An experimental investigation of patterns of parasitism at three spatial scales in an aphid-parasitoid system (Hymenoptera: Aphidiidae)

Abstract

Abstract. Density dependent host mortality in the interaction between the solitary endoparasitoid Aphidius colemani (Aphidiidae), and its host, the green peach aphid Myzus persicae, was examined on greenhouse peppers. The experimental approach attempted to eliminate spatial interdependence in the relationship between host density and host mortality by using different plants to measure parasitism at different spatial scales. Increasing host density at the plant scale caused a significant increase in the proportion of host mortality. However, at the shoot and leaf scale, increasing host density caused a significant decrease in host mortality. This may be one of the first experimental demonstrations of a switch from inverse to direct density dependence. The pattern is assumed to be a result of searching parasitoids using different cues at different spatial scales.

Host instar preference and functional response of Aphidius transcaspicus, a parasitoid of mealy aphids (Hyalopterus species)

“…It appears to be a specialist parasitoid of Hyalopterus species in its native range ), but can develop successfully on more polyphagous aphid hosts in captivity (Wang and Messing 2006). In contrast, A. colemani has been widely introduced around the world (Stary 1995;Takada 1998;Stary 2002) has a broad host range, and much is known of its reproductive and developmental biology, host preferences, and ecology (Jarosik and Lapchin 2001;Stary 2002;Jarosik et al 2003;Jones et al 2003;Lin and Ives 2003;Kalule and Wright 2004;Kavallieratos et al 2004;Perdikis et al 2004;Kalule and Wright 2005;Ode et al 2005;Sampaio et al 2005;Soglia et al 2006;Zamani et al 2006;Zamani et al 2007). Determination of predator preference for different types of prey has received much attention (Singer 2000;Underwood et al 2004;Manly 2006;Taplin 2007).…”

Drought and Root Herbivory Interact to Alter the Response of Above-Ground Parasitoids to Aphid Infested Plants and Associated Plant Volatile Signals

“…As the percent parasitism is similar between aphid instars [127], the present studies were conducted on mixed instars, which were exposed to parasitoids (five replicates per treatment in two blocks). Five paired parasitoids (one pair per 60 aphids [128]) were released per replicate under ventilated bell cloches. Parasitoids were removed 24 h after release and remaining aphids were allowed to develop for 10–14 days for mummy formation [127].…”

Improved Fitness of Aphid Parasitoids Receiving Resource Subsidies

“…However, the extent to which parasitoid fitness is enhanced by floral resources and the spatial scale over which effects on immigration and emigration operate, remain to be determined (Landis et al 2000). In natural environments, other factors such as numerical responses to patches of high host density (e.g., Jarosik and Lapchin 2001), crop edge effects (Dyer and Landis 1997), or windbreak effects (Corbett and Rosenheim 1996) may overwhelm the effects of floral resources on parasitoid aggregation. Additionally, nonfloral resource subsidies such as aphid honeydew may also be important for parasitoid fitness (e.g., Singh et al 2000b), particularly in agricultural systems where high aphid densities occur.…”