Trichogramma Species Research Articles

Pre-emptive augmentative biological control of Spodoptera frugiperda in Europe using Trichogramma spp.

BackgroundFall armyworm, Spodoptera frugiperda, is a highly invasive pest of maize and other crops worldwide. It has recently been detected in Europe, and it is urgent to test and develop new sustainable control methods adapted to the European context and market. Trichogramma spp. are egg parasitoids that are sometimes used as biological control agent against S. frugiperda in other continents. However, a major issue using Trichogramma spp. against this pest is that females cannot reach all eggs in an egg mass, which is usually composed of one to three layers of eggs, often covered with scales and hair. Three European Trichogramma species were tested for their ability to parasitize egg masses with one to three layers and with or without hair and scale cover.MethodsTrichogramma brassicae, T. dendrolimi and T. cacoeciae were offered five types of S. frugiperda egg masses: one-layer without hair; one-layer with hair; two-layers without hair; two-layers with hair; three-layers with hair. For each treatment, an egg mass laid on paper was placed in a small vial saturated with females, to be sure that all reachable eggs would be parasitized. For each egg mass, the number of eggs in each layer was counted. Fifteen replicates were made per treatment, as well as 10 control vials without Trichogramma sp. Parasitism rates were calculated for each egg mass.ResultsThere were significant differences in the ability of parasitoid species to oviposit through hair and scales and to reach the lower egg layers. Trichogramma dendrolimi was the most efficient species and T. cacoeciae the least. Depending on the number of egg layers and hair and scales, parasitism rates by T. brassicae, T. dendrolimi and T. cacoeciae varied between 99 and 41%, 100 and 43% and 100 and 28%, respectively.ConclusionsThe assays confirmed that Trichogramma females cannot easily oviposit through thick layers of hair and scales but overall parasitism rates were higher than found previously. Important variations between species were found, and more Trichogramma sp. and other local natural enemies should be tested pre-emptively before S. frugiperda has invaded Europe.

An evaluation of the growth, development, reproductive characteristics and pest control potential of three Trichogramma species on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Tuta absoluta is an invasive alien species that has caused major losses in the Chinese tomato industry. Investigating the growth, development, reproduction and pest control effects of three native species of Trichogramma species on the eggs of T. absoluta could provide an ecological tool for preventing and controlling T. absoluta in China. In this study, we constructed age-stage two-sex life tables for three common species of Trichogramma and determined their relative abilities to control T. absoluta in greenhouse insect cages, thus allowing us to identify the species with the most effective ability to prey on T. absoluta eggs. Analysis showed that the net reproductive rate (R0), gross reproduction rate (GRR) and intrinsic rate of increase (r) of Trichogramma ostriniae were the highest of the three species at 22.85, 32.58 and 1.31, respectively. In the presence of 10 eggs and under ideal conditions, T. ostriniae, Trichogramma chilonis, and Trichogramma dendrolimi produced 9451.04, 5199.56, and 1902.95 offspring, respectively. Following the release of T. ostriniae, tomato leaves incurred a damage index of 1 after the first week, while the number of T. absoluta reduced to 24.60 individuals by week 10 (8.75% of the control treatment). Of the three species of Trichogramma tested in this study, T. ostriniae exhibited the best growth, development, reproductive capacity and predatory ability against T. absoluta, and has broad application prospects. © 2024 Society of Chemical Industry.

Body Part Selection for Size Classification of Two Trichogramma Species.

Body size is an important morphological characteristic that covaries with the quality of parasitoids and predators. Data show that the larger the organism is, the better the biological parameters and the host location by natural enemies in the field. The standard way of evaluating the size of parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) is by measuring the tibia, but using only one body part to estimate the size of organisms can lead to miscalculations. In this paper, commercial Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) and Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) were mounted on slides for microscopy and photographed, and the photographs were used to measure their antennae, scutellum, ovipositor, tibia, and wing. Principal component analysis (PCA) and linear discriminant analysis (LDA) were performed to select the body part that best represents their size. PCA showed that all body parts represented size in a similar way, and LDA showed that the ovipositor was the most representative. We conclude that the best body parts for representing the size of the Trichogramma species studied are the wing and ovipositor, and at least two body parts are needed to detect two size groups.

