Food Preferences
In general, Coccinellidae are classified into two major groups — predaceous and phytophagous; a third class feed on pollen or nectar, usually as a supplement to a predatory diet.
The majority of predatory species of ladybirds prey upon a taxonomically narrow group of insects or mites, supplementing their diet with pollen, sap, nectar or honeydew. Apart from a wide range of Hemiptera, the prey may be beetle larvae, including other coccinellids, early instar larvae of Lepidoptera, Hymenoptera, Thysanoptera and Diptera.
Aphid feeders (aphidophages)
The feeding mechanism in aphidophagous species involves extra-oral digestion, with or without additional mastication of prey. Usually younger larval instars pierce their prey and inject digestive juices before sucking out the body contents and abandoning the empty exoskeleton. Mature larvae and adults not only consume body contents but also chew the exoskeleton, usually consuming the entire aphid.
Coccid feeders (coccidophages)
Predators that feed on armoured and soft scale insects are reviewed by Hodek (1973), Drea and Gordon (1990) and Ponsonby and Copland (1997). Richards (1981) studied the biology of two coccidophagous species of Rhyzobius in Australia and found distinct differences in their host preferences and biology. Significant groups of specialised scale feeders are Chilocorini and Hyperaspidini. Details of biology and the life cycle of laboratory reared Hyperaspis pantherina Fürsch feeding on ensign scale (Orthesia spp.) are provided by Booth et al. (1995).
Mite feeders (acarophages)
Among Coccinellidae, mite feeders belong exclusively to a single group classified in two genera, Stethorus and Parastethorus. Fleschner (1950) showed that the larva of Stethorus has grooved mandibles that are used for extraoral digestion.
Heteroptera feeders
A few known Coccinellini depart from the typical predatory pattern of feeding on sternorhynchous Hemiptera. These are dedicated predators on true bugs (Heteroptera). Synona Pope is known to prey on hemipterans of the family Plataspidae, mostly of the genus Coptosoma. Afroze and Uddin (1998) reported that adults and larvae of the Indian species S. melanaria Mulsant are voracious and effective predators of Coptosoma ostensum Distant, feeding on nymphs, but do not feed on late instars or adult bugs.
Mycophagy
All species of this group feed on conidia and hyphae of powdery mildews, fungi classified as Erisyphales (Ascomycota). This group is well represented in South America, Europe and Asia but in Australia limited to two species of the genus Illeis.
Pollen
Many predatory coccinellids feed on pollen which is an important food source when their main insect prey is hard to find. It is usually sufficiently nutritious for survive of a beetle, but not adequate enough for egg development. Observations on Australian Illeis galbula by Anderson (1982) found this principally mildew-feeding species supplementing its diet with Acacia or Ligustrum pollen.
Plant tissue
All species of Epilachnini are herbivorous and feed on various plants belonging to Cucurbitaceae, Solanaceae, Fabaceae, Convolvulaceae and Malvaceae. Some species are important pests in many parts of the world. The Australian species of this group belong all to Epilachna and have limited economical importance.
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