Zoophytophagous Predator Research Articles

Non-Herbivore-Induced Plant Organic Volatiles of Tomato Cultivars and Their Effect on Pest Biological Control

Herbivore-induced plant organic volatiles (HIPVs) have recently been studied to improve biological pest control. In contrast, the effects of volatile organic compounds (VOCs) that are not induced by herbivory (non-HIPVs) have received less attention. The latter are essential in the first stages of crop colonization by entomophagous insects (predators and parasitoids) used in biological pest control programs. Furthermore, the effects on entomophagous insects of different cultivars of a cultivated botanical species have not been studied. The aim of this work was to study the different non-HIPVs found in 10 tomato cultivars used in tomato greenhouses on two entomophages: the egg parasitoid Trichogramma achaeae (Hymenoptera, Trichogrammatidae) and the zoo-phytophagous predator Nesidiocoris tenuis (Hemiptera, Miridae). The results indicate that although there is considerable quantitative and qualitative variation in the emission of VOCs in the 10 tomato cultivars analysed, this variability made it difficult to determine the influence of the volatiles on the attraction of the predatory species N. tenuis, with only one cultivar (Rebelion) exhibiting a significantly higher attractiveness than the rest of the cultivars. For the parasitoid T. achaeae, these same volatiles had a significant effect (in part) on parasitoid behaviour. However, this attraction was not reflected in the discriminant analysis, at least for the volatiles analysed. The analysis showed four groups of well-differentiated cultivars, according to the non-HIPV composition, and this bore no relation to the levels of attractiveness registered in the different cultivars, with the exception again of the Rebelion cultivar, which seems not to be very attractive for the parasitoid and its parasitism activity. The implications of non-herbivore-induced (non-HPV) VOCs in the biological control of greenhouse pest species are described and discussed.

Benefits of intraguild interactions between zoophytophagous predators and of bottom-up effects of fertilisation for sustainable management of tomato pests

Benefits of intraguild interactions between zoophytophagous predators and of bottom-up effects of fertilisation for sustainable management of tomato pests

Host plants benefit from non-predatory effects of zoophytophagous predators against herbivores

Host plants benefit from non-predatory effects of zoophytophagous predators against herbivores

Effects of far-red light on the behaviour and reproduction of the zoophytophagous predator Macrolophus pygmaeus and its interaction with a whitefly herbivore.

Plants can detect neighbouring plants through a reduction in the ratio between red and far-red light (R:FR). This provides a signal of plant-plant competition and induces rapid plant growth while inhibiting defence against biotic stress, two interlinked responses designated as the shade avoidance syndrome (SAS). Consequently, the SAS can influence plant-herbivore interactions that could cascade to higher trophic levels. However, little is known about how the expression of the SAS can influence tritrophic interactions. We investigated whether changes in R:FR affect the emission of herbivore-induced plant volatiles (HIPVs), and whether these changes influence the attraction of the zoophytophagous predator Macrolophus pygmaeus. We also studied how the expression of the SAS and subsequent inhibition of plant defences affects the reproduction of M. pygmaeus in both the presence and absence of the greenhouse whitefly (WF) (Trialeurodes vaporariorum) as arthropod prey. The results show that changes in R:FR have little effect on HIPV emissions and predator attraction. However, a reduction in R:FR leads to increased reproduction of both the predator and the WFs. We discuss that shade avoidance responses can increase the population development of M. pygmaeus through a combination of reduced plant defences and increased herbivore densities.

Microbiome of Zoophytophagous Biological Control Agent Nesidiocoris tenuis.