Importance of Host Feeding in the Biological Control of Insect Pests: Case Study of Egg Parasitoid Species (Hymenoptera: Chalcidoidea: Trichogrammatidae).

Over recent decades, intraguild predation (IGP) has attracted special attention, both from the theoretical and practical standpoints. The present paper addresses the interference competition between two Trichogramma species (egg parasitoids)-on the one hand, the extrinsic interactions (i.e., the indirect competition between female T. achaeae and T. brassicae), and on the other, the intrinsic interactions between the larvae of both species. Furthermore, T. achaeae is a better competitor than T. brassicae due to a dual mechanism-the former acts as a facultative hyperparasitoid of the latter, exclusively considering parasitism relationships as well as presenting predation activity by host feeding, which gives preference to eggs previously parasitized by T. brassicae over non-parasitized eggs. Both mechanisms are dependent on the prey density, which is demonstrated by a change in the functional response (i.e., the relationship between the numbers of prey attacked at different prey densities) of T. achaeae adult female-it changes from type II (i.e., initial phase in which the number of attacked targets increases hyperbolically and then reaches an asymptote, reflecting the handling capacity of the predator), in the absence of competition (an instantaneous search rate of a' = 9.996 ± 4.973 days-1 and a handling time of Th = 0.018 ± 0.001 days), to type I (i.e., linear increase in parasitism rate as host densities rise, until reaching a maximum parasitism rate, and an instantaneous search rate of a' = 0.879 ± 0.072 days-1 and a handling time of Th ≈ 0) when interference competition is present. These results show that there is a greater mortality potential of this species, T. achaeae, in conditions of competition with other species, T. brassicae in this case. Based on this, their implications in relation to the biological control of pests by parasitoid species are discussed.

Assessment of the suitability of three native Trichogramma species for biological control of Tuta absoluta in China

Assessment of the suitability of three native Trichogramma species for biological control of Tuta absoluta in China

Influence of fall armyworm Spodoptera frugiperda egg mass scales and layers on the performance of three species of egg parasitoid Trichogramma with different ovipositor lengths

BackgroundThe fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a highly polyphagous and destructive pest of maize and other cereal crops. Biological control is a potential alternative to chemical insecticides used for the management of FAW in maize. Egg parasitoids are promising biocontrol agents as they kill the insect pest at their egg stage before it hatches, thus preventing the damaging larval stage. Trichogramma is widely used in augmentative biological control of FAW in native and invaded regions. However, FAW lay egg masses in layer by layer and eggs are covered with egg scales, this may affect the performance of Trichogramma parasitoids. Therefore, the parasitism potential of three Trichogramma species was studied on eggs with or without scales and layered eggs of FAW, further the impact of parasitoids ovipositor length on parasitism was also determined. This helps to understand the parasitism potential of parasitoids on different egg type for better implementation of biological control programs against FAW.ResultsThe effect of FAW egg mass with or without scales and layered eggs on the performance of Trichogramma chilonis, T. pretiosum and T. mwanzai was studied and results indicated that egg mass scales and the layered eggs were significantly affected the parasitism potential of Trichogramma species, but did not affect the parasitoid emergence. In general, T. chilonis parasitized a higher percentage of eggs with or without scales and layered eggs of FAW than the other two species. T. chilonis and T. mwanzai had a greater ovipositor length than T. pretiosum.ConclusionThe performance of evaluated Trichogramma species on FAW eggs with or without scales and layered eggs affected the parasitism success. The parasitism success of T. chilonis was comparably higher than other tested species. Hence, the scales on egg masses and layered eggs of FAW should be taken into account while selecting the Trichogramma species in the biological control of FAW.

Parasitism and Suitability of Trichogramma chilonis on Large Eggs of Two Factitious Hosts: Samia cynthia ricini and Antheraea pernyi.

