Anti-mosquito antibodies decrease the reproductive capacity of Aedes aegypti

Aedes aegypti (L.) fed on rabbits immunized with mosquito antigens showed a reduction in fecundity in the first oviposition and decreased viability of the progeny. Feeding behaviour of mosquitoes was not affected and no significant mortality was observed due to the presence of anti-mosquito antibodies in the bloodmeal. Antibodies were detected in the oocytes of mosquitoes 48 h after the bloodmeal. The role of specific antibodies in influencing fecundity is discussed.     

Respiratory Responses in Potato Tubers as an Index of the effect of Ethylene Chlorhydrin and Ammonium Thiocyanate

1. The variety Phulwa was worked upon for respiratory studiesandgrowth response to dormancy-breaking hormones. The hormoneswere used in single and double doses.
2. The respiratory studiesreveal that ethylene chlorhydrin affectsonly the bud areasand not the non-bud areas.
3. The intensity of the effect ofthe hormone progressively decreasesin the deeper layers ofcells, till finally no effect is visiblein the cells of thepith areas.
4. A distinct correlation exists between the respiratoryintensityand dormancy.
5. Of the two hormones used the respiratoryrates recorded forN. ethylene chlorhydrin treated tubers, givenin single anddouble doses, were the highest. Similarly thegrowth responseto both the doses showed the maximum reductionof the dormancyperiod, 01 N. ethylene chlorhydrin treatmentswere not effectivein breaking the dormancy or in significantlyaltering the rateof respiration.
6. Treatments with 05 percent, ammonium thiocyanate given insingle dose showed the lowestrespiratory rates and the germinationrecords showed no differenceover the control. With the doubledose a gradual rise in therespiratory rates was observed. Thegermination records alsoshowed an earliness of 20 and 22 daysover the control and single-dosetreatments respectively.
7. Treatments with 2 per cent, ammoniumthiocyanate depressed germination.The respiratory rates recordedwere also low.
8. In general the double-dose treatments showedbetter resultsthan the single-dose treatments. Also, treatmentson 3 weeksold tubers were more effective than on 6 weeks oldtubers.

     

Antibodies to Anopheles midgut reduce vector competence for Plasmodium vivax malaria

Anopheles tessellatus mosquitoes ingested Plasmodium vivax gametocytes in human erythrocytes suspended in rabbit sera with and without anti-mosquito midgut antibodies. When the mosquito bloodmeal contained anti-midgut antibodies, fewer oocysts of P. vivax developed on the mosquito midgut and the proportion of mosquitoes becoming infected was significantly reduced. Complement inactivated serum also reduced the infection rate and load. A second bloodmeal containing anti-midgut antibodies, given 48 or 72 h later, did not enhance the transmission-blocking effect. IgG purified from antimidgut sera was shown to mediate the transmission-blocking effect.     

Anti-mosquito antibodies reduce the susceptibility of Aedes aegypti to arbovirus infection

Aedes aegypti (L.) mosquitoes showed a significant reduction in susceptibility to infection with Ross River virus and Murray Valley encephalitis virus when they were fed on a blood-virus mixture containing rabbit antibodies to mosquito midgut components. Presence of the antibodies did not demonstrably affect virus titres in infected mosquitoes, nor the transmission of virus from infected mosquitoes to vertebrates.     

Interactions of human malaria parasites, Plasmodium wVaxand P.falciparum, with the midgut of Anopheles mosquitoes

Abstract Present understanding of the development of sexual stages of the human malaria parasites Plasmodium vivax and P.falciparum in the Anopheles vector is reviewed, with particular reference to the role of the mosquito midgut in establishing an infection. The sexual stages of the parasite, the gametocytes, are formed in human erythrocytes. The changes in temperature and pH encountered by the gametocyte induce gametogenesis in the lumen of the midgut. Macromolecules derived from mosquito tissue and second messenger pathways regulate events leading to fertilization. In An.tessellatus the movement of the ookinete from the lumen to the midgut epithelium is linked to the release of trypsin in the midgut and the peritrophic matrix is not a firm barrier to this movement. The passage of the P. vivax ookinete through the peritrophic matrix may take place before the latter is fully formed. The late ookinete development in P.falciparum requires chitinase to facilitate penetration of the peritrophic matrix. Recognition sites for the ookinetes are present on the midgut epithelial cells. N-acetyl glucosamine residues in the oligosaccharide side chains of An.tessellatus midgut glycoproteins and peritrophic matrix proteoglycan may function as recognition sites for P.vivax and P.falciparum ookinetes. It is possible that ookinetes penetrating epithelial cells produce stress in the vector. Mosquito molecules may be involved in oocyst development in the basal lamina, and encapsulation of the parasite occurs in vectors that are refractory to the parasite. Detailed knowledge of vector-parasite interactions, particularly in the midgut and the identification of critical mosquito molecules offers prospects for manipulating the vector for the control of malaria.