CC BY
38
UDC 574.32
V. P. Perevozkin, S. Yu. Semenov, V. S. Galkin, A. K. Sibataev, V. V. Lukiantsev
STABILITY TO ASPHYXIA AT PREIMAGINAL STAGES OF MALARIAL MOSQUITO ANOPHELES
ATROPARVUS (DIPTERA, CULICIDAE)
Experimental researches of stability to asphyxia at preimaginal stages of malarial mosquito Anopheles atroparvus are presented. In experiments of larvae and pupae of mosquitoes were in vessels with water without access to atmospheric air. The stability depends on concentration of the dissolved oxygen in water in different temperature conditions. At alternative concentration of oxygen in water two opposite tendencies of speed of destruction of preimaginal stages of development are fixed. At concentration of oxygen of 0 mg/l in three set modes of temperatures (15 °C; 23 °C; 30 °C) stability of individuals to an asphyxia from I age to pupae is increased. In the water sated with oxygen at initial concentration of oxygen of 7-8 mg/l, on the contrary - larvae of younger age differed the raised viability in comparison with individuals of advanced ages.
Key words: bloodsucking mosquitoes, preimaginal stages, regulation of population size, asphyxia.
Introduction
The damage caused by bloodsucking mosquitoes to health and capacity for work of mankind is huge. Mosquitoes of genus Anopheles (Diptera, Culicidae) can transfer a number of causative agent of transmissible illnesses from which malaria is most dangerous and widespread. Now about 2 billion persons on the Earth live in epidemiological dangerous zones where death rate is estimated in millions per annum [1, 2].
In this connection, malarial mosquitoes are objects of regular special attention from biologists, physicians and epidemiological surveillance services. It is necessary to emphasize, that high genetic variability and mutational process ensure fast nascence of steady forms of the mosquitoes to applied insecticides that aggravates a problem of full liquidation of malaria and raise a problem of working out of essentially new methods of regulation.
Among ways of regulation at preimaginal stages of mosquitoes it should be noted the approaches based on creation of oxygen starvation conditions for larvae and pupae with their subsequent elimination from asphyxia. Perspectives for use of the approaches are stimulated by the fact that species can’t acquire resistance for asphyxia. At the same time it is essential to investigate physiology mechanisms of viability at preimaginal stages for oxygen deficiency for adequate use of the insect control methods.
The purpose of this work is estimation of stability to asphyxia at preimaginal stages of mosquitoes Anopheles atroparvus depending on concentration of the dissolved oxygen in water at different temperature conditions.
Materials and methods
From first to forth age larvae and pupae of Anopheles atroparvus from a laboratory population were objects of experimental study in laboratory conditions.
Plastic transparent bottles (vol. 27 ml) were used in experiment. In each repeated trials 10 larvae of certain
age or pupae of mosquitoes were put in a bottle using a spray bulb. Vessels were filled with tap water to the brim and closed by covers so that no air was in vials and no access of atmospheric air.
In set of observations experimental vials were kept at stable water temperature in various series: 15 °C, 23 °C, 30 °C. The water temperature of 15 °C and 23 °C was kept up by laboratory controlled temperature conditions; for maintenance of 30 °C the bottles were kept in the HARDWARE 1-20 thermostat.
Besides a temperature conditions in each series of experiments we use two levels of oxygen concentration in water: 1) absence of oxygen (reached by addition of solution Na2SO3); 2) 7-8 mg/l (as result of natural saturation of water by contact with atmospheric air). Concentration of oxygen in water was defined by Clark’s electrode (oxymeter HI 9143).
Following set of variable conditions was studied in experiments:
1) water without 02 at 15 °C, 23 °C, 30 °C;
2) water with oxygen (7.0-8.0 mg/l) at the same temperatures.
Time was measured from beginning of experiment to perishing all larvae in vial.
Results and discussion
Anopheles larvae in water breathe by tracheal system of open type. On the last segment of abdomen two main tracheal tubes begin from stigma plate and reach the front part of a breast. In each segment of the body the main tubes divide to the smallest branching - tra-cheoles (1-2 microns in diameter) and reach a surface of cellular membranes. The dense tracheal plexus is located behind last chamber of a spinal vessel and supplies with oxygen a haemolymph cells - hemocytes. As is known, the haemolymph takes only indirect part in breath process as the respiratory pigments like haemoglobin which is absent at insects [3, 4].
