Plant response to eggs vs. Host marking pheromone as factors inhibiting oviposition byPieris brassicae

189

147

Oviposition behavior in phytophagous insects and entomophagous parasitoids is often modified by the presence of conspecific brood (eggs and larvae). Often, females avoid laying eggs on or in hosts bearing brood, a behavior that acts to reduce the level of competition suffered by their offspring. Avoidance of occupied hosts is typically mediated by cues and/or signals associated with brood. In this article, we review the role of Marking Pheromones (MPs) as signals of brood presence in both phytophagous and entomophagous insects. We place information about the function and evolution of MPs in the context of recent theory in the field of animal communication. We highlight the dynamics of host-marking systems and discuss how effects of MPs vary according to factors such as female experience and egg load. We also examine variation in the form and function of MP communication across a variety of insect taxa. While studies of MP communication in phytophagous insects have focused on the underlying behavioral mechanisms and chemistry of MP communication, studies in entomophagous insects have focused on the functional aspects of MPs and their role in 'decision-making' in insects. We argue that an approach that incorporates the important contributions of both of these somewhat independent, but complementary areas of research will lead to a more complete understanding of MPs in insects. Finally, we suggest that MP systems are model systems for the study of animal signaling and its evolution.

Section: Cues Versus Signals In Assessment Of Brood Presencementioning

confidence: 99%

Host marking behavior in phytophagous insects and parasitoids

Nufio¹,

Papaj²

2001

189

147

“…In honour of Miriam Rothschild they were named miriamids (Blaakmeer et al, 1994b). However, when Blaakmeer et al (1994a) tested how females of P. brassicae accept cabbage leaves from which conspecific eggs had been removed, they noticed that these leaves were also avoided for egg deposition even though no eggs were present anymore. Oviposition-deterring activity was also observed in leaves without eggs, but adjacent to those carrying eggs, indicating a systemic effect.…”

Section: Formation Of Neoplasmsmentioning

confidence: 99%

“…Since Blaakmeer and co-workers did not detect the above mentioned oviposition deterring components of the eggs on the leaves from which the eggs had been removed, they concluded that the leaves themselves had produced deterrents in response to the egg deposition. And indeed, oviposition deterring components could be extracted from leaves of Brassica oleracea from which eggs had been removed by briefly dipping the leaves into methanol (Blaakmeer et al, 1994a). Thus, the oviposition deterrents of cabbage leaves produced in response to the egg deposition of P. brassicae are most likely present on the surface of the leaves.…”

Section: Formation Of Neoplasmsmentioning

confidence: 99%

Induction of plant responses to oviposition and feeding by herbivorous arthropods: a comparison

Hilker

Meiners

2002

136

Plants may respond both to feeding and oviposition by herbivorous insects. While responses of plants to feeding damage by herbivores have been studied intensively during the past decades, only a few, but growing number of studies consider the reactions of plants towards egg deposition by herbivorous insects. Plants showing defensive response to oviposition by herbivores do not 'wait' until being damaged by feeding, but may instead react towards one of the initial steps of herbivore attack, the egg deposition. Direct plant defensive responses to feeding act directly against the feeding stages of the herbivores. However, a plant may also show direct defensive responses to egg deposition by (a) formation of neoplasms, (b) formation of necrotic tissue (= hypersensitive response), and (c) production of oviposition deterrents. All these plant reactions have directly negative effects on the eggs, hatching larvae, or on the ovipositing females. Indirect plant defensive responses to feeding result in the emission of volatiles (= synomones) that attract predators or parasitoids of the feeding stages. A few recent studies have shown that plants are able to emit volatiles also in response to egg deposition and that these volatiles attract egg parasitoids. Studies on the mechanisms of induction of synomones by egg deposition show several parallels to the mechanisms of induction of plant responses by feeding damage. When considering induced plant defence against herbivores from an evolutionary point of view, the question arises whether herbivores evolved the ability to circumvent or even to exploit the plant's defensive responses. The reactions of herbivores to oviposition induced plant responses are compared with their reactions to feeding induced plant responses.

“…Plant responses may be more adaptively variable than is commonly considered. After all, the ample evidence on responses of plants to competitors, herbivores, and pathogens (Blaakmeer et al, 1994;Bruin et al, 1995;Karban & Baldwin, 1997;Shulaev et al, 1997;Ballaré, 1999) should make us careful not to underestimate the potential of plants to respond to biotic components of the environment.…”

Section: Responses Of Herbivores To Induced Plant Volatilesmentioning

confidence: 99%

Multitrophic effects of herbivore‐induced plant volatiles in an evolutionary context

Dicke

Loon

2000

456

328

Herbivorous and carnivorous arthropods use plant volatiles when foraging for food. In response to herbivory, plants emit a blend that may be quantitatively and qualitatively different from the blend emitted when intact. This induced volatile blend alters the interactions of the plant with its environment. We review recent developments regarding the induction mechanism as well as the ecological consequences in a multitrophic and evolutionary context. It has been well established that carnivores (predators and parasitoids) are attracted by the volatiles induced by their herbivorous victims. This concerns an active plant response. In the case of attraction of predators, this is likely to result in a fitness benefit to the plant, because through consumption a predator removes the herbivores from the plant. However, the benefit to the plant is less clear when parasitoids are attracted, because parasitisation does usually not result in an instantaneous or in a complete termination of consumption by the herbivore. Recently, empirical evidence has been obtained that shows that the plant's response can increase plant fitness, in terms of seed production, due to a reduced consumption rate of parasitized herbivores. However, apart from a benefit from attracting carnivores, the induced volatiles can have a serious cost because there is an increasing number of studies that show that herbivores can be attracted. However, this does not necessarily result in settlement of the herbivores on the emitting plant. The presence of cues from herbivores and/or carnivores that indicate that the plant is a competitor-and/or enemy-dense space, may lead to an avoidance response. Thus, the benefit of emission of induced volatiles is likely to depend on the prevailing faunal composition. Whether plants can adjust their response and influence the emission of the induced volatiles, taking the prevalent environmental conditions into account, is an interesting question that needs to be addressed. The induced volatiles may also affect interactions of the emitting plant with its neighbours, e.g., through altered competitive ability or by the neighbour exploiting the emitted information.Major questions to be addressed in this research field comprise mechanistic aspects, such as the identification of the minimally effective blend of volatiles that explains the attraction of carnivores to herbivore-infested plants, and evolutionary aspects such as the fitness consequences of induced volatiles. The elucidation of mechanistic aspects is important for addressing ecological and evolutionary questions. For instance, an important tool to address ecological and evolutionary aspects would be to have plant pairs that differ in only a single trait. Such plants are likely to become available in the near future as a result of mechanistic studies on signal-transduction pathways and an increased interest in molecular genetics.