Impact of temperature on susceptible and resistant strains of Culex quinquefasciatus to synthetic pyrethroids.

Effect of temperature on the physiological activity and resistance status of Culex quinquefasciatus was studied. The LT(50) (lethal time) of deltamethrin, lambdacyhalothrin resistant and susceptible 4th-instar larvae decreased with increasing temperature. The LT(50) of deltamethrin resistant strains was significantly lower than the susceptible strains but not so in lambdacyhalothrin resistant strains. The developmental period of the thermal exposed and non-exposed larvae of resistant strains were nearly equal, however a significant difference was observed in case of susceptible strain. The thermal exposed susceptible larvae developed 3.3 days faster than the thermal un-exposed population. The percentage of survival of thermal exposed and un-exposed resistant strains were nearly equal. However, the thermal exposed population survived 12.9% less than the thermal un-exposed susceptible population. Longevity of thermal exposed deltamethrin and lambdacyhalothrin resistant females was significantly higher than the un-exposed population. The longevity of thermal exposed susceptible population was lower than the un-exposed population. The resistance of both the deltamethrin and lambdacyhalothrin resistant strains increased when exposed to high temperature for 3h. The difference in longevity between thermal un-exposed and exposed resistant male population was not significantly different. Among the un-exposed population, highest pupation was recorded in the susceptible strains, and lowest in the deltamethrin resistant strain. The fact that the thermal exposed resistant strains were more successful than the un-exposed population could be related to the presence of resistant gene.

Characterization of biochemical based insecticide resistance mechanism by thermal bioassay and the variation of esterase activity in Culex quinquefasciatus.

Biochemical mechanisms of insecticide resistance of thermal exposed and unexposed Culex quinquefasciatus strains are evaluated, which were not studied earlier. The activity of alpha- and beta-carboxylesterases and acetylcholinesterase of malathion susceptible and resistant strains were compared after thermal treatment. Three-day-old adult females were used for the malathion susceptibility test and biochemical assays, and males were used only for the susceptibility test. Thermal exposure brought about increase in resistance levels from 85% to 90% in males and 91% to 96.6% in females of resistant strain. The resistance status of the susceptibility strain was unchanged after thermal exposure. The activities of alpha- and beta-carboxylesterase of susceptible mosquitoes were within 800 and 700 U/mg protein, respectively. The alpha-carboxylesterase activity of the thermal exposed malathion-resistant population was significantly (t test, P < 0.05) higher than the unexposed resistant population, and the reverse was recorded in beta-carboxylesterase. The alpha-carboxylesterase activity of susceptible population was lower than the resistant population. The activity of alpha-carboxylesterase was higher than the beta-carboxylesterase in both the strains. Among the malathion resistant C. quinquefasciatus population, 2.3% population exhibited 30-40% inhibition which increased to 5.8% after the thermal exposure. Thermal exposure of mosquitoes increased the activity of both alpha-carboxylesterases and acetylcholinesterase but decreased the activity of beta-carboxylesterase.

A review on Anopheles culicifacies: from bionomics to control with special reference to Indian subcontinent.

Anopheles culicifacies, is a complex of five isomorphic sibling species A, B, C, D and E and is considered to be the major malaria vector in the Indian subcontinent. Despite numerous studies, it is difficult to have a global view of the ecological and bionomical characteristics of the individual sibling species, as different identification methods have been used. Major biological and ecological trends such as the high plasticity of behaviour and the sympatry of species are addressed. In spite of the availability of rapid molecular identification tools, we still lack important information concerning the biological characteristics of each sibling species. Resistance to insecticide is alarming as it has developed quadruple resistance in two states of India. An intensified and appropriate intervention measure to interrupt transmission is the call of the day. The authors focus on (1) reviewing the vectorial aspects of An. culicifacies (2) discussing recently published data on bionomics of each sibling species, (3) identifying lacunae in the understanding of the Culicifacies complex, and (4) exploring the possibility of proper control measures. Our understanding of the bionomics of all the five sibling species would certainly help, keeping in mind the climatic changes we are to face in the next few years.

