Herbivore Host Research Articles

Advanced phenology of intraguild predators shifts herbivore host plant preference and performance

1. The abundance of insect herbivores is mediated by interactions with higher and lower trophic levels. This research asks (i) how phenological change across trophic levels affects host plant quality and selection for aphids, and (ii) what higher trophic level mechanisms drive aphid abundance.2. Ligusticum porteri is a perennial host for the sap‐feeding aphid Aphis asclepiadis and intraguild mirid predators (chiefly Lygus hesperus) in Colorado. We used long‐term observational data to discover that aphids and mirids respond differently to phenological cues. These unique responses can impact aphid abundance through changes to host plant selection and quality.3. We used behavioural choice assays to assess how advanced mirid phenology influences aphid host plant selection. More alates landed and reproduced on mirid‐free control plants relative to host plants with prior mirid feeding. However, this preference did not correlate with aphid performance when we compared aphid relative growth rates between treatments. This suggests that advanced mirid phenology would impact aphid populations more through host plant choice, rather than reductions in host quality. The addition of mirids to experimental aphid colonies also demonstrated reduced aphid colony growth via predation.4. We measured plant cues involved in host selection and found differences in volatile composition between plants with prior mirid feeding compared to control plants, providing the potential for aphids to detect enemy‐free space using volatile cues.

Morphological description and phylogenetic assessment of 28S rRNA for Thelandros chalcidiae sp. nov. from Chalcides ocellatus.

Thelandros is a genus of oxyurid nematodes which parasitize both omnivorous and herbivorous hosts. Thelandros chalcidiae sp. nov. is a new taxa described from the large intestine of the ocellated skink, Chalcides ocellatus, from the South Sinai Desert in Egypt. The recovered parasite species was examined at both morphological and molecular levels in order to determine the exact taxonomic position within Pharyngodonidae family. The current pharyngodonid species is characterized by a mouth opening bounded by three bilobed lips; male worms are characterized by the presence of two pairs of cloacal papillae (pre- and adcloacal) and one single caudal papillae (postcloacal) and caudal alae in an auricular form and females with post-equatorial vulva, amphidelphic ovary in which anterior ovary extended to level of excretory pore and posterior ovary extended posteriorly up anal opening. The recovered nematodes were compared with other known species from different hosts and it was found to be morphologically different from them. Molecular characterization based on the partial 28S rRNA nuclear ribosomal gene sequence showed sequence identities ≥ 83.15% with taxa under family Pharyngodonidae, 74.84-87.37% with Oxyuridae, 80.54% with Heteroxynematidae, and 75.98-77.72% with Thelastomatidea. Phylogenetic analysis showed that parasite sequence in conjunction with existing data facilitate placement of this species within Oxyurida. The present species is deeply embedded in genus Thelandros with close relationships to previously described Thelandros sp. and T. galloti in same taxon. This study highlighted importance of combining morphological and genetic data with taxonomy in pharyngodonid species.

An autoparasitoid wasp, inferior at resource exploitation, outcompetes primary parasitoids by using competitor females to produce males

1. Autoparasitoids are intraguild consumers that attack and kill heterospecific and conspecific parasitoids as well as immature stages of hemipteran hosts, such as aphids, whiteflies and soft scales. Field experiments assessing the importance of interspecific competition between autoparasitoids and primary parasitoids, as well as its impact on herbivore suppression, are scarcely found in the ecological literature.2. Using field data from 40 olive orchards, this study examined the mechanisms that regulate: (i) the interspecific competition between primary parasitoids of the genus Metaphycus and the autoparasitoid Coccophagus lycimnia; and (ii) the density of their shared herbivore host, the soft scale Saissetia oleae.3. Metaphycus parasitoids used smaller hosts than C. lycimnia, yet did not outcompete C. lycimnia. On the other hand, C. lycimnia preferred to use Metaphycus females as secondary hosts for producing males rather than their own females. This preference might explain why the autoparasitoid negatively affected the density of the primary parasitoids.4. Parasitism by the autoparasitoid C. lycimnia at the beginning of the season was the sole variable positively related to host mortality throughout the season, showing its greater effect on herbivore suppression.5. In this study, an autoparasitoid, inferior at resource exploitation, was shown to outcompete a primary parasitoid without disrupting herbivore suppression.

Microbial Symbionts of Parasitoids.

