Teneral Adults Research Articles

Philaenus tesselatus (Hemiptera: Aphrophoridae), the main potential vector of Xylella fastidiosa in Morocco: seasonal abundance, phenology and host-plant colonization by nymphs

Summary The bacterium Xylella fastidiosa presents a potential risk to the Moroccan flora, particularly for the citrus, olive, almond and grapevine industries. Philaenus tesselatus, the meadow spittlebug, is the most important Moroccan spittlebug, though recorded with uneven occurrence and considered to be the main potential insect vector of X. fastidiosa. A three-year field survey (2019 to 2021) was conducted at three sites in the provinces of Larache and Kenitra in northwestern Morocco, to study seasonal abundance, phenology and host-plant colonization by nymphs. Philaenus tesselatus is a univoltine species. Nymphs occurred in groundcover from end of mid-March to mid-May, with abundance peaking between end of March and mid-May. Emergence of teneral adults occurred between April and May, depending on the year. Adults were present on ground vegetation from March until early August, with the highest abundances surveyed by sweep net in April, and occurred in canopy in low abundance between the end of May and mid-September, depending on site. Both nymphal and adult abundances were significantly higher in Larache than at the other two sites. Philaenus tesselatus, the meadow spittlebug, is a polyphagous species, recorded on nine botanical families of host plant species including Asteraceae, Poaceae, Fabaceae, Polygonaceae, Apiaceae, Primulaceae, Urticaceae, Papaveraceae and Malvaceae, and 37 host plant species, of which 29 were identified. The Asteraceae were best represented. Carduus pycnocephalus, Vulpia geniculata, Anthoxanthum odoratum and Cistus salviifolius were the most suitable for this spittlebug. Avena barbata, L. foemina, Scolymus hispanicus and S. oleraceus were dominant in the herbaceous layer. Philaenus tesselatus preferred to feed on the mid-section of the host plants. A single foam can host zero to five individuals, but foams with one or two nymphs were most frequent. Implications of our findings for the setting up of a survey program to control X. fastidiosa and its vectors in case the bacterium is introduced to Morocco are discussed.

Differential expression of “Candidatus Liberibacter solanacearum” genes and prophage loci in different life stages of potato psyllid

Psyllid species, including the potato psyllid (PoP) Bactericera cockerelli (Sulc) (Triozidae) serve as host and vector of “Candidatus Liberibacter spp.” (“Ca. Liberibacter”), which also infects diverse plant hosts, including citrus and tomato. Psyllid transmission of “Ca. Liberibacter” is circulative and propagative. The time of “Ca. Liberibacter” acquisition and therefore vector life stage most competent for bacterial transmission varies by pathosystems. Here, the potato psyllid-“Ca. Liberibacter solanacearum” (CLso) pathosystem was investigated to dissect CLso-prophage interactions in the tomato plant and PoP-psyllid host by real-time quantitative reverse transcriptase amplification of CLso genes/loci with predicted involvement in host infection and psyllid-CLso transmission. Genes/loci analyzed were associated with (1) CLso-adhesion, -invasion, -pathogenicity, and -motility, (2) prophage-adhesion and pathogenicity, and (3) CLso-lysogenic cycle. Relative gene expression was quantified by qRT-PCR amplification from total RNA isolated from CLso-infected 1st–2nd and 4th–5th nymphs and teneral adults and CLso-infected tomato plants in which CLso infection is thought to occur without SC1-SC2 replication. Gene/loci expression was host-dependent and varied with the psyllid developmental stage. Loci previously associated with repressor-anti-repressor regulation in the “Ca Liberibacter asiaticus”-prophage pathosystem, which maintains the lysogenic cycle in Asian citrus psyllid Diaphorina citri, were expressed in CLso-infected psyllids but not in CLso-infected tomato plants.