Many insects are associated with endosymbionts that influence the feeding, reproduction, and distribution of their hosts. Although the small green mirid, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), a zoophytophagous predator that feeds on plants as well as arthropods, is a globally important biological control agent, its microbiome has not been sufficiently studied. In the present study, we assessed the microbiome variation in 96 N. tenuis individuals from 14 locations throughout Japan, based on amplicon sequencing of the 16S ribosomal RNA gene. Nine major bacteria associated with N. tenuis were identified: Rickettsia, two strains of Wolbachia, Spiroplasma, Providencia, Serratia, Pseudochrobactrum, Lactococcus, and Stenotrophomonas. Additionally, a diagnostic PCR analysis for three typical insect reproductive manipulators, Rickettsia, Wolbachia, and Spiroplasma, was performed on a larger sample size (n = 360) of N. tenuis individuals; the most prevalent symbiont was Rickettsia (69.7%), followed by Wolbachia (39.2%) and Spiroplasma (6.1%). Although some symbionts were co-infected, their prevalence did not exhibit any specific tendency, such as a high frequency in specific infection combinations. The infection frequency of Rickettsia was significantly correlated with latitude and temperature, while that of Wolbachia and Spiroplasma was significantly correlated with host plants. The predominance of these bacteria and the absence of obligate symbionts suggested that the N. tenuis microbiome is typical for predatory arthropods rather than sap-feeding insects. Rickettsia and Wolbachia were vertically transmitted rather than horizontally transmitted from the prey. The functional validation of each symbiont would be warranted to develop N. tenuis as a biological control agent.

Induction of glandular trichomes to control whitefly-transmitted viruses in tomato crops: modulation by the natural enemy Nesidiocoris tenuis.

Whitefly-transmitted viruses are one of the biggest threats to tomato growing worldwide. Strategies based on the introgression of resistance traits from wild relatives are promoted to control tomato pests and diseases. Recently, a trichome-based resistance characterizing the wild species Solanum pimpinellifolium was introgressed into a cultivated tomato. An advanced backcross line (BC5S2) exhibiting the presence of acylsugars-associated type IV trichomes, which are lacking in cultivated tomatoes, was effective at controlling whiteflies (Hemiptera: Aleyrodidae) and limiting the spread of whitefly-transmitted viruses. However, at early growth stages, type IV trichomes density and acylsugars production are limited; thus, protection against whiteflies and whitefly-transmitted viruses remains irrelevant. In this work, we demonstrate that young BC5S2 tomato plants feeding-punctured by the zoophytophagous predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) displayed an increase (above 50%) in type IV trichomes density. Acylsugars production was consistently increased in N. tenuis-punctured BC5S2 plants, which was more likely associated with upregulated expression of BCKD-E2 gene related to acylsugars biosynthesis. In addition, the infestation of BC5S2 plants with N. tenuis effectively induced the expression of defensive genes involved in the jasmonic acid signaling pathway, resulting in strong repellence to B. tabaci and attractiveness to N. tenuis. Thus, by pre-plant release of N. tenuis in tomato nurseries carried out in some integrated pest management programs, type IV trichome-expressing plants can be prepared to control whiteflies and whitefly-transmitted viruses at early growth stages. This study emphasizes the advantage of reinforcing constitutive resistance using defense inducers to guarantee robust protection against pests and transmitted viruses.

Synergism of a mixed diet of Myzus persicae and egg of Ephestia kuehniella on fitness of the predator Nabis stenoferus

Nabis stenoferus is a zoophytophagous predator that lives in grasslands around agricultural fields. It is a candidate biological control agent for use via augmentation or conservation. To find a suitable food source for mass-rearing and to better understand this predator’s biology, we compared the life history characteristics of N. stenoferus under the three different diets: aphids only (Myzus persicae), moth eggs only (Ephestia kuehniella), or a mixed diet of aphids and moth eggs. Interestingly, when only aphids were supplied, N. stenoferus developed to the adult stage but lacked normal levels of fecundity. There was a significant synergism of the mixed diet on N. stenoferus fitness in both the immature and adult stages, i.e., a 13% reduction in the nymphal developmental period and an 87.3-fold increase in fecundity, compared to aphid-only diet. Furthermore, the intrinsic rate of increase was significantly higher for the mixed diet (0.139) than either aphids only (0.022) or moth eggs only (0.097). These results show that M. persicae alone is not a complete diet for the mass-rearing of N. stenoferus, whereas this aphid can be a supplementary food when combined with E. kuehniella eggs. Implications and applications of these findings for biological control are discussed.