Parasitoids depend on other insects for the development of their offspring. Their eggs are laid in or on a host insect that is consumed during juvenile development. Parasitoids harbor a diversity of microbial symbionts including viruses, bacteria, and fungi. In contrast to symbionts of herbivorous and hematophagous insects, parasitoid symbionts do not provide nutrients. Instead, they are involved in parasitoid reproduction, suppression of host immune responses, and manipulation of the behavior of herbivorous hosts. Moreover, recent research has shown that parasitoid symbionts such as polydnaviruses may also influence plant-mediated interactions among members of plant-associated communities at different trophic levels, such as herbivores, parasitoids, and hyperparasitoids. This implies that these symbionts have a much more extended phenotype than previously thought. This review focuses on the effects of parasitoid symbionts on direct and indirect species interactions and the consequences for community ecology.

The microbiota in spider mite feces potentially reflects intestinal bacterial communities in the host.

Microorganisms provide many physiological functions to herbivorous hosts. Spider mites (genus Tetranychus) are important agricultural pests throughout the world; however, the composition of the spider mite microbial community, especially gut microbiome, remains unclear. Here, we investigated the bacterial community in five spider mite species and their associated feces by deep sequencing of the 16S rRNA gene. The composition of the bacterial community was significantly different among the five prevalent spider mite species, and some bacterial symbionts showed host-species specificity. Moreover, the abundance of the bacterial community in spider mite feces was significantly higher than that in the corresponding spider mite samples. However, Flavobacterium was detected in all samples, and represent a "core microbiome". Remarkably, the maternally inherited endosymbiont Wolbachia was detected in both spider mite and feces. Overall, these results offer insight into the complex community of symbionts in spider mites, and give a new direction for future studies.

Determinants and consequences of plant-insect phenological synchrony for a non-native herbivore on a deciduous conifer: implications for invasion success.

Phenological synchrony between herbivorous insects and host plants is an important determinant of insect distribution and abundance. Non-native insects often experience novel climates, photoperiods, and host plants. How critical time periods of insect life cycles coincide with-or diverge from-phenological windows of host plant suitability could affect invasion success and the dynamics of outbreaks. Larch casebearer is an invasive defoliator that has recently undergone anomalous outbreaks on eastern larch in North America. We conducted growth chamber, greenhouse, and field studies to quantify the spring phenological window for larch casebearer on eastern larch and importance of phenological synchrony for casebearer development and survival. We constructed degree-day models of spring activity for both species and investigated responses of casebearers to early and delayed activation relative to bud break. Both species had lower developmental thresholds of ~ 5°C, but mean activation of casebearers occurred 245 degree-days after bud break by eastern larch. In addition to forcing temperatures, phenologies of eastern larch and casebearer larvae were significantly influenced by chilling and photoperiod, respectively. Larvae were robust to both starvation and delayed activation; days betweenlarval activation and bud break (range: 0-58days) had no influence on larval development and survival to adulthood. Disparateplant-insect responses to environmental cues and robustness of casebearers to changes in phenology result in a wide phenological window that likely has contributed to the insect's broad distribution in easternNorth America. Changes in phenological synchrony, however, do not appear to have facilitated recent outbreaks of larch casebearer on eastern larch.

Screening Sugars Can Benefit the Parasitoid Cotesia chilonis (Hymenoptera: Braconidae) Without Benefiting Its Host, Chilo suppressalis (Lepidoptera: Crambidae).

Most adult parasitoids depend on carbohydrate-rich food as an energy source for longevity, fecundity, and mobility. Thus, providing sugars has been proposed as a technique to maximize the biological control efficacy of parasitoids. However, the sugars provided for parasitoids need to be carefully selected because herbivore hosts might also benefit. Here we explore the effects of 12 naturally occurring sugars on the longevity and fecundity of the rice pest, Chilo suppressalis, and the longevity of its parasitoid, Cotesia chilonis, as well as the effect of sugars on sugar consumption of C. chilonis. Results showed that none of the tested sugars significantly impacted the longevity of C. suppressalis, but fructose, glucose, maltose, and sucrose significantly increased its fecundity. The longevity of C. chilonis was significantly increased when fed fructose, glucose, sucrose, maltose, trehalose, and melezitose. Our data suggest that C. chilonis consumed larger quantities of glucose, fructose, and sucrose followed by maltose, melezitose, and trehalose and the longevity of C. chilonis was positively correlated to sugar consumption. Our data also suggest that the herbivore C. suppressalis and its parasitoid C. chilonis responded differently to trehalose and melezitose. Although additional studies are needed, our data suggest that these sugars could be considered as candidate components for sugar sprays to enhance the activity and efficacy of C. chilonis, but without benefiting its pest host.