Trichogramma, an effective biological control agent, demonstrates promise in environmentally sustainable pest management through its parasitic action toward insect eggs. This study evaluates the parasitism fitness and ability of T. chilonis with regard to two factitious host eggs, aiming to develop a cost-effective biological control program. While T. chilonis demonstrated the ability to parasitize both host eggs, the results indicate a preference for ES eggs over COS eggs. The parasitism and emergence rates of T. chilonis regarding ES eggs (parasitism: 89.3%; emergence: 82.6%) surpassed those for COS eggs (parasitism: 74.7%; emergence: 68.8%), with a notable increase in the number of emergence holes observed in the ES eggs compared to the COS eggs. Moreover, the developmental time of T. chilonis for ES eggs (10.8 days) was shorter than that for COS eggs (12.5 days), resulting in a lower number of dead wasps produced. Notably, no significant difference was observed in the female ratios between the two species. A comprehensive analysis was conducted, comparing the size and shell thickness of the two factitious hosts. The ES eggs exhibited smaller dimensions (length: 1721.5 μm; width: 1178.9 μm) in comparison to the COS eggs (length: 2908.8 μm; width: 2574.4 μm), with the ES eggshells being thinner (33.8 μm) compared to the COS eggshells (47.3 μm). The different host species had an effect on the body length of the reared parasitoids, with T. chilonis reared on COS hosts exhibiting a larger body length (female: 626.9 µm; male: 556.7 µm) than those reared on ES hosts (female: 578.8 µm; male: 438.4 µm). Conclusively, the results indicate that ES eggs present a viable alternative to COS eggs for the mass production of Trichogramma species in biological control programs.

Biology and quality assessment of Telenomus remus (Hymenoptera: Scelionidae) and Trichogramma spp. (Hymenoptera: Trichogrammatidae) in eggs of Spodoptera spp. for augmentative biological control programs.

The Spodoptera complex of the family Noctuidae, represented here by S. frugiperda (J.E. Smith), S. eridania (Stoll), S. albula (Walker), and S. cosmioides (Walker), is an important group of crop pests in Brazil. Spodoptera frugiperda and S. eridania are invasive in Africa, and the former also in Asia and Oceania. The egg parasitoids Telenomus remus Nixon (Hymenoptera: Scelionidae) and Trichogramma spp. (Hymenoptera: Trichogrammatidae) are potential control agents for field use against these noctuids. We evaluated the parasitism efficiency, development, and flight capacity of an isofemale line and a regular line of T. remus, and 2 genetically variable populations of Trichogramma pretiosum Riley and Trichogramma atopovirilia Oatman and Platner (Hymenoptera: Trichogrammatidae) in these 4 members of the Spodoptera complex. All parasitoids were able to develop in the 4 hosts. The parasitoids showed good flight capacity, except for the regular line of T. remus. The Trichogramma species, despite having high viability and female:male sex ratios, showed poorer parasitism performances than T. remus. The regular T. remus line also showed good parasitism capacity and high viability but had a predominance of males. In general, the isofemale line of T. remus showed good rates of parasitism and flight capacity as well as a high viability and sex ratio, proving to be a potential candidate for an augmentative biological-control program for Spodoptera spp Guenée (Lepidoptera: Noctuidae).

Evaluation of comparative parasitic efficiency and biology of hymenopteran egg parasitoids, Trichogramma chilonis and T. japonicum on Corcyra cephalonica and Helicoverpa armigera

