Food or host: do physiological state and flower type affect foraging decisions of parasitoids?

Abstract

Within the Optimal Foraging Theory framework, parasitoids constitute ideal models to elucidate combined physiological and environmental determinism of foraging behavior between current and future fitness gains. Parasitoid females need hosts to lay eggs for their reproduction (immediate gain), but also sugar food resources for their survival (future gain). According to theoretical models and previous empirical studies, fed females should favor host foraging, whereas females with lower energetic reserves should search for food. Surprisingly, the influence of mating status and food quality has not been considered, whereas they may both constitute major factors altering animals' choices between reproducing and feeding. We tested decision-making on Aphidius rhopalosiphi parasitoid females with different life expectancy levels (as set by recent feeding history) and mating status, using two flower species with contrasted attractiveness and nectar suitability. Interestingly, all fed and unfed females with different expected lifetime levels favored reproduction over nutrition since they are mated. This could be explained by their reproductive status that appeared to be the main determinant of their foraging decisions. For a given expected lifetime, mated females favored more reproduction whereas unmated ones favored food. Interestingly, physiological status of females (mating and lifetime expectancy) did not interact with flower species on their foraging decisions nor did it modify their preferences, as they always favored the most attractive flower, which does not have the best nectar. These results highlight the need for more empirical studies to evaluate the interactions between different intrinsic factors and to carefully consider the mating status in model assumptions, as it influences foraging behavior between immediate and future fitness gains. Significance Statement: Parasitic wasps need hosts to lay eggs for their reproduction (immediate fitness gain) and sugar resources for their survival (future fitness gain). Empirical studies and related theoretical models about foraging decisions of parasitic wasps between current and future gains included influences of energetic and resource availability constrains. We examined assumptions used by those mathematical models by empirically testing two new factors, food qualities provided by two nectar provisioning flower species with contrasted functional traits, which had surprisingly no impact on decision-making, and mating status which we showed to play a decisive role on decision-making between food or host resources. These factors should henceforth be considered in model assumptions or in models themselves to realize accurate predictions and to provide a better understanding of foraging decisions made by female parasitic wasps.

Do fall armyworm’s Metaflumizone resistante populations affect the activity of Trichogramma pretiosum?

“…The exploratory characteristic of the parasitoid species (Roriz et al, 2006;Brotodjojo and Walter, 2006) indicates that the females of T. pretiosum, distinguished differences in the host eggs and consequently rejected them in some moment by means of some external or internal signal present in the host egg coming from individuals that developed under the conditions of exposure to the insecticide. In initial contact with the host eggs, signals are recognized by the antennas, and for insertion of the ovipositor, the females need to perfectly evaluate the external and internal conditions of the host eggs (Desneux et al, 2012;Alsaedi et al, 2016;Damien et al, 2019). This evaluation determines acceptance or non-acceptance of the host for oviposition, according to its nutritional quality (Roriz et al, 2006), ensuring the success of the offspring of the parasitoid (Roriz et al, 2006;Brotodjojo and Walter, 2006) Synergy trials conducted in populations of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) showed that resistance to Metaflumizone is associated with metabolic changes involving an increase in esterase (Su and Sun, 2014;Tian et al, 2014) and monooxygenase (Tian et al, 2014) activity.…”

Color, odor, and species preferences of Copidosoma bakeri to prospective cover crops to enhance control of cutworms

“…In dual‐choice color tests, female C. bakeri wasps preferred yellow over green and white, similar to other color choice experiments with parasitoids (Lucchetta et al, 2008; Mitsunaga et al, 2012). However, we used only unmated females in our experiments, and previous studies have found that mated females choose host patches more often than food patches (Damien et al, 2019), which suggests that mated females may have a different color preference than unmated females. The same study, however, found that mating status did not alter flower preference (Damien et al, 2019).…”

“…However, we used only unmated females in our experiments, and previous studies have found that mated females choose host patches more often than food patches (Damien et al, 2019), which suggests that mated females may have a different color preference than unmated females. The same study, however, found that mating status did not alter flower preference (Damien et al, 2019). Preference for yellow is not surprising given that it is the most common flower color (Weevers, 1952) and it is typically the most attractive color to many hymenopteran species (Abrahamczyk et al, 2010).…”

Plants for fitness enhancement of a coffee leaf miner parasitoid

“…Although totally expose, the extrafloral nectar must meet another requirement to be suitable for parasitoids exploitation in the field that is their attractiveness. Damien et al (2019) found that for the aphid's parasitoid Aphidius rhopalosiphi DeStefani-Peres (Hymenoptera: Braconidae), there was a preference for attractive flowers when compared to flowers with more accessible nectar. And in the case of extrafloral nectar, as it doesn't have any visual attractiveness, its odor must be enough for parasitoids to find it.…”

“…In terms of conservation biological control that means that introducing in the coffee agroecosystem feeding resources for P. coffeae can increase their success as biocontrol agents, not just by enhancing their survival but also their reproductive potential. Considering that parasitoids must deal with the decision of foraging for host or food, having the food near to the host can help solve this issue, and allow the permanence of the parasitoids in the agroecosystem (Damien et al, 2019).…”