The development of worker, male, and queen larvae of Bombus terrestris was analysed by measuring their mass and the amount of pollen they had ingested. The three kinds of larvae grew significantly differently. Workers and queens differed strongly in their growth from the beginning of the larval stage. On the other hand, males and queens were more similar in their development. Furthermore, during the later stages, pollen played a less important role in the increase of the queens' mass, which indicates that a different mechanism is probably involved in their growth. Two hypotheses are discussed: either there is a difference in the queens' metabolism or they receive a different diet, which improves their growth.

Summary.The frequency with which bumble bee larvae are fed during their development was studied using video-recordings. The behaviour of the workers while feeding worker, male and queen larvae of Bombus terrestris was recorded. At the beginning of development, female larvae of both castes were fed at a similar frequency. However, during their last phase queen larvae were fed much more often than worker larvae. Despite the differences in frequency, both queen and worker larval feeding followed a similar pattern. Male larvae were fed more often than worker larvae, but less often than queen larvae. They also differed from the female larvae in the way their feeding frequency increased during development. This suggests that the process of feeding male larvae occurs in a different way.The time intervals between feedings were very variable for all larvae: from a few seconds up to 3 h. Although there was a general tendency for the intervals to decrease in duration with larval development, the irregularity was always present.The differences in feeding frequency found at the individual level for larvae of the same age and the irregularity of the feeding process can be explained by the variation in the amount of food per feeding.Finally, our data suggest that larvae play an active role in the regulation of the feeding process. This subject is discussed and compared to the situation in honey bees.

Summary — The effects of two kinds of stored pollen (fresh and dried, kept in the freezer) on individuals and colonies of Bombus terrestris were investigated. The pattern of colony development, and the number and biomass of workers and males were similar for colonies fed on fresh-frozen pollen (FFP) and dried-frozen pollen (DFP). However, queens reared on DFP were smaller, had lower biomass, higher mortality and produced smaller colonies than queens reared on FFP.

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Summary. The duration of feedings received by Bombus terrestris larvae was studied using video-recordings. In the last days of development all larvae received feedings mainly of long duration. Worker larvae of the third brood received significantly longer feedings than worker larvae reared in the other broods. Throughout the development queen larvae and worker larvae received feedings of similar duration. Male larvae received shorter feedings than both kinds of female larvae. Therefore, the duration of feedings seems to be associated to the sex and stage of development of the larvae.The causes of the long-duration feedings seem not to be related to the amount of food provided, workers' age and size, to the workers' abdominal contraction or to the amount of pollen in the larval food. Perhaps the feeding duration is caused by the viscosity of the food, which is a consequence of the presence of pollen grains, sugar and glandular material. Although the precise amount of pollen was not measured, the differences in colour showed clearly that the larval food samples contained variable quantities of pollen grains. Some of the samples did not contain any pollen at all.It is suggested that the duration of feedings may be related (among other factors) to the presence of glandular material (proteins and enzymes) which is added to the larval food. This could be especially important for queen larvae in the last phase of their development. Because they have a long development and are fed with a high frequency they might receive large amounts of these substances. This could help them to grow more efficiently using a relatively smaller amount of pollen than expected.

This study aimed to analyze the details of collection of floral resources (pollen and nectar) by honeybees (Apis mellifera) on male and hermaphrodite flowers of melon (Cucumis melo). The experiments were conducted in areas located at Embrapa Semiárido and Embrapa Produtos e Mercado, Petrolina, state of Pernambuco, in November and December 2011, with crop of a hybrid yellow 10/00 F1 melon. Honeybee colonies housed in Langstroth hives, uniform concerning the number of individuals and brood area were used. The four experimental areas (0.5 ha each), received respectively 0, 1, 2 and 3 hives, from the first day on which the hermaphrodite flowers appeared to the end of the flowering period of the melon crop. The results showed that the bees visited more the hermaphrodite than the male flowers, in order to collect the resources (pollen and nectar), in all areas where honeybee hives were placed. In general, independently from the number of hives, the resource most collected was nectar. Pollen collection occurred mainly at the first hours of the morning, while nectar was collected throughout the day.

Amarante J.F., Ribeiro M.F., Costa M.M., Menezes F.G., Silva T.M.S., Amarante T.A.B., Gradela A. & Moura L.M.D. 2019. Chemical composition and antimicrobial activity of two extract of propolis against isolates of Staphylococcus spp. and multiresistant bacterials. Pesquisa Veterinária Brasileira 39 (9):734-743. There is a growing need to discover and develop alternative therapies for the treatment of mastitis caused by Staphylococcus spp. and multidrug-resistant bacterial infections. This study examined the chemical composition and antimicrobial potential of two propolis extracts (EPA and EPB) against seventy-seven isolates of Staphylococcus spp. obtained from subclinical bovine mastitis; three clinical strains of MRSA and two from clinical strains of S. aureus ATCC, identified as S. aureus ATCC 6538 and S. aureus ATCC 25923. The total phenolic content was determined by the Folin-Ciocalteau method, the total flavonoid content by the Dowd method and the phenolic profile was quantified by HPLC-DAD. The MBC values of the extracts were evaluated by broth microdilution method. The amount of total phenolic and flavonoid compounds was higher in EPA than EPB. Both extracts revealed the presence of caffeic, coumaric, cinnamic, ferulic and 3,4-dihydroxybenzoic acids, with higher concentrations of coumaric and cinnamic acids. Staphylococcus spp. isolates were susceptible to EPA (90.9%), EPB (83.1%) and oxacillin (80.5%). The oxacillin susceptible isolates were also susceptible to EPA (70.1%) and EPB (80.6%), whereas those oxacillin-resistant strains were also susceptible to EPA (40.0%) and to EPB (26.7%). MBC ranged from 34.3 to 68.7μm/mL for EPA and from 68.7 to 137.5μg/mL for EPB. Both extracts inhibited significantly (100%) the clinical strains of MRSA, S. aureus ATCC 6538 and S. aureus ATCC 25923 at the concentration of 68.7μg/mL. It is concluded that both extracts of propolis, whose main constituents are coumaric and cinnamic acids, have high antimicrobial activity against the microorganisms studied, and EPA also against oxacillin-resistant strains. These findings reinforce its potential use for the treatment of bovine mastitis.

Studying the pollinators' foraging behaviour is quite important for pollination. Time spent by the pollinator in floral handling is one of the aspects of this behaviour. Honeybees (Apis mellifera) are the main responsible for the pollination of melon (Cucumis melo), but there are few studies on their foraging, mainly in the region of Petrolina, state of Pernambuco, and Juazeiro, state of Bahia, in Brazil. This study aimed to compare bee visitation to hermaphrodite (HF) and male (MF) flowers in a crop area where different number of hives were used. For each floral type, 10 flowers were observed, in each experiment (0, 1, 2 or 3 hives). The duration of bee visits (n = 10) was registered in three times of the day: 8 a.m., 11 a.m., and 4 p.m. In general, HF received significantly longer visits than MF, in all experiments, except when using one hive. In fact, significant correlations were found between the duration of visits and number of hives for HF, but not for MF. This is probably related to the attractiveness of HF and to the availability of floral resources. The studies of duration of pollinator' visits are relevant in agriculture and should be considered when evaluating the efficiency of pollination in melon.