Kuehniella Eggs Research Articles

Parasitoid age and host age interact to improve life history parameters and rearing of Trichogramma euproctidis

ABSTRACT Trichogramma euproctidis (Girault) is an egg parasitoid under consideration for mass production and augmentative biological control of major lepidopteran pests in Iran and other countries. The main objective of this research was to determine the effects of T. euproctidis female age and Ephestia kuehniella Zeller egg age on life history parameters of T. euproctidis. Experimental design involved exposing 1-, 2-, 3-, or 4-d-old E. kuehniella eggs to 1-, 2-, 3-, or 4-d-old T. euproctidis females in glass test tubes. Results indicated that host egg age and parasitoid female age interacted significantly to improve parasitism rate, progeny emergence rate, sex ratio, longevity, and fecundity of T. euproctidis. The age of T. euproctidis females affected parasitism rate; 1-d-old females, rather than the other ages, parasitised more E. kuehniella eggs. The highest mean total fecundity (81.62 eggs) was recorded from adult progeny produced by 1-d-old T. euproctidis females reared from 1-d-old E. kuehniella eggs. Trichogramma euproctidis development time increased as the age of E. kuehniella eggs increased, but the parasitoid female age and host egg age interaction was not significant. A life table analysis confirmed the results that 1-d-old T. euproctidis females and 1-d-old E. kuehniella eggs resulted in optimal effects on T. euproctidis life history. This study implies that mass rearing systems designed to expose young-aged T. euproctidis females to young-aged E. kuehniella eggs would maximise T. euproctidis progeny production.

Combination of generalist predators, Nesidiocoris tenuis and Macrolophus pygmaeus, with a companion plant, Sesamum indicum: What benefit for biological control of Tuta absoluta?

Tuta absoluta is one of the most damaging pests of tomato crops worldwide. Damage due to larvae may cause up to 100% loss of tomato production. Use of natural enemies to control the pest, notably predatory mirids such as Nesidiocoris tenuis and Macrolophus pygmaeus, is increasingly being promoted. However, considering the potential damage caused to tomatoes by these omnivorous predators in the absence of T. absoluta, an alternative solution could be required to reduce tomato damage and improve the predators’ performance. The use of companion plants can be an innovative solution to cope with these issues. The present study aimed to determine the influence of companion plants and alternative preys on the predators’ performance in controlling T. absoluta and protecting tomato plants. We evaluated the effect of predators (alone or combined) and a companion plant (sesame (Sesamum indicum)) on T. absoluta egg predation and crop damage caused by N. tenuis. The influence of an alternative prey (Ephestia kuehniella eggs) on the spatial distribution of predators was also evaluated by caging them in the prey presence or absence, either on tomato or sesame plants or on both. We found that the presence of sesame did not reduce the efficacy of N. tenuis or M. pygmaeus in consuming T. absoluta eggs; hatched egg proportion decreased when N. tenuis, M. pygmaeus, or both predators were present. More specifically, this proportion was more strongly reduced when both predators were combined. Sesame presence also reduced necrotic rings caused by N. tenuis on tomato plants. Nesidiocoris tenuis preferred sesame over tomato plants (except when food was provided only on the tomato plant) and the upper part of the plants, whereas M. pygmaeus preferred tomato to sesame plants (except when food was provided only on the sesame plant) and had no preference for a plant part. Combination of predators N. tenuis and M. pygmaeus allows for better coverage of cultivated plants in terms of occupation of different plant parts and better regulation of T. absoluta populations. Sesamum indicum is a potential companion plant that can be used to significantly reduce N. tenuis damage to tomatoes.

Performance of Trichogramma japonicum under field conditions as a function of the factitious host species used for mass rearing.