Effect of temperature on development, eclosion, longevity and survivorship of malathion-resistant and malathion-susceptible strain of Culex quinquefasciatus.

Density of vectors and development of resistance against insecticides are two important aspects in the control of vector-borne diseases. Here, effect of temperature on different aspects of development of malathion-resistant and susceptible strains of Culex quinquefasciatus was evaluated in the laboratory. Fourth-instar larvae of C. quinquefasciatus were exposed to 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C, and their LT(50) values calculated. The fourth-instar larvae were subjected to heat for 4 h at 39 degrees C and live larvae were reared until the completion of life cycle. The larvae of malathion-resistant strain were more tolerant to heat than the larvae of malathion-susceptible ones. The difference in mortality between 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C of both the strains of C. quinquefasciatus were highly significant. Pupation percentage of heat-exposed larvae of both the strains was higher and delayed than the control ones. The percentage of adult emergence from the heat-exposed larvae was significantly lower than the control. The adult female of malathion-resistant strain showed increased longevity when exposed to heat at larval stage but reverse was true in case of malathion-susceptible. The highlights of the study would help in the management of resistance of mosquito vectors in the tropics where variable climatic condition is observed.

Nanosilica-from medicine to pest control.

Nanotechnology is a broad interdisciplinary area of research, development, and industrial activity that has been growing rapidly worldwide for the past decade. More ambitious uses of nanoparticles are bioremediation of contaminated environments, controlled release of fragrances, biocides, and antifungals on textiles. Silica nanocomposites have received much attention because of its thermal degradation behavior and applications in chromatography, medicine, optics, etc. Nanobiotech takes agriculture from the battleground of genetically modified organisms to the brave new world of atomically modified organisms where rice has been modified atomically. Silica has been widely applied in various industries. Application of gold-coated silica has been used in the treatment for benign and malignant tumor. Surface-modified hydrophobic as well as lipophilic nanosilica could be effectively used as novel drugs for treatment of chicken malaria and nuclear polyhedrosis virus (BmNPV), a scourge in silkworm industry. Here, the authors attempt to provide a review to explain the impact of nanosilica on basic biology, medicine, agro-nanoproducts, and use of amorphous nanosilica as biopesticide.

Sketches of surgical cases drawn in 1884-87 at the East London Hospital for Children, Shadwell.

Most of the surgical cases were under the care of the Surgeon Robert William Parker, who was on the staff of the East London Hospital for Children, Shadwell. He was born in 1842 and qualified in 1869, and after working at the London Hospital he served with distinction as a volunteer with the Anglo-American Ambulance in the Franco-Prussian War 1870-1871. Then he became Resident Medical Officer at the Children's Hospital, 49 Great Ormond Street, and later in 1876 joined the staff of the Shadwell Hospital and was an active member of several London medical societies at which he presented surgical topics and cases of paediatric interest. Also, having a knowledge of German and French, he translated several surgical works from the continent. This miscellany of sketches drawn by a Nurse Reeve in 1883-1887 consists of the following: first, talipes and genu recurvatum. Each supposed to be caused by their intrauterine position; flexion contractures of the knee and equinus deformity due to poliomyelitis; lesion, such as amniotic band of the fingers, naevus of the forearm and warty lesion of the finger; skin contracture of the wrist following burns; absence of the lower ends of the radiui; two fatal cases of cancrum oris (noma) following measles; one of cleft palate and lip; three drawings of malignant disease of the thigh and face; finally strumous dactylitis and cyst of the neck.

Milk bolus obstruction in the neonate.

Seventeen cases of neonatal intestinal obstruction due to inspissated milk curds were seen at this hospital in the 9 years 1964-1972. The obstruction started on the 2nd to 10th day of life. Half the babies passed blood from the rectum and in most the x-rays were diagnostic. All survived, 14 after operation and 3 after medical treatment with a Gastrografin enema. Incomplete absorption of solids, particularly the fat from cows' milk feeds, is suggested as the cause.