Companion plants for conservative management of Tupiocoris cucurbitaceus (Spinola 1852) (Heteroptera: Miridae: Dicyphini) on greenhouse tomato crops

In recent decades, greenhouse crops relevance increased due to the high demand for products outside their growing season, with tomato standing out as one of the most cultivated crops. In these production systems, insects and mites find optimal conditions for their development, achieving high populations that affect crops. Farmers usually control these populations using chemical insecticides, which affect the health of workers and consumers and have negative effects on the environment. Tomato crops suffer damage by lepidopterans and hemipterans, among which those known as whiteflies (Hemiptera: Aleyrodidae) perform regular attacks, causing yield and quality losses in the final product. Currently, the use of zoophytophagous predators of the Miridae family, Dicyphini tribe, as an alternative for their biological control, has intensified studies on Tupiocoris cucurbitaceus (Spinola, 1852), a predator of several species of aphids and whiteflies found in Uruguay. A strategy for the conservative management of those species was designed, using companion plants grown together with the crop. By the time the tomato plants were transplanted, Calendula officinalis, Smallanthus connatus, Tithonia rotundifolia, Nicotiana tabacum, Physalis peruviana and Petunia hybrida plants were established as companion species. These plants were monitored weekly together with the tomato plants, and a greater presence of T. cucurbitaceus in the crops with companion plants was found. The results suggest that the incorporated plants were useful for the preservation and retention of predaceous mirids in productive conditions.

Two in one: the neotropical mirid predator Macrolophus basicornis increases pest control by feeding on plants.

Plant defenses activated by European zoophytophagous predators trigger behavioral responses in arthropods, benefiting pest management. However, repellence or attraction of pests and beneficial insects seems to be species-specific. In the neotropical region, the mirid predator Macrolophus basicornis has proved to be a promising biological control agent of important tomato pests; nevertheless, the benefits of its phytophagous behavior have never been explored. Therefore, we investigated if M. basicornis phytophagy activates tomato plant defenses and the consequences for herbivores and natural enemies. Regardless of the induction period of M. basicornis on tomato plants, Tuta absoluta females showed no preference for the odors emitted by induced or control plants. However, Tuta absoluta oviposited less on plants induced by M. basicornis for 72 h than on control plants. In contrast, induced plants repelled Bemisia tabaci females, and the number of eggs laid was reduced. Although females of Trichogramma pretiosum showed no preference between mirid-induced or control plants, we observed high attraction of the parasitoid Encarsia inaron and conspecifics to plants induced by M. basicornis. While the mirid-induced plants down-regulated the expression of genes involving the salicylic acid (SA) pathway over time, the genes related to the jasmonic acid (JA) pathway were up-regulated, increasing emissions of fatty-acid derivatives and terpenes, which might have influenced the arthropods' host/prey choices. Based on both the molecular and behavioral findings, our results indicated that in addition to predation, M. basicornis benefits tomato plant resistance indirectly through its phytophagy. This study is a starting point to pave the way for a novel and sustainable pest-management strategy in the neotropical region. © 2022 Society of Chemical Industry.

Induction of plant defenses: the added value of zoophytophagous predators

Several biological control agents of the hemipteran insect families Miridae, Anthocoridae and Pentatomidae, as well as mites of the family Phytoseiidae are known as zoophytophagous predators, a subset of omnivores, which are primarily predaceous but also feed on plants. It has been recently demonstrated that zoophytophagous predators are capable of inducing defenses in plants through their phytophagy. Despite the vast fundamental knowledge on plant defense mechanisms in response to herbivores, our understanding of defense induction by zoophytophagous predators and applied implications is relatively poor. In this review, we present the physiological basis of the defense mechanisms that these predators activate in plants. Current knowledge on zoophytophagous predator-induced plant defenses is summarized by groups and species for the predators of economic importance. Within each group, feeding habits and the effects of their induced-plant defenses on pests and natural enemies are detailed. Also, the ecological implications of how the induction of defenses mediated by zoophytophagous predators can interact with other plant interactors such as beneficial soil microorganisms and plant viruses are addressed. Based on the above, we propose three approaches to exploit zoophytophagous predator-induced defenses in crop protection and to guide future research. These include using predators as vaccination agents, employing biotechnological approaches, as well as applying elicitors to elicit/mimic predator-induced defenses.

