Oudenhove and Vincent Calcagno (2022) Up and to the light: intra-and interspecific variability of photo-and geo-tactic oviposition preferences in genus Trichogramma, Peer Community Journal, 2: e3.

The petroleum ether, chloroformic, ethyl acetate and methanolic extracts of Limonium echioides L. (Plumbaginaceae) were screened for their antioxidant and antifungal activities through in vitro experiments. The 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS•+) decolorization and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH•) free radical‐scavenging method were used. All extracts were active with radical‐scavenging capacity reaching 100% in DPPH• reaction system and 85.6% in ABTS•+ reaction at the used concentrations. Methanolic extract was found to possess the highest free radical‐scavenging effects in both assays. An important correlation between antioxidant capacities and total phenolic contents of the polar extracts was found. The gallic acid, identified in this plant, seemed to be active against both radicals DPPH• and ABTS•+. The mycelium growth inhibition method was used for the antifungal testing. Ethyl acetate and methanolic extracts of L. echioides showed antifungal activities against Fusarium oxysporum and Penicillium sp. PRACTICAL APPLICATIONS This study may prove to be beneficial in the exploitation of natural antioxidant and antifungal sources, containing a large amount of phenolics, for the preservation and/or extension of the shelf life of raw and processed foods. Then, this could also be applied in the area of pharmaceuticals for the protection of human life.

Trichogramma are parasitic microwasps much used as biological control agents. The genus is known to harbor tremendous diversity, both inter- and intra-specific. The successful selection of appropriate strains rests on a careful evaluation of this diversity at the phenotypic level, especially regarding oviposition performance and behavior. Oviposition preferences in relation to environmental cues such as light and gravity, although suspected to play an important role in microhabitat selection and oviposition patterns, have received little attention so far in this group, either alone or in combination. The extent of their variability is thus virtually unknown. Here we use a novel experimental approach relying on automatic image analysis to characterize the oviposition preferences in relation to light, gravity, and their interaction, in 25 populations of Trichogramma from five species. We show that most Trichogramma populations and species harbour preferences for light and preferences for elevated parts. However, the two trait harbor significant inter and intraspecific variation. The effects of light and gravity on oviposition patterns were found to be almost perfectly additive overall, with two exceptions. Oviposition preference patterns were not static but very plastic in time: preferences tended to relax over consecutive days, and the strongest preferences relaxed the fastest, presumably because of the density-dependent effect of resource depletion. A correlation of oviposition patterns with the vegetation stratum at which populations were sampled suggests that different species/populations may be associated with different strata with corresponding differentiation in light- and gravity-related oviposition preferences.