Prevalence of Sarcocystis fusiformis and Hydatid cyst among Different Ruminants at Menofia Governorate, Egypt

Sarcocystis fusiformis cysts and Hydatid cysts are of the most prevailing parasitic infestations of meat having economic and public health importance. S. fusiformis is an intracellular protozoan of the Phylum Apicomplixa which has an indirect life cycle, Hydatid cysts caused by the parasitic cestode E. granulosus that also has an obligate two-host life cycle, so they require an intermediate herbivorous or omnivorous host. So, this study aimed to evaluate the prevalence of S. fusiformis and Hydatid cysts in ruminants at Menofia governorate, Egypt. Physical examination of 1916 ruminant animal at different abattoirs at Menofia governorate was carried out from Septemper 20161 to August 2017 and microscopic examination was also conducted. About 20.5% of the examined animals were found positive for S. fusiformis. Buffaloes were infected with 85.96% while cattle were infected with 0.1%. The highest infection rate was recorded in animals older than 5 years old with percentage of 92.28%, then the animals between 3 to 5 years 29.32%, while animals less than 3 years were about 0.54%. The highest infection was recorded in Winter and Spring seasons 33.3% and 27.13%. Hydatid cyst was recorded with overall prevalence 3.6%. It was found in camels with percentage of 29.18%, and 1.75% in buffaloes. In conclusion Sarcocystis fusiformis and Echinococcus granulosus cysts prevailed at Menofia governorate, Egypt with considerable percentages that require more molecular studies to determine their genes and require putting strategies to control stray dogs and cats near the abattoirs and efficient condemnation of affected organs.

Reduction of Plant Suitability for Corn Leaf Aphid (Hemiptera: Aphididae) Under Elevated Carbon Dioxide Condition.

In the current context of global climate change, atmospheric carbon dioxide (CO2) concentrations are continuously rising with potential influence on plant-herbivore interactions. The effect of elevated CO2 (eCO2) on feeding behavior of corn leaf aphid, Rhopalosiphum maidis (Fitch) on barley seedlings Hordeum vulgare L. was tracked using electrical penetration graph (EPG). The nutrient content of host plant and the developmental indexes of aphids under eCO2 and ambient CO2 (aCO2) conditions were also investigated. Barley seedlings under eCO2 concentration had lower contents of crude protein and amino acids. EPG analysis showed the plants cultivated under eCO2 influenced the aphid feeding behavior, by prolonging the total pre-probation time of the aphids (wandering and locating the feeding site) and the ingestion of passive phloem sap. Moreover, fresh body weight, fecundity and intrinsic population growth rate of R. maidis was significantly decreased in eCO2 in contrast to aCO2 condition. Our findings suggested that changes in plant nutrition caused by eCO2, mediated via the herbivore host could affect insect feeding behavior and population dynamics.

Differential regulation of host plant adaptive genes in Pieris butterflies exposed to a range of glucosinolate profiles in their host plants

Specialist herbivores have often evolved highly sophisticated mechanisms to counteract defenses mediated by major plant secondary-metabolites. Plant species of the herbivore host range often display high chemical diversity and it is not well understood how specialist herbivores respond to this chemical diversity. Pieris larvae overcome toxic products from glucosinolate hydrolysis, the major chemical defense of their Brassicaceae hosts, by expressing nitrile-specifier proteins (NSP) in their gut. Furthermore, Pieris butterflies possess so-called major allergen (MA) proteins, which are multi-domain variants of a single domain major allergen (SDMA) protein expressed in the guts of Lepidopteran larvae. Here we show that Pieris larvae fine-tune NSP and MA gene expression depending on the glucosinolate profiles of their Brassicaceae hosts. Although the role of MA is not yet fully understood, the expression levels of NSP and MA in larvae that fed on plants whose glucosinolate composition varied was dramatically changed, whereas levels of SDMA expression remained unchanged. In addition, we found a similar regulation pattern among these genes in larvae feeding on Arabidopsis mutants with different glucosinolate profiles. Our results demonstrate that Pieris larvae appear to use different host plant adaptive genes to overcome a wide range of glucosinolate profiles in their host plants.

