Chemical, Physiological and Molecular Responses of Host Plants to Lepidopteran Egg-Laying

Abstract

Plant-lepidopteran interactions involve complex processes encompassing molecules and regulators to counteract defense responses they develop against each other. Lepidoptera identify plants for oviposition and exploit them as larval food sources to complete their development. In turn, plants adopt different strategies to overcome and limit herbivorous damages. The insect egg deposition on leaves can already induce a number of defense responses in several plant species. This minireview deals with the main features involved in the interaction between plants and lepidopteran egg-laying, focusing on responses from both insect and plant side. We discuss different aspects of direct and indirect plant responses triggered by lepidopteran oviposition. In particular, we focus our attention on the mechanisms underlying egg-induced plant defenses that can i) directly damage the eggs such as localized hypersensitive response (HR)-like necrosis, neoplasm formation, production of ovicidal compounds and ii) indirect defenses, such as production of oviposition-induced plant volatiles (OIPVs) used to attract natural enemies (parasitoids) able to kill the eggs or hatching larvae. We provide an overview of chemical, physiological, and molecular egg-mediated plant responses induced by both specialist and generalist lepidopteran species, also dealing with effectors, elicitors, and chemical signals involved in the process. Egg-associated microorganisms are also discussed, although little is known about this third partner participating in plant-lepidopteran interactions.

Screening for Sarawak Paddy Landraces with Resistance to Yellow Rice Stem Borer, Scirpophaga incertulas (Walker) (Lepidoptera: Crambidae)

“…Evidence of oviposition deterrent chemicals forming after egg mass deposition on plants had been reported for cabbage against Pieris brassicae, the cabbage butterfly (Blaakmeer et al, 1994). According to Bertea et al (2019), insects produce substances during ovipositing which act as elicitors that triggers plant defence response. The elicitors were able to trigger electrical signals and change Ca 2+ homeostasis resulting in defensive responses from the plant through hormone signalling pathways (salicylic acid pathway) (Bertea et al, 2019).…”

“…According to Bertea et al (2019), insects produce substances during ovipositing which act as elicitors that triggers plant defence response. The elicitors were able to trigger electrical signals and change Ca 2+ homeostasis resulting in defensive responses from the plant through hormone signalling pathways (salicylic acid pathway) (Bertea et al, 2019). The condition may be similar for rice in response to ovipositing of S. incertulas.…”

Spider mite egg extract modifies Arabidopsis response to future infestations

“…Research on herbivore oviposition has recently become a topic of great interest, where numerous results are emerging. Out of the wide array of known plant defences in response to eggs, such as ovicidal compound production, local tissue necrosis, and egg crushing 1 – 3 , information on the complex network of transcriptional plant responses is of specific interest. Such studies have described early Ca 2+ , electrical and Reactive Oxygen Species (ROS) imbalances 3 , 4 and have revealed the importance of Jasmonic Acid (JA) and Salicylic Acid (SA) as the major plant hormonal regulators in response to oviposition 5 .…”

“…Out of the wide array of known plant defences in response to eggs, such as ovicidal compound production, local tissue necrosis, and egg crushing 1 – 3 , information on the complex network of transcriptional plant responses is of specific interest. Such studies have described early Ca 2+ , electrical and Reactive Oxygen Species (ROS) imbalances 3 , 4 and have revealed the importance of Jasmonic Acid (JA) and Salicylic Acid (SA) as the major plant hormonal regulators in response to oviposition 5 . In Arabidopsis, responses associated with phytophagous insect eggs are mainly dominated by SA defence cascades 6 , 7 , and are similar to those activated by pathogens 6 , 8 – 10 .…”

Battle between insect eggs and host plants : Ecology and evolution of pierid egg-induced responses in Brassicaceae

“…The observed differences in oviposition preferences of P. brassicae are likely caused by differences in plant chemistry and OIPV blends as explained above. Egg deposition has been shown to induce quantitative changes in plant volatile blends, which in turn affect oviposition preferences of herbivorous insects, including butterflies and moths (Bertea et al, 2020;Hilker and Fatouros, 2015). Similar to the work on parasitoids, β -caryophyllene present in host plant odours has been shown to elicit oviposition in codling moths (Witzgall et al, 2005) and attraction of mated females of grapevine moths to grapes (Tasin et al, 2006).…”