Tenebrio Molitor Pupae Research Articles

Olfaction Response and Fertility Life Table Parameters of Tetrastichus howardi (Hymenoptera: Eulophidae) Parasitizing Plutella xylostella (Lepidoptera: Plutellidae) and the factitious host Tenebrio molitor (Coleoptera: Tenebrionidae).

Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae) parasitizes the diamond back moth Plutella xylostella (L.) (Lepidoptera: Plutellidae), but not much is known about its potential as a biocontrol agent. A rearing protocol has been established for this parasitoid on pupae of the factitious host Tenebrio molitor (L.) (Coleoptera: Tenebrionidae), with the aim of releasing it in the field to manage several lepidopteran species. The potential population growth of a parasitoid can be measured through fertility life tables and provide supporting information for using T. howardi in the management of P. xylostella. Also, the fitness and behavior of T. howardi reared on a factitious host can be indicators of its potential to control P. xylostella. Thus, in this study, the fertility life table parameters of T. howardi parasitizing P. xylostella were determined, as well as the effects of the natal host on the behavior of T. howardi towards host volatiles and parasitism rate. The results showed that net reproduction rate (Ro) and the intrinsic rate of population growth (rm) of T. howardi parasitizing P. xylostella were 13.6 (♀/♀) and 0.124 (♀/♀*day), respectively, whereas the mean generation time was 20.9days. Moreover, the natal host (T. molitor or P. xylostella) did not affect the fitness, parasitism rate, or olfactory response of T. howardi. In general, regardless of the natal host, parasitoid females responded to volatiles of both host species and exhibited the same rate of parasitism on P. xylostella. Therefore, T. howardi reared on the factitious host maintains its attraction and potential to parasitize P. xylostella, and can contribute to the biological control of this pest.

Nematicidal and Insecticidal Activity of Proteases from Carica papaya and Ananas comosus

Plant proteases are well known for their various industrial applications. Papain, present in papaya latex (Carica papaya) and pineapple bromelain (Ananas comosus), is undoubtedly the most studied and widely used vegetable protease in the food and pharmaceutical industry worldwide. However, its potential as a biopesticide has been little explored. The objective of this study was to evaluate the activity of proteases from Carica papaya latex and peel and crown of Ananas comosus fruits on agricultural pests. To evaluate proteolytic activity on nematodes, extracts, and approximately 50 juveniles of Panagrellus sp. were placed in microtubes. To evaluate the insecticidal effect, larvae and pupae of Tenebrio molitor L. were submerged in active and denatured extracts. Additionally, larvae of T. molitor were fed an artificial diet at doses of 0, 100, 250, and 500 mg/g of wheat bran. The weight and number of dead larvae were recorded, and feeding behavior was evaluated. The proteases of papaya latex and papain caused reduction (p < 0.05) on Panagrellus sp. The extracts showed a toxic effect (p < 0.05) against the larvae of T. molitor. Active papain resulted in the absence of wings in 53.3% of adults from the pupae, and no malformation caused by denatured papain was observed. No mortality was observed in larvae fed an artificial diet. However, there was a strong feed reduction, reduction in the relative rate of consumption, reduction in growth and feed conversion efficiency caused by papaya latex. The results of this study show that plant proteases have the potential for the development of sustainable alternatives for the control of arthropod pests and parasitic nematodes.

Molecular Characterization and Functional Analysis of the Dipeptidyl Peptidase IV from Venom of the Ectoparasitoid Scleroderma guani.

Dipeptidyl peptidase IV (DPPIV) is a proline-specific serine peptidase that remains poorly investigated in terms of venom composition. Here, we describe the molecular characteristics and possible functions of DPPIV as a major venom component of the ant-like bethylid ectoparasitoid, Scleroderma guani, named SgVnDPPIV. The SgVnDPPIV gene was cloned, which encodes a protein with the conserved catalytic triads and substrate binding sites of mammalian DPPIV. This venom gene is highly expressed in the venom apparatus. Recombinant SgVnDPPIV, produced in Sf9 cells using the baculovirus expression system, has high enzymatic activity, which can be efficiently inhibited by vildagliptin and sitagliptin. Functional analysis revealed that SgVnDPPIV affects genes related to detoxification, lipid synthesis and metabolism, response to stimuli, and ion exchange in pupae of Tenebrio molitor, an envenomated host of S. guani. The present work contributes towards understanding the role of venom DPPIV involved in the interaction between parasitoid wasp and its host.