Different factitious hosts were used to mass rear Trichogramma japonicum Ashmead in different parts of the globe because thorough details were lacking in both the laboratory and the field. The objective of this study was to compare, parasitoid, T. japonicum reared in different factitious hosts. Three commonly used factitious host eggs, Corcyra cephalonica (Stainton), Ephestia kuehniella Zeller and Sitotroga cerealella Olivier were tested under laboratory conditions and then in the field over a yellow stem borer, Scirpophaga incertulus (Walker) of rice. The highest parasitism by T. japonicum was observed on E. kuehniella eggs. The parasitoid’s highest emergence (88.99%) was observed on S. cerealella eggs at 24 h exposure, whereas at 48 h it was on E. kuehniella eggs (94.66%). Trichogramma japonicum females that emerged from E. kuehniella eggs were significantly long-lived. The days of oviposition by hosts and the host species were significant individually, but not their interaction. Higher proportions of flying T. japonicum were observed when reared on E. kuehniella and C. cephalonica eggs. Field results showed that T. japonicum mass-reared on E. kuehniella showed higher parasitism of its natural host, S. incertulus eggs. Hence, by considering these biological characteristics and field results, E. kuehniella could be leveraged for the mass rearing of quality parasitoids of T. japonicum in India, the Asian continent and beyond.

Intraguild Interactions between the Mealybug Predators Cryptolaemus montrouzieri and Chrysoperla carnea.

Simple SummaryThe ladybird Cryptolaemus montrouzieri is a widely commercialized biological control agent of mealybugs. The green lacewing Chrysoperla carnea is mainly released for aphid control, but also attacks mealybugs. Both species have shown potential to control various economically important species of mealybug pests of greenhouse crops. As these predators may be simultaneously present in a crop, the risk of negative interactions between both predators was evaluated in this laboratory study. Individuals of different life stages of either predator were placed together in petri dish arenas and predation was recorded. Attacks between individuals of both species were frequently observed, with lacewing larvae being the dominant predators in most combinations. When mealybug nymphs or lepidopteran eggs were added to the arena, the incidence of attacks between the predators was greatly diminished. The relevance of these observations for the use of the predators in the biological control of greenhouse pests is discussed.The ladybird Cryptolaemus montrouzieri and the green lacewing Chrysoperla carnea have shown potential for use in augmentative biological control of mealybug pests in greenhouse crops. In the context of combining these predators within an integrated pest management system, the risk of negative intraguild interactions between both predators was evaluated in a laboratory setting. Different life stages of either predator were confronted in petri dish arenas containing a Ficus benjamina leaf, and after 24 h the incidence and direction of intraguild predation (IGP) was recorded for each combination. The effect of adding Planococcus citri nymphs or Ephestia kuehniella eggs as extraguild prey on the level of IGP was also studied. IGP was frequently observed between the two predator species and was asymmetrical in favour of C. carnea in most cases. The presence of extraguild prey reduced the number of IGP events between the predators to a similar extent. The relevance of the observed intraguild interactions for the combined use of these predators in protected cultivation is discussed.

Evaluation of Artemiafranciscana Cysts to Improve Diets for Mass Rearing Stethorusgilvifrons, a Predator of Tetranychusturkestani.

Simple SummaryThe ladybird beetle Stethorus gilvifrons is a native predator of spider mites in the Mediterranean region that could be mass-reared and released to control spider mite populations on crop plants. The aim of this research was to test the hypothesis that brine shrimp cysts can improve diets for mass rearing of S. gilvifrons in the absence of prey, i.e., spider mites. The diet treatments included brine shrimp cysts alone (D1), brine shrimp cysts plus a vitamin B complex (D2), brine shrimp cysts plus date palm pollen (D3), or brine shrimp cysts plus date palm pollen and Mediterranean flour moth eggs (D4). The results revealed that only two diets, D3 and D4, supported predator development to the adult stage and reproduction. The predator reproductive rate and life table estimates indicated that D4 was superior. In conclusion, only a mixed diet of brine shrimp cysts, date palm pollen, and flour moth eggs is suitable for mass rearing S. gilvifrons.Stethorus gilvifrons is an acarophagous coccinellid distributed in the Mediterranean region and could potentially be mass-reared for the augmentative biological control of Tetranychus turkestani and related species on crop plants. The hypothesis that brine shrimp Artemia franciscana cysts can improve diets for rearing of S. gilvifrons was tested in laboratory experiments. The diet treatments included A. franciscana cysts (D1), A. franciscana cysts plus a vitamin B complex (D2), A. franciscana cysts plus date palm pollen (D3), and A. franciscana cysts plus date palm pollen and Ephestia kuehniella eggs (D4). The results indicated that D1 did not support immature development. D2 supported egg–larval development but not pupal–adult development. Both D3 and D4 supported development to the adult stage and reproduction. However, D4 was the most effective diet, determined by observations of S. gilvifrons oviposition behavior and fecundity. A life table analysis corroborated these results; an intrinsic rate of increase, net and gross reproductive rates, and mean generation time were best for S. gilvifrons fed D4 rather than D3. A mixed diet composed of A. franciscana cysts, date palm pollen, and E. kuehniella eggs can be used to mass rear S. gilvifrons.

