The parasitoids Pachycrepoideus vindemmiae Rondani (Hymenoptera: Pteromalidae) and Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae) have great potential in controlling Drosophila suzukii (Matsumura); however, both, compete for the same resources. In this study, we evaluated whether the different stages of development of the primary parasitoid reduce the negative effect of intrinsic competition. For this, we first defined the duration of each immature stage of both parasitoid species and then offered D. suzukii pupae containing the first parasitoid (P. vindemmiae or T. anastrephae) at different stages of development to the second parasitoid (P. vindemmiae or T. anastrephae). We also checked the second parasitoid's preference (P. vindemmiae or T. anastrephae) for the primary parasitoid at different stages of development (P. vindemmiae or T. anastrephae) or D. suzukii pupae nonparasitized. Our evaluations showed that T. anastrephae preferred to parasitize pupae that were not previously parasitized and that had not parasitized puparia of D. suzukii when P. vindemmiae was in later stage to the 1st instar. However, P. vindemmiae preferred to parasitize pupae previously parasitized by T. anastrephae. In an environment of intrinsic competition, the first parasitoid to parasitize has an advantage, except when the pupal stage of T. anastrephae is parasitized by P. vindemmiae. The variation in the parasitoids' oviposition time mitigates the competition effect; however, for use in biological control programs, the hyperparasitoids P. vindemmiae, does not prove to be advantageous, as they can affect the establishment of primary parasitoids such as T. anastrephae, and can act as competitors for resources.

Diplolepis ogawai Abe and Ide sp. nov. (Hymenoptera: Cynipidae) induces galls on Rosa hirtula (Regel) Nakai (Rosales: Rosaceae), which is endemic to a restricted area of Honshu, the main island of Japan. The gall is induced mainly on the leaf of R. hirtula in spring and the mature gall falls to the ground in early summer. The gall-inducing wasp emerges from the gall on the ground in the following spring, suggesting that D. ogawai is univoltine. From spring to summer, the braconid Syntomernus flavus Samartsev and Ku and the eulophid Aprostocetus sp. are parasitic on the larva of D. ogawai in the gall, and the adult wasp of both parasitoid species emerges from the gall on the ground in summer. For S. flavus, this is the first distribution record in Japan and the first host record. Since R. hirtula is threatened with extinction by succession and deforestation, D. ogawai and its two parasitoid wasp species are considered to be at risk of coextinction with the threatened rose. In the event that the population size of this rose species is further reduced, D. ogawai and its parasitoids may become extinct prior to the extinction of R. hirtula. To conserve these three wasp species associated with R. hirtula, protection of remnant vegetation where individuals of this threatened rose species grow is necessary.

The nutritional quality of herbivorous insects' food can not only directly affect the herbivorous insects themselves, but can also indirectly affect their parasitoids. To investigate these cascading, multi-trophic effects, we reared cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), on artificial diets (8.1, 11.5, 16.75, 25.5, 34.25, and 43 g protein/liter diet) to assess how diet protein content affected the development of this common pest and its suitability as a host for the gregarious parasitoid, Cotesia vanessae (Reinhard) (Hymenoptera: Braconidae). Nonparasitized caterpillars experienced increased mortality when reared on 8.1 g protein/liter diet, and slower development and reduced pupal mass when reared on ≤16.75 g protein/liter diet. Host diet did not affect the percentage of hosts with parasitoid emergence nor the mass of individual parasitoids. However, parasitoid broods emerging from caterpillars reared on ≤25.5 g protein/liter diet were smaller and those reared on ≤16.75 g protein/liter diet exhibited prolonged development. The consequences of host diet on these latter F₁ parasitoids did not affect their reproductive fitness. Caterpillars compensated for nutrient stress, induced by either low quality diet or parasitism, by increasing the amount of diet that they consumed. These collective results demonstrate the plasticity of host-parasitoid systems. Compensatory feeding allows the host caterpillar to moderate the consequences of low quality diets, which may subsequently affect the F₁ parasitoids developing within the host, but not necessarily affect the F₂ parasitoid generation.

