Third Day Poster Session, 17 June 2010 - NanoTR-VI

Poster Session, Thursday, June 17
Theme F686 - N1123
Effects of dehydrating conditions on Dermatophagoides farina and Dermatophagoides pteronyssinus
Nada O. Edrees
Department of Biology, Faculty of Sciences for Girls, king Abdelaziz university .Jeddah , Kingdom of Saudia arabia
E-mail : nada_algalb@hotmail.com
nedrees@kau.edu.sa
Abstract
House dust mites have lived in human contact from time immemorial dander or dead skin constitutes the major organic
component of house dust ecosystem . Because the mites feed on dander , dust mite and human association will continue to co
exist as part of our environment . Efficient house – draying practice is the best form of control to reduce infestation , keeping
home dray ( Nadchatram , 2005). Sensitization and development of allergic respiratory disease result from complex genetic and
environmental interactions . Specific measures to reduce indoor allergen exposure when vigorously applied may reduce the risk
of sensitization and symptoms of allergic respiratory disease (Bush , 2008) . Survival experiments with D.farnae and
D.pteronyssinus were. In environments containing water vapor below the CEA , more water is transpired than absorbed from the
atmosphere and thus dehydration occur . An increase in temperature seems to increase the rate of dehydration . When exposed to
dehydrating condition (35% , 25% ,15% RH) . D.pteronyssinus and D.farinae exhibited increase mortality in response to an
increase of temperature . The lower mortality for males may be accounted for by their larger surface area to volume ratio , which
result in transpiration occurring at a greater rate than in females .
Key word: Dermatophagoides pteronyssinus , Dermatophagoides farina , humidity, dehydration , saudia Arabia .
Introduction
The house dust mite Dermatophagoides farinae ,Dermatophagoides pteronyssinus are the major sources of indoor allergens
and are therefore considered important health problems worldwide . Many allergic individuals (hay fever , asthma , atopic
dermatitis ) are sensitive to these mite ( Adgate , et al ,2008 ; Van Gysel et al , 2007, Edrees ,2008d) The worm , humid
environment in modern homes favours the dust mite population , most homes contain one or more species of these house dust
mite (Wu et al , 2009) . Carpets , mattresses , bedding , pillows, pillow covers , and clothing may contain breeding population
of house dust mite . Saudi Arabia is a fast developing country situated in the middle of the Arabian Peninsula . Due to the
variation in geography and climate . Particularly humidity of the regions which vary significantly . Riyadh in the central region
is considered to have low humidity . While humidity in western coastal region , Jeddah and southern region of Abha is
comparatively higher . which helps house dust mites thrive , in autumn and winter not during summer specially in Jeddah due to
the increasing of temperature up to 50°C (Edrees , 2009) .
In Jeddah most homes contain both D.farinae ,D.pteronyssinus (Edrees,2006,2008 a,b,c). However , special precautions are
important when individuals are susceptible or sensitive to house dust mite .This the extremely important for a possible integrated
control that can be taken to eliminate house dust mite and their allergens from the indoor environment .Most adult of D.farinae
and all adult of D.pteronyssinus cannot survive when exposed to 45°c for at least 48hr . Dehydration and survival of the house
dust mite D.farinae and D.pteronyssinus at specific ambient conditions , was undertaken to determine the possibility of
temperature and humidity manipulation as a natural control method (Arlian 1975 , Brandt & Arlian ,1976). The purpose of this
study was to systematically investigate survival of D.pteronyssinus and D.farinae Exposure to specific relative humidity and
temperatures , determine whether these additives would increase mortalities during dehydration .
Matrrial and mehod
D.farinae and D.pteronyssinus used for experimentation were obtained from thriving pure laboratory culture at 75% RH and
25°C , as described by Arlian (1975) incubator to provide the desired temperature . the critical equilibrium activity(CEA) of adult
females to be 0.70 and 0.73 (70% and 73%RH) , respectively , (Robert ,et al 1976) .
Statistical analysis :The data in tables ( 1 , 2 ,3) are presented as mean ± . The statistical analysis between the mites species and
the different six of each species were performed using paring " t – test " (Armitage , 1974 ) . All statistical were computed by
SPSS 14 .
Exposure to specific relative humidity and temperatures : Survival experiments with D.farnae and D.pteronyssinus were
conducted by placing 10 adults of 1 sex together in a glass vial containing a sufficient amount of yeast for food. Eight to 15 vials
(100 mite) were used per experiment . The vials were constructed from 5 mm diam. X 20 mm lengths of glass tubing . To confine
the mite , the ends were plugged with a nylon mesh screen by inserting a Teflon washer into each end of the cage . An average
distance of 10 mm was maintained between the plugs . After being equilibrated at 25°C and 75% RH for 24 hr , the vials were
suspended in closed ,4-oz(0.12-liter)bottles containing the appropriate glycerol solution to maintain the desired test RH'S. In turn
, these bottles were placed in a BOD (Biochemical Oxygen Demand ) incubator to provide the desired temperature . Survival
counts were made every 42 hr until 100%mortality was achieved (Robert et al ., 1976) . In this study the relative humidity is
recorded after each 48 it showed gradually decreasing (75% RH , 65% RH , 55% RH , 45% RH , 35 RH %,25 RH %, 15% RH )
, during the gradually increasing of temperature( 32°C , 37°C , 42°C, 44°C , 46°C , 48°C , 50°C ) .
RESULTSIncreasing in mortality is recorded gradually by increasing temperature which consequently lead to decrease the
humidity as a result of dehydration, the investigation had been recorded each 48 hours to count the survival mites . The
calculated of mortality and survival in test population male, at specific time intervals when exposed to various temperature and
humidity were shown in tables. male have tolerated desiccation better than fmales at all RH tested at all temperature regimes
tested( tables 1,2,3) .
6th Nanoscience and Nanotechnology Conference, zmir, 2010 817