Influence of tobacco on the behavior, parasitism and mortality of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) associated with eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae)

Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), is widely used in augmentative biological control programs. However, there is no information on the behavior and biology of this parasitoid in stored tobacco. Thus, this study aims to evaluate the chemotactic response, parasitism, and mortality of females of T. pretiosum parasitizing eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in the presence of different tobacco types. The chemotactic responses of T. pretiosum females were observed with a double and multiple choice olfactometer. The odors of dry Burley and Virginia tobacco and of Virginia tobacco seedlings were evaluated. Treatments with or without the presence of E. kuehniella eggs were compared. To evaluate parasitism with and without choice, eggs of E. kuehniella adhered to the same tobacco used in the olfactometer. The eggs of E. kuehniella were offered to a female of T. pretiosum for 2 h, with adult parasitoid mortality recorded. In double-choice olfactometer there was no attraction of T. pretiosum females to the odors of the different types and classes of dry tobacco evaluated when compared to the control (air). Only tobacco seedlings and E. kuehniella eggs attracted the parasitoid. Females of T. pretiosum preferred tobacco infested with host eggs regardless of the type and class of tobacco. In multiple-choice olfactometer T. pretiosum females spent the same time in the area of the arms containing tobacco as in the area of arm containing control (air). The percentage of apparent parasitism of T. pretiosum varied according to the surface on which the host's eggs adhered. Although females of T. pretiosum responded positively to the host's volatiles, even with the presence of dry tobacco, when they came into direct contact with some types and classes of tobacco there was no parasitism.

Toxicological and behavioral impacts of atrazine on Trichogrammatidae (Hymenoptera) in choice tests

Weeds should be controlled with low impact methods and selective agrochemicals that have little or no effect on non-target organisms. This study aimed to evaluate the effect of the herbicide atrazine (triazine class) on 10 Trichogrammatidae (Hymenoptera) species. A female of 10 species of these natural enemies was individually placed in a glass test tube (free-choice test) with two paper cards containing 45 Anagasta (Ephestia) kuehniella (Lepidoptera: Pyralidae) eggs (treatment and control), with 10 replications. The cards were sprayed with the herbicide atrazine at 8.07 L/ha; the control was sprayed with distilled water. Parasitism by these natural enemies was allowed for 48 h. Atrazine changes the behavior of female parasitoids, reducing the parasitism (≈ 71 %) and emergence (≈ 74 %) rates and sex ratio (≈ 74 %) of the Trichogrammatidae species, except for Trichogramma galloi and T. bennetti. No females emerged from eggs parasitized by T. acacioi, Trichogrammatoidea annulata, T. atopovirilia, T. bruni, T. brasiliensis, T. demoraesi, and T. soaresi with atrazine. The results revealed that atrazine herbicide is harmless to T. bennetti and T. galloi, but it was moderately harmful (80 – 99 % reduction) to the other Trichogrammatidae species based on the parasitism and emergence rates.

Functional Response and Predation Rate of Dicyphus cerastii Wagner (Hemiptera: Miridae).