La qualité nutritionnelle de la nourriture des insectes herbivores peu non seulement affecter directement les insecte herbivores mais aussi indirectement les parasitoïdes des insectes herbivores. Pour examiner ces effets multitrophiques, nous avons élevé des larves de la fausse-arpenteuse du chou, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), sur des milieux nutritif artificiel (8,1; 11,5; 16,75; 25,5; 34,25 et 43 g de protéine par litre) pour évaluer comment le taux de protéine du milieu nutritif affectait le développement de ce ravageur commun et sa qualité en tant qu'hôte pour le parasitoïde grégaire Cotesia vanessae (Reinhard) (Hymenoptera: Braconidae). Pour les chenilles non-parasitées, un accroissement de mortalité a été observé pour celles élevées sur le milieu nutritif contenant 8,1 g de protéines par litre, et un accroissement du temps de développement et une réduction de la masse des chrysalides ont été observé pour celles élevées sur les milieux nutritifs contenant au plus 16,75 g de protéines par litre. Le taux de protéines dans l'alimentation des chenilles n'a pas influencé le pourcentage de chenilles parasitées qui ont produits des parasitoïdes, ni la masse individuelle des parasitoïdes. Cependant, les chenilles parasitées élevées sur les milieux nutritifs contenant au plus 25,5 g de protéines par litre ont produit moins de parasitoïdes par chenilles, et celles élevées sur les milieux nutritifs contenant au plus 16,75 g de protéines par litre ont produit des parasitoïdes qui se sont développés plus lentement. Aucun effet du taux de protéine dans l'alimentation des chenilles n'a été détecté sur la seconde génération de parasitoïdes. Les chenilles ont compensé le stress nutritif, induit par de faible taux de protéine dans leur alimentation ou par les parasitoïdes, en accroissant la quantité de nourriture consommée. Ces résultats démontrent la plasticité des systèmes hôtes/parasitoïdes. En ajustant leur consommation de nourriture, les chenilles ont pu mitiger les effets négatifs des milieux nutritifs pauvre en protéine, et ces effets peuvent avoir des répercussions sur le développement des parasitoïdes à l'intérieur des chenilles, mais pas forcément sur la génération suivante de parasitoïdes.

Invertebrates that successfully colonize new habitats often share life history characteristics including high fertility, rapid development, and early maturation. Since its introduction into Florida, USA, the non-native Brown Widow, Latrodectus geometricus (Kock 1841, Araneae: Theridiidae), has rapidly expanded its range into urban areas as far north as Kansas and as far west as California. During its expansion, the Brown Widow has displaced Florida's Southern Black Widow, L. mactans (Fabricius 1775, Araneae: Tjerodoodae) and California's Western Black Widow, L. Hesperus (Chamber lin & Ivie 1935, Araneae: Theridiidae). Here, based on a field survey and controlled laboratory experiments, we report possible causes for the rapid disappearance of Florida's Southern Black Widows. Our field survey revealed that Brown Widows have twice the fertility potential as Southern Black Widows. In experiments comparing development, we show that sub-adult Brown Widows grew faster and matured earlier relative to Southern Black Widows. In our experiments on cohabitation with neighbors, bold Brown Widows were six times more likely to kill and consume shy Southern Black Widows than bold cobweb spiders and three times more likely to cohabitate with bold cobweb spiders than with shy Southern Black Widows. Our model of maternal risk-management revealed that competition for scarce prey was not a significant cause of offspring mortality for Latrodectus species. Hence, Brown Widows are not predating Black Widows or other cobweb spiders because prey is scarce. To our knowledge, this study is the first to suggest that aggressive predation by Brown Widows is a significant factor contributing to the local extinction of the shy Southern Black Widow in urban structures.