No special respiratory movements are observed in tracheas. Breath is realized by diffusion of oxygen
from atmosphere or water in tracheas owing to a difference in its partial pressure through spiracle of stigma plate. On a water surface the mosquito larvae are in horizontal position, if not disturbed by any external influences. They are attached to a surface film by stigma plates, and also by means of villi of body [3]. Mosquito pupae inhale the air by respiratory tubes. They are funnel-shaped and located on dorsal side of cephalothorax. The tube cavity is partitioned by branchy filtering hairs and is opened in a cavity of a tracheal trunk. Anopheles pupae have a poorly developed filtering hairs, but the external aperture is tightened by thin cuticle membrane through which air diffusion goes [5, 6].
Typical reaction of preimaginal stages on flush is the sharp diving deep into waters, sometimes up to tens centimeters [4]. At diving stigmas are closed by clasps of stigma plates. However the closing never happens completely: the air cavity is formed between front and lateral clasps. Water can’t get in stigma and displace the air because of water-repellency of stigma plate which is periodically greased with a secretion of salivary glands. Often it is possible to observe how the bent larva works up the stigma plates by clasps of an upper lip [3]. Such structures of the sphincter complex, as well as ability to breath by the dissolved in water oxygen through integuments and gills, allow larvae to dive only for the limited time. Pupae also can dive and move actively in the water column. At the same time increased retention under water for larvae and pupae results in death from asphyxia.
Experimental results show varied perishing speed of mosquito preimaginal stages at different conditions of water oxygen concentration. It is noticed, that in high water temperature the larvae or pupae remained viable less time, and this rule was showed in both series of experiments, irrespective of oxygen saturation of water (Fig. 1, 2). It indicates that, like all at typical poikilothermic organisms, processes of a metabolism at larvae and pupae of mosquitoes directly depend on temperature of environment, in this case water.
At the same time experiments demonstrate, that in the oxygen saturated water (7-8 mg/l) preimaginal stages remained viable at all temperature rates significantly longer, than in water without 02 (Fig. 1, 2). Thus, larvae by gills and integument breath, and pupae only by integument breath can be essentially longer viable in the water column under conditions of isolation from atmosphere oxygen.
Two opposite tendencies are revealed in speed of perishing of preimaginal stages in two series of experiments at alternative concentration of oxygen. Almost linear increase of stability to asphyxia from the first larval age to pupae (Fig. 3) was observed at oxygen concentration of 0 mg/l in three sets of temperature conditions. On the contrary larvae of younger ages differs by increased viability in comparison with advanced stages of development (Fig. 4) in the oxygen saturated water at initial concentration of 7-8 mg/l.
The deviation from directly proportional change of viability is noted in series of experiments with initial oxygen concentration of 7-8 mg/l at temperature of
15 23
t, °C
III
t, °C
IV
t, °C
Fig. 1. Perish time dependence on temperature of preimaginal stages of Anopheles atroparvus at 0 mg/l oxygen concentration. Designations:
I, II, III, IV - stages of larvae; P - pupae; T - perish time; t - temperatures
.E 3000 E
l_" 2000 1000 0
15 23 30
t, °C
5000
4000
3000
E
l_" 2000 1000 0
15
23 t, °C
30
6000 5000 c 4000 Ë 3000 ^ 2000 1000 0
t, °C
IV
2000
1500
c
£ 1000 I-"
500
0
s'
1
A 1
15
23 t, °C
30
t, °C
Fig. 2. Perish time dependence on temperature of preimaginal stages of Anopheles atroparvus at 8 mg/l oxygen concentration. Designations:
I, II, III, IV - stages of larvae; P - pupae; T - perish time; t - temperatures
Fig. 3. Perish time for preimaginal stages at 0 mg/l oxygen concentration. Designations: I, II, III, IV - stages of larvae; P - pupae; T - perish time; t - temperatures
Fig. 4. Perish time for preimaginal stages at 8 mg/l oxygen concentration. Designations: I, II, III, IV - stages of larvae; P - pupae;T - perish time; t - temperatures
O
15 °C when the greatest viability was shown by second and third age larvae (Fig. 4).
However in such conditions they stay alive for 3-4 days; therefore their viability might be defined by some individual specific physiology features which become apparent at prolonged experiment series. But at the same time a natural tendency of increased viability of younger stages comparatively the last remains in oxygen saturated water and low temperatures.
Obviously, integumentary breath of advanced larval stages provides a small part of oxygen requirements, at the same time they are characterized by the big stock of air in tracheas and stigma apparatus.
Thus, it is necessary to consider temperature and oxygen concentration as well as age structure of insect population in realization of programs for control population sizes of mosquitoes by the asphyxia methods.
References
1. Onishchenko G. G. About epidemic situation and morbidity of natural seats' infection in Russian Federation and measures of their prevention // ZhMEI, 2001. № 3. P. 22-28.