Differentiated Effects of Secondary Metabolites from Solanaceae and Brassicaceae Plant Families on the Heartbeat of Tenebrio molitor Pupae.

The usage of insects as model organisms is becoming more and more common in toxicological, pharmacological, genetic and biomedical research. Insects, such as fruit flies (Drosophila melanogaster), locusts (Locusta migratoria), stick insects (Baculum extradentatum) or beetles (Tenebrio molitor) are used to assess the effect of different active compounds, as well as to analyse the background and course of certain diseases, including heart disorders. The goal of this study was to assess the influence of secondary metabolites extracted from Solanaceae and Brassicaceae plants: Potato (Solanum tuberosum), tomato (Solanum lycopersicum), black nightshade (Solanum nigrum) and horseradish (Armoracia rusticana), on T. molitor beetle heart contractility in comparison with pure alkaloids. During the in vivo bioassays, the plants glycoalkaloid extracts and pure substances were injected at the concentration 10−5 M into T. molitor pupa and evoked changes in heart activity. Pure glycoalkaloids caused mainly positive chronotropic effects, dependant on heart activity phase during a 24-h period of recording. Moreover, the substances affected the duration of the heart activity phases. Similarly, to the pure glycoalkaloids, the tested extracts also mainly accelerated the heart rhythm, however S. tuberosum and S. lycopersicum extracts slightly decreased the heart contractions frequency in the last 6 h of the recording. Cardioacceleratory activity of only S. lycopersicum extract was higher than single alkaloids whereas S. tubersoum and S. nigrum extracts were less active when compared to pure alkaloids. The most cardioactive substance was chaconine which strongly stimulated heart action during the whole recording after injection. A. rusticana extract which is composed mainly of glucosinolates did not significantly affect the heart contractions. Obtained results showed that glycoalkaloids were much more active than glucosinolates. However, the extracts depending on the plant species might be more or less active than pure substances.

Direct and Indirect Effect of Bt Cotton and No Bt Cotton on the Development and Reproduction of the Predator <i>Podisus nigrispinus</i> (Dallas, 1851) (Hemiptera: Pentatomidae)

This paper aimed to evaluate the direct and indirect effects of Bt cotton and no Bt cotton on the development and reproduction of the predator Podisus nigrispinus (Dallas). The experiments related to the direct and indirect effects on immature and adult stages of the predator were conducted, respectively, in greenhouse and laboratory of the Embrapa Agropecuaria Oeste in Dourados, Mato Grosso do Sul State, Brazil. To evaluate the indirect effects of Bt cotton and non-Bt, larvae of Spodoptera frugiperda (Smith) were fed with these plants and later offered to the predator. To evaluate the direct effect of the Bt cotton and non-Bt, the predator P. nigrispinus was kept in contact with these plants and fed with pupae of Tenebrio molitor (L.). The direct and indirect effects were evaluated by the biological parameters as follows: period of nymphal development, nymphal survival, and duration of pre-oviposition and oviposition periods and longevity of adults (females and males) of P. nigrispinus. It was observed higher period of second instar of P. nigrispinus in Bt cotton, when compared to the development in its isoline non-Bt. All other biological parameters evaluated, have no influence of the Bt cotton plants considering the direct and indirect effects.

