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Background: Vector control of Malaria is mainly made by using impregnated bed nets and insecticides pulverizations indoor or/and outdoor. Besides, appearance and development of resistance’s phenomenon among mosquito populations to insecticides, constitute a significant obstacle this fighting. Aims: To highlighting a neutralization phenomenon of three insecticides (methyl-parathion, dimethoate and cypermethrin) during development of the Anopheles gambiae s.s. larvae. Methodology: Two setups followed one after the other were designed. In setup 1, four concentrations (with four replicates each) were freshly prepared and independently received a first batch of 100 first instars An. gambiae s.s. After emergence of adults from this first batch, the same test media were simply filtered and received a second batch of first instars larvae to make setup 2. Three endpoints were measured in this study: the duration of larval phase, the larval mortality, and the size of adults. Results: The development duration and mortality of larvae decreased significantly at setup 2 with cypermethrin and methyl-parathion. Thus, the duration of larval stage decreased from 10.18 days at setup 1 to 7.84 days at setup 2 for 0.010 µg/l (highest concentration) with cypermethrin and from 10.20 days at setup 1 to 8.27 days at setup 2 for 0.144 µg/l (highest concentration) with methyl-parathion. The larval mortality dropped from 79.32 % at setup 1 to 12.00 % at setup 2 for the highest concentration of cypermethrin and from 76.42 % at setup 1 to 12.50 % at setup 2 for the highest concentration of methyl-parathion. While adults size significantly increased in setup 2. For males, wing’s length increased from 3.28 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of cypermethrin, from 3.31 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of methyl-parathion. In female, wing’s length increased from 3.52 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of cypermethrin, from 3.49 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of methyl-parathion. Conclusion: This work shows that mosquito larvae, especially An. gambiae are able to modify breeding medium to improve its fitness during their development.

Background: The present work aimed to highlight process of transmission of tolerance to insecticides in An. gambiae population over several generations. Methodology: The experiment was carried out at the laboratory with the strain of An. gambiae that was continuously raised under laboratory conditions for more than five years. The insecticides used during this study belong to three families: methyl-parathion (carbamates), dimethoate (organophosphate), and cypermethrin (pyrethroids). For each insecticide we chose the concentration of insecticide able to exert a selective pressure on An. gambiae without inducing a total mortality. The experiment was done through 12 consecutive generations of An. gambiae s.s. the Endpoints measured: the duration of larval development, larval mortality, and the size of adults. Results: For cypermethrin (pyrethroid) and methyl-parathion (carbamates), the development duration of the larval phase as well as larval mortality decreases significantly from the 7th generation onwards. In the other hand, the size of the adults increases significantly as early as the 5th generation for females especially for cypermethrin and the 7th generation for males. However, with dimethoate, the duration of the larval phase did not vary significantly over the generations. A decrease in larval mortality was noted from the 8th generation but it remained too high. Adult size also increased significantly from the 8th generation onward in both the two genera. This work showed the improvement over generations of certain biological indicators of the resistance. Thus, Conclusion: we can state that resistance appears fairly early in An. gambiae s.s., especially for insecticides that are effective at low doses, such as cypermethrin and methyl-parathion

Aims: This study aimed to investigate the levels of efficacy of anthelmintics that were most commonly used in sheep farms in Nziih locality. Study Design: Longitudinal prospective study. Place and Duration of Study: The study was carried out in Nziih locality in August 2019 and September 2020. Methodology: Resistance against Albendazole (12.5 mg/kg) and Ivermectin (0.2 mg/kg) was evaluated using faecal egg count reduction test in naturally occurring gastrointestinal strongyles of sheep in Nziih. A total of 300 young animals were randomly selected from 5 farms in 2019 and in 2020. Faecal samples were collected from each animal on the first day of treatment (D0) and collected again 14 days later (D14). Faecal Egg Counts were performed using the Willis and Mac Master techniques and resistance was declared when faecal egg count reduction (FECR) was less than 95 % and the lower limit of confidence interval (LCI) less than 90%. Pooled faecal samples for each treatment group were set for D0 and D14 to identify resistant strongyles genera by calculating persistent larval rate (PLR). Results: Resistance against Ivermectin was detected while there was none against Albendazole. Moreover, it was declared only in 2 farms out of the 5 selected. From 2019 to 2020, the status of resistance has shifted from suspicion to resistance for ivermectin and from absence of resistance to suspicion to Albendazole. Resistance was recorded in 2 sites: Pastorale1 (FECR= 85 %, LCI= 42.61 %) and Pastorale 3 (FECR=90.5 %, LCI= 72.26 %) in large flock herds and in farms where sheep were dewormed at least 4 times per year. Trichostrongylus were more persistent than Haemonchus and Oesophagostomum/Chabertia with PLR of 21.22 %, 13.71 %, and 7.40 % respectively. Conclusion: Anthelmintics must be used correctly in conjunction with farmer education in Nziih.

Introduction: Gastrointestinal nematodes have a deleterious effect on animal health and production. In search of alternative to synthetic anthelminthics in the control of strongylosis among small ruminants, this study was conducted to evaluate the in situ adulticidal properties of Moringa oleifera on gastro-intestinal strongyles of goats. Methods: Twenty (20) goats naturally infested with mixed gastrointestinal nematodes were distributed into 5 groups (n=4): a negative control group receiving Tween 80 at 2.8%, a positive control group treated with Albendazole at 5 mg/kg and tested groups treated with doses of extract (125, 250 and 500 mg/kg). In situ anthelminthic activity was assessed through determination of the faecal eggs count reduction, total worm count reduction, variation of packed cell volume (PCV) and body weight after treatment. Results: Five species of nematodes were identified among experimental animals, with Strongyloides papillorus as the most prevalent (93.8%) followed by Haemonchus contortus (87.5%). At dose of 500 mg/kg, ethanolic extract of M. oleifera registered 76.4 % and 69.8 % eggs density reduction of gastro-intestinal strongyles eggs and parasitic load nineteen days post-treatment respectively while Albendazole induced 100 % reduction of these same parameters at the dose of 5 mg/kg. Moreover, the extract did not significantly affect PCV nor body weight of experimental goats. Conclusion: This study validates scientifically the use of alcoholic leaves extract of M. oleifera in the treatment of gastro-intestinal strongyles. The standardization of this extract is however necessary for his use as a sustainable tool for controlling strongylosis in small ruminants.