Lymantia dispar (L.) (Lepidoptera: Lymantriidae), commonly known as the gypsy moth, is a serious forest pest, and beneficial insects are particularly important for reducing its population numbers. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) is an arrhenotokous, solitary egg parasitoid of L. dispar. In this study, we evaluated a new substitute host, Philosamia ricini (Danovan) (Lepidoptera: Saturniidae) for O. kuvanae. We investigated some of the biological effects of O. kuvanae on P. ricini eggs. In this context, the importance of the age of the female parasitoid (1, 3 or 5 days old), host age (1-2 and 3-4 days old) and host number (40, 60 and 80 host eggs) were examined under laboratory conditions (25 ± 1 °C, 65 ± 5% relative humidity and a 16 : 8 h photoperiod [light : dark]). The highest rate of offspring production (89.90%) occurred with 40 (1-2-day-old) host eggs and 5-day-old females. The mean developmental period ranged from 16.5 ± 0.08 days to 18.7 ± 0.08 days. The mean lifespan of the parasitoid was 51.10 ± 1.1 (n = 60) days with bio-honey and 3.92 ± 0.14 (n = 60) days without food. The mean fecundity was 68.88 ± 3.22 offspring/female. Peak adult emergence occurred between 2 and 9 days. The mean oviposition and mean post-oviposition periods of the female parasitoid were 22.76 ± 1.37 days and 13.64 ± 1.40 days, respectively. O. kuvanae was reared for more than ten generations on the eggs of P. ricini. Based on our findings, P. ricini can be used to rear O. kuvanae for the biological control of L. dispar.

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The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae) originates from Asia and has recently disseminated to America and Europe, where it is considered as an invasive pest of various crops. Developing biological control strategies is necessary, and egg parasitoids are among the best candidates. In this context, the objective of this study was to evaluate the fitness of the egg parasitoid Ooencyrtus pityocampae Mercet (Hymenoptera: Encyrtidae) reared on H. halys eggs, under laboratory conditions. We specifically investigated the impact of host age, host density and length of exposure on O. pityocampae life history traits. Host age × host density and host age × length of exposure affected the performance of O. pityocampae. The optimal emergence rate of the parasitoid was obtained from one-day-old H. halys eggs and 3 days of exposure. The parasitoid embryonic development ranged from 17.1 to 18.3 days. The mean longevity of O. pityocampae was 44.1 days. This species reproduces by thelytokous parthenogenesis and the female parasitoid produced an average of 42.6 progeny during their lifespan. Pre-oviposition, oviposition and post-oviposition periods were 1.9 days, 18.8 days and 24.8 days, respectively. These results suggest that H. halys is a suitable host for O. pityocampae, and may help for the development of a pest-management strategy against H. halys.

Halyomorpha halys (Stål), the brown marmorated stink bug, is an invasive pentatomid species native to Asian countries (Hamilton et al., 2018).

Description du sujet. Dans le cadre d’un projet de biocontrôle de la processionnaire du pin, Thaumetopoea pityocampa Denis & Schiffermüller, l’utilisation de parasitoïdes indigènes pour lutter contre ce ravageur a été étudiée au sein du Laboratoire Biocontrôle à l’UEFM (Unité Expérimentale Entomologie et Forêt Méditerranéenne) à l’INRA PACA. Objectifs. Il est nécessaire de rechercher le meilleur hôte de substitution et de mettre au point son élevage. Plus particulièrement, l'espèce Ooencyrtus pityocampae (Mercet) a été étudiée. Méthode. Thaumetopoea pityocampa étant une espèce allergisante, plusieurs hôtes de substitution ont été comparés pour l’élevage des parasitoïdes : Philosamia ricini (Danovan), Nezara viridula (L.) et Halyomorpha halys (Stål). Les caractéristiques biologiques et la fitness des descendants ont été comparées en conditions de laboratoire (25 ± 1 °C, 75 ± 5 % HR, 16L:8D). Résultats. Philosamia ricini est le meilleur hôte de substitution pour l’élevage d’O. pityocampae pour ce qui est de la quantité et de la qualité des individus produits. Conclusions. Cette étude servira de base à une réflexion sur les possibilités d’utiliser ce parasitoïde dans le cadre de la lutte biologique contre certains ravageurs méditerranéens.

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Ooencyrtus pityocampae and Ooencyrtus kuvanae are egg parasitoids that are considered potential candidates for the control of different pest species through inundative release. The aim of this study was to assess the effects of different cold-storage periods of Philosamia ricini eggs (host) on the rearing parameters of O. pityocampae and O. kuvanae. Host eggs were stored at 3 °C, and a factorial experiment involving two parasitoid species, nine host storage periods (1, 5, 10, 15, 30, 45, 60, 75 and 90 days) and a control, and two host ages (1 and 2 days) was conducted, with 10 replications including 40-P. ricini eggs each. Adult emergence, development time, longevity, and fecundity were investigated. The parasitoid adult emergence percentage significantly varied with storage duration. These values were lower in O. kuvanae than in O. pityocampae. The development time of O. kuvanae progeny increased in both host age groups except in the 1-day storage period subgroup. However, the development times of the progeny of O. pityocampae reared on one-day-old eggs stored for 5, 10, 60, and 75 days were increased, and the development times of the progeny of O. pityocampae reared on 2-day-old eggs stored for 45 and 90 days were increased. The longevity of the F1 progeny of O. kuvanae was negatively affected by storage time. There was no difference in the longevity of the F1 progeny of O. pityocampae compared to that of the control. Additionally, the fecundities of the F1 progeny of O. pityocampae and O. kuvanae were 54.7 and 47.0 offspring/female, respectively. These results provide useful information for guiding the development of mass rearing methodologies for both parasitoid species.