Prey scarcity at the beginning of fifth instar: effect of Eucalyptus urophylla (Myrtaceae) plants on reproduction, longevity, and weight of the predator Brontocoris tabidus (Heteroptera: Pentatomidae: Asopinae)

Intervals without prey during the fifth instar and nutrient quality may affect reproduction, longevity, and weight of the zoophytophagous predator Brontocoris tabidus (Heteroptera: Pentatomidae: Asopinae). This asopine was reared on Eucalyptus urophylla (Myrtaceae) trees under field conditions at 23 ± 6 o C, 76 ± 9 % RH and 13:11 (dark:light) h photoperiod. The experiment was developed with 60 B. tabidus nymphs individualized in organza bags (31 cm long × 21 cm diameter). One group of nymphs received only Tenebrio molitor (Coleoptera: Tenebrionidae) pupae and water without E. urophylla trees (T1). Other nymphs were reared on E. urophylla trees and fed with T. molitor pupae and water during the second, third, and fourth instars and twenty of them per group after zero, five, and 10 days from the beginning of the fifth instar making up the treatments T2, T3, and T4, respectively. The period without prey increased duration of the fifth instar for males in the T3 and T4 while female weight was lower in the T4. The oviposition period was shorter and the number of egg masses of B. tabidus was lower in the T1 than in the T2, T3, and T4. The highest egg numbers were found in the T2 and T3 with about 4 times more eggs than in the T1. The number of nymphs was low and the percentage of nymph hatching higher in the T1. The interval of five and 10 days without prey from the beginning of the fifth instar did not affect the duration and survival of this instar and supplementation with E. urophylla increased the reproductive capacity of the predator B. tabidus.

Does the Ingestion of Isoxaflutole Herbicide Affect the Midgut and Salivary Glands of Pentatomidae Predators?

Podisus nigrispinus is a generalist predator naturally occurring in agricultural and forestry systems that effectively contributes to the population balance of phytophagous insects, especially defoliating caterpillars. Histological changes were evaluated in the salivary glands and midgut of P. nigrispinus caused by ingestion of systemic herbicide isoxaflutole. These predator females were fed with leaves of eucalyptus plants, Tenebrio molitor pupae or water, contaminated or not by herbicide. Salivary glands and midguts were dissected, processed and analyzed under a light microscope. Activity level and cell morphology of the salivary glands and midgut showed differences among insects fed on plants, contaminated water or pupae. The epithelia of the salivary gland and midgut of individuals which had no contact with the herbicide showed homogeneous cytoplasm, nucleus with predominance of decondensed chromatin and evident nucleoli, intense cell activity features. As for the insects in contact with contaminated food, they presented undeveloped nucleus and condensed chromatin. The luminal contents of the salivary glands in the contaminated insects had become more acidophilus than in insects without poisoning, as well as having heterogeneous and granular secretion, being more evident in the bioassay in which the insects fed on contaminated water. There was a marked morphological change in the midgut cells in contaminated insects. High degree of apoptosis, disorganization and secretory vacuoles in the epithelial cytoplasm were observed. The apical portion of the midgut cells proved undeveloped, irregular and partially destroyed. It is concluded that isoxaflutole causes morphological changes in the digestive system of the predator P. nigrispinus.

The modulating effect of weak combined magnetic fields on the duration of the stages of metamorphosis of the Tenebrio molitor mealworm beetle

It is shown that exposure of the mealworm beetle Tenebrio molitor pupae to combined static (42 μT) and very weak alternating (250 nT) magnetic fields has different effects on the duration of metamorphosis processes in these insects depending on the frequency of the alternating magnetic field. For instance, the exposure of pupae to weak combined magnetic fields adjusted to the frequency of ion cyclotron resonance for glutamic add (4.4 Hz) stimulated metamorphosis, with the transitional stage from pupae to imago being shorter. An inhibitory effect was observed when magnetic fields were adjusted to the frequency of ion cyclotron resonance for Ca2+ (32.2 Hz). At some frequencies, this effect was not observed. For instance, the exposure at a frequency of ion cyclotron resonance for K+ (16.5 Hz) had no noticeable effect on the duration of the pupal metamorphosis stage.

