Biology of the Parasitoid Melittobia (Hymenoptera: Eulophidae)

Abstract

As parasitoids upon solitary bees and wasps and their nest cohabitants, Melittobia have an intricate life history that involves both female cooperation and variably expressed male siblicidal conflict. Inter- and intrasexual dimorphism includes blind, flightless males and (probably nutritionally determined) short- and long-winged females. Thought to be highly inbred, Melittobia do not conform to local mate competition (LMC) theory but exhibit simple forms of many social insect traits, including overlapping adult generations, different female phenotypes, close kinship ties, parental care, and altruistic cooperative escape behaviors. Most host records and research findings are based on only 3 species--M. acasta, M. australica, and M. digitata--but any of the 12 species could have pest potential due to their polyphagy, explosive population growth, cryptic habits, and behavioral plasticity. Readily cultured in the laboratory, Melittobia offer considerable potential as a model for genetic, developmental, and behavioral studies.

The bizarre male of Spalangia dozieri (Hymenoptera: Pteromalidae): adaptations for male phoresy or the result of sexual selection?

“…Sexual dimorphism correlated with sex is known for some gregarious species in Chalcidoidea, although extreme dimorphism is characteristic only of those species in which males not only are far fewer in number than females but also compete for females and normally do not emerge from the host. This includes males of species of Melittobia Westwood (Eulophidae) in the cocoons or puparia of their Aculeata (Hymenoptera) hosts and dipteran parasites (Assem 1975;Matthews et al 2008), and males of pollinating Agaonidae and other non-pollinating chalcid taxa that are intimately associated with the synconia of figs (Ficus L., Moraceae) (Weiblen 2002;Greeff et al 2003). Unlike S. dozieri males, the males of these two groups are usually less pigmented than the females, are brachypterous or apterous, and have vestigial eyes and often large mandibles (Assem et al 1980;Weiblen 2002).…”

Semiochemical Exploitation of Host-Associated Cues by Seven Melittobia Parasitoid Species: Behavioral and Phylogenetic Implications

“…Melittobia wasps are small (1.0-1.5 mm) ectoparasitoid idiobionts that develop gregariously on their hosts (Matthews et al, 2009). They exhibit sexual dimorphism and females are polymorphic (short-winged and long-winged; González et al, 2004a;González and Matthews, 2005a).…”

“…They exhibit sexual dimorphism and females are polymorphic (short-winged and long-winged; González et al, 2004a;González and Matthews, 2005a). Long-winged females, also called macropterous females, are the dispersal individuals in all Melittobia species, while some non-dispersing short-winged females, also known as brachypterous females, may be produced in order to fully exploit large high quality hosts (Matthews et al, 2009). van den Assem et al (1982) and Dahms (1984) placed all Melittobia species in four species-groups based on male displays during courtship and morphological characteristics, respectively.…”

“…According to Tanner et al (2011), the 12 known Melittobia species are classified in four phylogenetically-distinct groups ranging from most primitive to more advanced in the following order: assemi species-group (2 species), hawaiiensis species-group (2 species), clavicornis species-group (1 species), and acasta species-group (7 species). Melittobia wasps tend to be polyphagous and they are usually recorded as natural enemies of solitary wasps and bees, such as mud dauber wasps in the genera Trypoxylon (Crabronidae) and Sceliphron (Sphecidae) and several cavity-nesting bees including important pollinators such as megachilid leaf-cutter bees (Krombein, 1967;Matthews et al, 2009). Melittobia have been also occasionally recorded to attack honey bees as well as several insects from different orders and can reproduce fine in factitious hosts (i.e., flesh flies) (Matthews et al, 2009).…”

“…Melittobia wasps tend to be polyphagous and they are usually recorded as natural enemies of solitary wasps and bees, such as mud dauber wasps in the genera Trypoxylon (Crabronidae) and Sceliphron (Sphecidae) and several cavity-nesting bees including important pollinators such as megachilid leaf-cutter bees (Krombein, 1967;Matthews et al, 2009). Melittobia have been also occasionally recorded to attack honey bees as well as several insects from different orders and can reproduce fine in factitious hosts (i.e., flesh flies) (Matthews et al, 2009). The ancestral host of Melittobia species is not known but it is possible that some solitary cavity-nesting bees which nested in aggregated situations are closely related to the original natural hosts, from which the host range could have been expanded to include solitary wasps such as mud dauber wasps which are notable because females tend to build nests in clusters (Malyshev, 1968;Cross et al, 1975;Molumby, 1995).…”