Simple SummaryBiological control (BC) is an effective way to regulate pest populations in horticultural crops, allowing the decrease of pesticide usage. On tomato, predatory insects like plant bugs or mirids provide BC services against several insect pests. Native predators are adapted to local conditions of climate and ecology and therefore may be well suited to provide BC services. Dicyphus cerastii is a predatory mirid that is present in the Mediterranean region and occurs in tomato greenhouses in Portugal. However, little is known about its contribution to BC in this crop. In this study, we evaluated how prey consumption is affected by increasing prey abundance on four different prey, in laboratory conditions. We found that the predator can increase its predation rate until a maximum is reached and that prey characteristics like size and mobility can affect predation. Dicyphus cerastii showed high predation rates for all prey species tested, allowing us to conclude that this species is an interesting predator for BC in tomato crops.Dicyphine mirids are important biological control agents (BCAs) in horticultural crops. Dicyphus cerastii Wagner can be found in protected tomato crops in Portugal, and has been observed feeding on several tomato pests. However, the predation capacity of this species is poorly studied. In order to investigate the predation capacity of D. cerastii, and how it is affected by prey size and mobility, we evaluated the functional response (FR) and predation rate of female predators on different densities of four prey species: Myzus persicae 1st instar nymphs (large mobile prey), Bemisia tabaci 4th instar nymphs, Ephestia kuehniella eggs (large immobile prey) and Tuta absoluta eggs (small immobile prey). Experiments were performed on tomato leaflets in Petri dish arenas for 24 h. Dicyphus cerastii exhibited type II FR for all prey tested. The predator effectively preyed upon all prey, consuming an average of 88.8 B. tabaci nymphs, 134.4 E. kuehniella eggs, 37.3 M. persicae nymphs and 172.3 T. absoluta eggs. Differences in the FR parameters, attack rate and handling time, suggested that prey size and mobility affected predation capacity. Considering the very high predation rates found for all prey species, D. cerastii proved to be an interesting candidate BCA for tomato crops.

Toxicity of imidacloprid, fenpropathrin, and dimethoate to Ceraeochrysa cubana (Neuroptera: Chrysopidae) through different exposure routes

Ceraeochrysa cubana (Hagen) (Neuroptera: Chrysopidae) is an important predator with potential use to control various agricultural pests, including Diaphorina citri Kuwayama (Hemiptera: Liviidae). However, the indiscriminate use of insecticides may affect the performance of this lacewing, reducing its efficiency as a natural enemy. The goal of this study was to evaluate the lethal effect of imidacloprid, fenpropathrin, and dimethoate on C. cubana using different routes of exposure. Bioassays of topical, residual, ingestion, and residual + ingestion (simultaneous exposure) of the active ingredients on the lacewings were performed. The tolerance ratio (TR) was calculated from the lowest LC50 observed. In addition to the lethal effect, we also studied the repellent effect of imidacloprid and fenpropathrin on first instar larva of C. cubana when Ephestia kuehniella Zeller (Lepidoptera, Pyralidae) eggs were treated with those insecticides. In the toxicity bioassay, the residual exposure of dimethoate was the most lethal (lower value of LC50), followed by residual + ingestion exposure of dimethoate and fenpropathrin. With topical exposure, insecticides had similar toxicity and TR was between 20.76 and 23.61-fold. Imidacloprid was not toxic via ingestion and residual exposure; consequently, we did not estimate LC50 in those cases. Ephestia kuehniella eggs treated with imidacloprid did not repel C. cubana larvae while those treated with fenpropathrin had a repellent effect. Dimethoate was toxic to C. cubana and it should be used with caution while imidacloprid has a lower lethal effect via residual and ingestion exposure and it does not have a repellent effect on C. cubana.

Effects of essential oils on biological attributes of Trichogramma galloi adults

Abstract Bioactivity of nine essential oils (EOs) was studied on Anagasta kuehniella eggs in relation to the longevity of females, parasitism and emergence rates and sex ratio in the generations parental, F1 and F2 of Trichogramma galloi in comparison to a trade formulation of Azadirachta indica. There was no F1 and F2 progeny with Zingiber officinale being the most harmful. The greatest reductions in the parasitism rates (57, 43 and 28%) in the parental generation was caused by Allium sativum, Carapa guianensis and A. indica, respectively. In addition, A. sativum reduced the longevity (4.7 days) in the parental generation and emergence (33%) of F1. Tested EOs did not affect the sex ratio in the generations F1 and F2 and emergence in the F2. Allium sativum and Z. officinale were non-selective to T. galloi; while A. indica, C. guianensis and P. nigrum oils may compromise the progeny; therefore, their use must be avoided. Citrus sinensis, Mentha piperita, Origanum vulgare, Syzygium aromaticum and Thymus vulgare were selective to T. galloi, and these EOs are promising for IPM programs.

