Stingless Bees As Important Tropical Crop Pollinators

M. S. Castro
Empresa Baiana de Desenvolvimento Agrícola -Brazil

Agricultural policies still emphasise short-term gains and high productivity. This often leads to various environmental problems such as soil erosion, fragmentation of natural ecosystems, loss of cultural and biological diversity and contamination of waterways and water tables through extensive use of pesticides. The level of impact depends on the level of technology and the production system adopted. The expansion of agricultural borders is always linked to a reduced number of agricultural crops with little variation or rotation. Thus, monocultures occupy great expanses of land, adversely affecting the diversity of all wildlife.

New perspectives on sustainable production are opening for the expansion of agriculture in a global economy. Although biodiversity does not stem from the concept of sustainability, it is essential for agricultural production because it is the key to the creation of balanced agricultural systems and carries with it both socio-economic and environmental benefits. Crop productivity can be entirely dependent upon pollination for fruit and seed production. There are many highly social bee species that contribute to the pollination of agricultural crops, the most well known of which (honeybee) is neither the only nor the most important pollinator of tropical crops.

In Brazil, bee diversity in natural ecosystems has been studied for the last thirty years (Pinheiro Machado, 2002) and the importance of stingless bees for tropical plants at the local level has been shown in various ways. Until now, very few studies have been done on agricultural crops in Brazil that depend upon stingless bees for pollination. Nevertheless, field experiments on fruit pollination have been done. Some of our field observations and preliminary experiments showed the importance of stingless bees as pollinators for tropical and native fruits. Stingless bees in NE Brazil are potential pollinators for :

1 "Umbu" (Spondias tuberosa), an Anarcadiaceae tropical tree, important for local people in semiarid areas. It could be efficiently pollinated by two species of stingless bee, Frieseomelitta silvestrii languida and Tetragonisca angustula ;

2 Some species of Myrtaceae that are economically important in Brazil at regional levels. Species of fruits cultivated in coastal areas of NE Brazil are: guava (Psidium guajava); rose apple (Eugenia jambosi), malay rose apple (Eugenia malaccensis), watery rose apple (Eugenia aquea), Brazilian cherry - "pitanga" (Eugenia uniflora). Despite of the economic importance of these fruits and the lack of knowledge about their pollination, some field studies performed in orchards located in the Atlantic Forest from NE Brazil indicated the importance of stingless bees as efficient pollinators for some species of this plant family. The stingless bees Nannotrigona punctata and Melipona scutellaris have been identified as important pollinators of some guava cultivars (araçá, thais large guava and ruby supreme). Watery rose apple and Brazil cherry - "pitanga" were frequently pollinated by Melipona scutellaris, while rose apple was pollinated by Trigona fuscipennis.

3 "Pitomba" (Sapindaceae: Talisia esculenta), a native fruit of the Amazon and NE areas in Brazil. Melipona scutellaris is important for its pollination.

Ecosystem studied: Atlantic forest of NE Brazil and semiarid areas.
Organisms: stingless bees as pollinators; orchards in Atlantic forests and a native fruit (Spondias tuberosa) in semiarid areas.
Main lessons learned: The study highlights the need to improve field experiments in order to understand all relevant factors in the use of stingless bees in tropical fruit pollination.

Edited from Castro, M.S. (2002). Bee fauna of some tropical and exotic fruits: potential pollinators and their conservation. In: Kevan, P. & Imperatriz-Fonseca, V. L. (2002) Pollinating bees: the conservation link between agriculture and nature. Ministry of Environment, Brasília, Brazil. p. 275 - 288.