Factitious Prey Research Articles

Effect of Ephestia kuehniella Eggs on Development and Transcriptome of the Ladybird Beetle Propylea japonica.

The eggs of the Mediterranean flour moth, Ephestia kuehniella, are frequently utilized as alternative diets and have demonstrated promising outcomes when consumed by various insects. Nonetheless, the specific reasons for their effectiveness remain unclear. In our study, we assessed the developmental performance of the ladybird Propylea japonica when fed E. kuehniella eggs, alongside 12 factitious prey or artificial diets. Our findings revealed that ladybirds fed E. kuehniella eggs displayed a performance comparable to those fed the natural prey Megoura crassicauda. Transcriptome profiling of larvae raised on E. kuehniella eggs and M. crassicauda revealed that genes upregulated in the former group were enriched in metabolic pathways associated with carbohydrates, lipids, and other essential nutrients. This suggests that E. kuehniella eggs may have a higher nutrient content compared to natural prey. Furthermore, a notable downregulation in the expression of immune effector genes, such as Attacin and Coleoptericin, was observed, which might be attributed to the lower microbial content in E. kuehniella eggs compared to M. crassicauda. We suggest that the difference between E. kuehniella eggs and M. crassicauda as food sources for P. japonica lies in their nutrient and microbial contents. These findings provide valuable insights for the advancement of innovative artificial breeding systems for natural enemies.

Testing the Effects of Prey Type on the Life History and Population-Level Parameters of Chrysoperla externa (Neuroptera: Chrysopidae).

Green lacewings are valuable predators, utilized in augmentative biological control against various agricultural pests. However, further studies are required to comprehend the performance of these predators when consuming natural prey. We investigated the capacity of Chrysoperla externa (Hagen) to utilize the following three distinct prey types: the pupae of the coffee leaf miner Leucoptera coffeella (Guérin-Mèneville & Perrottet), the eggs of the sugarcane borer Diatraea saccharalis (F.), and the eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller). The first two of these species are naturally occurring prey found in field crops, while the last serves as a factitious prey species for the mass rearing of natural enemies. We hypothesized that the type of prey would differentially affect the life history and population-level parameters of C. externa. Laboratory experiments were conducted to compare the pre-imaginal survival and developmental times, adult longevity and reproduction, and population growth of C. externa when larvae were provided with each of the three prey items. Results indicated that C. externa utilized the two natural prey items, L. coffeella pupae and D. saccharalis eggs, for its development, reproduction, and population growth. However, larvae developed significantly faster and females exhibited higher reproductive parameters, including fecundity and daily oviposition, when consuming the factitious prey, E. kuehniella eggs. This resulted in a higher intrinsic rate of population increase, as well as shorter times for the population to double in size. Understanding the population dynamics of C. externa when consuming different prey items is crucial for optimizing their utilization in augmentative biological control programs.

Prey consumption and conversion efficiency in females of two feral populations of Macrolophus pygmaeus, a biocontrol agent of Tuta absoluta

Macrolophus pygmaeus (Rambur, 1839) (Hemiptera: Miridae) is a polyphagous predator used in programs of biological control and integrated pest management as a natural enemy against small arthropod pests including whiteflies, thrips, spider mites and aphid. This mirid is also successfully mass reared under factitious prey for commercial purposes. In the present study we assessed and compared the prey consumption, weight gain and conversion efficiency in females of two populations of M. pygmaeus, from mainland Portugal and the Azores, fed on single prey diets of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, or Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs. We found that female’s prey consumption on eggs of T. absoluta was higher than that of E. kuehniella, presumably due to the comparative size/amount of biomass of the eggs. Translating prey consumption in biomass ingested, we only found a significant difference for consumption on E. kuehniella eggs by M. pygmaeus from the Azores. Despite the smaller size of females from the Azores, they were able to consume more prey and ultimately reaching a similar body weight and conversion efficiency compared with females from mainland, independently of the prey provided. Our results are in line with a previous study, showing differences in the life-history traits of M. pygmaeus from mainland Portugal and Azorean populations fed on alternative prey. From an applied perspective, our results are a contribution to the decision-making on the use of the most effective biocontrol agents for different prey and/or agroecosystem contexts.

