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THE STATUS OF RESEARCH ON HYMENOPTERA IN MALAYSIA
The suborder Apocrita contains the vast majority of species of Hymenoptera. It is divided into
two groups, the Parasitica and Aculeata. The aculeates represent the most diverse group of
Hymenoptera, in which the ovipositor structure has been modified into a sting. This group
contains the groups of Hymenoptera known to most people, such as bees, wasps, hornets and
ants. Some species are quite large in size, having a wing span of up to 10 cm (eg. the Spider
wasps, Pompilidae). The majority of species are predatory (eg. wasps and hornets) or pollen
feeding (eg. bees), but parasitism is common, particularly in the lower aculeates (Chrysidoidea).
There are 19 families in Aculeata, and together they account for over 45% of described
Hymenoptera species (Gaston 1993), with the families Apidae (bees), Formicidae (ants) and
Sphecidae containing the most species.
The Parasitica is the largest group of Hymenoptera, and includes all non-aculeate Apocrita.
Members have a constricted waist, but in which the ovipositor has not been developed into a
sting. The vast majority of the species are parasitoids. However, there are species which are
phytophagous, gall-forming, or predatory. The Parasitica contains 48 families in 10
superfamilies, and encompasses almost half the described species of Hymenoptera, with most
of the species in superfamilies Ichneumoniodea and Chalcidoidea (Gaston 1993). The majority
of the species, especially the Chalcidoidea, are very small (eg. 0.18 mm in length for some
species in the family Trichogrammatidae), and most people are not even aware of their existence
and role.
The insect order Hymenoptera is one of the dominant life forms on earth, both in terms of the
number of species as well as in the diversity of life styles that have evolved within the group.
The Hymenoptera contain the vast majority of socially organized insects and parasitoids, as
well as a great variety of specialist predators and herbivores. They have emerged as the most
speciose group in many studies on terrestrial biodiversity and they are pre-eminent as biological
control agents of insect pest species.
The number of species of Hymenoptera is unknown and, at present, is almost impossible to
estimate with any accuracy. Even the number of described species has not been accurately
documented, given that there are many families for which there are no checklists or catalogues
available. Some good checklists or catalogues are those of Johnson (1992), Bolton (1995),
Noyes (1998), Townes (1983), van Achterberg (1983, 1988, 1997), Quicke (1987) and Sharkey
(1988). La Salle and Gauld (1993) and Gaston (1993) have estimated the number of described
species of Hymenoptera at more than 115,000 species. However, the total number (including
undescribed and uncollected species) could be 5–10 times more, given that this is often the
proportion of new species that are discovered following taxonomic revision of highly speciose
families (Austin 1999). Determining the number of species for the ‘megadiverse’ regions of
the world is a major problem. These areas include tropical or subtropical countries such as
Australia, India, Malaysia, Indonesia, China, Brazil, Equador, Peru, Columbia, Mexico, Zaire
and Madagascar; with a few exceptions, they have generally been poorly surveyed (McNeely
et al. 1990). The hymenopteran fauna of Costa Rica is particularly well-studied (Hanson &
Gauld 1995), and this work serves as a useful foundation for future research on the fauna of
Costa Rica itself, and for other regions. The extent of species richness and biological complexity
within the Hymenoptera dictates that the group should be at the center of studies assessing
arthropod diversity. The full extent of their diversity will only be revealed when detailed
studies similar to those in Costa Rica are undertaken for other species-rich regions of the
world. Limiting factors common to many countries are the unavailability of up-to-date
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