Insect Eggs Research Articles

Heat and Cold Shocks Decrease the Incidence of Diapause in Trichogramma telengai Larvae.

Insect diapause and response to thermal stress are similar in the variety of manifestations. However, the influence of thermal shocks on the incidence of insect diapause has not been sufficiently studied. Our laboratory experiments showed that both cold (-10 °C) and heat (43 °C) shocks experienced for at least 20-30 min significantly reduced the incidence of facultative larval winter diapause in the insect egg parasitoid Trichogramma telengai. However, the patterns of these responses were substantially different. In particular, the peaks of the sensitivity to diapause-averting effects of heat and of cold shocks fell, correspondingly, on middle-stage (5 days of development at 15 °C) and late-stage (9-11 days of development at 15 °C) larvae. Heat shocks influence the incidence of diapause mostly via the changes in the initial proportions of diapause-destined and non-diapause-destined individuals, whereas the effect of cold shocks is mostly based on differential mortality (i.e., the difference in mortality among treatments of the same experiment) with better survival of non-diapause-destined individuals. These results elucidate the peculiarities of the interaction between stress and diapause, allowing us to specify the methods for Trichogramma mass rearing and storage.

First Activity of Aspergillus flavus as Entomopathogen Infecting Diaphania indica and Control Efficacy Across Different Developmental Stages

Diaphania indica (Lepidoptera: Crambidae) is one of the most important pests infesting many cucurbitaceous vegetables. During the rearing of insect eggs, we observed a fungal infection in these insect eggs which causes the death of pests. Therefore, this work aimed to isolate and identify this fungus by amplifying the internal transcribed spacer (ITS) region of the rDNA, as well as evaluating the efficiency of this fungus in control. Aspergillus flavus, ‘PP125556’, showcased robust pathogenicity against a range of D. indica pests. The results showed that colonies of ‘PP125556’ cultivated on potato dextrose agar (PDA) exhibited distinctive morphological characteristics, transitioning from pristine white to verdant green. Bioassays demonstrated concentration-dependent mortality rates of D. indica larvae and adults when exposed to varying concentrations of ‘PP125556’ conidia, with the highest concentration (1 × 109 conidia/mL) inducing significant death, with the highest mortality (53.06% for eggs, 70.57% for larvae, and 86.65% for adults). Furthermore, examination under a stereomicroscope revealed conspicuous external symptoms in infected larvae, including reduced mobility, darkened body pigmentation, and the emergence of white hyphae, indicative of mortality. Additionally, infected eggs exhibited inhibited hatching and the emergence of green hyphae, while infected adults displayed mortality and white hyphae colonization, underscoring the potent biocontrol efficacy of A. flavus ‘PP125556’ against D. indica across diverse developmental stages.

Seven New Species of Anastatus Motschulsky (Hymenoptera: Chalcidoidea: Eupelmidae) from China Identified Based on Morphological and Molecular Data.

Anastatus is the second-largest genus in the family Eupelmidae, with 150 species found worldwide and fourteen known species in China. Most species in this genus are the primary parasitoids of insect eggs, particularly those of Lepidoptera and Hemiptera, and several species have been used for the biological control of various insect pests. In this paper, seven new species of Anastatus Motschulsky, 1859 (Hymenoptera: Eupelmidae) from China are described, of which A. caeruleus Wang and Peng n. sp. and A. garygibsoni Zhou and Peng n. sp. were reared from the eggs of Tessaratoma papillosa (Hemiptera: Tessaratomidae), while A. daiyunensis Wang and Peng n. sp., A. makrysourus Zhou and Peng n. sp., A. polikiarkoudus Wang and Peng n. sp., A. taibaiensis Wang and Peng n. sp., and A. zdenekbouceki Zhou and Peng n. sp. were collected by malaise traps or sweeping. The new species are all described and illustrated based on female specimens, and the key to all 21 Chinese Anastatus species, based on females, is provided. Partial COI sequences of A. caeruleus n. sp., A. garygibsoni n. sp., and A. taibaiensis n. sp. are provided, and a phylogenetic reconstruction based on maximum likelihood analyses, while showing similar results at high taxonomic levels to our morphological feature classification results, provides additional information on the placement of Anastatus at the species level.

The SA-WRKY70-PR-Callose Axis Mediates Plant Defense Against Whitefly Eggs.

