The Potential of Semiochemicals for Control ofPhorodon humuli(Homoptera: Aphididae)

Abstract

Field experiments employing yellow water-traps with vials releasing methyl salicylate, butyl isothiocyanate, 4-pentenyl isothiocyanate and diethyltoluamide were conducted during the spring migration of Phorodon humuli (Schrank), with the aim of identifying substances which might be used in the field to deter landing on hop plants. Methyl salicylate and the two isothiocyanates reduced trap catches of P. humuli. During the spring of 1994 a slowrelease formulation of methyl salicylate and a /?-acid-rich hop resin sprayed on to hop plants did not reduce aphid infestations significantly. In autumn cis,cis-nepetalactol, the main component of P. humuli's sex pheromone, prepared by various synthetic routes, increased trap catches of males and gynoparae equally. Catches of males in pheromone traps situated in a hop garden decreased with increasing trap height. Catches of males in traps charged with increasing doses of the cis,cisnepetalactol peaked at 1 mg and then plateaued, whereas catches of gynoparae peaked similarly at 1 mg and then decreased. The effects of kairomones from an extract of the primary host, sex pheromone and a visual cue from yellow compared with clear water-traps were additive. The prospects for developing a semiochemicals-based control strategy against P. hurnuli, using some or all of the above elements, are discussed.

A survey of antennal responses by five species of coniferophagous bark beetles (Coleoptera: Scolytidae) to bark volatiles of six species of angiosperm trees

“…Component in a tritrophic plant-herbivore-predator interaction, plant-released volatile from lima bean, Phaseolus lunatus L. (Fabaceae), infested with the spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), attractive to predatory mites Phytoseiulus persimillis Athias-Henriot and Amblyseius potentillae (Garman) (Dicke et al 1990). Potential repellent for aphid Phorodon humili (Schrank) (Homoptera: Aphididae) (Lö sel et al 1996). A component of an attractive (Yunker et al 1992) and attachment inducing (Norval et al 1991b(Norval et al , 1992b) mixture for Salicylaldehyde…”

Effects of plant spacing and interplanting with oilseed rape on colonisation of dwarf hops by the damson‐hop aphid, Phorodon humuli

“…However, that experiment also showed that migrants of P. humuli respond olfactorily to volatiles from some non-host plants as well as to the known response to host volatiles (Campbell et al, 1993;Lösel et al, 1996). Campbell (1977) reported that strings supporting two hop bines were colonised by about twice the numbers of aphids as those with a single bine.…”

“…In Campbell's (1977) study of tall hops, aphids may have responded to variation in concentrations of odours from their hosts (Visser, 1988), rather than to physical patterns of wind shelter, but the experiments were not designed to investigate that possibility. Later, it was demonstrated that migrants of P. humuli respond to host-derived stimuli when seeking hosts (Campbell et al, 1993), raising the possibility of exploiting plant volatiles as part of a control strategy (Lösel et al, 1996).…”

Trap Cropping

“…In simulation models, Potting et al (2005) concluded that small insects with limited ability to detect hosts and move to them would be unsuitable for trap cropping, citing studies conducted with the hop aphid, Phorodonhumuli (Losel et al, 1996),and the whitefly, Bemisiaargentifolii, as evidence (Smith and McSorley, 2000). Colonization patterns of these insects are largely due to passive, random, highaltitude aerial dispersal.…”