Parasitization by Scleroderma guani influences protein expression in Tenebrio molitor pupae

Ectoparasitoid wasps deposit their eggs onto the surface and inject venom into their hosts. Venoms are chemically complex and they exert substantial impact on hosts, including permanent or temporary paralysis and developmental arrest. These visible venom effects are due to changes in expression of genes encoding physiologically relevant proteins. While the influence of parasitization on gene expression in several lepidopterans has been reported, the molecular details of parasitoid/beetle relationships remain mostly unknown. This shortcoming led us to pose the hypothesis that envenomation by the ectoparasitic ant-like bethylid wasp Scleroderma guani leads to changes in protein expression in the yellow mealworm beetle Tenebrio molitor. We tested our hypothesis by comparing the proteomes of non-parasitized and parasitized host pupae using iTRAQ-based proteomics. We identified 41 proteins that were differentially expressed (32↑- and 9↓-regulated) in parasitized pupae. We assigned these proteins to functional categories, including immunity, stress and detoxification, energy metabolism, development, cytoskeleton, signaling and others. We recorded parallel changes in mRNA levels and protein abundance in 14 selected proteins following parasitization. Our findings support our hypothesis by documenting changes in protein expression in parasitized hosts.

Production and Use of Heteroptera Predators for the Biological Control of Eucalyptus Pests in Brazil

The Asopinae predators of Eucalyptus spp. (Myrtaceae) pests in Brazil include Brontocoris tabidus, Podisus distinctus, Podisus nigrispinus, and Supputius cincticeps (Heteroptera: Pentatomidae). These insects feed on the larvae and pupae of Coleoptera and Lepidoptera defoliators. Asopinae predators are reared in the laboratory in wooden cages with wood screens on the upper and lateral sides and the front closed with a glass door, whereas, in the field they are raised in organza bags with branches of Eucalyptus spp. or Psidium guajava (Myrtaceae). An alternative prey, such as Tenebrio molitor (Coleoptera: Tenebrionidae) pupae and Musca domestica (Diptera: Muscidae), or Bombyx mori (Lepidoptera: Bombycidae) larvae, or the natural prey Anticarsia gemmatalis (Lepidoptera: Noctuidae), and Thyrinteina arnobia and Thyrinteina leucocerae (Lepidoptera: Geometridae) caterpillars may be provided to the nymphs of predators in cages and/or rearing bags. Vallourec & Mannesmann Forest Ltda. has two laboratories to mass rear M. domestica to produce annually 300,000 individuals of P. nigrispinus which are released with or without pests in the field. In the first case, predators are released after detection of the pest by a monitoring process, which is the first major step in integrated pest management (IPM). This predator is efficient when the pest population level is below the economic injury level, i.e., nine caterpillars/100 leaves of Eucalyptus spp. Releasing are made in outbreaks every 10 m and the population increase of this predator can control pests. Podisus nigrispinus usually prey on 4-5 first and second instars larvae or 2-3 fourth and fifth instar caterpillars per day. Asopinae predators are reared and released in the field to control pests in the Eucalyptus spp. plantations of the Vallourec &

Transcriptomic Immune Response of Tenebrio molitor Pupae to Parasitization by Scleroderma guani

BackgroundHost and parasitoid interaction is one of the most fascinating relationships of insects, which is currently receiving an increasing interest. Understanding the mechanisms evolved by the parasitoids to evade or suppress the host immune system is important for dissecting this interaction, while it was still poorly known. In order to gain insight into the immune response of Tenebrio molitor to parasitization by Scleroderma guani, the transcriptome of T. molitor pupae was sequenced with focus on immune-related gene, and the non-parasitized and parasitized T. molitor pupae were analyzed by digital gene expression (DGE) analysis with special emphasis on parasitoid-induced immune-related genes using Illumina sequencing.Methodology/Principal FindingsIn a single run, 264,698 raw reads were obtained. De novo assembly generated 71,514 unigenes with mean length of 424 bp. Of those unigenes, 37,373 (52.26%) showed similarity to the known proteins in the NCBI nr database. Via analysis of the transcriptome data in depth, 430 unigenes related to immunity were identified. DGE analysis revealed that parasitization by S. guani had considerable impacts on the transcriptome profile of T. molitor pupae, as indicated by the significant up- or down-regulation of 3,431 parasitism-responsive transcripts. The expression of a total of 74 unigenes involved in immune response of T. molitor was significantly altered after parasitization.Conclusions/Significanceobtained T. molitor transcriptome, in addition to establishing a fundamental resource for further research on functional genomics, has allowed the discovery of a large group of immune genes that might provide a meaningful framework to better understand the immune response in this species and other beetles. The DGE profiling data provides comprehensive T. molitor immune gene expression information at the transcriptional level following parasitization, and sheds valuable light on the molecular understanding of the host-parasitoid interaction.

