Background
The intensive use of chemical insecticides against mosquitoes has led to the development of widespread insecticide resistance. Control of
Anopheles
mosquitoes in malaria endemic areas of sub-Saharan Africa has become increasingly difficult. There is an urgent need for malaria control programmes to adopt more integrated mosquito management approaches that include sustainable, nonchemical solutions. The mermithid nematode
Romanomermis iyengari
is one of several natural control alternatives to synthetic pesticides for mosquito suppression. This study evaluated the effectiveness of the nematode
R. iyengari
for control of
Anopheles gambiae
.
Methods
The nematode
R. iyengari
was mass-produced, and pre-parasitic stage (J2) were used for laboratory and field experiments. In laboratory experiments, two concentrations of pre-parasitics (5 and 10 J2 per larva) were tested against first- (L1), second- (L2) and third-instar (L3) larvae of
An. gambiae
. Infected larvae were observed daily to determine their mortality rate and the number of post-parasitic nematodes emerging from dead larvae. In field experiments, 3500, 4000 and 5000 J2/m
2
were sprayed in separate natural
Anopheles
breeding sites. After treatment, the larval mosquito density in the breeding sites was assessed every 5–7 days.
Results
Laboratory results showed that larval
An. gambiae
is susceptible to nematode infection: 100% L1 larvae died within 24 hours post-treatment, and 100% of both L2 and L3 larvae died within 7 days, regardless of nematode concentrations. The average number of post-parasitic nematodes emerging per larva increased with increasing nematode concentration. In field experiments, the monthly applications of 3500 to 5000 pre-parasitic nematodes per m
2
eliminated larval mosquito development in
Anopheles
- and mixed breeding sites. Larval mosquito density dramatically decreased five days after the first treatment in all treated sites and was maintained at a very low level during the whole experimental period. Basically, only early instar larva were detected in treated sites throughout the test period. The average number of post-parasitic nematodes emerging per larva collected in treated sites was 1.45, 2, and 5.7 respectively for sites treated with 3500, 4000, and 5000 J2/m
2
.
Conclusions
Malaria mosquito larvae is susceptible to
R. iyengari
infection in West Africa. Parasitism intensity depends on tested nematode concentrations. Monthly application of 3500 J2/ m
2
was enough to control effectively larval
An. gambiae
in wetlands and f...
Fournier's Gangrene is a fulminating necrotizing fasciitis of the perineum and genitalia. Standard treatment involves immediate excision of all necrotic tissue, aggressive antibiotic coverage, and supportive medical care. Still, the infection is commonly fatal or disfiguring. Wound treatment with disinfected blowfly larvae (maggot debridement therapy or MDT) has been shown to be highly effective, with multiple studies demonstrating effective debridement, disinfection, and promotion of granulation tissue. MDT also has been associated with preservation of viable tissue and minimised blood loss. This report describes a prospective clinical study of MDT for Fournier's gangrene aimed to test the hypothesis that early use of maggots could decrease the number of surgical treatments required to treat Fournier's gangrene. Subjects were provided with one initial surgical excision, followed by debridement using only medical grade Lucilia sericata larvae. Only two subjects were enrolled, both diabetic men. Intensive care and culture‐directed antimicrobial coverage were administered as usual. Maggot debridement was associated with the disappearance of necrotic tissue, control of infection and granulation tissue growth. In both subjects, wounds healed without requiring further surgical resection or anatomical reconstruction. Maggot therapy decreased the number of surgical procedures that otherwise would have been necessary, and led to favourable outcomes.
The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat of Pseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration.
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