Selection by parasitoid females among closely related hosts based on volatiles: Identifying relevant chemical cues

Abstract

Parasitoid fitness is influenced by the ability to overcome host defense strategies and by the ability of parasitoid females to select high‐quality host individuals. When females are unable to differentiate among hosts, their fitness will decrease with an increasing abundance of resistant hosts. To understand the effect of mixed host populations on female fitness, it is therefore necessary to investigate the ability of female parasitoids to select among hosts. Here, we used behavioral assays, headspace volatile collection, and electrophysiology to study the ability of Asecodes parviclava to use olfactory cues to select between a susceptible host (Galerucella calmariensis) and a resistant host (Galerucella pusilla) from a distance. Our studies show that parasitoid females have the capacity to distinguish the two hosts and that the selection behavior is acquired through experiences during earlier life stages. Further, we identified two volatiles (α‐terpinolene and [E]‐β‐ocimene) which amounts differ between the two plant–herbivore systems and that caused behavioral and electrophysiological responses. The consequence of this selection behavior is that females have the capacity to avoid laying eggs in G. pusilla, where the egg mortality is higher due to much stronger immune responses toward A. parviclava than in larvae of G. calmariensis.

Chemical cues and genetic divergence in insects on plants: conceptual cross pollination between mutualistic and antagonistic systems

“…Parasitoids are also able to distinguish between closely related host herbivore species. For example, parasitoids can use cues experienced in larval stages to find oviposition sites later in life [23], further connecting larval experience to adult behaviour. Therefore, a continuous chain exists along which chemical information can travel, linking host herbivore chemistry to parasitoid behaviour.…”

Lineage-specific targets of positive selection in three leaf beetles with different defence capacity against a parasitoid wasp

“…Whereas G. pusilla has a strong capacity to encapsulate wasp eggs, encapsulation is rarely observed in G. calmariensis , and at an intermediate frequency in G. tenella (Fors, Markus, Theopold, Ericson, & Hambäck, 2016;Fors et al, 2014). These differences also match selection by wasp females to larval odour cues (Fors, Mozūraitis, Blažytė-Čereškienė, Verschut, & Hambäck, 2018) We collected 45 adult individuals, 15 samples from eachGalerucella species, during May and June 2019 from the following sites: three G. calmariensis populations: Norrfjärden (62°3'28"N, 17°26'18"E), Våtnäs (61°32'93"N, 17°12'77"E ) and Hölick (61°37'22"N, 17°27'18"E); three G. pusilla populations: Rastsjön (60°6'36"N, 17°53'97"E ), Lörudden (62°14'14"N, 17°39'12"E) and Haversjön (59°2'31"N, 17°9'49"E); three G. tenella populations: Umeå-1 (63°46'72"N, 20°36'00"E ), Umeå-2 (63°46'36"N, 20°37'48"E ) and Umeå-3 (63°47'18"N, 20°35'89"E ). For each population, five individuals were sampled.…”

Anastrepha ludens (Loew) (Diptera: Tephritidae) larvae irradiated at higher doses improve the rearing of two species of native parasitoids

“…The situation is different for the other native parasitoid species, with which A. ludens has an evolutionary development of coexistence (López et al., 1999; Ovruski et al., 2000). On the whole, hosts in that sympatric environment seek to develop a strategy of physiological or physical defence through a shelter (Fors, Mozuraitis, Blazte‐Cereskiene, Verschut, & Hambäck, 2018; Kraaijeveld, van Alphen, & Godfray, 1998; Roderick & Navajas, 2003).…”