Aim: To evaluate the comparative parasitic efficiency and biology of Trichogrammatid wasps on noble laboratory host Corcyra cephalonica as well as on Helicoverpa armigera, the cosmopolitan, polyphagous and precarious insect pest of many cultivated crops. Methodology: The biology of Trichogramma chilonis and T. japonicum, their sex ratio, and parasitic efficiency were studied. Host insects were reared on artificial diet to obtain their eggs for initiating the experiment. Egg-card pieces were prepared with the irradiated eggs of respective host insects. Egg-cards were introduced into the tubes containing freshly emerged adult parasitoids. Parasitized egg-cards (Trichocards) were kept separately in plastic tube to study the biological attributes and percent parasitization of the parasitoids. Egg cards of different host eggs taking eggs of different age groups were prepared to study the effect of age of host eggs on the biological efficiency of the parasitoids. Results: Irrespective of Trichogramma species, the duration (d) of eggs to adult period was more when reared on the eggs of H. armigera than on the eggs of C. cephalonica. Maximum life stage duration of T. chilonis and T. japonicum from egg to adult was 8.2 days and 10.2 days, respectively, when reared on H. armigera eggs. There was maximum parasitization (84.8%) of fresh eggs of C. cephalonica by T. chilonis as compared to the egg parasitization of 73.4% by T. japonicum. Likewise, extreme parasitization of fresh eggs of H. armigera was recorded as 62.4% when parasitized by T. chilonisas against 59.7% parasitization by T. japonicum. Interpretation: According to the study, H. armigera eggs have the finest biological and parasitic features in terms of the highest adult longevity, sex ratio, mean progeny female-1, and mean adult egg-1, making them the best for mass production of the egg parasitoids, T. chilonis. Key words: Corcyra cephalonica, Host eggs, Helicoverpa armigera, Parasitization, Trichogramma

Restricted diet prevents the induction of diapause in Trichogramma larvae

Photoperiodic and thermal diapause-inducing responses of insect parasitoids are well known whereas the trophic response is rather poorly studied. Our experiments showed that restricted diet prevented the induction of diapause in Trichogramma telengai parasitizing the grain moth (Sitotroga cerealella) eggs. In particular, the incidence of diapause decreased (1) with the rate of superparasitism (parasitoid:host ratios of 1:50, 1:25, 1:10, and 1:2 were tested), (2) with the time of host storage at 5 °C (0, 20, 40, 60, and 80 days), and (3) with host embryo development (1, 3, 5, 7, and 9 days at 20 °C). Both changes in the initial proportions of diapause-destined and non-diapause-destined individuals and differential mortality in these two categories were observed. These effects are most probably based on high nutritional demands of diapause-destined individuals: restricted diet causes nutrients deficiency and thereby prevents diapause. For the practice we conclude that if the induction of diapause for cold storage of mass or laboratory reared Trichogramma species is planned, host quality requirements should be tightened.

Bacterial Community Survey of Wolbachia-Infected Parthenogenetic Parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) Treated with Antibiotics and High Temperature.

Wolbachia has been shown to induce thelytokous parthenogenesis in Trichogramma species, which have been widely used as biological control agents around the world. Little is known about the changes of bacterial community after restoring arrhenotokous or bisexual reproduction in the T. pretiosum. Here, we investigate the emergence of males of T. pretiosum through curing experiments (antibiotics and high temperature), crossing experiments, and high-throughput 16S ribosomal RNA sequencing (rRNA-seq). The results of curing experiments showed that both antibiotics and high temperatures could cause the thelytokous T. pretiosum to produce male offspring. Wolbachia was dominant in the thelytokous T. pretiosum bacterial community with 99.01% relative abundance. With the relative abundance of Wolbachia being depleted by antibiotics, the diversity and relative content of other endosymbiotic bacteria increased, and the reproductive mode reverted from thelytoky to arrhenotoky in T. pretiosum. Although antibiotics did not eliminate Wolbachia in T. pretiosum, sulfadiazine showed an advantage in restoring entirely arrhenotokous and successive bisexual reproduction. This study was the first to demonstrate the bacterial communities in parthenogenetic Trichogramma before and after antibiotics or high-temperature treatment. Our findings supported the hypothesis that Wolbachia titer-dependence drives a reproduction switch in T. pretiosum between thelytoky and arrhenotoky.