Influence of Alternative Food Sources on Different Biological Aspects of Cydnoseius negevi (Acari: Phytoseiidae) تأثير مصادر الغذاء البديلة على النواحي البيولوجيه المختلفه للمفترس الأکاروسي Cydnoseius Negevi (Acari: Phytoseiidae)

The predatory mite Cydnoseius negevi (Swirski & Amitai), (Family Phytosidae), is a predaceous mite of different mite and insect pests, such as two-spotted spider mite and castor whitefly. This work aimed to study the role of C. negeviin controlling the four arthropod pests, Spodoptera littoralis (Boisduval), Trialeurodes ricini (Misra), and Anagasta (Ephestia) kuehniella (Keller) as wellas spider mite Tetranychus urtica (Koch) compared with date palm pollenas food options under controlled conditions. The predatory mite C. negevican feed and complete its life span successfully on these foods. Trialeurodes ricini and A. kuehniella eggs prolonged the life cycle of C. negevi. Likewise, the shortest period observed when male and female fed on eggs of T. urtica. Egg production of the tested mite was the highest when it fed on pollen, while oviposition was lower when the predatory mite fed on T. ricini. Food sources also affected all life tables where spider mite eggs and pollen grains were the most favorable foods increased Ro, rm, erm and GRR values. Insect eggs prolonged T and Dt times ofthe tested mite C. negevi. Therefore, C. negevi could be reared successfully on date palm pollen and eggs of S. littoralis, T. ricini, A. kuehniella and T. urticae.

DsRNA-Mediated Pest Management of Tuta absoluta Is Compatible with Its Biological Control Agent Nesidiocoris tenuis

Simple SummaryThe zoophytophagous mirid bug Nesidiocoris tenuis is an efficient predator of the tomato leafminer, Tuta absoluta. RNA interference (RNAi) targeting the alphaCOP (αCOP) (Coatomer subunit alpha protein) gene of N. tenuis (Nt-αCOP) was proven to be functional in N. tenuis, causing downregulation of gene expression, mortality and sub-lethal effects. In contrast, when N. tenuis were fed with dsRNA (dsTa-αCOP) targeting the ortholog αCOP gene of T. absoluta, no lethal nor sub-lethal effects were observed. These results indicate the compatibility of this biocontrol agent along with RNAi-mediated management in order to suppress T. absoluta efficiently in tomato crop.RNAi-mediated insect pest management has recently shown promising results against the most serious pest of tomato, the tomato leafminer, Tuta absoluta. This study aimed to investigate whether dsRNA (dsTa-αCOP) designed to target the T. absoluta-αCOP gene could cause adverse effects to its biocontrol agent, the mirid predator, Nesidiocoris tenuis. Oral exposure of N. tenuis to dsRNA (dsNt-αCOP) designed to target N. tenuis-αCOP resulted in a 61%, 67% and 55% reduction in its transcript level in comparison to the sucrose, dsGFP and dsTa-αCOP treatments, respectively. In addition, significantly higher mortality of 57% was recorded in dsNt-αCOP-treated N. tenuis when compared to the sucrose (7%), dsGFP (10%) and dsTa-αCOP (10%) treatments. Moreover, the predation rate of ~33–39 Ephestia kuehniella eggs per N. tenuis adult dramatically reduced to almost half in the surviving dsNt-αCOP-treated N. tenuis. This worst-case exposure scenario confirmed for the first time that the RNAi machinery is functional in this species and that the risk of exposure through the oral route is possible. In contrast, dsTa-αCOP did not cause any sub-lethal effects to N. tenuis upon oral exposure. Oral exposure of T. absoluta to dsTa-αCOP resulted in 50% mortality. In the context of a biosafety risk assessment of RNAi-mediated insect management, investigating the effects on non-target organisms is essential in order to include this method as part of an integrated pest management strategy. Based on our laboratory assays, RNAi-mediated control is compatible with the biological control of T. absoluta by its natural enemy N. tenuis, adding the RNAi approach in the armoire of integrated pest management of T. absoluta.