The molecular mechanisms of plant responses to phytophagous insect eggs are poorly understood, despite their importance in insect-plant interactions. This study investigates the plant defense mechanisms triggered by the eggs of whitefly Bemisia tabaci, a globally significant agricultural pest. A transcriptome comparison of tobacco plants with and without eggs revealed that whitefly eggs may activate the response of defense-related genes, including those involved in the salicylic acid (SA) signaling pathway. SA levels are induced by eggs, resulting in a reduction in egg hatching, which suggests that SA plays a key role in plant resistance to whitefly eggs. Employing Agrobacterium-mediated transient expression, virus-induced gene silencing assays, DNA-protein interaction studies, and bioassays, we elucidate the regulatory mechanisms involved. Pathogenesis-related proteins NtPR1-L1 and NtPR5-L2, downstream of the SA pathway, also affect whitefly egg hatching. The SA-regulated transcription factor NtWRKY70a directly binds to the NtPR1-L1 promoter, enhancing its expression. Moreover, NtPR1-L1 promotes callose deposition, which may impede the eggs' access to water and nutrients. This study establishes the SA-WRKY70-PR-callose axis as a key mechanism linking plant responses and defenses against whitefly eggs, providing new insights into the molecular interactions between plants and insect eggs.

Mechanism of Exogenous Jasmonic Acid-Induced Resistance to Thrips palmi in Hemerocallis citrina Baroni Revealed by Combined Physiological, Biochemical and Transcriptomic Analyses

Jasmonic acid (JA) is a regulator of plant resistance to phytophagous insects, and exogenous JA treatment induces plant insect resistance. This study investigated the mechanism of exogenous JA-induced resistance of Hemerocallis citrina Baroni (daylily) to Thrips palmi at the biochemical and molecular levels. Daylily leaves sprayed with JA showed significantly higher levels of secondary metabolites—tannins, flavonoids, and total phenols, and activity of defense enzymes—peroxidase, phenylalanine ammonia lyase, polyphenol oxidase, and protease inhibitor (PI) than control leaves; the most significant effects were observed with 1 mmol L−1 JA. Owing to an improved defense system, significantly fewer T. palmi were present on the JA-treated plants than control plants. The JA-treated leaves had a smoother wax layer and fewer stomata, which was unfavorable for insect egg attachment. The differentially expressed genes (DEGs) were significantly enriched in insect resistance pathways such as lignin and wax biosynthesis, cell wall thickening, antioxidant enzyme synthesis, PI synthesis, secondary metabolite synthesis, and defense hormone signaling. A total of 466 DEGs were predicted to be transcription factors, mainly bHLH and WRKY family members. Weighted gene co-expression network analysis identified 13 key genes; TRINITY_DN16412_c0_g1 and TRINITY_DN6953_c0_g1 are associated with stomatal regulation and lipid barrier polymer synthesis, TRINITY_DN7582_c0_g1 and TRINITY_DN11770_c0_g1 regulate alkaloid synthesis, and TRINITY_DN7597_c1_g3 and TRINITY_DN1899_c0_g1 regulate salicylic acid and ethylene biosynthesis. These results indicate that JA treatment of daylily improved its resistance to T. palmi. These findings provide a scientific basis for the utilization of JA as an antagonist to control T. palmi in daylily.

Thin‐film iridescence in the eggshell of a stick insect (Myronides glaucus)

AbstractColours in nature can be pigmentary, structural or a combination of both. The prevalence, function and nanostructural origin of structural coloration in eggs is largely unknown. Stick and leaf insect eggs display a wide variety of colours, most of which are produced by pigments. The eggs of Myronides glaucus (Phasmida: Lonchodidae; Hennemann, 2021), however, show a clear purple to green iridescence. Here, we use micro‐spectrophotometry, Fourier‐transform infrared reflectance, transmission‐ and scanning electron microscopy, atomic force microscopy, finite‐difference time‐domain optical simulations and experimental approaches to elucidate the mechanism for iridescence in M. glaucus eggshells, which together reveal that iridescence is caused by thin‐film interference by a 200‐ to 450‐nm‐thick outermost layer. These results highlight the diversity of phasmid eggs and the need to study the different mechanisms and functions of structural coloration.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini) from Korea, with a revised key to species of the genus.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini), Notodoma koreanum sp. nov., is described from Korea. Most of them recognized from various fungi colonies, feeding on small insect eggs or larvae, as well as fungi. We present the descriptions and images of diagnostic characters for Korean Notodoma species, including Notodoma fungorum Lewis, 1884. Additionally, a revised key to all seven species of the genus Notodoma worldwide, including the newly described species, is provided.