No direct effects of resistant soybean cultiva IAC-24 on Podisus nigrispinus (Heteroptera: Pentatomidae)

The parameters of survival, development and reproduction of Podisus nigrispinus Dallas, 1851 (Heteroptera: Pentatomidae) may be affected by feeding on soybean ( Glycine max [L.] Merr.; Fabaceae) cultivars. The direct effect was evaluated of the insect-resistant soybean 'IAC-24' (insect-susceptible soybean 'UFVS-2006' + pupae of Tenebrio molitor L., 1758 [Coleoptera: Tenebrionidae] versus 'IAC-24' plants + pupae of T. molitor) in the nymph and adult stages of the predator P. nigrispinus. The duration of the nymph stage was similar between treatments, but 'IAC-24' reduced the duration of the IV instar of this predator. The survival of P. nigrispinus was similar between treatments in the instars I, II, IV and V and in the nymph stage, but the survival of the III instar was longer with 'IAC-24' plants. The body mass of nymphs in the first day of the III, IV, and V instars after ecdysis and newly emerged adults; reproductive characteristics (periods of pre-oviposition, oviposition, post-oviposition and egg incubation; egg laying interval, number of egg masses per female, nymphs per female, nymphs per egg mass and percentage of nymphs hatching) and life span of males and females of P. nigrispinus were similar between treatments. The resistant soybean 'IAC-24' showed no direct deleterious effects on P. nigrispinus, which implies its innocuity and compatibility with this predator.

Effect of gossypol on survival and reproduction of the zoophytophagous stinkbug Podisus nigrispinus (Dallas)

Effect of gossypol on survival and reproduction of the zoophytophagous stinkbug Podisus nigrispinus (Dallas). Gossypol is a sesquiterpene aldehyde found in cotton plants conferring resistance against herbivory. Although the effect of this sesquiterpenoid on insect pests of cotton is known, the interaction of this compound with zoophytophagous predators such as Podisus nigrispinus (Dallas) (Hemiptera, Pentatomidae) has not been studied so far. Thus, the objective of this study was to evaluate the effect of the purified gossypol on nymphs and adults of P. nigrispinus. Nymphs and adults of this predator were fed on Tenebrio molitor pupae and supplemented with solutions of gossypol at concentrations of 0.00, 0.05, 0.10, and 0.20% (w/v) during the nymphal and adult stages or, only during the adult stage of P. nigrispinus. The nymphal stage of the predator was, on average, two days longer when suplemmented with gossypol. Emerged adults had lower fecundity and egg hatching, especially at the highest gossypol concentration (0.20%) ingested during the nymphal and adult stages. However, this predator was not affected when it ingested the compound only during the adult stage. P. nigrispinus can have delayed nymphal development and lower reproductive performance when ingesting the gossypol during the nymphal and adult stages, but only at higher concentrations of gossypol than that produced by cotton plants.

Survival and Reproduction of Podisus nigrispinus (Heteroptera: Pentatomidae): Effects of Prey Scarcity and Plant Feeding

The spined soldier bug Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) is a generalist predator that can alternatively feed on plant tissue to survive under prey scarcity. This research aimed to evaluate the effects of plant feeding forced by a shortage of prey on the survival and reproduction of P. nigrispinus on Eucalyptus urophylla S.T. Blake�(Myrtaceae)�plantsinthefield.� Podisus nigrispinus adults were enclosed on branches of eucalyptus by using gauze bags. These adults were fed daily with Tenebrio molitor pupae (T1) or after 5 (T2), 10 (T3) or 15 (T4) days from mating to simulate prey shortage. The pre-oviposition period, number of egg masses, number and viability of eggs and longevity of females were evaluated. Females of P. nigrispinus had a longer pre-oviposition period and produced lower number of egg masses as the period of prey shortage increased. However, the average number of eggs per egg mass, emergence of nymphs and longevity of P. nigrispinus females were not affected by prey shortage. Females of P. nigrispinuscansurvive�15�dayswithoutpreybyfeedingoneucalyptusleavesandifitfindsprey� afterwards can still reproduce. This shows that plant feeding is a successful incidental strategy to survive periods of foodscarcity�(andthusincreasetheefficiency)�ofthispredatorasabiologicalcontrolagent.