2. Litvin V. Y., Korenberg E. I. Natural nidality of diseases: continuation of conception to the end of century. In the book: Natural nidality of diseases: observations of institute Gamaleya RAMS. Under the editorship of E. I. Korenberg. M., 2003. 254 p.
3. Pat. 2370952 S1 RF, А01М 1\20 (2006.01). Way of Mosquitoes' larvae Destruction / Semenov S. Yu., Sibataev A. K., Perevozkin V. P.; declarant
and possessor of patent, GOUVPO Tomsk State University. 2008133300/12, declarant 13.08.2008, published 27.10.2009.
4. Monchadsky A. S. Larvae of Bloodsucking Mosquitoes USSR and Adjacent Countries (Subfamily Culicinae). М.: Publishing House: AS USSR,
1951. 290 p.
5. Yasyukevich V. V., Rasnitsyn S. P. Role of scraping of substratum in nutrition of malarial mosquitoes' larvae // Medical Parasitology and Parasitical Diseases. 1989. № 1. P. 19-22.
6. Shvanvich B. N. Course General Entomology. M.: Soviet Science, 1949. 900 p.
Perevozkin V. P
Tomsk State Pedagogical University.
Ul. Kievskaya, 60, Tomsk, Russia, 634061.
Tomsk State University.
Pr. Lenina, 36, Tomsk, Russia, 634050.
E-mail: pvptomsk@rambler.ru
Semenov S. Yu.
Tomsk State University.
Pr. Lenina, 36, Tomsk, Russia, 634050.
E-mail: pure@sibmail.com
Galkin V. S.
Tomsk State Pedagogical University.
Ul. Kievskaya, 60, Tomsk, Russia, 634061.
E-mail: vitalygalkin2008@rambler.ru
Sibataev A. K.
Tomsk State University.
Pr. Lenina, 36, Tomsk, Russia, 634050.
E-mail: anuar@res.tsu.ru
Lukiantsev V. V.
Tomsk State University.
Pr. Lenina, 36, Tomsk, Russia, 634050.
E-mail: vvluk@Sibmail.com
Received 14.03.2011.
В. П. Перевозкин, С. Ю. Семёнов, В. С. Галкин, А К Сибатаев, В. В. Лукьянцев
УСТОЙЧИВОСТЬ К АСФИКСИИ преимагинальных стадий развития малярийного комара ANOPHELES ATROPARVUS (DIPTERA, CULICIDAE)
Представлены результаты экспериментальных исследований устойчивости к асфиксии преимагинальных стадий малярийного комара Anopheles atroparvus. В экспериментах личинки и куколки комаров находились в сосудах с водой без доступа к атмосферному воздуху. Устойчивость зависит от концентрации растворенного кислорода в воде при разных температурных условиях. Зафиксированы две противоположные тенденции скорости гибели преимагинальных стадий развития при альтернативных концентрациях кислорода в воде. При концентрации кислорода 0 мг/л в трех вариантах температурных режимов (15 °С, 23 °С, 30 °С) наблюдалось повышение устойчивости особей к асфиксии от первого возраста до куколки. В воде, насыщенной кислородом, при начальной концентрации кислорода 7-8 мг/л, наоборот, личинки младших возрастов отличаются повышенной жизнеспособностью по сравнению с индивидуумами старших возрастов.
Ключевые слова: кровососущие комары, преимагинальные стадии, регуляция численности популяции, асфиксия.
Перевозкин В. П., кандидат биологических наук, доцент, старший научный сотрудник.
Томский государственный педагогический университет.
Ул. Киевская, 60, Томск, Россия, 634061.
Томский государственный университет.
Пр. Ленина, 36, Томск, Россия, 634050.
E-mail: pvptomsk@rambler.ru
Семёнов С. Ю., кандидат биологических наук, зав. кафедрой, зав. лабораторией.
Томский государственный университет.
Пр. Ленина, 36, Томск, Россия, 634050.
E-mail: pure@sibmail.com
Г алкин В. С., аспирант.
Томский государственный педагогический университет.
Ул. Киевская, 60, Томск, Россия, 634061.
E-mail: vitalygalkin2008@rambler.ru
Сибатаев А. К., доктор биологических наук, профессор кафедры, старший научный сотрудник. Томский государственный университет.
Пр. Ленина, 36, Томск, Россия, 634050.
E-mail: anuar@res.tsu.ru
Лукьянцев В. В., научный сотрудник.
Томский государственный университет.
Пр. Ленина, 36, Томск, Россия, 634050.
E-mail: vvluk@Sibmail.com