Spatial arrangement or amount? Spatially variable oviposition habitat can determine aquatic insect egg abundance

Spatial arrangement or amount? Spatially variable oviposition habitat can determine aquatic insect egg abundance

The Effect of Alkaloid and Phenolic Extracts of Some Plants on the Biological of the Periplaneta Americana

The study was conducted to determine the extent of the effect of some plant extracts on the death of some of the biological stages of the Periplaneta americana, it tested two types of terpenoids extracts and the alkaloid extract of Xanthium strumarium and Achillea L. the extract of terpenoids and alkaloid compounds of the Achillea L in killing eggs, and it was also noted that the extract of terpenoids in both the X.strumarium and Achillea L was superior to the rest of the extracts of the same two plants. The two extract recorded an effect on the adults of the P.americana, as it was noted that the terpenoids and alkaloids of the extract were clearly superior to the X.strumarium, it was also noted that the superiority of the alkaloid extract in the X.Strumarium. We also note that there is a direct relationship between the concentrations of the extract and the percentage of death. The extracts work to kill insect eggs in several ways that have a physiological effect, including that they contain a percentage of oils that cover the surface of the eggs with a thin layer that prevents the exchange of gases between the egg embryo and its external environment, it hardens, thus preventing the egg shell from hatching, or the penetration of the extract into the egg, which affects the protoplasm, leading to the killing of embryos, or the inhibitory effect of the terpenoids compounds present in the extract of the two plants, which affects the growth of the embryos of these eggs.

Citrus Fruits Produce Direct Defense Responses against Oviposition by Bactrocera minax (Diptera: Tephritidae).

Plants perceive and orchestrate defense responses when herbivorous insects are ovipositing. Fruits, as a crucial reproductive organ in plants, have rarely been researched on the responses to insect eggs. Here, we found that oviposition by the specialist insect Bactrocera minax in navel oranges activated the lignin synthesis pathway and cell division, causing mechanical pressure that crushed the eggs. Transcriptome and metabolome analyses revealed an enrichment of oviposition-induced genes and metabolites within the lignin synthesis pathway, which was confirmed by histochemical staining. Furthermore, hydrogen peroxide (H2O2) accumulation was observed at the oviposition sites. Plant defense-related hormones jasmonic acid (JA) and salicylic acid (SA) exhibited rapid induction after oviposition, while indole-3-acetic acid (IAA) activation occurred in the later stages of oviposition. Additionally, secondary metabolites induced by prior egg deposition were found to influence larval performance. Our studies provide molecular evidence that host fruits have evolved defense mechanisms against insect eggs and pave the way for future development of insect-resistant citrus varieties.

Larvicidal Activity of Melissa officinalis and Rosmarinus officinalis Extracts and Their Lethal Impact on Detoxifying Enzymes in Aedes aegypti L. Larvae

Background & Objectives: Mosquito-borne diseases significantly impact global health, particularly in tropical regions. While synthetic insecticides are currently employed to control mosquito vectors, their detrimental effects on ecosystems and persistence necessitate alternative control methods. Botanicals, owing to their diverse phytocompounds, offer potential for controlling and preventing vector-borne diseases by targeting insect eggs and larvae. This study aimed to evaluate the toxicity of Melissa officinalis and Rosmarinus officinalis extracts (methanolic and aqueous) against Aedes aegypti larvae, a vector of arboviruses. Materials & Methods: Total protein content in control and plant extract-exposed larval homogenates was estimated using bovine serum albumin as a standard. Acetylcholinesterase (AChE) and carboxylesterase assays were performed to determine larvicidal effects. Larval mortality was assessed after 24 hours of exposure. Results: Our findings revealed that the methanolic leaf extract of M. officinalis exhibited superior larvicidal activity (100% at 1000 ppm) compared to the methanolic R. officinalis extract (84±2.45% at 1000 ppm). In contrast, the aqueous extracts of both plant species inferred no larvicidal activity. The LC50 and LC90 values for M. officinalis methanolic extract were 378.7 ppm and 795.8 ppm, respectively, whereas those for R. officinalis were 648.9 ppm and 1152.9 ppm, respectively. Furthermore, biochemical assays measuring total protein, acetylcholinesterase, α-carboxylesterase, and β-carboxylesterase activities were conducted for M. officinalis, corroborating and substantiating its larvicidal properties. Conclusion: This study demonstrates that the methanolic leaf extract of M. officinalis possesses significant larvicidal efficacy against A. aegypti. These findings suggest that this plant or its phytocompounds could serve as a bioinsecticide, offering a potential alternative to environmentally toxic and non-biodegradable synthetic insecticides.