Herbivory affects ovarian development in the zoophytophagous predator Brontocoris tabidus (Heteroptera, Pentatomidae)

The effect of prey-based and combination prey and plant-based diets [Tenebriomolitor pupae alone; T. molitor pupae and Eucalyptus cloeziana plants; T. molitor pupae and Eucalyptus urophylla plants; and T. molitor pupae and Psidium guajava (guava) plants] on the morphometry of the ovary of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae) was analyzed in the field. Females fed on T. molitor pupae without plants presented with smaller ovarioles. The number of oocytes per ovary was higher for B. tabidus females fed on a combination diet of E. urophylla and T. molitor pupae when compared to females fed only on prey. In addition to diet, the number of oocytes in the ovariole was shown to vary with the age of B. tabidus. The 21-day-old B. tabidus females were found to have a higher number of oocytes per ovariole than the 15-day-old females in all diet conditions. The 15-day-old females exhibited more developed oocytes when fed on diets containing both prey and eucalypts plants and less developed oocytes when fed with a combination diet containing guava plants or T. molitor pupae alone. The 21-one-day-old B. tabidus females which were fed with a diet without plants had smaller oocytes than those fed with plants. Herbivory improves the morphology of the ovary of B. tabidus, affecting the size of the reproductive structures and the oogenesis of this natural enemy in the field.

The effect of a static magnetic field on the morphometric characteristics of neurosecretory neurons and corpora allata in the pupae of yellow mealworm Tenebrio molitor (Tenebrionidae)

Purpose: The morphometric characteristics of A1 and A2 protocerebral neurosecretory neurons (cell and nuclei size, number of nucleoli in the nuclei); corpora allata size, nuclei size, cell number, were investigated in the pupae of yellow mealworm, Tenebrio molitor (L.), exposed to a strong static magnetic field of 320 mT maximum induction (10,000 times higher than the Earth's).Materials and methods: The experimental groups of Tenebrio molitor pupae were: A control group exposed only to natural magnetic field and sacrificed at the eighth day of pupal development (C); and pupae kept in a strong static magnetic field for eight days and then sacrificed (MF). Serial brain cross-sections were stained using the Alcian Blue Floxin technique. All the parameters were analyzed and measurements were performed using an image processing and analysis system (Leica, Cambridge, UK) linked to a Leica DMLB light microscope (program is QWin – Leica's Quantimet Windows-based image analysis tool kit).Results: The values of morphometric parameters of neurosecretory neurons and corpora allata were significantly increased after exposure of the pupae to the strong magnetic field.Conclusions: The strong magnetic field influence characteristics of protocerebral neurosecretory neurons and corpora allata in the late Tenebrio molitor pupae.

Protocerebral Mediodorsal A2′ Neurosecretory Neurons in Late Pupae of Yellow Mealworm (Tenebrio molitor) after Exposure to a Static Magnetic Field

The activity of large dorsomedial protocerebral A2′ neurosecretory neurons were investigated in late pupae of Tenebrio molitor L, which were exposed to a static magnetic field of 320 mT. Experimental groups were C: the control group which was kept at 5 meters from the magnet; CMF: pupae which were reared in control conditions and sacrificed on the eighth day of pupal stage (parents were kept in a magnetic field); and MF: pupae kept in a permanent magnetic field for eight days. Our results indicate the effects of a static magnetic field on the cytological characteristics and activity of large A2′ neurosecretory neurons of Tenebrio molitor pupae.