Heavy metals used as fungicide may positively affect Trichogramma species used as biocontrol agents in IPM programs

Heavy metals used as fungicide may positively affect Trichogramma species used as biocontrol agents in IPM programs

Genome Assembly and Comparative Analysis of the Egg Parasitoid Wasp Trichogramma dendrolimi Shed Light on the Composition and Evolution of Olfactory Receptors and Venoms

Trichogramma dendrolimi is one of the most successfully industrialized Trichogramma species used to control agricultural and forestry pests in China. However, the molecular mechanisms underlying its host recognition and parasitism remain largely unknown, partially due to the limited genome information of this parasitoid wasp. Here, we present a high-quality de novo assembly of T. dendrolimi through a combination of Illumina and PacBio sequencing technologies. The final assembly had a length of 215.2 Mb and contains 316 scaffolds with a scaffold N50 size of 1.41 Mb. Repetitive sequences with a length of 63.4 Mb and 12,785 protein-coding genes were identified. Significantly expanded gene families were identified to be involved in the development and regulatory processes, while remarkably contracted gene families were involved in the transport processes in T. dendrolimi. The olfactory and venom-associated genes were identified in T. dendrolimi and 24 other hymenopteran species, using uniform methods combining BLAST and HMM profiling. The identified venom genes of T. dendrolimi were enriched in antioxidant activity, tricarboxylic acid cycle, response to oxidative stress and cell redox homeostasis. Our study provides an important resource for comparative genomics and functional studies to interpret the molecular mechanisms underlying host recognition and parasitism of Trichogramma species.

First discovery of the natural egg parasitoid of Cydalima perspectalis (Walker, 1859) in Turkey with molecular methods (Lepidoptera: Crambidae

The genus Trichogramma Westwood, 1833 are important biological control agents of especially Lepidoptera pests in all around the world. These tiny wasps can’t be reliably identified owing to their small size and lack of definable morphological characters. ITS2 (Internal transcribed spacer 2) sequence-based identification has been performed successfully for years for parasitoids of the genus Trichogramma. The use of indigenous Trichogramma species against pests is very important for the success of biological control. Therefore, accurate and precise species identification of Trichogramma plays a key role in biological control programs. In the study, egg parasitoids were obtainedfrom parasitized egg masses of Cydalima perspectalis (Walker, 1859) collected in Hatay province of Turkeyin May 2021. Trichogramma wasps were collected and only one species was determined by using both ribosomaland mitochondrial sequences. According to ribosomal and mitochondrial sequence results, all of the collectedsamples were determined to be Trichogramma evanescens Westwood, 1833. This is the first report of T. evanescensas egg parasitoid of C. perspectalis in the worldwide.

Effect of Carbohydrate Nutrition on Egg Load and Population Parameters of Four Trichogramma Species

Trichogramma parasitoids are the most widely used biocontrol agents and play a crucial role in the biological control of agricultural and forest pests. Many studies have shown that Trichogramma parasitoids feeding on carbohydrate rich diet can effectively improve their egg laying capacity and longevity. However, few studies have reported the impact of carbohydrate-rich diet on the biological parameters of different species of Trichogramma parasitoids. In this study, we compared the differences between the biological parameters of four Trichogramma species (T. dendrolimi, T. chilonis, T. leucaniae and T. ostriniae) before and after feeding on carbohydrate-rich diet. The results showed that all the biological parameters of Trichogramma species improved after feed on carbohydrate-rich diet. After eclosion, T. dendrolimi had the highest egg load (51.89 eggs) followed by T. chilonis (26.86 eggs), T. ostriniae (24.71 eggs), and T. leucaniae (12.44 eggs). Trichogramma dendrolimi showed an increased trend in egg load (66.7–86.21 eggs) after feeding on carbohydrate-rich diet, followed by T. chilonis (33.12–45.56 eggs), as compared to the other three species. Furthermore, T. leucaniae and T. ostriniae benefited much less from the ingestion of carbohydrate-rich diet, as only accelerated egg maturation in T. ostriniae was observed. Most of the egg loads consisted of matured eggs, so the trend of mature eggs was the same as that of the egg load. We also tested the population parameters of the Trichogramma species using the TWOSEX-MSChart. The results showed that the Trichogramma species fed with a honey diet had higher fecundities, i.e., T. dendrolimi (146.64), T. chilonis (173.53), T. leucaniae (83.69), and T. ostriniae (80.45), than when fed with water, i.e., 78.49, 40.15, 32.45 and 35.47, respectively. T. dendrolimi and T. chilonis had a higher intrinsic rate of increase r (0.4178 d−1, 0.3933 d−1), finite rate of increase λ (1.5186 d−1, 1.4818 d−1), and net reproductive rate R0 (130 offspring, 147.4 offspring), than T. leucaniae and T. ostriniae (r = 0.3373 d−1, 0.3317 d−1; λ = 1.4011 d−1, 1.3934 d−1; R0 = 73.2 offspring, 68.1 offspring) after feeding on a honey diet. We conclude that carbohydrate-rich diet significantly enhanced the biological control efficacy of Trichogramma, but the performance differed among different species. The results of this study contribute to improving the efficient application of Trichogramma parasitoids in the field.

