Maintenance and Productivity of a Lutzomyia longipalpis (Diptera: Psychodidae) Colony from an Area Endemic for Visceral and Cutaneous Leishmaniasis in Northeastern Brazil.

Studies on experimental sand fly infection require the availability of colonies and laboratory conditions. In Brazil, Lutzomyia longipalpis (Diptera: Psychodidae) (Lutz and Neiva 1912) is responsible for the highest infection rates by Leishmania spp. and this species is one of the most suitable species for laboratory colonization. In this study, we describe a method for growing Lu. longipalpis in laboratory conditions (10 generations) from natural populations sampled from a region of high endemicity for visceral leishmaniasis in the state of Maranhão, Northeastern Brazil. Using two methods (individualized or grouped females), the colony's highest productivity occurred in the first four generations, where all stages presented with high frequency. Nonviable eggs represented more than 50% of the total eggs produced by engorged females, while pupae were more resistant to fungal contamination, with a mortality rate of only 2%. In both methods, there was a predominance of female emergence; however, the ratio between males and females did not show significant differences, IF (P = 0.8023) and GF (P = 0.1831). Using the method of individualized females, the F4 generation took the longest to appear (234 d; 64 ± 57 d); by grouped females, F3 took the longest to appear (102 d; 47 ± 20 d). This method provides sufficient numbers of insects to perform vector competence tests for Leishmania spp. that cause the cutaneous form of leishmaniasis, usually found in Lu. longipalpis sampled from the study location.

What is the most suitable native bee species from the Neotropical region to be proposed as model-organism for toxicity tests during the larval phase?

Currently, Brazil has a full framework for pesticide risk assessment established for Apis mellifera, based on the North American approach. However, the use of Apis mellifera as model-organism as a surrogate for Brazilian native species of stingless bees has been questioned. Assessments on other stages of development than adult individual are essential. Our study aimed to standardize in vitro larval rearing method for the stingless bee species Scaptotrigona postica and Tetragonisca angustula, comparing the results to those obtained for M. scutellaris (previously described), for proposing the most suitable one for using in toxicological larval tests. We used the most efficient method for determining the toxicity of dimethoate on S. postica larvae. We presented the first comparative approach of responses to in vitro larval rearing methods among native bee species from Neotropical region, for use in risk assessment. Our results showed that S. postica was the most suitable native species to be proposed as model-organism. In addition, our results are also very useful for a ring test to validate the method, in accordance to OECD.

Productive performance of white leghorn hens based on the type of housing during rearing: floor versus cage

Poultry farmers in the southeastern of Mexico consider that the productivity of the hens that comes from rearing on floor has a higher productive performance than reared hens in cages, mainly due to higher percentage of egg laying and lower mortality. The aim of this study was to evaluate the productive performance of the laying hen in relation to the type of rearing. A total of 79680 pullets Bovans White of 17 weeks of age were housed in cages with five pullets cage-1 (405 cm2pullet-1). They were divided in two treatments according to their type of rearing (floor vs cage) with four replicates. The study period was from week 20 to week 40 of age. The variables evaluated were daily (%) and cumulative mortality (%), egg production (%), egg weight (g), feed intake (g pullet d-1), cumulative feed intake (g pullet-1), daily and cumulative egg mass, number of eggs per hen housed, egg loss (%) and productivity index. The variables were analyzed using a randomized block design. It was observed that daily and cumulative mortality, feed intake and egg loss was higher (p < 0.05), while the number of eggs per hen housed and productivity index (p < 0.05) was lower for hens in cages. We conclude that it is possible to associate detriments in the productive performance of laying hens based on the type of housing during its growth phase.

Productive performance of white leghorn hens based on the type of housing during rearing: floor versus cage

Poultry farmers in the southeastern of Mexico consider that the productivity of the hens that comes from rearing on floor has a higher productive performance than reared hens in cages, mainly due to higher percentage of egg laying and lower mortality. The aim of this study was to evaluate the productive performance of the laying hen in relation to the type of rearing. A total of 79680 pullets Bovans White of 17 weeks of age were housed in cages with five pullets cage-1 (405 cm2pullet-1). They were divided in two treatments according to their type of rearing (floor vs cage) with four replicates. The study period was from week 20 to week 40 of age. The variables evaluated were daily (%) and cumulative mortality (%), egg production (%), egg weight (g), feed intake (g pullet d-1), cumulative feed intake (g pullet-1), daily and cumulative egg mass, number of eggs per hen housed, egg loss (%) and productivity index. The variables were analyzed using a randomized block design. It was observed that daily and cumulative mortality, feed intake and egg loss was higher (p < 0.05), while the number of eggs per hen housed and productivity index (p < 0.05) was lower for hens in cages. We conclude that it is possible to associate detriments in the productive performance of laying hens based on the type of housing during its growth phase.(AU)