Tracking the movement of Nesidiocoris tenuis among banker plants and crops in a tomato greenhouse by DNA markers of host plants

The zoophytophagous predator, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), is an important biological control agent. To maintain this insect, several non-crop host plants are used as banker plants in greenhouse crop systems. To optimize the efficiency of the predator-banker plant interaction, it is necessary to investigate how individual predators move between banker plants and crops. However, the movement is difficult to quantify under field conditions. Therefore, we investigated the movement of N. tenuis between tomato plants (Solanum lycopersicum L., Solanales: Solanaceae) and three banker plants (Cleome hassleriana Chod., Brassicales: Cleomaceae; Sesamum indicum L., Lamiales: Pedaliaceae; and Verbena × hybrida Voss, Lamiales: Verbenaceae) in a greenhouse by conducting PCR using plant-species-specific primers. Laboratory analysis results showed that our molecular method could detect N. tenuis activity within a relatively short time (≤ 24 h). In addition, N. tenuis predation on a pest species was unlikely to result in false detection of plant DNA in the pest (suggesting that N. tenuis had been on the plants). Multiple plant species were detected in adult insects collected from the greenhouse plants, indicating that N. tenuis frequently moved across the mentioned plant species. The movement patterns of N. tenuis between plant species varied substantially based on the plant species from which they were collected, which suggested each of the plant species had different functions for N. tenuis. Our findings revealed that planting multiple host plants would stabilize the N. tenuis population in biological control programs.

Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is a zoophytophagous predator that feeds on plants as well as prey. Several non-crop host plant species have been used to maintain this mirid as a biological control agent in different crop systems. To evaluate the benefit of these non-crop host plants on biological control services, data on the life-history traits of N. tenuis on these plants are important as fundamental information. Herein, we studied the demographic growth parameters of N. tenuis reared on three alternative non-crop host plants (Cleome hassleriana Chod., Brassicales: Cleomaceae; Verbena × hybrida Voss, Lamiales: Verbenaceae; and Sesamum indicum L., Lamiales: Pedaliaceae) and one crop plant (tomato) in the absence of prey under laboratory conditions (25 ± 1 °C, 16:8 h L:D). The estimated intrinsic rate of increase in each plant was significantly greater in the following order: S. indicum (0.094) > C. hassleriana (0.074) > tomato (−0.002) > Verbena × hybrida (−0.060). The results indicated that C. hassleriana and S. indicum were able to fully support the development and reproduction of N. tenuis with nutrients derived from only its plant tissues, whereas Verbena × hybrida and tomato were not. Our findings revealed that C. hassleriana is a promising resource for the conservation or mass rearing of N. tenuis besides S. indicum.

Compatibility of Orius insidiosus (Hemiptera: Anthocoridae) with Amblyseius swirskii (Acari: Phytoseiidae) for control of Flankliniella occidentalis (Thysanoptera: Thripidae) in pepper

Biological control programs in greenhouses increasingly resort to the release of several natural enemies simultaneously. In Uruguay, pest management in peppers is based on the release of Orius insidiosus and Amblyseius swirskii, to control Frankliniella occidentalis and Bemisia tabaci. Amblyseius swirskii can feed on both preys. Zoophytophagous predators not only feed on pests or plant food, but also on natural enemies with which they share prey (intraguild predation). Hence, the combined release of generalist predators could have a negative result in the control of the target pest. Thus, it was important to evaluate the compatibility of O. insidiosus and A. swirskii as predators of F. occidentalis. Studies carried out at Petri dishes level assessed: (1) the effect of the density and the composition of the prey on their predation by O. insidiosus, (2) the change of prey by O. insidiosus and (3) the effect of the genus of O. insidiosus on prey preference. Results show that if the relative densities of F. occidentalis and A. swirskii varied, O. insidiosus always changed to the most abundant prey. Male and female O. insidiosus preferred nymphs of F. occidentalis over A. swirskii, and females killed more prey than males. Since O. insidiosus fed on A. swirskii, it is advisable to be cautious when combining anthocorids and phytoseid mites for the F. occidentalis control. Studies at greenhouse will be necessary to clarify the final effect of both predators.