Development and reproduction of four predatory mites (Parasitiformes: Phytoseiidae) feeding on the spider mites Tetranychus evansi and T. urticae (Trombidiformes: Tetranychidae) and the dried fruit mite Carpoglyphus lactis (Sarcoptiformes: Carpoglyphidae)

The tomato red spider mite, Tetranychus evansi, a notorious crop pest, invaded New Zealand in 2020. In an effort to identify potential biological control agents for this species, we investigated the capabilities of four phytoseiid predators found in New Zealand—Amblyseius herbicolus, Amblyseius lentiginosus, Amblydromalus limonicus, and Neoseiulus californicus. For comparison, we also used the two-spotted spider mite, T. urticae, and the dried fruit mite, Carpoglyphus lactis, as prey for these predators. In our first experiment we monitored immature development and oviposition rate (over the first 5 days) of the phytoseiid predators when presented with the three prey species. While all four species of predators could develop and reproduce on the factitious (alternative and easily available) prey species C. lactis, they had limited success when feeding on T. evansi and T. urticae. Amblyseius herbicolus, A. lentiginosus, and Amblyd. limonicus were unable to reach adulthood when feeding on T. evansi and T. urticae in the presence of the protective webbing spun by the mites. While N. californicus matured when exposed to T. evansi reared on black nightshade leaves, it did not lay eggs—indicating potential limitations in prey suitability. In our second experiment, gravid females of all four predators failed to maintain their reproduction when provided with T. evansi in the presence of webbing. Neoseiulus californicus exhibited phenotypic plasticity in its developmental time, body size, and oviposition rate when feeding on the three prey species. This suggests that N. californicus has the flexibility to switch diets to survive during food scarcity, especially when their primary prey, T. urticae, is limited. This study is also the first to offer life history information about A. lentiginosus. Our findings underscore the difficulties of controlling T. evansi using phytoseiid predators and highlight the need for diversified pest management strategies, including the use of alternative insect predators or entomopathogenic fungi.

Automated identification and counting of predated Ephestia kuehniella (Zeller) eggs using deep learning image analysis

Predation or kill rate of biological control agents is often used as a proxy to evaluate the efficacy of different species of natural enemies and under different conditions. For generalist predators and many egg parasitoids, eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) are used as factitious prey or hosts in laboratory and field experiments, as they are widely available from mass rearings of the biological control industry. Evaluating the predation or parasitism activity of natural enemies on E. kuehniella is a valuable tool for biological control practitioners around the world. However, manual assessments are laborious and prone to error, as observations may be subjective and depend on the individual performing the task. Here, we developed an automated protocol based on the deep learning object detection algorithm YOLOv5, for the accurate estimation of predated E. kuehniella eggs by piercing-sucking generalist predators. The application of the trained deep learning model achieved high precision (0.90) and recall (0.93) in the identification of predated eggs among intact eggs in our test experiment and was more accurate and faster than two independent observers that performed manual counting under a stereo microscope based on the mean absolute percentage error metric. Furthermore, a case study is presented where the predation activity of the generalist predators Orius laevigatus, Orius majusculus, Orius minutus, Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus errans is compared. Further applications and expansions of the protocol are discussed.

Evaluation of the Predatory Mite Neoseiulus barkeri against Spider Mites Damaging Rubber Trees.