Herbivore-specific induction of indirect and direct defensive responses in leaves and roots.

Herbivory can induce both general and specific responses in plants that modify direct and indirect defence against subsequent herbivory. The type of induction (local versus systemic induction, single versus multiple defence induction) likely depends both on herbivore identity and relationships among different responses. We examined the effects of two above-ground chewing herbivores (caterpillar, weevil) and one sucking herbivore (aphid) on indirect defence responses in leaves and direct defence responses in both leaves and roots of tallow tree, Triadica sebifera. We also included foliar applications of methyl jasmonate (MeJA) and salicylic acid (SA). We found that chewing herbivores and MeJA increased above-ground defence chemicals but SA only increased below-ground total flavonoids. Herbivory or MeJA increased above-ground indirect defence response (extrafloral nectar) but SA decreased it. Principal component analysis showed there was a trade-off between increasing total root phenolics and tannins (MeJA, chewing) versus latex and total root flavonoids (aphid, SA). For individual flavonoids, there was evidence for systemic induction (quercetin), trade-offs between compounds (quercetin versus kaempferitrin) and trade-offs between above-ground versus below-ground production (isoquercetin). Our results suggest that direct and indirect defence responses in leaves and roots depend on herbivore host range and specificity along with feeding mode. We detected relationships among some defence response types, while others were independent. Including multiple types of insects to examine defence inductions in leaves and roots may better elucidate the complexity and specificity of defence responses of plants.

Quantitative measure of fitness in tri-trophic interactions and its influence on diet breadth of insect herbivores.

Herbivore-plant interactions should be studied using a tri-trophic approach, but we lack a quantitative measure of the combined effect of top-down and bottom-up forces on herbivore fitness. We propose the combination of the bi-trophic fitness slopes as a tri-trophic fitness measure. We use the relationship between fitness associated with top-down and bottom-up forces and the frequency of host plant use to calculate the top-down and bottom-up fitness slopes, which we then combine to obtain three possible directions of tri-trophic slopes. A positive tri-trophic slope indicates that herbivores have overall greater tri-trophic fitness on the more frequently used hosts. A null tri-trophic fitness slope indicates that herbivores have similar fitness on all host plants. A negative tri-trophic slope indicates that herbivores have generally lower fitness on the more frequently used hosts. We tested the explanation power of our method using data from the literature that tested herbivore host shifts and experimentally using a generalist herbivore with variable diet breadth across populations. We found that in host shifts, herbivores have higher tri-trophic fitness on the novel host, while in generalist populations, herbivores use most frequently the best host available. We present applications in other research areas and consider the limitations of our approach. Our approach is a first step towards a comprehensive model of multiple selective forces acting on the evolution of interactions.

Dynamics of soluble sugars and secondary metabolites in fruit of Juglans australis attacked by Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae)

The development and fitness of phytophagous insects are tightly linked to the nutritional quality of their host plants and many studies have examined the influence of primary and secondary metabolites of plants and their effects on the development of insects. Herbivore tactics to modify plant metabolic pathways to lower host toxicity need to be better understood as they are critical to a better understanding of herbivore–host plant relationships. To contribute to this end, in this study we analyzed temporal patterns of glucose, sucrose, fructose, and total soluble sugar contents, as well as tannins, phenols, and flavonoids in the mesocarp of fruit of native walnut (Juglans australis), uninfested and infested by Anastrepha fraterculus and Ceratitis capitata (sometimes simultaneously in a single fruit). Both fly species are polyphagous tephritids whose larvae feed on a wide variety of hosts. We observed a high correlation between infestation and adult emergence of these two insects which was positive in the case of sugar content and negative in the case of toxic secondary metabolites in fruit. At particular ripening stages, infested fruit contained higher levels of sugars and lower levels of phenols and tannins than non-infested fruit. We discuss the possibility that A. fraterculus and C. capitata, each with different egg-laying strategies, may modify metabolical pathways in the fruit for their own benefit through larval activity with the help of bacteria in their gut. Alternatively, the patterns observed may be simple side effects of larval feeding and associated growth of opportunistic microorganisms.