Fertility table and rate of population growth of the predator Supputius cincticeps (Heteroptera: Pentatomidae) on one plant of Eucalyptus cloeziana in the field

SummaryThe reproductive potential and population growth (rm and λ) of the predator Supputius cincticeps (Heteroptera: Pentatomidae) were evaluated using a life and fertility table. S. cincticeps was reared on one plant of Eucalyptus cloeziana in the field and fed with Tenebrio molitor (Coleoptera: Tenebrionidae) pupae. Females of this predator had a net reproductive rate (R0) of 21.02 females/female; an intrinsic rate of population increase (rm) of 0.041 and finite rate of increase (λ) of 1.042. This resulted in population growth of S. cincticeps in the eucalyptus plant with a doubling time of 17.01 days. This natural enemy can be reared under field conditions with alternative prey for use in biological control. Such individuals of S. cinticeps will be better adapted to field conditions when they are liberated.

Development and reproduction of a predatory stinkbug, Podisus nigrispinus in relation to two different prey types and environmental conditions

Abiotic factors, prey availability, prey type, and plant host actsimultaneously under field conditions. Their combined effects werepartially investigated for the predatory stinkbugPodisus nigrispinus(Dallas) (Heteroptera: Pentatomidae) preying on tomato leafminer (TLM)caterpillars Tuta absoluta (Meyrick)(Lepidoptera: Gelechiidae) (a preyfeeding on a plant host), and compared to yellow mealworm (YMW)Tenebrio molitor (Coleoptera: Tenebrionidae)pupae (a prey not feeding ona plant host). These experiments were carried out in the laboratory and inan open-sided greenhouse. In general, the environmental variationsbetween laboratory and open-sided greenhouse did not induce differencesin life history characteristics forP. nigrispinus feeding on the sameprey type. However, development and reproductionof P. nigrispinuswas greatly affected by prey type. Nymphal developmental times weresimilar between prey types under laboratory conditions; but were longer(and produced adults of lower body weight) when predators in theopen-sided greenhouse were fed on TLM compared with YMW. Mean mortalityduring the second instar was higher on both prey types in the open-sidedgreenhouse than in the laboratory. Adult emergencewas 38.5 and 50% inthe laboratory, and 32.5 and 48.6%in the open-sided greenhouse for bugsfed on TLM and YMW, respectively. Reproductive characteristics weresimilar for the different environmental conditions when the predator fed onthe same prey, but offspring production was greater for females fed on YMWcompared to females fed on TLM. These results suggest thatP. nigrispinus can adjust its performance accordingto the type of prey available, independently from environmentalvariations. It has the ability to survive on alternative prey,enabling it to maintain a presence in thetomato ecosystem until a primary pest species arrives.

Activity of RH-0345 on Ecdysteroid Production and Cuticle Secretion in Tenebrio molitor Pupae In Vivo and In Vitro

The activity of RH-0345 (halofenozide), a novel benzoylhydrazine analogue, was investigated on ecdysteroid production, cuticle secretion, and hemolymph protein concentrations in Tenebrio molitor pupae. The compound was applied topically (5 and 10 μg/pupa) on newly ecdysed pupae or added to the culture medium (1 and 10 μM) of sternal integuments explanted from newly ecdysed pupae. Enzyme immunoassay measurements of ecdysteroid titers in the hemolymph revealed that RH-0345 applied topically on newly ecdysed pupae had no effect on the peak position of ecdysteroids in the hemolymph, but it caused a significant increase of the peak values. With in vitro cultured integument explants, RH-0345 caused a significant increase of the amounts of ecdysteroids released into the culture medium. Further, integuments were cultured in medium containing RH-0345 and/or 20-hydroxyecdysone (20E) and the effects on apolysis and cuticle growth were tested. In the presence of 20E alone, the epidermis was able to secrete a new cuticle under the apolyzed pupal cuticle. Similarly, integument explants from RH-0345-treated series cultured without 20E underwent apolysis and then secreted a new cuticle. The thickness of such a newly induced cuticle did not change as a function of the concentration of RH-0345 nor of the incubation period. In contrast, integument explants from RH-0345-treated series cultured in the presence of 20E secreted a new significantly thicker cuticle. The observed differences in cuticle thickness could be explained by differences in the protein content.