Safety and Efficacy of Pure and a Nanosuspension of D-limonene for Controlling Pigeon Lice.

This study investigated the safety and efficacy of two forms of D-limonene (DL) against Columbicola columbae (pigeon feather lice); pure and a nanoemulsion formulation (DLN). The cell cytotoxicity of the prepared forms of DL/DLN was investigated using skin cell lines. In vitro and ex vivo bioassays were applied on lice. The ex vivo bioassay was done on cut feathers containing lice eggs. The in vivo experiment was conducted on pigeons naturally infested by lice. The infested pigeons were treated with DL, DLN, or deltamethrin (D) as a positive control. Both forms of D-limonene were found to be safe when applied to the normal human skin fibroblast cell line, but DLN was toxic to skin cell carcinoma. The in vitro and ex vivo results of both DL and DLN forms were similar. All eggs treated with DL, DLN, and D failed to hatch (100%). The in vivo results showed complete elimination of lice 24 h post-treatment (PT), and biochemical analysis showed that the treated birds retained normal kidney and liver functions. Treated groups also showed improved productivity in the 4 months PT. In conclusion, DL and DLN are safe and effective in controlling feather lice infestation in pigeons and successful treatment encourages bird productivity.

PHEROMONE COMMUNICATION IN FEATHER-FEEDING WING LICE (INSECTA: PHTHIRAPTERA).

Pheromone communication is central to the life history of insect parasites. Determining how pheromones affect parasite behavior can provide insights into host-parasite interactions and suggest novel avenues for parasite control. Lice infest thousands of bird and mammal species and feed on the host's feathers or blood. Despite the pervasiveness of lice in wild populations and the costs they exact on livestock and poultry industries, little is known about pheromone communication in this diverse group. Here, we test for pheromone communication in the wing lice (Columbicola columbae) of Rock Doves (Columba livia). Wing lice spend the majority of their lives on bird flight feathers where they hide from host preening by inserting their bodies between coarse feather barbs. To feed, wing lice must migrate to bird body regions where they consume the insulating barbs of contour feathers. We first show that wing lice readily form aggregations on flight feathers. Next, using a Y-tube olfactometer, we demonstrate that wing lice use pheromone communication to move toward groups of nearby conspecifics. This pheromone is likely an aggregation pheromone, as wing lice only produce the pheromone when placed on flight feathers. Finally, we found that when forced to choose between groups of male and female lice, male lice move toward male groups and females toward female groups, suggesting the use of multiple pheromones. Ongoing work aims to determine the chemical identity and function of these pheromones.

The prevalence and intensity of external parasites in domestic pigeons (Columba livia domestica) in Egypt with special reference to the role of deltamethrin as insecticidal agent.

This study aimed to investigate the prevalence and intensity of external parasites in domestic pigeons in Giza, Egypt, from January 2020 to December 2020. A total of 300 domestic pigeons (25 pigeons per month) were examined. The birds were divided into groups based on their age. The oxidative stress parameters; serum zinc concentration, serum malondialdehyde (MDA), and serum Nitric oxide were evaluated in single and mixed external parasitic infestations. The prevalence of external parasites in examined pigeons was 80.3%. The detected parasites were Pseudolynchia canariensis (P. canariensis), Hippobosca equina (H. equina), Columbicola columbae (C. columbae), Menopon gallinae (M. gallinae), Knemidocoptes species (spp.) and Dermanyssus gallinae (D. gallinae); their incidences were 41.6, 26, 7, 5,0.33 and 0.33%, respectively. The highest infestation was recorded in both spring and summer. . The incidence of disease was higher in squabs and young birds than in adults. The mixed external parasitic infestation was recorded in this study. The infected birds showed decreased serum zinc concentration and elevated MDA and serum Nitric oxide levels. In conclusion, regular monthly treatment with deltamethrin is recommended as an effective drug in the treatment of the infested birds and succeeded in reducing the incidence of externalparasites in the treated birds; in addition, pigeon management measures must be implemented to reduce the risk of external parasites.

Evidence for idiothetic and allothetic control of thermo-orientation in feather-feeding lice.