Host‐related volatile cues used by a parasitoid wasp during foraging for its woodboring host

AbstractParasitoids rely mainly on infochemicals to search for their herbivore hosts to oviposit on. Megarhyssa nortoni (Cresson) (Hymenoptera: Ichneumonidae) is a parasitoid of siricid wasp larvae which are concealed inside tree stems of several coniferous tree species. This parasitoid is used as a biological control agent against the global pine pest Sirex noctilio Fabricius (Hymenoptera: Siricidae), which engages in an obligate nutritional symbiosis with the fungus Amylostereum areolatum (Chaillet ex Fr.) Boidin (Russulales). We explore the chemical cues that could be used by M. nortoni females while foraging for hosts on the two pine species most commonly planted in commercial forests in Patagonia, Argentina, Pinus contorta Douglas ex Loudon var. latifolia Engelm. ex S Watson and Pinus ponderosa Douglas ex C Lawson (Pinaceae). Behavioural assays were conducted in an olfactometer and the following odour sources were tested in pairwise combinations: (1) P. contorta, (2) P. ponderosa, (3) P. contorta with host fungal symbiont, (4) P. ponderosa with host fungal symbiont, and (5) air (control). Megarhyssa nortoni females discriminated the odours of infested wood (host fungal symbiont‐pine complex) from those of healthy trees, irrespective of the pine species. Additionally, when offered both pine species infested with the fungal symbiont, the parasitoids displayed a bias towards P. contorta. Even though the identity of the compounds responsible for the behavioural bias towards the symbiont was not established at this stage, our findings emphasize the relevance of chemical information derived from the fungal symbiont‐pine complex during parasitoids that forage for woodboring insect hosts.

A change in the bacterial community of spider mites decreases fecundity on multiple host plants.

Bacterial symbionts may influence the fitness of their herbivore hosts, but such effects have been poorly studied across most invertebrate groups. The spider mite, Tetranychus truncatus, is a polyphagous agricultural pest harboring various bacterial symbionts whose function is largely unknown. Here, by using a high‐throughput 16S rRNA amplicon sequencing approach, we characterized the bacterial diversity and community composition of spider mites fed on five host plants after communities were modified following tetracycline exposure. We demonstrated that spider mite bacterial diversity and community composition were significantly affected by host plants and antibiotics. In particular, the abundance of the maternally inherited endosymbionts Wolbachia and Spiroplasma significantly differed among spider mites that were reared on different plant species and were completely removed by antibiotics. There was an overall tendency for daily fecundity to be lower in the mites with reduced bacterial diversity following the antibiotic treatment. Our data suggest that host plants and antibiotics can shape spider mite bacterial communities and that bacterial symbionts improve mite performance.

Modulation of plant-mediated interactions between herbivores of different feeding guilds: Effects of parasitism and belowground interactions

Herbivory affects subsequent herbivores, mainly regulated by the phytohormones jasmonic (JA) and salicylic acid (SA). Additionally, organisms such as soil microbes belowground or parasitoids that develop inside their herbivorous hosts aboveground, can change plant responses to herbivory. However, it is not yet well known how organisms of trophic levels other than herbivores, below- and above-ground, alter the interactions between insect species sharing a host plant. Here, we investigated whether the parasitoid Aphidius colemani and different soil microbial communities (created through plant-soil feedbacks) affect the JA and SA signalling pathways in response to the aphid Myzus persicae and the thrips Frankliniella occidentalis, as well as subsequent thrips performance. Our results show that the expression of the JA-responsive gene CaPINII in sweet pepper was more suppressed by aphids than by parasitised aphids. However, parasitism did not affect the expression of CaPAL1, a biosynthetic gene of SA. Furthermore, aphid feeding enhanced thrips performance compared with uninfested plants, but this was not observed when aphids were parasitised. Soils where different plant species were previously grown, did not affect plant responses or the interaction between herbivores. Our study shows that members of the third trophic level can modify herbivore interactions by altering plant physiology.

Metabotype variation in a field population of tansy plants influences aphid host selection.

It is well known that plant volatiles influence herbivores in their selection of a host plant; however, less is known about how the nonvolatile metabolome affects herbivore host selection. Metabolic diversity between intraspecific plants can be characterized using non-targeted mass spectrometry that gives us a snapshot overview of all metabolic processes occurring within a plant at a particular time. Here, we show that non-targeted metabolomics can be used to reveal links between intraspecific chemical diversity and ecological processes in tansy (Tanacetum vulgare). First, we show that tansy plants can be categorized into five subgroups based up on their metabolic profiles, and that these "metabotypes" influenced natural aphid colonization in the field. Second, this grouping was not due to induced metabolomic changes within the plant due to aphid feeding but rather resulted from constitutive differences in chemical diversity between plants. These findings highlight the importance of intraspecific chemical diversity within one plant population and provide the first report of a non-targeted metabolomic field study in chemical ecology.

