Pediculus humanus capitis (head lice) and Pediculus humanus humanus (body lice): response to laboratory temperature and humidity and susceptibility to monoterpenoids

Abstract

Human pediculosis is produced by Pediculus humanus humanus (Linnaeus 1758) and Pediculus humanus capitis (De Geer 1767). Laboratory-reared body lice, susceptible to insecticides, were used as reference in toxicological studies on head lice. In this work, we evaluated the survival of both subspecies at different temperatures and relative humidities and we propose the optimal conditions for comparative bioassays. Moreover, we used these conditions to test the activity of three monoterpenoids against both lice. The results showed differential response to changes in temperature and humidity between both organisms. The survival of body lice ranged between 83% and 100% and was not affected for the tested conditions. The survival of head lice depended on temperature, humidity, and exposure time. The optimal conditions for head lice were 18 masculineC and 97% relative humidity at 18 h of exposition. The insecticidal activity of three monoterpenoids (pulegone, linalool, and 1,8-cineole), evaluated according the selected conditions by topical application, showed no significant differences between males of body and head lice. To conclude, as head lice required more special laboratory conditions than body lice, the optimal head lice conditions should be used in both organisms in comparative bioassays. Body louse is an appropriate organism for testing products against of head louse.

Activity of increased specific and non-specific esterases and glutathione transferases associated with resistance to permethrin in pediculus humanus capitis (phthiraptera: pediculidae) from Argentina

“…Five permethrin-resistant populations with different levels of resistance were collected, namely Bandera Argentina (BA), Hogar Loyola (HL), República de Turquía (RT), Hogar Mitre (HM), Guardia de Honor (GH) and Ricardo Guiraldes (RG). Adults and third instar were selected at the laboratory for the bioassays (Mumcuoglu et al 1995;Picollo et al 2000;Vassena et al 2003;Gallardo et al 2009). Once collected, the lice were kept in an environmental chamber (Lab-Line Instruments, Melrose Park, IL) at 18±0.5°C and 70-80% RH, in the dark and without food for a maximum of 2 h before the toxicological bioassays and 15 h before biochemical assays.…”

Terpenes: Natural Products for Controlling Insects of Importance to Human Health—A Structure-Activity Relationship Study

“…Usually, the lice that infest humans are sucking lice that live in close association with the host and lay their eggs on hair shafts or in the seams of clothing [9]. Pediculus humanus humanus (Linnaeus 1758) and Pediculus humanus capitis (De Geer 1767) are two obligate ectoparasites which affect the body and head of the host, respectively, with Pediculus humanus appearing to be the vector of Rickettsia prowazeki and Borrelia recurrentis, two microorganisms of importance to human health [10][11][12]. The management of head lice infestation has a major disadvantage compared to the control of other insect pests, as the human hosts want the head lice to be completely eliminated [13].…”

Response of Pediculus humanus humanus (Pediculidae: Phthiraptera) to water or 70% ethanol immersion and determination of optimal times for measuring toxic effects

“…Although head and body lice show similar toxicological phenotypes, the results in body lice might be different from those obtained in head lice, which in general die earlier and require more restricted laboratory conditions of temperature and humidity for the survival than body lice (Gallardo et al 2009). …”

“…These categories were determined by inspecting each louse with an Olympus SZ4045 stereomicroscope. All bioassays were performed at the optimal temperature for comparative bioassays of head and body lice, 18°C and 97% RH (Gallardo et al 2009). …”

“…As head and body lice show similar toxicological phenotypes, a laboratory-reared P. humanus humanus is frequently used as a reference colony in insecticide resistance studies for head lice and as a test organism to evaluate the efficacy of potential pediculicides (Mumcuoglu et al 1990;Downs et al 2000;Kristensen et al 2006;Priestley et al 2006;Mougabure Cueto et al 2008;Gallardo et al 2009). Furthermore, a laboratory-reared colony allows carrying out bioassays under standardized physiological conditions.…”