The spider mites Eotetranychus sexmaculatus, Eutetranychus orientalis and Oligonychus biharensisin are severe pests of rubber trees in China. The predatory mite Neoseiulus barkeri has been found to be a natural enemy of these three pests, while nothing is known about the biological performance of this phytoseiid predator against these phytophagous mites. In this study, the development, survivorship, reproduction, adult longevity, fecundity, sex ratio and population growth parameters of N. barkeri fed on these pests were evaluated in comparison to the factitious prey Tyrophagus putrescentiae in the laboratory at 25 ± 1 °C, 75 ± 5% relative humidity and a 12:12 (L:D) h photoperiod. The results showed that N. barkeri could develop from egg to adult and reproduced successfully on the three preys. The survival rate of N. barkeri from egg to adult was higher when fed on E. orientalis (100%) and T. putrescentiae (100%) than when fed on O. biharensisin (93.60%) and E. sexmaculatus (71.42%). The shortest and longest generation time for N. barkeri were observed on E. orientalis with 6.67 d and E. sexmaculatus with 12.50 d, respectively. The maximum fecundity (29.35 eggs per female) and highest intrinsic rate of increase (rm = 0.226) were recorded when N. barkeri fed on E. orientalis, while feeding on E. sexmaculatus gave the minimum fecundity (1.87 eggs per female) and lowest reproduction rate (rm = 0.041). The values of these parameters for N. barkeri evaluated on O. biharensisin were found to be comparable to those obtained on T. putrescentiae. The sex ratio of N. barkeri progeny on the preys mentioned above, apart from O. biharensisin, was female biased. According to the findings, N. barkeri could serve as a promising biocontrol agent against E. orientalis and O. biharensisin, and possibly E. sexmaculatus on rubber trees.

Contrasting Phenotypic Variability of Life-History Traits of Two Feral Populations of Macrolophus pygmaeus (Hemiptera: Miridae) under Two Alternative Diets

Tuta absoluta is a major pest attacking tomato crops. This invasive species emerged in Europe (Spain) in 2006, and 3 years later it spread to Portugal. In 2009/2010, it was recorded for the first time in the Azores archipelago. Macrolophus pygmaeus is a predator widely used as biological control agent against the tomato leaf miner. This study contrasted the life-history traits and population growth parameters of two feral populations of M. pygmaeus, one from Portugal mainland and one from the Azores archipelago. The predators were tested on single prey diet, either of Ephestia kuehniella eggs, a factitious prey used for mass rearing of mirids, or T. absoluta eggs. We predicted that populations would express differences in its phenotypic characteristics, with the Azorean population displaying low performance due to likely low genetic diversity, as expected for insular populations. Our results revealed the inexistence of phenotypic differences in several life history traits, such as immature developmental time, female longevity, males’ body weight and sex ratio. Contrary to our predictions, traits with direct impact on fitness, such as lifetime fertility (95.78 ± 14.23 vs. 61.38 ± 13.52 nymphs), explain better performances for the population of the Azores. Azorean M. pygmaeus females were larger, matured earlier and reproduced at a higher rate for longer periods, than mainland females. Therefore, population growth parameters show a positive advantage for the population of the Azores, fed on T. absoluta (time required for doubling the population Azores, Ek: 8.42 ± 0.50, Ta: 5.76 ± 0.31 and mainland, Ek: 10.88 ± 1.94, Ta: 12.07 ± 3.15). Biological performance of M. pygmaeus was similar when fed with T. absoluta or E. kuehniella that could be beneficial both to optimize mass production of the predator and biological control of the pest. Our results are discussed as well in a fundamental perspective, seeking if differences in biological performance can be explained by lower genetic diversity driven by geographic isolation.

Alternative food sources for Amblydromella caudiglans (Phytoseiidae) and effects on predation.