How does a predator find its prey? Nesidiocoris tenuis is able to detect Tuta absoluta by HIPVs

• Tomato leaf miner is one of the most destructive tomato pests. • Predatory mirid bugs are very effective biocontrol agents. • Nesidiocoris tenuis uses herbivore-induced plant volatiles to find its prey. • Nesidiocoris tenuis prefers infested tomato plants by T. absoluta than healthy plants. The Zoophytophagous predator, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is one of the most important candidates for controlling Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in tomato crops. This predator uses different signals including morphological plant traits, prey insects, and volatile substances produced by the infested plants and prey signals to find its suitable prey. These signals are different in each cultivar of a plant. We aimed to understand how N. tenuis finds its prey using volatiles from tomato plants damaged or infested with T. absoluta . The predator’s responses to various plant treatments on two cultivars of tomato plants were tested in a flight tunnel and a four-choice olfactometer. The volatile compounds released from the treatments were also collected and identified. The results of the olfactory experiments showed that the predators even in the absence of light chose the plants bearing their insect prey. This behavior was not the same in both cultivars, and N. tenuis had a tendency toward mechanically damaged of Early Urbana Y cultivar more than Cal JN3 cultivar. The differences in the amount of monoterpenes, sesquiterpenes, and eugenol between cultivars may play a role in the differential attraction of N. tenuis towards infested plants. The difference in the volatile compounds was evident in two cultivars, and this was consistent with our bioassay results. Therefore, the choice of appropriate cultivar and use of herbivore-infested plant volatiles are important for developing a control strategy against T. absoluta and attract its predators.

Biological Control Potential and Drawbacks of Three Zoophytophagous Mirid Predators against Bemisia tabaci in the United States.

Simple SummaryThe silverleaf whitefly, Bemisia tabaci, is a serious economic pest of tomatoes, particularly as this insect can carry devastating plant diseases. Growers currently rely on costly insecticides and biocontrol agents may offer a viable alternative in the integrated pest management of tomatoes. We studied one established and two native omnivorous plant bugs’ (mirids) ability to control whiteflies, whether they damaged tomato plants, and their ability to persist in the crop. Established biocontrol agents have advantages as they typically have little impact on non-target native species, they have adapted to the local environment and are less expensive than importing and testing exotic agents. In field cage studies, all three species controlled whiteflies. However, the damage the mirids caused to tomato plants varied greatly. We also tested whether an alternate host plant, sesame, could increase mirid numbers and reduce plant damage. These experiments showed that the benefits of sesame varied among the mirid species. Although not all established generalist mirids would be suited for use as biocontrol agents, this study showed that two of USA’s mirid species could be immediately available to help manage existing and future invasive pests of tomato.Miridae (Hemiptera) of the tribe Dicyphini are important zoophytophagous predators use to control pest arthropods in vegetable crops. However, the risk that their herbivory may cause economic damage could hinder their application as useful biocontrol agents and may limit the likelihood they would meet regulatory requirements for importation. We conducted field cage studies to assess the predation capacity and tomato plant damage of three mirid species established in south USA, a known biocontrol agent (Nesidiocoris tenuis), and two native species (Macrolophus praeclarus and Engytatus modestus). All three species significantly reduced the number of whiteflies (Bemisia tabaci) on tomato plants compared to tomato plants without mirids. More damage, evaluated as the number of necrotic rings, was observed on tomato plants with E. modestus and N. tenuis compared to M. praeclarus. In our experiments that included sesame plants (Sesamum indicum) with tomato plants, mirid numbers increased despite a low number of prey, thus showing a benefit of the plant-feeding habit of these predators. USA’s established mirids may therefore prove to be immediately available biological agents for the management of present and future tomato pests.