Coevolution between eggs and sperm of insects.

Sexual selection is known to play a major role in the evolution of insect sperm size, whereas natural selection is thought to be a major driver of insect egg size. Despite these differing forms of selection operating, it is possible coevolution between male and female gametes can occur owing to their vital interactions during fertilization. We tested egg-sperm coevolution in insects and found that longer sperm correlated to longer and wider eggs. Moreover, the size of the entry point of sperm into insect eggs (micropyles), was positively related to the diameter of sperm, on average being approximately three times the diameter of the sperm. This suggests a function in reducing and channelling sperm entry, but potentially still leaving space for movement. Our work suggests that greater attention needs to be paid to egg-sperm interactions prior to the point of fertilization as they may influence the evolution of gametes.

Effect of microfilaments produced by eggs of Dalbulus maidis (Hemiptera: Cicadellidae), against egg parasitoids

Abstract Insect eggs, once oviposited, defend against abiotic and biotic factors using thickness, secretions, or other defenses. The eggs of most insect species are attacked by parasitoid wasps, which are often their most significant mortality factors. The present study is the first investigation of microfilaments as defense from parasitoids. Specifically, the effect of the corn leafhopper Dalbulus maidis DeLong (Hemiptera: Cicadellidae) egg microfilaments against parasitism by Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) and Paracentrobia subflava (Girault) (Hymenoptera: Trichogrammatidae) was evaluated. Field and laboratory experiments were conducted to evaluate several biological traits related to parasitism in D. maidis eggs with and without microfilaments. An initial field experiment found no difference in parasitism by A. virlai and P. subflava of eggs with vs. without microfilaments after 5 days of exposure of healthy D. maidis eggs to parasitism. A second field experiment then looked at exposure for 1 day, and this treatment found greater parasitism of healthy D. maidis eggs by each parasitoid species in eggs without microfilaments vs. in eggs with microfilaments. Laboratory experiments conducted separately for A. virlai and P. subflava parasitism after 1 day of exposure to healthy D. maidis eggs confirmed a higher percentage of parasitoid emergence in the eggs without microfilaments (both young and mature eggs) vs. mature eggs with microfilaments. These results suggest that eggs without microfilaments are more parasitized than eggs with microfilaments during a 1-day exposure, but that this difference disappears as egg microfilaments regrow over a 5-day period.

Resource allocation strategies and mechanical constraints drive the diversification of stick and leaf insect eggs

The diversity of insect eggs is astounding but still largely unexplained. Here, we apply phylogenetic analyses to 208 species of stick and leaf insects, coupled with physiological measurements of metabolic rate and water loss on five species, to evaluate classes of factors that may drive egg morphological diversification: life history constraints, material costs, mechanical constraints, and ecological circumstances. We show support for all three classes, but egg size is primarily influenced by female body size and strongly trades off with egg number. Females that lay relatively fewer but larger eggs, which develop more slowly because of disproportionately low metabolic rates, also tend to bury or glue them in specific locations instead of simply dropping them from the foliage (ancestral state). This form of parental care then directly favors relatively elongated eggs, which may facilitate their placement and allow easier passage through the oviducts in slender species. In addition, flightless females display a higher reproductive output and consequently lay relatively more and larger eggs compared with flight-capable females. Surprisingly, local climatic conditions had only weak effects on egg traits. Overall, our results suggest that morphological diversification of stick insect eggs is driven by a complex web of causal relationships among traits, with dominant effects of resource allocation and oviposition strategies, and of mechanical constraints.

Root inoculation with beneficial soil microbes enhances indirect plant defences induced by insect feeding and egg deposition