Effectiveness of factitious foods and artificial substrate in mass rearing and conservation of Neoseiulus californicus (Acari: Phytoseiidae)

ABSTRACT The use of factitious food instead of natural prey, and artificial substrates instead of leaf-based, could be important steps towards reducing natural enemies̓ rearing costs. Nutritional values of four factitious foods comprising Ephestia eggs, decapsulated Artemia cysts, mould mite immature individuals, and Aspergillus hyphae as alternative food sources for Neoseiulus californicus (McGregor) were determined under laboratory conditions. In addition, suitability of artificial (plastic sheet) and leaf-based substrates for rearing of the predator was assessed. The duration of egg to adult developmental time was shorter when the predator fed on the mould mite compared with the other diets. Artemia cysts and Aspergillus hyphae were not suitable diets. The individuals reared on the mould mite had the highest fecundity and intrinsic rate of increase (r). Due to weak mouthpart of the immature predator in feeding of factitious foods, most of them died in immature stages, or their fecundity in adult stage was low. In a separate experiment, almond pollen was also used in addition to factitious foods for rearing of immature stages of the predator. The adult stage of these individuals had the ability to feed and oviposit on the factitious foods, and female longevity and fecundity of these individuals were higher on E. kuehniella egg (and after that on mould mite) than the others. In addition, the results indicated that the rearing performance of the predator fed on the same diet was higher on the artificial substrate than the leaf-based one. The potential of alternative foods and artificial substrates for mass production and conservation of N. californicus is a suitable and cheap method.

Biological traits of the predatory mirid Macrolophus praeclarus, a candidate biocontrol agent for the Neotropical region.

The predatory mirid Macrolophus praeclarus is widely distributed throughout the Americas, and is reported to prey upon several horticultural pest species. However, little is known about its biology, thermal requirements, crop odour preferences, phytophagy, and capability to induce defensive responses in plants. When five temperatures studied (20, 25, 30, 33 and 35°C) were tested and Ephestia kuehniella was used as prey, the developmental time from egg to adult on tomato, was longest at 20°C (56.3 d) and shortest at 33°C (22.7 d). The ability of nymphs to develop to adults decreased as the temperature increased, with the highest number of nymphs reaching the adult stage at 20°C (78.0%) and lowest at 35°C (0%). The lower and upper developmental thresholds were estimated at 11.2° and 35.3°C, respectively. The maximum developmental rate occurred at 31.7°C and the thermal constant was 454.0 ± 8.1 degree days. The highest predation rate of E. kuehniella eggs was obtained at 30°C. In Y-tube olfactory choice tests, M. praeclarus selected tomato, sweet pepper and eggplant odours more frequently than no plant control treatment. Macrolophus praeclarus feeding did not damage tomato plants compared to another zoophytophagous mirid, Nesidiocoris tenuis, which caused necrotic rings. The phytophagy of M. praeclarus induced defensive responses in tomato plants through the upregulation of the jasmonic acid metabolic pathway. The implications of the findings for using M. praeclarus in tomato biological control programmes in the Americas are discussed.

Influence of the eggs of Ephestia kuehniella (Lepidoptera: Pyralidae) reared on different diets on the performance of the predatory bug Orius laevigatus (Hemiptera: Anthocoridae)

The predatory bug, Orius laevigatus (Fieber, 1860) (Hemiptera: Anthocoridae), is an important biological control agent and widely used for augmentative biological control of the western flower thrips, Frankliniella occidentalis Pergande, 1895 (Thysanoptera: Thripidae) in greenhouse crops. This bug is generally reared using the Mediterranean flour moth, Ephestia kuehniella Zeller, 1879 (Lepidoptera: Pyralidae). The aim of this study was to determine the effects of E. kuehniella eggs produced by adult moths reared on different larval diets on the performance of O. laevigatus. The diets were 95% cornmeal + 5% yeast (CY diet), 53.3% cornmeal + 26.7% wheat bran + 15% Glycerine + 5% yeast (CBGY diet) and 53.3% wheat flour + 26.7% wheat bran + 15% Glycerine + 5% yeast (WBGY diet). Laboratory studies started with newly emerged nymphs of O. laevigatus kept in a climate chamber at 27°C, 60% relative humidity and a 14L :10D photoperiod. Eggs of E. kuheniella adults that were fed on one of the three different larval diets were provided to the nymphs as a source of food and bean pods of water. Following adult emergence, all individuals were sexed, and female and male pairs were put in plastic containers (30 cc) with eggs of E. kuehniella and bean pods. Nymphal development time, fecundity and longevity of O. laevigatus were not differently affected by feeding on the eggs of E. kuehniella reared on the three diets. In addition, the daily and total egg consumption of adults of O. laevigatus were similar. Because the CY diet eggs contain more nutrients, their consumption by nymphs was lower. This study indicates that the CY diet is an adequate diet for rearing E. kuehniella for producing eggs for rearing O. laevigatus.