Does the plant defense priming compound β-aminobutyric acid affect the performance of Macrolophus pygmaeus when used to control Bemisia tabaci in tomato?

The β-aminobutyric acid (BABA) is a plant defense priming compound highly effective in controlling important tomato diseases and plant-parasitic nematodes. It has also been shown to induce resistance against phytophagous insects such as aphids. This study examines the effect of BABA on the performance of the tomato pest Bemisia tabaci (MEAM 1, previously known as Biotype B) and its zoophytophagous predator Macrolophus pygmaeus under laboratory and greenhouse conditions. Tomato plants were treated with BABA 25 mM applied by soil drenching. The effect of BABA on the fertility and juvenile development of two generations of B. tabaci and M. pygmaeus was evaluated. Our results showed no effect of BABA on the juvenile development or adult fecundity/fertility of both the whitefly and its predator. The non-interference of BABA with M. pygmaeus and B. tabaci assures that the control of the whitefly with this mirid bug will not be affected when this elicitor is applied to the crop. Further studies are needed to clarify the mechanisms underlying BABA-plant-whitefly-predatory myrids interactions.

Use of zoophytophagous mirid bugs in horticultural crops: Current challenges and future perspectives.

In recent years, the use of predatory mirid bugs (Hemiptera: Miridae) in horticultural crops has increased considerably. Mirid bugs are zoophytophagous predators, that is, they display omnivorous behavior and feed on both plants and arthropods. Mirid bugs feed effectively on a wide range of prey, such as whiteflies, lepidopteran eggs and mites. In addition, the phytophagous behavior of mirid bugs can activate defenses in the plants on which they feed. Despite the positive biological attributes, their use still presents some constraints. Their establishment and retention on the crop is not always easy and economic plant damage can be caused by some mirid species. In this review, the current strategies for using zoophytophagous mirid bugs in horticultural crops, mainly Nesidiocoris tenuis, Macrolophus pygmaeus and Dicyphus hesperus, are reviewed. We discuss six different approaches which, in our opinion, can optimize the efficacy of mirids as biocontrol agents and help expand their use into more areas worldwide. In this review we (i) highlight the large number of species and biotypes which are yet to be described and explore their applicability, (ii) present how it is possible to take advantage of the mirid-induced plant defenses to improve pest management, (iii) argue that genetic selection of improved mirid strains is feasible, (iv) explore the use of companion plants and the use of alternative foods to improve the mirid bug management, and finally (vi) discuss strategies for the expansion of mirid bugs as biological control agents to horticultural crops other than just tomatoes. © 2020 Society of Chemical Industry.

Plant feeding by Nesidiocoris tenuis: Quantifying its behavioral and mechanical components

Zoophytophagous predators play an important, though sometimes controversial, role in pest management programs in different crops. In tomato crops, damage caused by phytophagy of the mirid Nesidiocoris tenuis has mainly been reported at high predator population levels or when prey is scarce. Previous research has focused on predator/prey ratios, stylet morphology and saliva composition to explain plant damage by N. tenuis. In this study, we investigated the behavioral and mechanical components of the damage. For this, we compared the feeding behaviors of males, females and fifth-instar nymphs ofN. tenuis. Additionally, we investigated the type of stylet activities performed by each stage while probing in plant tissue, using the electrical penetration graph technique (EPG). Furthermore, stylectomy was performed and plant histology studied with the aim to correlate the feeding activities observed in the EPG recordings with stylet tip positions in specific tissues of the leaf petioles. Behavioral observations during a 30-min period showed thatnymphs probed more frequently (38.6 ± 1.5 probes) than males and females (25.3 ± 1.1 and 24.3 ± 1.1 probes, respectively). Similarly, nymphs spent a higher proportion of time (656.0 ± 67.6 s) feeding on tomato apical sections compared to males and females (403.0 ± 48.8 s and 356.0 ± 43.7 s, respectively). The EPG recordings during 5 h indicated that cell-rupturing was the main stylet activity for all insect stages, and that fifth-instar nymphs spent a higher proportion of time on cell-rupturing events compared to adults. The histological studies revealed a trend ofN. tenuisfor the tissues within the vascular semi-ring. The stylet tips were found both in the vascular bundles and in the parenchyma of the interfascicular region. The findings of this study confirm an important role of fifth-instar nymphs feeding behavior in the damage potential of N. tenuis. Moreover, the increased time spent on cell rupturing behaviour suggests that stylet laceration and enzymatic maceration of the saliva occurring during this event might greatly contribute to the inflicted damage. A comprehensive understanding of the interactions of N. tenuis with the plant, at both the behavioral and mechanical levels, might shed light on new approaches to minimize its damage potential to tomato while maintaining its benefits as biocontrol agent.

