No abstract

Exposure to agrochemicals and pathogens has been indicated as critical factors of declining pollinator populations, including species of native tropical bees. In the present study, we investigated the sublethal effects of acute oral exposure to azadirachtin and spinosad bioinsecticides on the expression of immunity-related genes and the number of hemocytes in uninfected and Escherichia coli -infected workers of the stingless bee Melipona quadrifasciata . Expression of the immune-related gene vitellogenin decreased and the number of circulating hemocytes increased in bioinsecticide-exposed uninfected bees and in unexposed E. coli -infected bees as compared with unexposed uninfected bees. Our results show that though bioinsecticides are considered safe, contamination by sublethal doses of azadirachtin and spinosad can interfere with the immune system of bees.bioinsecticides / hemocytes / spinosad / stingless bees / vitellogenin

Paratransgenesis consists of genetically engineering an insect symbiont to control vector-borne diseases. Biosafety assessments are a prerequisite for the use of genetically modified organisms (GMOs). Assessments rely on the measurement of the possible impacts of GMOs on different organisms, including beneficial organisms, such as pollinators. The bacterium Serratia AS1 has been genetically modified to express anti-Plasmodium effector proteins and does not impose a fitness cost on mosquitoes that carry it. In the present study, we assessed the impact of this bacterium on the native bee Partamona helleri (Meliponini), an ecologically important species in Brazil. Serratia eGFP AS1 (recombinant strain) or a wild strain of Serratia marcescens were suspended in a sucrose solution and fed to bees, followed by measurements of survival, feeding rate, and behavior (walking and flying). These bacteria did not change any of the variables measured at 24, 72, and 144 h after ingestion. Recombinant and wild bacteria were detected in the digestive tract up to 144 h after ingestion, but their numbers decreased with time. The recombinant strain was detected in the midgut at 24 h and in the hindgut at 72 h and 144 h after ingestion. As reported for mosquitoes, Serratia eGFP AS1 is a safe candidate for combating vector-borne diseases, as it did not compromise the native and ecologically relevant bee, P. helleri.

Bee populations are declining because of various synergistic threats, and therefore bee survey and monitoring programs are needed. Several techniques have been developed to survey bees, but the most cost-effective and suitable methods to sample bees in several sites at the same time are passive approaches, such as methods involving colored pan traps (also known as Moericke or bowl traps). Several bee surveys using pan traps have been conducted in North America, Europe, and Australia, but only a few such surveys have been done in tropical regions. We used colored pan traps (blue, yellow, and white) to assess the bee community in the Brazilian savanna ecosystem in Rio Preto State Park. Sampling was conducted in October 2013 and March 2014 along permanent trails. We also characterized the local habitat of each trail, and then we compared bee abundance with habitat complexity. In total, 187 individual bees (n = 15 species) were collected, mainly using blue and white traps. Although we were not able to sample most species that were previously recorded in this park, the pan trap method can be used to survey and monitor bee assemblages in combination with another sampling method. Habitat complexity also affected the numbers of bees sampled using the pan traps, and more bees were collected at open sites.