Aphid species

Susceptible plants Most plants may be attacked by aphids. Many aphid species are plant-specific, such as the lupine aphid, while others, such as the peach potato aphid, will attack hundreds of different types of plants. Aphids may spend the summer on certain plants, moving to a different host species for the winter. 

The effect of plant age on the host selection process has been observed by comparison of two aphid species on brasslca plants (56). A specialist, Brevicoryne brassicae prefers young leaves, which are higher in glucoslnolates, whereas the generalist, Myzus persicae prefers older leaves, where amino acids are more Important in the selection process. 

Identification of aphid species is often difficult due to the low number of adults as compared to larvae. Another problem is that lipid and hydrocarbon composition appear highly dependent on the host plant (Neal et al., 1994). Analysis of CHCs has been used alone or in combination with molecular techniques to differentiate close Aphidae species (Lazzari et al., 1991 Raboudi et al., 2005). For example, analysis of the lipid and hydrocarbon compositions of pupal exuviae has been used to differentiate greenhouse and sweetpotato whiteflies (Neal et al., 1994). 

Raboudi, F Mezghani, M., Makni, H., Marrakchi, M., Rouault, J.D. and Makni, M. (2005). Aphid species identification using cuticular hydrocarbons and cytochrome b gene sequences J. Appl. Entomol., 129, 75-80. 

Vrieling, K., Smit, W. and Van der Meijden, E. 1991. Three-trophic interactions with pyrrolizidine alkaloids lead to general variation in PA concentrations between aphid species (Aphis jacobaea) and Tyria jacobaeae. Oecologia 86, 177-182... 

Blackman and Eastop (2000) listed six aphid species from Jerusalem artichoke (compared to 21 species from sunflower) Macrosiphum euphorbiae Thomas, Protrama penecaeca Stroyan, Trama troglodytes von Heyden, Uroleucon compositae Theobald, Uroleucon gobonis Matsumura, and Uroleucon helianthicola Olive. They do not cause serious damage to either the above- or belowground plant parts. 

Two aphid species were listed by Hills (1987) as minor pests (Aphis fabae Scopoli and Aphis gossypii Glover). A number of other aphid species (e.g., Aphis debilicornus Gillette Palmer, Aphis helianthi Monell, Aphis ranunculi Kaltenbach, and Trama rara Mordvilko) have also been... 

CONTROL. Under no circumstances should the apple grass aphid be harmed, as its early occurrence attracts a very large number of benefi-cials. If large numbers of enemies of aphids appear very early, natural regulation of other aphid species is much easier. 

Some aphid species depend on ants (they are myrmecophilous) while others do not (nonmyrmecophilous aphids). The latter are better at defending themselves They move faster and defend themselves chemically. When attacked by ladybird beetles, they release the alarm pheromone (fj-P-famesene. In response to the pheromone other aphids walk around or drop from the plant. Pea aphids even may grow wings in response to alarm pheromone, allowing them to fly from the host plant. Ants also prey on other herbivorous insects, thus lowering their impact on the host plant. 

Variability in induced plant volatiles complicates the reliance of natural enemies on these cues. One way of dealing with variability is through associative learning, which may allow parasitoids to learn which cues are most likely to lead them to suitable hosts at a particular time in a particular area. Moreover, recent studies suggest that plant volatile blends alone carry specific information on the herbivores by which they are attacked. For example, predatory mites can distinguish between the blends of apple trees infested by two herbivores species (20). Du et al. (21) showed that different aphid species elicit different volatile blends in bean plants and that the aphid parasitoid, Aphidius ervi, can use these differences to distinguish plants infested by its host. Aphis pisum from those infested by a nonhost. Aphis fabae... 

Beneficial Effect Larvae paralyze aphids with toxic saliva, then suck their body fluids. Can attack more than 60 aphid species. 

Its physicochemical properties are quite different than those of spirodidofen 7f and spiromesifen 8a, furthermore spirotetramat 32 effectively acts on a broader spectrum of pests, e.g., it shows an excellent efficacy against different aphid species, including Myzus persicae, Aphis gossypii and Phorodon humuli (Table 28.4.5). 

The Kd-values for THIAM 6 were in the upper nM range - but still more than 100-fold higher than those foiuid for IMI 1 for the same aphid species. 

The principal non-volatile constituents of the cornicle droplets of A. pisum and Myzus persicae were reported by Strong (1967) to be triglycerides. In M persicae, the major fatty acid is myristic acid. Callow et al. (1973) later examined the cornicle droplets of 28 aphid species and confirmed triglycerides... 

The receptors for aphid alarm pheromones are located on the antennae (Nault et al., 1973). Shambaugh et al. (1978) detailed the ultrastructure of potential alarm pheromone receptors in 17 aphid species. Excision of the terminal (6th) antennal segments of M. persicae, that bear the primary sensoria eliminated its response to alarm pheromone. Such excisions reduced but did not eliminate the response of A. pisum and Aulacarthum solani, both of which bear secondary sensoria on their 3rd antennal segments. Only removal of this segment eliminated response in these species. 

The suffixes -fb, -jc, -si and -tt refer to the aphid species from which the relevant pigments are obtained, e.g. -fb pigments from Aphis fabae [7]. 

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