Temperature Affects Biological Control Efficacy: A Microcosm Study of Trichogramma achaeae.

Simple SummaryThe performance of biological control agents (BCAs) under field conditions is of importance to successfully suppress pests following release. However, the quality of BCAs is usually evaluated with laboratory measurements under controlled conditions, which has been shown unable to predict the performance in complex field conditions. In this study, we quantified the quality of the parasitoid Trichogramma achaeae in microcosms at four constant temperatures and evaluated its ability to locate and parasitise pest eggs. We also compared parasitisation efficiency with fecundity as determined under laboratory conditions. We found the biological control efficacy as determined in our microcosms was strongly regulated by temperature and was unlikely to be predicted by laboratory fecundity. These findings suggest that more complex assays, including behavioural responses, might be developed to demonstrate the field quality of BCAs.Current quality control of mass-reared biological control agents (BCAs) is usually performed in the laboratory and often fails to include behavioural aspects of the BCAs. As a result, the use of efficacy measurements determined solely under laboratory conditions to predict field efficacy can be questioned. In this study, microcosms were designed to estimate biological control efficacy (realised parasitisation efficiency) of Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) parasitising Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs across the operational temperature range (15–30 °C). Temperature greatly affected the success of females in finding and parasitising E. kuehniella eggs, with parasitisation being reduced at 15 and 20 °C, as both the percentage of parasitised host eggs and the percentage of leaves per plant with parasitised host eggs decreased sharply compared with higher temperatures. Graphing previous data on laboratory fecundity against parasitisation efficiency shows that the laboratory-measured fecundity of T. achaeae was unlikely to predict field efficacy across temperatures. Results also showed that leaf side had no effect on the preference of T. achaeae in parasitising E. kuehniella eggs; however, T. achaeae preferred to lay their eggs on the top tier of plants. These findings suggest that more complex assays, which include behavioural responses, might be developed for optimised quality control of BCAs intended for field application.

Role of host diet on the fitness of the egg parasitoid species, Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae)

BackgroundEgg parasitoids belonging to the genus Trichogramma (Hymenoptera: Trichogrammatidae) are important natural enemies that have been successfully used in biological control programs and mostly reared on the Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae). Host quality is a crucial factor that can determine parasitoid fitness.Main bodyLaboratory studies were carried out to evaluate the effects of 3 different larval diets CY diet (95% cornmeal + 5% yeast), CBGY diet (53.3% cornmeal + 26.7% wheat bran + 15% glycerine + 5% yeast), and WBGY diet (53.3% wheat flour + 26.7% wheat bran + 15% glycerine + 5% yeast) on some demographic parameters of E. kuehniella. Moreover, the performance of the species Trichogramma evanescens Westwood reared on the E. kuehniella eggs reared on the 3 artificial diets were determined. For the E. kuehniella rearing, the CY diet had a higher fecundity and greater emergence ratios. Nevertheless, CY diet also provided shorter developmental time, greater fecundity, and relatively higher female ratios of subsequent generations of the parasitoids.ConclusionThe results suggest that the CY diet could be considered as a standard diet for the multigenerational rearing of T. evanescens.