The addition of supplemental food sources for natural enemies is a growing component of conservation and augmentative biological control. Supplemental foods can be used to retain natural enemies when prey are scarce and to promote survival, fecundity, longevity, and development of natural enemy populations, especially generalist natural enemies. Amblydromella caudiglans (Schuster) (Acari: Phytoseiidae) is one of the most abundant predatory mites found in commercial apple orchards in Washington, USA, and contributes to spider mite control. However, because its widespread presence in commercial apple orchards was only recently discovered, how supplementary food sources affect its performance is unknown. In laboratory studies, we evaluated the performance (fecundity, retention, prey consumption) of the generalist phytoseiid A. caudiglans on commercially available supplemental food sources, including factitious prey (Ephestia eggs and Artemia brine shrimp cysts), and pollens of apple, pear, and cattail. We determined that A. caudiglans will not consume Ephestia eggs and performs best on cattail and pear pollens. Combinations of food sources did not enhance the performance of this predator compared to the best performing single-sources. The presence of alternative food sources did not decrease A. caudiglans predation of twospotted spider mite nymphs, except for Artemia brine shrimp cysts, which had a substantial handling time. These results lay the groundwork for identifying a way to promote and retain this natural enemy in tree fruit cropping systems through the use of food resource applications or floral plantings.

Frozen lepidopteran larvae as promising alternative factitious prey for rearing of Orius species

Frozen lepidopteran larvae as promising alternative factitious prey for rearing of Orius species

Effects of factitious prey on the biology and growth rate of the predatory mites Neoseiulus californicus (McGregor) (Acari: Phytoseiidae)

Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is being used on a commercial scale to control Tetranychus urticae Koch in open fields and greenhouses (Schausberger and Walzer 2001; Sato et al. 2007; Rezaie et al. 2017). To reduce the cost of rearing, phytoseiid mites are often cultured using factitious prey. To find out the most suitable factitious prey species for rearing N. californicus in this study, the development and reproduction of the predatory mite were assessed when fed on four factitious prey species: Carpoglyphus lactis, Lepidoglyphus destructor, Tyrophagus putrescentiae, Rhizoglyphus robini and the natural prey Tetranychus urticae (control). The results showed that N. californicus could survival on all prey species, however, their populations could increase when fed on C. lactis, L. destructor, and T. urticae. The life cycles of N. californicus fed on C. lactis and L. destructor (5.13 and 5.17 days respectively) were significantly shorter than those fed on T. urticae (5.89 days). The total number of eggs per female N. californicus fed on L. destructor was the highest (51.48 eggs/female), intermediate on T. urticae (45.11 eggs/female) and the lowest on C. lactis (38.68 eggs/female). When fed on L. destructor and T. urticae, the sex ratios (% female) in the 2nd generation of N. californicus reached approx. 70%—significantly higher than those predators fed on C. lactis (58.65%). The intrinsic rate of increase of N. californicus fed on L. destructor (0.338) was significantly higher than those females fed on C. lactis (0.304) and T. urticae (0.314). In conclusion, the factitious prey L. destructor is the best food source for mass rearing the predatory mite N. californicus.

Effect of Relative Humidity on the Population Dynamics of the Predator Amblyseius swirskii and Its Prey Carpoglyphus lactis in the Context of Slow-Release Sachets for Use in Biological Control in Greenhouses.

Amblyseius swirskii is a predatory mite that is widely used for biological control in greenhouses. One way this predator is released is in a formulation in slow-release sachets. These sachets are prepared with the predatory mite, the factitious prey mite Carpoglyphus lactis, and a food substrate for the latter. The objective of the present study was to study the effects of microclimatic conditions in this type of formulation on the population dynamics of mites inside the sachets and on the release of predatory mites. These experiments were conducted under laboratory conditions in two trials. The ambient relative humidity affected the water content of the food substrate of the prey mite inside the sachets, with an initial value of 21.49 ± 0.42%, which was reduced to values of 4.7 ± 0.25%, 10.87 ± 1.03% and 17.27 ± 0.82% after 21 days of trials when they were exposed to low, medium and high ambient relative humidity levels, respectively. Relative humidity significantly altered the dynamics of the populations of both species inside the sachets and the exits of the predator from the sachets to the external environment.

Population dynamics of mites in slow-release sachets used in biological control: a new study methodology.