Genetic Variation in the Feeding Behavior of Isofemale Lines of Nesidiocoris tenuis.

Simple SummaryBreeding of species for the benefit of humans is a well-known practice in plants and some vertebrates. However, its application to invertebrates, specifically biocontrol agents, is rather new and there is still a lack of information on breeding parameters of key traits. In this study, we address two important traits for biocontrol, i.e., the phytophagy and zoophagy of a population of the zoophytophagous predator Nesidiocoris tenuis. Here, we determine whether there is variation in these two traits and the proportion of that variation that has a genetic basis. Our results revealed the presence of genetic variation in both traits for this population. Genetic variation observed in zoophagy was larger than that found in phytophagy. These findings are relevant to the field of genetic improvement of biocontrol agents, since it reports quantitative values necessary for potential breeding programs. Moreover, our results suggest that if such variation is maintained in larger populations, it might be possible that selection for more zoophagous individuals could entail a reduction of the damages derived from its phytophagy. Furthermore, this study sheds light on genetic tools that could be applied to improve the biocontrol practice and, consequently, contribute to a more sustainable agriculture.Zoophytophagous predators provide biocontrol services in various major crops of modern horticulture due to the combination of its predatory capacity and the induction of plant defenses derived from its phytophagy. However, under certain conditions of prey scarcity, these natural enemies can inflict plant damage. Exploitation of genetic variation and subsequent selective breeding on foraging traits is a potential alternative to overcome this inconvenience. In this study, we quantified the genetic variation of phytophagy and zoophagy of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), a zoophytophagous predator widely used in tomato crops to suppress key pests. We compared nine isofemale lines on their capacity to produce necrotic rings and wilting on tomato plants as a proxy for phytophagy, as well as their efficacy to prey on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, as a proxy for zoophagy. Differences between isofemale lines in phytophagy and zoophagy indicated a genetic basis. Variation found in the zoophagy levels was larger than that in phytophagy levels. Our results showed that there is a genetic basis for the variation observed in the feeding behavior of isofemale lines of N. tenuis, highlighting the potential importance of selective breeding for such traits of biocontrol interest.

Estimation of movement from insectary plants to crop plants in Orius bugs (Heteroptera: Anthocoridae) by molecular gut content analysis

The introduction of insectary and banker plants is widely used in agroecosystems to improve the survival and reproduction of natural enemies of pest arthropods. Natural enemies that are attracted to and/or maintained on insectary plants need to move from the insectary plants to crop plants to suppress pest populations effectively. In many cases, however, direct evidence supporting the migration of natural enemies is lacking. To investigate the movement of Orius bugs (Hemiptera: Anthocoridae), which are efficient zoophytophagous predators used in biological control, we performed gut content analyses based on DNA markers. Specific PCR primers were designed to detect the DNA of the insectary plant, Scaevola aemula. We also carried out gut content analyses using prey insect DNA markers to estimate Orius bugs’ predation spectrum. DNA of the insectary plant was detected in the abdomen of Orius bugs collected on eggplant leaves, suggesting that Orius bugs had consumed food resources from the insectary plants and relocated to the crop plants. DNA of three prey insect species—two thrips species, Thrips palmi and Frankliniella intonsa, and cotton aphid, Aphis gossypii—was detected in Orius bugs in the eggplant field, indicating that Orius bugs preyed on them.