Amphibitic stoneflies (Plecoptera) are integrators of ecosystem processes in alluvial aquifers of gravel‐bed river floodplains

AbstractOver 50 years ago nymphs of the Plecoptera species, Paraperla frontalis Banks, 1906 (Plecoptera: Chloroperlidae), were shown to exist in a shallow floodplain aquifer of the Tobacco River, a gravel‐bed river in western Montana and later they were documented throughout the main stems of the Flathead River system. Nymphs are almost never found in surface waters, until they emerge on the river shorelines. As teneral adults, they mate and subsequently deposit fertilized eggs into the river. This novel life cycle is termed “amphibitic.” Over the years we and others have found P. wilsoni Ricker, 1965 (Plecoptera: Chloroperlidae), Kathroperla perdita Banks, 1920 (Plecoptera: Kathroperlidae), and five species of Isocapnia Banks, 1938 (Plecoptera: Capniidae), including long‐winged and brachypterous adults and wingless dwarfs (male and female), occupying amphibitic niches in the alluvial aquifers of rivers in Washington, Idaho, Colorado, Alaska and British Columbia. These stoneflies are remarkably tolerant of hypoxia which allows them to exist as abundant consumers in aquifer food webs subsidized by ancient methane. Indeed, stonefly tissues contain carbon that is up to 7000 years old, underscoring the existence of a strong interaction involving the uptake of labile carbon derived from methanogenic and methanotrophic process in aquifers. Details of life cycles, trophic relationships, distribution and abundance have been documented by a suite of studies on the Nyack Floodplain of the Middle Flathead River, Montana. In this paper we review the ecophysiology and ecology of these unique stoneflies in the context of their functional role in gravel‐bed river ecosystems.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness

Compatibility of soil application of Metarhizium brunneum and cover crops against Ceratitis capitata soil-dwelling stages

Fruit fly ground-dwelling stages (late third instar larvae, pupae, and teneral adults) are susceptible to predation from generalist ground-dwelling predators and to infection by entomopathogenic fungi (EPF). The effect of predators can be enhanced with cover crops and that of EPF by augmentative releases. However, whether these two biological control methods could be combined has not been studied under field conditions yet. Here, we studied in the field whether the enhanced activity of predators against the medfly, Ceratitis capitata, already observed in a Lolium arundinaceum ground cover could be impaired by a soil application of Metarhizium brunneum. Our results show that C. capitata adult emergence was reduced by this EPF for up to three months after fungal application, with the combination of the cover and M. brunneum being the most effective at reducing C. capitata emergence relative to bare soil (92.5% reduction). Although M. brunneum reduced the activity density of ground-dwelling predatory beetles up to 93 days after application, it showed no clear negative effects on earwigs, no effects on spiders, and a positive effect on ants up to 65 days after application. Therefore, the combined use of a ground cover of L. arundinaceum and M. brunneum against the soil-dwelling stages of C. capitata seems to work synergistically and appears as a strong and sustainable control tactic against the medfly and other fruit orchard pests.

Optimal dsRNA Concentration for RNA Interference in Asian Citrus Psyllid.

The Asian citrus psyllid (ACP) is a citrus pest and insect vector of "Candidatus Liberibacter asiaticus", the causal agent of citrus greening disease. Double-stranded RNA (dsRNA) biopesticides that trigger RNA interference (RNAi) offer an alternative to traditional insecticides. Standardized laboratory screening of dsRNA requires establishing the minimal effective concentration(s) that result in effective RNAi "penetrance" and trigger RNAi, resulting in one or more measurable phenotypes, herein, significant gene knockdown and the potential for mortality. In this study, knockdown was evaluated for a range of dsRNA concentrations of three ACP candidate genes, clathrin heavy chain (CHC), vacuolar ATPase subunit A (vATPase-A), and sucrose non-fermenting protein 7 (Snf7). Gene knockdown was quantified for ACP teneral adults and 3rd instar nymphs allowed a 48 h ingestion-access period (IAP) on 10, 50,100, 200, and 500 ng/µL dsRNA dissolved in 20% sucrose followed by a 5-day post-IAP on orange jasmine shoots. Significant gene knockdown (p < 0.05) in ACP third instar nymphs and adults ranged from 12-34% and 18-39%, 5 days post-IAP on dsRNA at 10-500 and 100-500 ng/µL, respectively. The threshold concentration beyond which no significant gene knockdown and adult mortality was observed post-48 h IAP and 10-day IAP, respectively, was determined as 200 ng/µL, a concentration indicative of optimal RNAi penetrance.