Integrated Management of Chrysodeixis chalcites Esper (Lepidoptera: Noctuidae) Based on Trichogramma achaeae Releases in Commercial Banana Crops in the Canary Islands

Chrysodeixis chalcites is one of the major pests on banana in the Canary Islands (Spain), where it is widely distributed and causes significant economic losses when larvae feed on developing leaves and fruits. Control of this pest is based on a limited number of pesticides, as growers lack other effective solutions, including biological control. Nevertheless, previous studies have shown some potential against C. chalcites of the egg parasitoid Trichogramma achaeae. We conducted two field trials over two consecutive years in commercial banana crops, comparing the results against C. chalcites of augmentative T. achaeae releases (IPM) and conventional chemical control. In total, 215 and 366 wasps/m2 were released in 2016 and 2017, respectively. Naturally occurring Trichogramma species contributed to C. chalcites control in both treatments, but the maximum number of parasitized eggs in IPM plots nearly tripled and doubled those recorded in chemical control plots in 2016 and 2017. Thus, T. achaeae releases significantly increased the parasitism by more than 10% compared to that observed in chemical control plots, amounting to 65.6 ± 7.7% and 56.7 ± 5.8% in 2016 and 2017, respectively. This was enough to keep the pest at tolerable levels in IPM plots, avoiding the need for pesticide applications, whereas in chemical control plots, repeated applications were needed during the experiment for that. Moreover, there were not significant differences in the abundance of larvae and severity of plant damage (<6% in 2016 and <12% in 2017), even when pest pressure in 2016 was two-fold greater in IPM plots. Fruit damage was also similar between treatments in 2016 (<2%) but was significantly reduced from 5.1 ± 1.5% in chemical control to 4.2 ± 1.4% in IPM in 2017. Overall, this study provides guidelines for the biological control of C. chalcites in banana, based on augmentative releases of T. achaeae, and demonstrates that this method can be effective, constituting an environmentally and sustainable alternative to conventional chemical control for banana growers.

Additions to the knowledge of Trichogramma from Turkey (Hymenoptera: Trichogrammatidae), with description of a new species

New country and host records of Trichogramma species for Turkey are presented. Trichogramma aurosum Sugonjaev & Sorokina is recorded for the first time from Turkey, and a new species, T. zerynthiae Polaszek & Bolu, is described. Morphological identification based on dissected male genitalia is supplemented by molecular sequence data. http://www.zoobank.org/urn:lsid:zoobank.org:pub:9CFF5E39-F1D2-42FB-86B8FC8475EC3560

Survey of Trichogramma (Hymenoptera: Trichogrammatidae) Natural Populations in Quebec Cranberry Bogs and Identification Using rDNA ITS-2 Sequence Analysis.

The province of Quebec, Canada is the most important organic cranberry growing region worldwide. However, insect pest management methods are limited, and growers face significant yield loss each year, mostly caused by lepidopteran pests. Egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) are effective biocontrol agents of lepidopteran pests in many forests and agricultural systems. Herein, a two-year, large-scale population survey of Trichogramma spp. was performed using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) as sentinel eggs in Quebec organic cranberry bogs. Collected specimens were identified by sequencing ribosomal DNA of the Internal Transcribed Spacer 2 (ITS-2) region and subjected to resemblance analysis with reference specimens for identification. Our results confirm that at least four Trichogramma species naturally occur in the studied agroecosystem. Those species are T. brassicae Bezdenko, T. minutum Riley, T. ostriniae (Pang et Chen), and T. pretiosum Riley. While some species have already been reported in cranberry bogs, this represents the first mention of T. brassicae and T. ostriniae as well as the first mention of T. minutum in Quebec cranberry bogs. All species collected are native from Eastern Canada except T. ostriniae. These species can be considered as biocontrol agent candidates for cranberry lepidopteran pests, but further efficacy trials are needed to identify the best species for each pest.