Predatory mite species (Acari: Phytoseiidae) are essential tools in the biological control of greenhouses pests. The natural enemies can be released directly into a crop. A better, partly preventive system is to place slow-release sachets on the plants. Inside such sachets is a factitious prey's food substrate-which also acts as refuge-and the predator. The objective of this study was to develop a new methodology to evaluate the population dynamics of this sachet system, based on the factitious prey Carpoglyphus lactis and the predatory mite Amblyseius swirskii. Through two tests carried out under laboratory conditions, the sachets were first compared to the traditional extraction method that uses Berlese-Tullgren funnels and an extraction method using flotation in hexane. The latter method proved more effective at sampling the motile states (larvae, nymphs, and adults), both for the predatory species and for the factitious prey, extracting up to 3.7 × more mites than the Berlese-Tullgren funnel. Second, the population dynamics of both mite species was studied in a laboratory test, both inside and outside the sachets. In this way, a positive correlation was demonstrated between the number of predatory mites and the number of prey mites inside the sachets. Conversely, no correlation was found between the interior population of predatory mites and the number that venture outside. We can conclude that hexane extraction is very useful both in quality control of predatory mites and in studying how the sachets behave when faced with various factors.

Development, Predation, and Prey Preference of Chrysoperla externa on Liorhyssus hyalinus and Nysius simulans, Two Emerging Pests of Quinoa.

In recent years, Liorhyssus hyalinus (Fabricius) (Hemiptera: Rhopalidae) and Nysius simulans Stål (Hemiptera: Lygaeidae) have emerged as important pests of quinoa in Peru, when the crop started to be cultivated at relatively low elevations. The potential of the native lacewing Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) was evaluated as a biological control agent of these two pest species. Prey consumption on all immature stages of L. hyalinus and N. simulans was assessed, as well as development on first instars of these heteropterans and eggs of Sitotroga cerealella (Olivier) (Lepidoptera: Pyralidae) as a factitious prey. In addition, prey preference was examined in the absence and presence of a preferred prey, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae). Larvae of the predator were not able to feed on L. hyalinus eggs, but they effectively did on N. simulans eggs as well as on all nymphal instars of both species. Nymphs of L. hyalinus were less suitable prey for larval development of C. externa than eggs of S. cerealella, whereas N. simulans was overall an unsuitable prey. There was a clear prey preference of C. externa for aphids over the two heteropteran species, as well as a preference for N. simulans over L. hyalinus. The predation rates in this study indicate the potential of C. externa as a predator of these heteropteran pests that can play a role in both conservation and augmentation biological control programs.

Effect of the Amount of Ephestia kuehniella Eggs for Rearing on Development, Survival, and Reproduction of Orius laevigatus.

Simple SummaryEconomical mass rearing of natural enemies is pivotal for their use as augmentative biological control agents. To this end, the conditions for mass production have been widely investigated for different natural enemies, including the predator Orius laevigatus. The key component for cost optimization of production systems is the type and amount of diet supplied. In the case of O. laevigatus, Ephestia kuehniella eggs have proved to be nutritionally superior to other cheaper natural and artificial foods. Consequently, the current practice in industrial production is the use of these eggs as food. Therefore, there is a need to know the minimum amount of Ephestia eggs needed per individual leading to a cost reduction, which in turn will favor biological control adoption. In this study, we established a minimum of 1 and 3 Ephestia eggs per day for the first two nymphal instars, respectively, and 8 eggs per day for subsequent development until adulthood. Benefits and savings for industrial production of O. laevigatus and its use in biological control are discussed.Orius laevigatus is a key tool for the success of augmentative biological control programs in protected crops. This biological control agent is mass-reared feeding on eggs of Ephestia kuehniella. However, this factitious prey is expensive, accounting for a significant percentage of the rearing costs. Therefore, there is a need to optimize the amount of Ephestia eggs needed per individual leading to a cost reduction, which in turn will favor biological control adoption. This study investigated the effect of the amount of Ephestia eggs provided on the developmental and reproductive fitness of O. laevigatus. At least a daily supply of 1 and 3 Ephestia eggs was needed for optimal development of the first two nymphal instars, respectively, although for maximum survival, 1 egg was enough for both instars. For subsequent development until adulthood, a minimum of 8 eggs per day were needed to fully support growth, but only 3 eggs for optimal survival. Similarly, male body size was also maximized by feeding 8 eggs, but for maximum female body size 10 eggs per day were required. Oviposition rate of females increased with the daily number of Ephestia eggs provided, until a plateau was reached at 8 eggs/day. Benefits and savings for industrial production of O. laevigatus are discussed.