Evaluation of Black Soldier Fly Hermetia illucens as Food for Pink-Spotted Lady Beetle Coleomegilla maculata.

The discovery of new and improved factitious and artificial diets is necessary for cost-effective rearing of predatory arthropods. This study evaluated Hermetia illucens black soldier fly (BSF) as a suitable alternative food source for rearing the predatory coccinellid Coleomegilla maculata (Cmac). The hypothesis that BSF larval powder was suitable food to support the growth, development, and reproduction of Cmac was tested in the laboratory. When compared to a standard in-house diet containing brine shrimp egg powder plus Chlorella vulgaris green algae and myristic acid (BSE+CM), the BSF and BSF+CM diets reduced immature growth and development. Immatures successfully reared to teneral adults were smaller when fed BSF or BSF+CM rather than BSE+CM. Combining BSF with a powdered artificial diet (AD), i.e., BSF+AD, did not improve predator growth or development, compared to Cmac reared on BSE+CM. Cmac oviposition responses, i.e., egg clutch production, to BSF vs. BSE+CM or BSF+AD vs. BSE+CM did not differ significantly. In conclusion, BSF has the potential to be food that supports Cmac oviposition behavior. Future research is necessary to discover an ideal mixture of BSF, BSE+CM, or AD that supports Cmac growth, development, and reproduction over multiple generations.

Do adult Magicicada (Hemiptera: Cicadidae) feed? Historical perspectives and evidence from molecular gut content analysis.

The periodical cicadas in the genus Magicicada are remarkable for their unusual life histories and dramatic synchronized emergences every 13 or 17 years. While aspects of their evolution, mating behaviors, and general biology have been well-characterized, there is surprising uncertainty surrounding the feeding habits of the short-lived adult stage. Despite a tentative scientific consensus to the contrary, the perception that adult Magicicada do not feed has persisted among the general public, and recent studies are lacking. We directly investigated the feeding behavior of Magicicada spp. through high-throughput sequencing (HTS)-based dietary analysis of nymphs, freshly molted (teneral) adults, and fully sclerotized adults collected from orchard and wooded habitats during the 2021 emergence of Brood X. Identifiable plant DNA (trnF, ITS amplicons) was successfully recovered from nymphs and adults. No plant DNA was recovered from teneral adults, suggesting that all DNA recovered from sclerotized adults was ingested during the post-teneral adult stage. Both nymphs and adults were found to have ingested a range of woody and herbaceous plants across 17 genera and 14 families. Significantly more plant genera per individual were recovered from adults than from nymphs, likely reflecting the greater mobility of the adult stage. We hypothesize that the demonstrated ingestion of plant sap by Magicicada adults is driven by a need to replace lost water and support specialized bacteriome-dwelling endosymbionts that cicadas depend upon for growth and development, which constitutes true feeding behavior.

Differential gene expression of Asian citrus psyllids infected with 'Ca. Liberibacter asiaticus' reveals hyper-susceptibility to invasion by instar fourth-fifth and teneral adult stages.

The bacterial pathogen Candidatus Liberibacter asiaticus (CLas) is the causal agent of citrus greening disease. This unusual plant pathogenic bacterium also infects its psyllid host, the Asian citrus psyllid (ACP). To investigate gene expression profiles with a focus on genes involved in infection and circulation within the psyllid host of CLas, RNA-seq libraries were constructed from CLas-infected and CLas-free ACP representing the five different developmental stages, namely, nymphal instars 1-2, 3, and 4-5, and teneral and mature adults. The Gbp paired-end reads (296) representing the transcriptional landscape of ACP across all life stages and the official gene set (OGSv3) were annotated based on the chromosomal-length v3 reference genome and used for de novo transcript discovery resulting in 25,410 genes with 124,177 isoforms. Differential expression analysis across all ACP developmental stages revealed instar-specific responses to CLas infection, with greater overall responses by nymphal instars, compared to mature adults. More genes were over-or under-expressed in the 4-5th nymphal instars and young (teneral) adults than in instars 1-3, or mature adults, indicating that late immature instars and young maturing adults were highly responsive to CLas infection. Genes identified with potential for direct or indirect involvement in the ACP-CLas circulative, propagative transmission pathway were predominantly responsive during early invasion and infection processes and included canonical cytoskeletal remodeling and endo-exocytosis pathway genes. Genes with predicted functions in defense, development, and immunity exhibited the greatest responsiveness to CLas infection. These results shed new light on ACP-CLas interactions essential for pathogenesis of the psyllid host, some that share striking similarities with effector protein-animal host mechanisms reported for other culturable and/or fastidious bacterial- or viral- host pathosystems.