Back to the Wild: The Parasitoid Community of Lobesia botrana (Lepidoptera: Tortricidae) in a Grapevine-Free Natural Environment.

Simple SummaryIn a framework of sustainable agriculture, strategies aimed at preserving and enhancing pest natural enemies are crucial. However, knowledge about the parasitoid complex associated with a particular pest is often fragmentary. Herein, we investigated the parasitoids associated with the European grapevine moth, one of the main vine pests in the Mediterranean area, in a natural context, where the moth lives on Daphne gnidium, deemed as its original host plant. We observed a heterogeneous and complex community, consisting of a few predominant parasitoid species, followed by satellite species, and occasional parasitoids. Parasitic wasps, such as Campoplex capitator and Trichogramma spp., can be also found in the vineyards, thus understanding their dynamics in the wild could be useful to improve biological control strategies for managing EGVM populations.The European grapevine moth (EGVM), Lobesia botrana (Lepidoptera: Tortricidae), is one of the major concerns for vineyard managers in the Mediterranean area. It is a polyphagous moth, which develops on a wide variety of host plants, among which the spurge flax, Daphne gnidium (Thymelaeaceae), very likely represents its originary wild host plant. In this study, we investigated the parasitoid complex of L. botrana feeding on D. gnidium during a three-year sampling in a natural reserve in Tuscany, Italy, where this plant is extremely abundant while the grapevine is absent. A total of 24 species of parasitoids were obtained from eggs, larvae, and pupae of EGVM, belonging to 6 families of Hymenoptera and a family of Diptera. The ichneumonid wasp Campoplex capitator was the most abundant larval parasitoid. Four species of the genus Trichogramma were obtained from parasitized eggs during the first year of sampling, with a peak in the parasitisation during the EGVM 3rd generation. Some of the main EGVM parasitoids on spurge flax were also observed in vineyards, although a certain degree of redundancy was observed in the wild, due to several less frequent “satellite” species exploiting the same host. Overall, this research sheds light on the parasitoid community and dynamics of this important moth pest in a grapevine-free natural ecosystem, discussing the possible role of natural areas as ecological reservoirs of pest natural enemies.

Early Detection and Identification of Parasitoid Wasps Trichogramma Westwood (Hymenoptera: Trichogrammatidae) in Their Host Eggs Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism.

Parasitoid wasps are invaluable agents in pest biological control. Early detection and identification of parasitoid immatures are vital in characterizing parasitoid-host interactions and for evaluating parasitism rates accurately in the field. Trichogramma is the most widely used parasitoid wasp, and several studies have been performed for its molecular identification. However, those studies were mainly focused on Trichogramma adults and rarely on immatures. Here, we report a method to detect and identify Trichogramma larvae in their host eggs. We designed a pair of Trichogramma-specific primers that amplified Trichogramma mtCOI sequences from Corcyra cephalonica (Stainton) eggs parasitized by any of eight Trichogramma species tested but not from nonparasitized eggs of four lepidopteran hosts. This PCR method reliably detected Trichogramma immatures in parasitized eggs as early as 1 h after parasitism. We further developed an RFLP (restriction fragment length polymorphism) assay using restriction enzymes SspI and VspI to differentiate eight Trichogramma species at their immature stage. Overall, we developed a sensitive and reliable PCR-RFLP method to detect and identify immature-stage Trichogramma in their lepidopteran hosts. This method shows promise for conveniently identifying Trichogramma in insectaries and accurately evaluating parasitism rates in the field.