A prevailing hypothesis for the evolution of parasitism posits that the fitness benefits gained from parasitic activity results in selection for and fixation of parasitic strategies. Despite the potential fitness advantage of parasitism, facultative parasites continue to exhibit genetic variation in parasitic behaviour in nature. We hypothesized that evolutionary trade-offs associated with parasitic host-attachment behaviour maintain natural variation observed in attachment behaviour. In this study, we used replicate lines of a facultatively parasitic mite, previously selected for increased host-attachment behaviour to test whether increased attachment trades off with mite fecundity and longevity, as well as the phenotypic plasticity of attachment. We also tested for potential correlated changes in mite morphology. To test for context-dependent trade-offs, mite fecundity and longevity were assayed in the presence or absence of a host. Our results show that selected and control mites exhibited similar fecundities, longevities, attachment plasticities and morphologies, which did not provide evidence for life history trade-offs associated with increased attachment. Surprisingly, phenotypic plasticity in attachment was maintained despite directional selection on the trait, which suggests that phenotypic plasticity likely plays an important role in maintaining attachment variation in natural populations of this facultative parasite.

Education is essential for lowering cases of Angiostrongyliasis in Hawaii. A professional development course on rat lungworm disease (RLWD) prevention was offered to Hawaii K-12 teachers during the 2018–2019 school year. Fourteen teachers, 11 from Hawaii Island and three from Maui, representing grades K, 2, 6–8, and 10−12, completed workshops and activities and received course credit. Teachers reached 652 students and educated 86 teachers and staff and approximately 900 community members including parents. A pre-course survey showed 55% of teachers agreed to a basic understanding of rat lungworm and its impact on Hawaii; this increased to 100% post-course. A sixth-grade class was the first to document the arrival of a highly competent intermediate host of the rat lungworm in a new location, an important discovery that initiated community awareness and control efforts. Six, 1-day workshops were held in 2018–2019, each on one of the main Hawaiian Islands. These were attended by 106 participants including teachers, community educators, and interested individuals from agencies, non-profits, businesses and the private sector. Of participants surveyed, 100% responded the workshop improved their overall understanding of RLWD. Efforts are being made to continue these programmes.

The host contact network structure results from the movement and behaviour of hosts (e.g. degree of sociability; vagility and greater or lesser fidelity of shelters), which can generate heterogeneity in the transmission of parasites and influence the parasitic burden of individual hosts. In the current study, we tested the hypothesis that the burdens of Gigantolaelaps oudemansi mites are related to the characteristics of the transmission networks of individuals of Oecomys paricola, a solitary rodent. The study was carried out in a savannah habitat in north-eastern Brazil. In the dry season, the rodent network presented sub-groups of rodent individuals interacting with each other, whereas in the wet season, no modules were formed in the network. Mite burden was positively related to the number of connections that an individual host had with other host individuals in the dry season. The pairwise absolute difference between the mean mite burdens among individual rodents was negatively correlated with the similarities of node interactions. No relationships were observed during the wet season. There was a higher heterogeneity of mite burden among hosts in the dry season compare to that in the wet season. In solitary species, spatial organization may show seasonal variation, causing a change in the opportunities of host contacts, thereby influencing the transmission and dispersion of their ectoparasite burdens.

Both parasitism and social contact are common sources of stress that many gregarious species encounter in nature. Upon encountering such stressors, individuals secrete glucocorticoids and although short-term elevation of glucocorticoids is adaptive, long-term increases are correlated with higher mortality and deleterious reproductive effects. Here, we used an experimental host-parasite system, social rodents Acomys cahirinus and their characteristic fleas Parapulex chephrenis, in a fully-crossed design to test the effects of social contact and parasitism on stress during pregnancy. By analysing faecal glucocorticoid metabolites, we found that social hierarchy did not have a significant effect on glucocorticoid concentration. Rather, solitary females had significantly higher glucocorticoid levels than females housed in pairs. We found a significant interaction between the stressors of parasitism and social contact with solitary, uninfested females having the highest faecal glucocorticoid metabolite levels suggesting that both social contact and infestation mitigate allostatic load in pregnant rodents. Therefore, the increased risk of infestation that accompanies group-living could be outweighed by positive aspects of social contact within A. cahirinus colonies in nature.