Herbivores avoid host plants previously exposed to their omnivorous predator Macrolophus pygmaeus

Herbivorous arthropods use various cues to choose suitable host plants. We investigated whether three species of herbivores use cues associated with their omnivorous predator Macrolophus pygmaeus to select host plants. Earlier, we found that this omnivore induces plant defences which decreased the performance of two of the herbivores, i.e. the spider mite Tetranychus urticae and the western flower thrips Frankliniella occidentalis, whereas the green peach aphid Myzus persicae was not affected. Hence, the spider mite and thrips were expected to avoid plants that were previously exposed to M. pygmaeus because of their lower quality, and the aphid was not expected to avoid exposed plants because they were of equal quality as unexposed plants. However, the cues left behind by M. pygmaeus may also be indicative of predation risk, in which case all three herbivores were expected to avoid exposed plants. Spider mites and western flower thrips preferred clean plants over plants that had previously been exposed to M. pygmaeus, but no longer harboured this omnivore. Aphids showed no preference, in agreement with their performance, but not in agreement with reducing predation risk. We furthermore showed that the preference of spider mites and thrips for clean plants increased through time. Higher proportions of aphids left plants previously exposed to M. pygmaeus than clean plants through time. Hence, omnivorous predators can decrease herbivore densities on plants not only by killing them but also by indirectly affecting herbivore host plant selection.

Whole-genome data reveal the complex history of a diverse ecological community

How widespread ecological communities assemble remains a key question in ecology. Trophic interactions between widespread species may reflect a shared population history or ecological fitting of local pools of species with very different population histories. Which scenario applies is central to the stability of trophic associations and the potential for coevolution between species. Here we show how alternative community assembly hypotheses can be discriminated using whole-genome data for component species and provide a likelihood framework that overcomes current limitations in formal comparison of multispecies histories. We illustrate our approach by inferring the assembly history of a Western Palearctic community of insect herbivores and parasitoid natural enemies, trophic groups that together comprise 50% of terrestrial species. We reject models of codispersal from a shared origin and of delayed enemy pursuit of their herbivore hosts, arguing against herbivore attainment of "enemy-free space." The community-wide distribution of species expansion times is also incompatible with a random, neutral model of assembly. Instead, we reveal a complex assembly history of single- and multispecies range expansions through the Pleistocene from different directions and over a range of timescales. Our results suggest substantial turnover in species associations and argue against tight coevolution in this system. The approach we illustrate is widely applicable to natural communities of nonmodel species and makes it possible to reveal the historical backdrop against which natural selection acts.

Selective effects of floral food sources and honey on life‐history traits of a pest–parasitoid system

AbstractMany parasitoids and their herbivorous hosts forage on the same floral resources in agroecosystems. Floral resources that benefit natural enemies without supporting pests can improve the efficacy of biological control agents. Here, we report the results of a study on selective effects of floral and non‐floral food sources on the life‐history traits of the parasitoid Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae) and its host Plutella xylostella (L.) (Lepidoptera: Plutellidae). Under standard laboratory conditions, insects were exposed to four flowering plant species, 10% honey solution, and water. All food sources increased the longevity of the herbivore and its parasitoid by as much as four‐ to nine‐fold, respectively, compared to the water control diet. Diadegma insulare survived the longest on Thlaspi arvense L. (Brassicaceae) and P. xylostella on Sinapis arvensis L. (Brassicaceae). However, none of the food sources tested was beneficial to the parasitoid alone, though Lobularia maritima L. (Brassicaceae) was found to selectively favor the longevity of D. insulare. Diadegma insulare adults were heavier when fed on S. arvensis, whereas feeding on the honey solution led to higher body weights of P. xylostella. In conclusion, we demonstrated that floral and non‐floral food sources varied in their suitability and acted differently on life‐history traits of a host–parasitoid system. The selective characteristics of nectar‐producing plants and their influence on the herbivore‐natural enemy combination can, therefore, be employed to increase their impact in integrated P. xylostella management.