Influences of Some Insect Pests as Prays on Biology and Consumption Rate of Predator, Oruis albidipennis (Reuter) (Hemiptera, Anthocoridae) under Laboratory Conditions

Results clarified that, prey-type profound effects on measured performance traits. Lowest eggs incubation period recorded for predators fed on A. craccivora nymphs, while highest observed for those fed on P. citri nymphs. Shortest total nymphal developmental period recorded for nymphs fed on A. craccivora nymphs, while longest for those fed on P. citri nymphs. Highest survival rate observed for predator that fed on eggs of E. kuehniella, while shortest recorded for those fed on P. citri nymphs. Daily female ovipositional rate was high in predator culture reared on E. kuehniella eggs comparing with those fed on P. citri nymphs. Fecundity was high for predator fed on E. kuehniella eggs, while low when fed on P citri nymphs. Adult females and males fed on A. craccivora nymphs had significantly longer life spans compared with those fed on others. Sex-ratio (%female) was significantly high when predator fed on A. craccivora nymphs. During the nymphal period, O. albidipennis consumed significantly more eggs of E. kuehniella than other-types, whereas lowest were P citri nymphs. Adult females consumed significantly more E. kuehniella eggs than other-types, while Adult males preferred to consume A. craccivora nymphs. Data obtained suggested that O. albidipennis biology and consumption rate influenced by three tested preys. E. kuehniella eggs and A. craccivora nymphs were most favorable diet for predator. Although, P citri nymphs were less suitable for predator,but O. albidipennis could survive and reproduce feeding on it which considered as an important advantage attributed as a biological control agent.

Evaluation of biological parameters of Eriopis connexa (Germar, 1824) and Coleomegilla maculata (DeGeer, 1775) (Coleoptera: Coccinellidae) fed with alternative prey developed at the Integrated Center for Pest Management - UFRRJ

The aim of this work was to evaluate the potential of live larvae of Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) as alternative prey used in the E. connexa and C. maculata rearings developed at the Integrated Center for Pest Management (CIMP) (UFRRJ, Seropédica campus, state of Rio de Janeiro, Brazil), in comparison to the use of flour moth eggs, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), sterilized by ultraviolet radiation. The obtained results showed that the larvae of the two lady beetles developed adequately, as well as generating fertile adults and viable eggs when fed on live larvae of D. melanogaster, similar to E. kuehniella eggs. It can be concluded that the live larvae of this fly can replace the eggs of the flour moth in the rearing of the two lady beetles in the laboratory.

Effects of Three Artificial Diets on Life History Parameters of the Ladybird Beetle Stethorus gilvifrons, a Predator of Tetranychid Mites.

Simple SummaryThe ladybird beetle Stethorus gilvifrons is an important natural enemy of spider mites, which are pests of numerous agricultural crops. Mass production of S. gilvifrons would be necessary to generate large numbers of individuals for augmentative biological control. Using alternative prey/foods or artificial diets as a substitute to natural prey (spider mites) would be important in the cost-effective production of S. gilvifrons. The objectives of the current study were to determine the developmental and reproductive characteristics of S. gilvifrons fed on different artificial diets. Artificial diets consisted of sucrose, honey, royal jelly, agar, yeast, date palm pollen supplemented with hen’s egg yolk (AD1, as basic diet), Ephestia kuehniella eggs (AD2), or E. kuehniella eggs and 2,4-dihydroxybenzoic acid (AD3). Adults and larvae of S. gilvifrons performed best on AD3, indicating the potential of this artificial diet for mass rearing of this important predatory ladybird beetle.Background: The ladybird beetle Stethorus gilvifrons (Mulsant) is an important natural enemy of tetranychid mites and functions as a biological control of these plant pests. The development, survival and reproduction of S. gilvifrons were studied when fed on three artificial diets. The components of the artificial diet that S. gilvifrons could be reared successfully on for one generation with no use of tetranychid mites were examined. Methods: Artificial diets consisted of sucrose, honey, royal jelly, agar, yeast, date palm pollen supplemented in different diets with hen’s egg yolk (AD1, as basic diet), Ephestia kuehniella Zeller eggs (AD2), or E. kuehniella eggs and 2,4-dihydroxybenzoic acid (AD3). Results: Adults and larvae of Stethorus gilvifrons fed on AD1 had a shorter immature development and preoviposition periods than those fed on AD2 and AD3. The total number of deposited eggs was significantly higher for the females fed on AD3 than on the other diets. The intrinsic rate of increase (r) of S. gilvifrons was highest on AD3, followed by AD2, and AD1. Conclusion: Stethorus gilvifrons performed best on AD3, indicating the potential of this artificial diet for the mass rearing of this important predatory ladybird beetle.