicaeatrae Diesing in the third stage in the amblyceran chewing louse Pseudomenopon pilosum Scopoli, as well as the biting-lice mediated transmission of this avian filarioid worm in coots. The microfilariae and developing first-stage larvae have been
detected in nymphs and adults of P. pilosum, while third-stage larvae have been found only in adult insects (Bartlett and Anderson 1987). Lastly, Bartlett (1993) reported that Amblycera and
Ischnocera can act as vectors of Eulimdana spp. (Nematoda: Filarioidea) in charadriiform birds, pointing out very short reproductive periods in adult worms. Besides the ability of Mallophaga to vector filarial worms, it should be also mentioned that live and virulent Pasteurella multocida, the agent of avian or fowl cholera, was found in the gut of Menacanthus stramineus Nitzch and M.
gallinae fed on the blood of hens affected with fowl cholera; it has been observed that P. multocida
appeared in the gut of Mallophaga seven hours after experimental infection of hens on which they were feeding (Derylo, 1970).
1.5 Aim
This thesis investigated several issues related to the behavioral ecology, monitoring and control of arthropod vectors and pests of medical and veterinary importance. The first part of this study was dedicated to the evaluation of the innate color preferences in C. vomitoria adults, testing binary combinations of painted cardboards. In most cases, the innate preference for black color was evident. This ethological information could be useful to project simple and cheap traps excluding the use of pheromones and insecticides for blowflies monitoring.
the right or the left foreleg to climb on a host, here a simple mechatronic device that moved a tuft of fox fur as host-mimicking stimulus was developed. This engineered approach allow to display a realistic stimulus that is prolonged over the time and standardized for each replicate (Todd, 1993; Partan, 2004; Krause et al., 2011; Romano et al., 2017). The robotic stimulus was presented
frontally to the tick, in order to evaluate the leg preference as response to a symmetrical stimulus. In addition, I also provided the stimulus laterally, in an equal proportion to the left and to the right of the tick, to investigate if the host direction affects the tick perception. To the best of our knowledge this is the first report showing evidence of lateralization in ticks.
Furthermore, I also studied lateralization of selected traits during the reproductive behavior, including pre-copula and copula traits, of L. sericata in order to improve their control methods, with particular reference to the “Sterile Insect Technique” (SIT). The interest about this control tool was renewed in recent years (Lees et al., 2014; 2015) and seems to be very promising, particularly if associated with auto-dissemination (boosted SIT) (Bouyer and Lefrançoise, 2014). Many
calliphorid pests, such as Cochliomya hominivorax Coquerel and Chrysomya bezziana Villeneuve, were successfully treated with SIT (Hall and Wall, 1995).
Lastly, I made a review study about Mallophaga vector activity and control. Their control still relied to the employ of chemical pesticides widely used to fight other primary pests and vectors of livestock, such as ticks, while the development of eco-friendly control tool is scarce. Behavior-based control of Mallophaga, using pheromone-Behavior-based lures or even the Sterile Insect Technique may also represent a potential route for their control, but our limited knowledge on their behavioral ecology and chemical communication strongly limit any possible approach. In this framework, a careful improvement of mass-rearing techniques of these insects can be also extremely helpful to boost basic research on them (Saxena and Agarwal, 1983).