Cost-effective and efficient factitious prey for mass production of Neoseiulus cucumeris (Acari: Phytoseiidae): assessing its quality compared with natural prey

BackgroundUsing alternative diets for the mass production of phytoseiid predatory mites may facilitate their cost-effective rearing. Factitious prey is often used as an alternative food source for mass rearing of generalist phytoseiids. The generalist predator, Neoseiulus cucumeris (Oudemans), is a commercially available biocontrol agent against various pests. We assessed the suitability of two factitious prey, Ephestia kuehniella Zeller eggs and Tyrophagus putrescentiae (Schrank), as diets for long-term rearing (up to 30 generations) of N. cucumeris, when compared with a natural prey, Tetranychus urticae Koch.ResultsThe predator completed its development on all tested diets successfully. Under laboratory conditions, Tyrophagus putrescentiae could support the development and oviposition of the predator for up to 30 generations even better than its natural prey T. urticae. However, the eggs of E. kuehniella were not suitable for this predator because of the longer pre-adult period and adults failed to reproduce.ConclusionsSince rearing on T. putrescentiae for a long time had no adverse effects on the predator’s performance, this factitious prey could be considered as a suitable and cost-effective diet for mass production of N. cucumeris.

Hyperaspis polita Weise functional response: effects of predator stages, prey species, and previous feeding experiences

At the moment, Hyperaspis polita Weise is a key predator of mealybugs in southern Iran. In this study, the efficiency of this predator on Phenacoccus solenopsis Tinsley, a serious pest, and Planococcus citri Risso as a factitious prey in predator mass rearing, was examined. The functional response experiment was performed for 4th instar larvae, adult male and female of H. polita at five prey densities (2, 4, 8, 12, 16, and 32 adult female stage) on these two preys. The shape of functional response curves well fitted the type II for 4th instar larvae, adult male and female of H. polita on both preys, whenever reared on one prey, while being exposed to the other prey (previous feeding experiences). Comparisons of attack rates and handling time for 4th instar larvae and adult female did not show any difference for various preys as well as previous feeding experiences. For the adult male, when reared on P. solenopsis, the handling time was significantly longer, while it was shorter on P. citri and again the same prey was given to it. The predation was highest for the 4th instar larva followed by adult females and adult male on all treatments. In addition, the maximum predation rate was shown when these predators were reared on P. solenopsis and were exposed to P. citri. The results of this study indicated that H. polita can be an effective biological control agent for mealybugs. It also emphasizes the importance of previous feeding experiences in release program protocols for H. polita.

Impact of a tarsonemid prey mite and its fungal diet on the reproductive performance of a predatory mite.

Phytoseiid predatory mites are the most important group of biocontrol agents currently used in protected cultivations worldwide. The possibility to produce these predators at high densities on factitious prey mites is a crucial factor for their success. Commonly used factitious prey mites comprise mainly species belonging to the cohort of Astigmatina. In the present study, we investigated the potential of tarsonemid prey mites as a food source for the spider mite predator Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The oviposition of N. californicus on mixed stages of Tarsonemus fusarii Cooreman (Acari: Tarsonemidae) was similar to that on its natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). As most tarsonemids are specialized fungus-feeders, we tested the effect of different fungal species on the growth of T. fusarii. Subsequently, we analysed the impact on the fungal growing medium on the oviposition of N. californicus. The fungal growing medium of T. fusarii had a significant negative effect on the reproductive output of the predatory mite. When T. fusarii was separated from the rearing medium, these detrimental effects were not observed. The present study shows the potential of using tarsonemid prey mites in the production of phytoseiid predatory mites.