Abstract Plants can respond to insect egg deposition by emitting oviposition‐induced plant volatiles (OIPVs) recruiting parasitoids. The recruitment of carnivore insects in response to egg deposition is considered an indirect defence strategy that is widespread in the plant kingdom. In recent years, there has been increasing evidence showing that microbial colonization can influence the strength of plant responses to insect herbivory, yet no information is available on how beneficial microbes modulate indirect defences induced by insect egg deposition. In this work, we evaluated the effects of inoculation with the beneficial soil fungus Trichoderma harzianum strain T22 on a tritrophic system consisting of tomato, the southern green stink bug Nezara viridula and its associated egg parasitoid Trissolcus basalis. We used Y‐tube olfactometer assays to evaluate the behavioural responses of the parasitoids to OIPVs emitted by plants colonized with beneficial soil microbes. We also used gas chromatography coupled with mass spectrometry (GC–MS) to investigate whether and how root inoculation with T. harzianum T22 affects the chemical composition of induced plant volatiles. In olfactometer assays, we found that root inoculation with T. harzianum T22 enhanced the attraction of the egg parasitoid towards tomato plants induced by N. viridula feeding and oviposition activities. In particular, the egg parasitoid preferred OIPVs emitted by tomato plants previously inoculated with T. harzianum T22 over OIPVs emitted by non‐inoculated plants. Furthermore, chemical analysis showed that root inoculation with T. harzianum T22 resulted in changes in the composition of OIPVs, which was consistent with the behavioural observations. Among the compounds that strongly contribute to the chemical differences between OIPVs from non‐inoculated and inoculated plants, chemical analysis identified green leaf volatiles ((Z)‐3‐hepten‐1‐ol, (E,E)‐2,4‐hexadienal), along with terpenoids (terpinen 4‐ol, α‐tujene and δ‐elemene). Taken together our results indicate that beneficial soil microbes enhance indirect plant defences induced by feeding and oviposition, broadening our understanding of plant responses to insect eggs. Our results underscore the importance of taking into account the role of microorganisms to fully comprehend the intricate interactions among plants, herbivore eggs and their associated egg parasitoids. Read the free Plain Language Summary for this article on the Journal blog.

The innovation of Wolbachia mosquito technology to control dengue hemorrhagic fever

Wolbachia is a bacterium that generally occurs naturally in 50% of insect species, lives in insect cells, and is passed from one generation to the next through insect eggs. Wolbachia in the mosquito's body can inhibit the replication of the Dengue virus or other viruses. Based on the Decree of the Minister of Health of the Republic of Indonesia Number 1341 concerning the Implementation of the Pilot Project for the Implementation of Wolbachia as a Dengue Management Innovation, the application of this technology was carried out in five cities, namely Semarang City, West Jakarta, Bandung City, Kupang City, and Bontang City. The effectiveness of Wolbachia itself has been proven and researched since 2011, when it was conducted in Yogyakarta. As a result, Wolbachia was proven to reduce dengue fever cases by up to 77% and reduce the proportion of hospital admissions by 86%. This method of spreading Wolbachia mosquitoes in several cities will reduce local transmission of infection in those areas. This reduction in local transmission of dengue infection occurs both in the rainy and dry seasons. Scientifically, the success of the Wolbachia method is apparent, but the controversy is due to confused information circulating, giving rise to concern among the public. Vector control using Wolbachia is an alternative disease control method that uses mosquito vectors and is quite effective. However, the application of Wolbachia in the community must be monitored continuously to determine its impact on humans, local mosquitoes, and the ecosystem.

Alternating Low and High Temperatures Increases the Hatching Rate of Eupolyphaga sinensis (Blattaria: Polyphagidae) Eggs

The hatching rates and developmental durations of Eupolyphaga sinensis Walker eggs were studied under variable combinations of low temperatures (5 °C and 10 °C) and high temperatures (25 °C and 30 °C). Our findings were intended to provide new evidence on the effect of temperature on the hatching of insect eggs. The results showed that both low temperatures and high temperatures significantly affected the hatching rate and time of E. sinensis eggs. Further analysis revealed a significant interactive effect between low temperatures and high temperatures. The 5 °C + 30 °C treatment achieved the highest egg hatching rate (77.33%) and the shortest hatching time (44.11 ± 1.55 d), which was significant compared with three other temperature treatments. The effects of high temperatures treatments on the hatching rate and the hatching time were more significant than that in the low temperature treatments. Hatching began earlier at 5 °C + 30 °C and 10 °C+30 °C temperatures, and single-day hatching first increased rapidly before declining afterwards within a short period. Comparatively, the hatching of eggs under the (5 °C+25 °C) and (10 °C+25 °C) temperatures was initially significantly delayed, including the peak single-day hatching rate. Under these treatments, the hatching rate tended to be gradual in terms of the temporal dynamics without showing any prominent peak. These results showed that low and high temperatures significantly affect the hatching rates of E. sinensis eggs. This study provided basis for the large-scale breeding of E. sinensis.