Parasites have evolved a myriad of attachment structures closely adapted to their hosts and sites of attachment. Here, using members of the genus Acanthobothrium van Beneden, 1850 (Cestoda: Tetraphyllidea: Onchobothriidae), we (i) examined the influence of host body size and phylogeny, in addition to morphological features of these tapeworms, on the size of 3 structures used in attachment (bothridia, accessory suckers and hooks) by means of general linear models and phylogenetic-independent contrasts methods, and (ii) quantified the scaling exponents of relationships between size of attachment structures and tapeworm body size. Our results indicate that there exists a positive relationship, albeit not directly proportional, between size of attachment structures and Acanthobothrium spp. body size, and hook size and size of bothridia and accessory suckers. These results suggest that the resource investment in whole-body growth is greater than that in attachment structures, and that a greater investment in development of bothridia and accessory suckers is required to maintain an equivalent functional efficacy to hooks. In addition, host body size also influences, though less markedly, the size of attachment structures in Acanthobothrium spp. independently of parasite size itself. Acanthobothrium species have evolved a generalized mode of attachment that is successful in maintaining their position on various intestinal mucosal topographies across a variety of hosts exploiting different food resources.

Extraordinary as any of the Mallophaga are when compared with conventional insect forms, there are some species of the order which are still more peculiar than the majority of their fellows. Among these unusually strange forms is that here to be dealt with, a species that seems to combine within itself the characteristics of two otherwise trenchantly separated groups, that possesses striking specific peculiarities and that in addition is decidedly aberrant in its choice of host. It has but once been recorded. The availability of further specimens makes possible additions to our knowledge of its structure and a reconsideration of its relationships.

The effects of parasitization by Hyposoter exiguae on the nutritional physiology of Trichoplusia ni were influenced by the dietary sucrose level. The results confirmed that host nutrition plays a significant role in the manifestation of parasitic infection during the insect parasite-host association. Increased dietary sucrose level resulted in an increase in haemolymph trehalose concentration in both control and parasitized insects, but the increase was greater in the latter group. However, when the sucrose level was increased without energetic compensation and the dietary casein level was maintained constant, the haemolymph trehalose concentration was affected very little in unparasitized individuals but was markedly elevated in parasitized hosts. This result suggests that the de novo synthesis of carbohydrate in parasitized T. ni may not be regulated by dietary sugar intake.

Male and female congenitally athymic nude (nu/nu) mice infected with a single cysticercoid of Hymenolepis diminuta at 6 weeks of age retain the infection for at least 33 days. In the males of their phenotypically normal litter-mates, however, a single cysticercoid infection establishes and grows but is expelled between days 11 and 17. The unresponsiveness of the nude mouse to single H. diminuta infection is evidence that the immune rejection from normal mice is thymus-dependent.

The parasite herein described was found in the intestinal contents of Blatta americana at Calcutta. A single specimen was observed.

Among the bird-parasites included in the family Hippoboscidae, are four small closely conneceted genera, in all of which the wings exhibit more or less extensive reduction and are apparently useless for the purpose of flight. In various parts of the world species belonging to one or other of three of these genera, namely Crataerina, v. Olf., Myophthiria, Rond., and Brachypteromyia, Will., infest Swifts (Micropus, Collocalia, etc.) and their nests; while the solitary representative of the fourth genus Stenepteryx, Leach, at present known is similarly parasitic on the House-Martin (Delichon urbica, L.), which, though in no wise related, is closely associated with the Common Swift in the popular mind.

The capillariid nematodes present in passeriform hosts collected in Taiwan are recorded and described. Two new species are established, Capillaria parusi sp.n. from Parus monticolus insperatus and Sitta europaea formosana, and C. madseni sp.n. from Corvus macrorhynchus colonorum, and their affinities are discussed. Capillaria tridens, C. longifila and C. contorta are recorded from a number of new hosts.