<p class="Body"><strong><em>Thyreophagus plocepasseri</em></strong><strong> sp. n., a new parthenogenetic species of acarid mites (Acariformes: Acaridae) from Kenya</strong></p>

To date, some species in the genus Thyreophagus, such as Th. entomophagus and Th. cracentiseta, have been shown to be useful factitious prey for mass-rearing of predacious phytoseiid mites, one of the most common groups of mites used for biological control. Here, we describe a new species, Thyreophagus plocepasseri sp. n. from Kenya that can serve as a factitious prey as well. In addition, the new species is asexual, a trait that can be advantageous for its mass-rearing in industrial settings. In the description, we use high-resolution light microscope imaging and extensive comparison with a similar species, Thyreophagus athiasae, for which the type was studied. We review the literature on asexual acarid mites and point to a lack of data on the presence of sex-manipulating bacteria (Wolbachia, Cardinium) in these asexual mite lineages. Based on the literature, these bacteria are known to induce parthenogenesis in several haplodiploid mites, but they have not been linked so far to parthenogenesis inducement in diplodiploid acarid mites.

Genetic improvement of Orius laevigatus for better fitness feeding on pollen

In many protected crops, augmentative biological control heavily relies on generalist predators, which continuous presence on the crop allows an early response to pest immigration and outbreaks. Persistence is possible by their ability to feed on alternative food, such as pollen, plant-provided or artificially supplemented. However, fitness is decreased when feeding on alternative foods, hindering performance. We present a new approach to face this challenge: genetic improvement for better fitness feeding on suboptimal food. Orius laevigatus is one of the main biological control agents used in greenhouse vegetable crops. A breeding process was carried out on the basis of a broad intraspecific variability exploration for 10-day fecundity feeding on pollen (14.2–37.9 eggs/female for 30 wild and commercial populations). Life history traits were finally compared between our two selected strains and three commercial, wild and acclimated-to-pollen unselected populations, both on rich (Ephestia eggs) and suboptimal (dry honeybee pollen) diets. Selected lines showed considerably improved values for longevity (1.5-fold), early (1.3-fold) and lifetime fecundity (1.9-fold), nymphal survival (3.5-fold), intrinsic rate of natural increase (rm) (7.3-fold) and net reproductive rate (R0) (6.7-fold) as compared to reference unselected strains when they were fed on pollen, although still lower than on the optimal diet. Selection feeding on plant material resulted in no trade-offs when feeding on the factitious prey. This improvement was due to genetic gain rather than to phenotypic plasticity to tolerate nutritious restriction. Finally, some potential contributions of these improved lines not only for augmentative biocontrol but also for artificial rearing are provided.

<p class="Body"><strong>Indirect effects in predator-prey interaction: development and predation rates by immature <em>Neoseiulus cucumeris</em> increased by odour from its prey (<em>Tyrophagus putrescentiae</em>) </strong></p>

Predator-prey interactions have long been of great interest to ecologists. Although the direct consumptive effects have received extensive research, indirect influences of odour derived from their conspecifics and prey on predators have largely been underestimated and overlooked. In this study, the indirect effects of predator-prey interactions were determined with predatory mites Neoseiulus cucumeris and its factitious prey Tyrophagus putrescentiae. The responses of immature N. cucumeris to mixed odour with their conspecifics and prey were determined in a laboratory experiment. Our results showed that the mixed odour with their conspecifics did not demonstrate any obvious influences on the survival rates, developmental periods, predation rates and activities of the predatory mites. Intriguingly, the predators prolonged their protonymphal stage and consumed more prey eggs when exposed to mixed odour with their prey. Our results indicated that the mixed odour with their conspecifics was weak and its influence was insignificant for this species, but the prey odour showed a signifcant influence on the growth and consumption rates of immature predators, which highlighted that the indirect influences of predator-prey interactions on the predator were substantial and cannot be neglected.