Thermal cues are widely used by ectoparasites to find and exploit hosts. Recently, the wing louse Columbicola columbae (Phthiraptera: Ischnocera) was shown to use thermo-orientation when migrating between host microhabitats. Here, we study the control systems governing thermo-orientation by motion tracking wing lice on spatial and temporal heat gradients. As previously demonstrated, lice placed on spatial heat gradients successfully located nearby heat targets. Unilateral antennectomies were then used to remove spatial aspects of the thermal cue. These lice were still capable of locating heat targets, suggesting their response relied on tracking changes in the cue over time (idiothetic control). Course control was accomplished via angular corrections after louse body-angles deviated from the heat target. Louse behavior on temporal heat gradients provided additional evidence for idiothetic control- lice altered turn size and velocity after temperatures uniformly shifted without any spatial reference. We also show that lice are likely capable of responding to spatial aspects of the cue, consistent with allothetic control. On the spatial heat gradient, lice with two antennae were more efficient at locating heat targets as compared to those with unilateral antennectomies. Additionally, when traveling along temperature isoclines (where lice can detect spatial but not temporal aspects of the cue), lice with two antennae consistently turned towards the heat target, while those with unilateral antennectomies showed no preference. In all, we find evidence that lice can use both idiothetic and allothetic control during thermo-orientation, and likely integrate information from these two systems to guide movements on hosts.

Is Allopreening a Stimulus-Driven Defense Against Ectoparasites?

Allopreening occurs when 1 bird preens another bird. The behavior is normally directed at the head and neck of the recipient, i.e., regions that the bird cannot self-preen. Studies of penguins, pigeons, and other groups of birds suggest that allopreening plays a role in the control of ectoparasites, such as ticks and feather lice. However, it is not known whether allopreening increases in response to increases in parasite load, or whether it is a programmed response that occurs independently of parasite load. We conducted a laboratory experiment using wild-caught rock pigeons (Columba livia) to test the relationship between ectoparasite load and allopreening rate. We added feather lice (Columbicola columbae) to captive pigeons and tested for changes in allopreening rates compared to control birds with no lice added. Allopreening rates did not change in response to the addition of lice. Interestingly, however, our data revealed a negative correlation between allopreening and self-preening rates.

Impact of epidemiological factors on the prevalence, intensity and distribution of ectoparasites in pigeons.

This study was carried out on domestic pigeons (Columba livia domestica) from September (2014) to June (2015) to determine the prevalence, intensity and species of ectoparasites in Sargodha region, east of Pakistan. A total of 200 domestic pigeons were inspected from the study area. Parasites were collected by forceps and stored in 70% ethanol. The epidemiological information e.g. health condition, color of plumage, mode of living, breed, intensity etc. were recorded in the form of questionnaire. The overall prevalence of ectoparasites in pigeon was 90.5% (181/200). Of the total of 200 (83 males and 117 females) domestic pigeons inspected, 73 (87.95%) and 108 (92.30%) were infected, respectively. The ectoparasites spp. were identified as Columbicola columbae (Linnaeus, 1758) and Colpocephalum turbinatum (Denny, 1842). The Qasid breed showed highest infestation rate (91.25%) as compared to other two observed breeds. Pigeon of white color were more infested (91%) as compared to other colors. Thus color and breed factors showing the random differences. In medicated birds the rate of infestation of ectoparasites was 87% reflecting that drugs are unable to control or might be due to resistance. There was significant difference between the number of parasites on tail, neck, chest and wings within different breeds, as well as in the months. The mean intensity of parasites was in urban areas (28.5), rural areas (14.98), and sub-rural areas (23.55). In conclusion the prevalence of ectoparasites in pigeons is very high in north-east region of Pakistan.

COMPARATIVE TRANSMISSION DYNAMICS OF COMPETING PARASITE SPECIES.

Competition-colonization trade-off models explain the coexistence of competing species in terms of a trade-off between competitive ability and the ability to colonize competitor-free patches of habitat. A simple prediction of these models is that inferior competitors will be superior dispersers. This prediction has seldom been tested in natural populations because measuring dispersal is difficult. Host-parasite systems are promising in this regard, especially those involving "permanent" parasites that complete their entire life cycle on the body of the host. Because of this close association with the host, the dispersal, i.e., transmission, of these parasites can be monitored very accurately. We tested the dispersal prediction of the competition-colonization model by documenting the transmission dynamics of feather-feeding lice, which are permanent, relatively host-specific parasites of birds. We compared two groups known as "wing" lice and "body" lice that are common parasites of Rock Pigeons (Columba livia Gmelin). The two groups are ecologically similar, and they compete for resources on the host. Previous work shows that body lice are competitively superior to wing lice, leading us to predict that wing lice should be better than body lice at dispersing to new host individuals. We tested this prediction by comparing the ability of wing and body lice to disperse between hosts using vertical- and horizontal-transmission mechanisms, including phoretic hitchhiking on parasitic flies (Diptera: Hippoboscidae). A series of experiments with both captive and wild birds confirmed that wing lice are much better than body lice at colonizing new hosts. Wing lice showed significantly greater vertical transmission to nestlings, and they were quite capable of phoretic transmission to new hosts on flies. In contrast, body lice were not phoretic. These results provide the first rigorous demonstration of phoretic transmission in lice, and they underscore the importance of a community-level approach to understanding the ecology of parasite transmission dynamics.