After 24 h desiccation at 28–29 °C and approximately 50 % relative humidity about 70 % of B. microplus larvae drank sufficient solution containing 1·5 mCi of 32P per ml for their movements on the host to be followed with a portable G-M counter. Reduced viability of the labelled ticks could not be detected when they were kept for 24 h on the host and either allowed to feed or prevented from doing so. When feeding was continued for 72 h or when larvae were incubated for 3–4 weeks, adverse effects were found, the severity of which could not be directly related to the amount of 32P label. Desiccation, handling of larvae and exposure to radiation in the drinking solution may have contributed to their reduced viability.

Since resistance to the tick is manifest within the first 24 h after infestation labelled larvae could be used to compare development on different hosts during this time. Even after feeding for 72 h, larvae were more adversely affected by host resistance than by labelling damage.

We would like to thank Mr C. A. Schuntner for helpful advice and Mrs J.Galligan for technical assistance. The financial support of the Australian Meat Research Committee is gratefully acknowledged. Messrs D. Hancox and S. R.Henderson assisted with some of the experiments.

The daily rate at which a young lamb acquired keds from its mother was studied. Keds applied themselves closely to the skin of the lamb, many on the under, sheltered parts of the body. It is concluded that there was almost completely oneway traffic of keds from the ewe to the lamb. A fall in the rate of transfer of keds to the lamb was attributed to declining frequency of contact between the latter and its mother, associated with transition from a wholly milk diet to one in which pasture became of increasing importance. It was found that during the hours of darkness and some hours of daylight few, if any, keds were acquired by the lamb. Keds tended to accumulate on the lamb in greater numbers during periods of many hours of bright sunshine and little rain than those of few hours of sunshine and much rain. The running totals of keds acquired by the lamb more nearly paralleled the running totals of hours of bright sunshine than other meteorological factors. It is concluded that the connexion was indirect and that sunshine raised the temperature of the fleece of the mother in the regions directly exposed to the rays, causing greater numbers of keds to appear on the surface, so that the lamb was exposed to a risk of heavier infestation. At one stage of the experiment a greater proportion of the males than females transferred from the ewe to the lamb. This is explained in terms of there being a higher proportion of males in the hinder part of the body of the ewe, a region with which the lamb, in feeding, came more frequently into contact. The higher ratio of males to females in the posterior half of the lamb than in the anterior is explained by the more pronounced habit of males than females to migrate through the fleece.

Neurotoxocariasis (NT) is a serious condition that has been linked to reduced cognitive function, behavioural alterations and neurodegenerative diseases. Unfortunately, the available drugs to treat toxocariasis are limited with unsatisfactory results, because of the initiation of treatment at late chronic stages after the occurrence of tissue damage and scars. Therefore, searching for a new therapy for this important disease is an urgent necessity. In this context, cytotherapy is a novel therapeutic approach for the treatment of many diseases and tissue damages through the introduction of new cells into the damaged sites. They exert therapeutic effects by their capability of renewal, differentiation into specialized cells, and being powerful immunomodulators. The most popular cell type utilized in cytotherapy is the mesenchymal stem cells (MSCs) type. In the current study, the efficacy of MSCs alone or combined with albendazole was evaluated against chronic brain insults induced by Toxocara canis infection in an experimental mouse model. Interestingly, MSCs combined with albendazole demonstrated a healing effect on brain inflammation, gliosis, apoptosis and significantly reduced brain damage biomarkers (S100B and GFAP) and T. canis DNA. Thus, MSCs would be protective against the development of subsequent neurodegenerative diseases with chronic NT.

Infective 3rd-stage larvae of three species of marine ascaridoid nematodes, Pseudoterranova (= Phocanema = Porrocaecum = Terranova) decipiens, Anisakis simplex and Phocascaris/Contracaecum sp. were cultured in vitro in 0·9% saline or Medium 199 at 37°C beneath an atmosphere of either air or 95% air:5% CO2 All three species responded to culture at 37°C by producing a new cuticle. The majority of P. decipiens completed ecdysis under all the culture conditions employed. Ecdysis in A. simplex was stimulated by a high concentration of CO2; this effect was particularly noticeable in saline cultures. Both A. simplex and Phocascaris/Contracaecum sp. developed more effectively in a nutrient medium than in saline.