ABSTRACT
Effect of Citrus floral extracts on the foraging behavior of the stingless bee Scaptotrigona pectoralis (Dalla Torre). Stingless bees have an important role as pollinators of many wild and cultivated plant species in tropical regions. Little is known, however, about the interaction between floral fragrances and the foraging behavior of meliponine species. Thus we investigated the chemical composition of the extracts of citric (lemon and orange) flowers and their effects on the foraging behavior of the stingless bee Scaptotrigona pectoralis. We found that each type of flower has its own specific blend of major compounds: limonene (62.9%) for lemon flowers, and farnesol (26.5%), (E)-nerolidol (20.8%), and linalool (12.7%) for orange flowers. In the foraging experiments the S. pectoralis workers were able to use the flower extracts to orient to the food source, overlooking plates baited with hexane only. However, orange flower extracts were seemingly more attractive to these worker bees, maybe because of the particular blend present in it. Our results reveal that these fragrances are very attractive to S. pectoralis, so we can infer that within citric orchards they could be important visitors in the study area; however habitat destruction, overuse of pesticides and the competitive override by managed honeybees might have put at risk their populations and thus the ecological services they provide to us.
Extratos florais de Citrus no comportamento de forrageamento da abelha sem ferrão Scaptotrigona pectoralis (Dalla Torre). As abelhas sem ferrão têm um papel importante na polinização de muitas espécies de plantas nativas e plantas cultivadas em regiões tropicais. Pouco se sabe, no entanto, sobre a interação entre as fragrâncias florais e comportamento de forrageamento de espécies de meliponíneos. Assim, investigou-se a composição química dos extratos de cítricos florais (limão e laranja) e seus efeitos sobre o comportamento de forrageamento da abelha sem ferrão Scaptotrigona pectoralis. Nós descobrimos que cada tipo de flor tem a sua própria composição específica de mistura de compostos: limoneno (62,9%), e farnesol (26,5%) para flores de limão, (E)-nerolidol (20,8%), e linalol (12,7%) para flores de laranja. Nos experimentos de forrageamento, as operárias de S. pectoralis foram capazes de utilizar os extratos de flores para se orientarem até a fonte de alimento, não sendo atrapalhadas por placas com iscas apenas de hexano. No entanto, os extratos de flores de laranja foram aparentemente mais atraentes para essas abelhas operárias, talvez por causa da mistura particular do extrato. Nossos resultados revelam que essas fragrâncias são muito atraentes para S. pectoralis, assim pode-se inferir que dentro de pomares cítricos poderiam ser visitantes importantes na área de estudo; no entanto a destruição do habitat, o uso excessivo de pesticidas e a substituição competitiva por abelhas Apis poderia por em risco suas populações e, assim, os serviços ecológicos que prestam para nós.
ABSTRACT
The native bee Nannotrigona perilampoides Cresson (Apidae: Meliponini) has been evaluated with promising results in greenhouse pollination of Solanaceae in Mexico. However, no comparison has been done with imported bumble bees (Apidae: Bombini), which are the most common bees used for greenhouse pollination. We compared the foraging activity and fruit production of habanero pepper. Capsicum chinense Jacquin, by using N. perilampoides and Bombus impatiens Cresson in pollination cages. Both bee species collected pollen on a similar number of flowers per unit time, but N. perilampoides visited significantly more flowers per trip, lasted longer on each flower, and spent more time per foraging trip. Ambient temperature and light intensity significantly affected the foraging activity of N. perilampoides. Light intensity was the only environmental variable that affected B. impatiens. Except for the fruit set, there were not significant differences in the quality of fruit produced by both bee species; however, N. perilampoides and B. impatiens performed better than mechanical vibration for all the variables measured. The abortion of fruit caused the low fruit set produced by B. impatiens, and we speculate it might be due to an excessive visitation rate. Pollination efficiency per visit (Spear's pollination efficiency index) was similar for both bee species in spite of the significantly lower amount of pollen removed by N. perilampoides. We suggested that the highest number of flowers visited per foraging trip coupled with adequate amounts of pollen transported, and transferred between flowers, could explain the performance of N. perilampoides as a good pollinator of habanero pepper. Our experiments confirm that N. perilampoides could be used as an alternative pollinator to Bombus in hot pepper under tropical climates.
