Detailing the physical features, habits, territorial reach and other identifying qualities of the Oleander Aphids. The first sighting of a yellow-orange cluster of Oleander Aphids should put a gardener on the defensive. They feed on the plant juices of oleander, milkweed, butterfly weed, and wax plants - all popular plants in homes and butterfly gardens. Quick to reproduce during their short lives, Oleander Aphids need little time to infest a plant.
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Description Back to Top It is thought that the oleander aphid is an obligate parthenogenetic species; thus the adult aphids are all female and males do not occur in the wild. Adult females may be winged or wingless. The winged adult females alata are yellow and black with dark wing veins while the wingless forms apterae are yellow with black cornicles, antennae, legs, and cauda tip of abdomen. Nymphs are similar to apterae in appearance except that they are smaller. Size ranges from 1.
Figure 1. Alata and nymphs of oleander aphid, Aphis nerii Boyer de Fonscolombe, on oleander leaf. Photograph by J. Castner, University of Florida. Life Cycle Back to Top Females are viviparous and parthenogenetic, meaning that they deposit nymphs rather than eggs and that the progeny are clones of the adult female i.
Nymphs progress through five nymphal instars. As in all Sternorrhyncha, there is no pupal stage and adults are produced from the final nymphal instar. Normally apterous adults are produced but alate adults occur under conditions of overcrowding and when plants are senescing, allowing the aphidsto migrate to new host plants.
The parthenogenetic mode of reproduction, high fecundity, and short generation time allow large colonies of oleander aphids to build quickly on infested plants.
Figure 2. Large colony of oleander aphids, Aphis nerii Boyer de Fonscolombe, on plant terminal growth. It can occasionally be found infesting plants in the families Compositae, Convolvulaceae, and Euphorbiaceae.
In addition, it has been found on citrus. This aphid is able to transmit several viruses including sugarcane mosaic potyvirus and papaya ringspot potyvirus. However, in Florida, the main concern with oleander aphid is the large and unsightly colonies produced on oleander and milkweeds. The oleander aphid ingests sap from the phloem of its host plant.
The damage caused by aphid colonies is mainly aesthetic due to the large amounts of sticky honeydew produced by the colony members and the resulting black sooty mold that grows on the honeydew. In addition, the growing terminals can be deformed.
Of more concern to nursery managers is the potential for stunted plant growth due to repeated heavy infestation throughout the year. Figure 3. Inflorescence of scarlet milkweed heavily infested with oleander aphids, Aphis nerii Boyer de Fonscolombe. Photograph by Lyle Buss, University of Florida. Figure 4.
Terminal growth of oleander heavily infested with oleander aphids, Aphis nerii Boyer de Fonscolombe. Management Back to Top Cultural controls offer the best means of managing oleander aphid infestation on oleander. Reduced levels of watering, pruning, and fertilization will reduce the production of tender shoots, the favorite food of oleander aphid. On smaller apocynaceous plants grown as nectar sources for butterflies or as larval host plants for monarch butterflies, the infested shoot can be pruned out and discarded or aphids can be dislodged with a strong stream of water.
Natural biological control can be quite effective in controlling populations of the oleander aphid Hall and Ehler The most common species of parasitoid attacking the oleander aphid is the wasp, Lysiphlebus testaceipes Cresson Hymenoptera: Aphidiinae. The female parasitoid lays eggs in the aphid nymphs. The parasitized aphid develops into a papery, light brown, swollen mummy and the parasitoid develops within this mummy. In addition, generalist insect predators such as syrphid larvae ; lacewings in the families Chamaemyiidae, Chrysopidae, and Hemerobiidae ; and coccinellid larvae have been observed feeding on aphid colonies.
Figure 5. Winged adult oleander aphid, Aphis nerii Boyer de Fonscolombe, with hole through which the parasitoid, Lysiphlebus testaceipes Cresson , emerged. Figure 6. Colony of oleander aphid, Aphis nerii Boyer de Fonscolombe, that has suffered heavy parasitism by Lysiphlebus testaceipes Cresson. Figure 7. Syrphid fly larva feeding on nymph of oleander aphid, Aphis nerii Boyer de Fonscolombe. Figure 8. Syrphid pupa on scarlet milkweed inflorescence infested with oleander aphid, Aphis nerii Boyer de Fonscolombe.
Oleander aphids sequester cardiac glycosides, recognized heart poisons, from their host plants Rothschild et al. They also fortify their cornicle secretions with these bitter, poisonous chemicals. Their bright aposematic warning coloration and possession of toxins protects them from predation by certain species of birds and spiders Malcolm Spiders that have the cornicle secretion applied to their mouthparts immediately retreat and attempt to clean them.
These cardiac glycosides appear not to harm the parasitoids and generalist insect predators associated with oleander aphid. Insecticidal soaps and oils are often effective against soft-bodied insects such as aphids. Other insecticides are not necessary in the home garden environment given the high level of natural biological control, ease of killing aphids with insecticidal soaps and oils, and incompatibility of use on butterfly nectar or larval host plants.
Wiley, New York. Essig EO. Insects and Mites of Western North America. MacMillan Publishers, New York. Population ecology of Aphis nerii on oleander. Environmental Entomology 9: Malcolm SB. Aposematism in a soft-bodied insect: a case for kin selection. Behavioral Ecology and Sociobiology Cardiac glycosides in the oleander aphid, Aphis nerii.
Journal of Insect Physiology Shelton, A. Lysiphlebus testaceipes, Hymenoptera: Aphidiinae. Author: Heather J. Castner, L. Buss and H.
The pictures below show live immatures on one of their prefered hosts , milkweed an Asclepias species. Both images copyright Alan Outen, all rights reserved. Identification characteristics refer to adult Aphis nerii apterae see first picture below. The antennal terminal process is 3. The abdominal dorsum is entirely membranous.
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