The Diet and Prey Preference of the Indian Pangolin (Manis crassicaudata) in a Human-Intervened Montane Landscape

Indian pangolin (Manis crassicaudata) is a solitary, elusive, and predominantly nocturnal mammal highly adapted to an insectivorous diet. It has become endangered due to hunting for bush meat and scales, illegal trafficking and poaching. Rescue and captive breeding programs for Indian pangolins have limited success due to the lack of understanding of the species‘ dietary preferences and foraging ecology. The stomach contents and prey preference of Indian pangolin have been less studied owing to the difficulty of acquiring suitable specimens. Such scientific information is unavailable, especially in Sri Lanka. In this study, we analyzed the stomach content of three (03) Indian pangolin specimens collected from human-intervened montane landscapes in the Kandy District, thus allowing a deeper understanding of the Indian pangolin‘s foraging ecology in a specific habitat. Stomach content analysis revealed that a greater proportion of the pangolin diet consists of grit which was 96.13% of the average dry mass (DM%). Plant matter (pieces of twigs, leaf particles, stems and barks) was least present, which was 0.26% of the average dry mass percentage. The plant matter is likely to be ingested while praying on arboreal insect nests, insects living under barks, and decaying logs. Insect matter consisted of ants, termites, their body parts, and wings which were 1.84% of the average dry mass and insect eggs accounted for 2.83%. A total of 13 ant species belonging to 05 subfamilies and 02 termite species of the same subfamily were identified in the stomach contents. Insect species representing terranean, subterranean, semi-arboreal and arboreal habitats were found in the stomach content. Approximately 13.97% of the insect matter belonged to the species in the terranean foraging layer, while sub-terranean, semi-arboreal and arboreal species accounted for 19.53%, 64.58% and 1.59% respectively. Accordingly, it appears that Indian pangolin in the studied montane landscape predominantly feed on semi-arboreal insects. The study further provides detailed insights into the prey preference and foraging ecology of the Indian pangolin in the montane landscape. 
 Keywords: Indian pangolin, Stomach content, Foraging ecology, Prey preference

Possibility of growing insect eggs on human cadavers preserved at sub‐zero temperatures for different time intervals

AbstractInsects are the first arthropods to invade cadavers and, thus, can be used as evidence in criminal investigations. The current study aimed to investigate the possibility of breeding insect eggs in the lab that would be collected from male human cadavers kept in the mortuary refrigerators at sub‐freezing temperatures for different periods. Egg specimens were collected from different human cadavers preserved from −16 to −20°C for different time intervals. All collected eggs were incubated at 25–30°C and 60%–70% and observed until hatched larvae complete their life cycle. All obtained larvae and adults were identified based on morphological characteristics. Data showed that, at selected ranges of temperature and humidity, some eggs were hatched to the first larval stage and then stopped growing, while others completed their life cycle to the adult insect stage. The obtained adult insects were identified using morphological classification and found to belong to Dermestes frischii.

The impact of insect egg deposition on Pinus sylvestris transcriptomic and phytohormonal responses to larval herbivory.

Plants can improve their resistance to feeding damage by insects if they have perceived insect egg deposition prior to larval feeding. Molecular analyses of these egg-mediated defence mechanisms have until now focused on angiosperm species. It is unknown how the transcriptome of a gymnosperm species responds to insect eggs and subsequent larval feeding. Scots pine (Pinus sylvestris L.) is known to improve its defences against larvae of the herbivorous sawfly Diprion pini L. if it has previously received sawfly eggs. Here, we analysed the transcriptomic and phytohormonal responses of Scots pine needles to D. pini eggs (E-pine), larval feeding (F-pine) and to both eggs and larval feeding (EF-pine). Pine showed strong transcriptomic responses to sawfly eggs and-as expected-to larval feeding. Many egg-responsive genes were also differentially expressed in response to feeding damage, and these genes play an important role in biological processes related to cell wall modification, cell death and jasmonic acid signalling. EF-pine showed fewer transcriptomic changes than F-pine, whereas EF-treated angiosperm species studied so far showed more transcriptional changes to the initial phase of larval feeding than only feeding-damaged F-angiosperms. However, as with responses of EF-angiosperms, EF-pine showed higher salicylic acid concentrations than F-pine. Based on the considerable overlap of the transcriptomes of E- and F-pine, we suggest that the weaker transcriptomic response of EF-pine than F-pine to larval feeding damage is compensated by the strong, egg-induced response, which might result in maintained pine defences against larval feeding.