The role of host plant usage and the accumulation of toxic secondary chemical compounds across the life cycle of a passion vine specialist butterfly

Abstract Host plant specialisation by herbivorous insects is ubiquitous, especially among the Lepidoptera. Many taxa have the ability to accumulate toxic compounds from their host plants that serve as chemical defences against natural enemies. Despite common knowledge of this pattern among insect ecologists, we still have much to learn about how dietary variation affects an insect's ability to acquire toxic plant chemicals. Longwing butterfly larvae (Heliconius) accumulate toxic cyanogenic glucosides from their host plants, passion vines (Passiflora), that make them toxic to most predators. Here, we present on zebra longwing (H. charithonia) caterpillar cohorts that were reared on native P. affinis, P. biflora, P. lutea, or P. suberosa to determine how host usage affected cyanide accumulation over larval developmental stages, and ultimately the toxicity of adult butterflies. Samples were collected at third, fourth and fifth instars, and teneral adults. Cyanogenic glucosides were extracted, the cyanide molecules were captured as sodium cyanide (CN), and CN content was quantified colorimetrically. The quantity of CN acquired increased linearly over larval ontogeny and was variable among host plants. CN concentration increased over larval development for two hosts but declined on the third. There was no clear relationship between host plant and adult CN concentrations, but adults that consumed certain hosts as larvae ended up accumulating significantly more CN, and thus expressed higher CN concentrations, than others. We demonstrated that some host plants provide specialist insects with more toxins than others and that larval secondary chemical accumulation may predict which life stages are more vulnerable to natural enemies. These conclusions support the hypothesis that host choice affects the survival of specialist insect herbivores.

Umbonia crassicornis (Amyot &amp; Serville, 1843) (Hemiptera: Membracidae) nymphal aggregation size and density affect host plant and treehopper growth

There was a significant negative relationship between the density of Umbonia crassicornis (Amyot & Serville, 1843) aggregations and the average length of the newest growth on its host plant, Lysiloma latisiliquum Benth. (Fabaceae). There was also a significant negative relationship between aggregation size and the dry mass of the teneral adults of both sexes. Teneral female U. crassicornis were significantly longer and had a significantly greater dry mass than their male siblings. I suggest that feeding by treehopper nymphs reduces the nutrient pool of the host plant, resulting in reduced plant and treehopper growth.

Silencing of V-ATPase-E gene causes midgut apoptosis of Diaphorina citri and affects its acquisition of Huanglongbing pathogen.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is among the most important pests of citrus. It is the main vector of the Huanglongbing (HLB) pathogen Candidatus Liberibacter asiaticus (CLas), which causes severe losses in citrus crops. Control of D. citri is therefore of paramount importance to reduce the spread of HLB. In this regard, using RNA interference (RNAi) to silence target genes is a useful strategy to control psyllids. In this study, using RNAi, we examined the biological functions of the V-ATPase subunit E (V-ATP-E) gene of D. citri, including its effect on acquisition of CLas. The amino acid sequence of V-ATP-E from D. citri had high homology with proteins from other insects. V-ATP-E was expressed at all D. citri life stages analyzed, and the expression level in mature adults was higher than that of teneral adults. Silencing of V-ATP-E resulted in a significant increase in mortality, reduced body weight, and induced cell apoptosis of the D. citri midgut. The reduced expression of V-ATP-E was indicated to inhibit CLas passing through the midgut and into the hemolymph, leading to a majority of CLas being confined to the midgut. In addition, double-stranded RNA of D. citri V-ATP-E was safe to non-target parasitic wasps. These results suggest that V-ATP-E is an effective RNAi target that can be used in D. citri control to block CLas infection.

Ground-covers affect the activity density of ground-dwelling predators and their impact on the Mediterranean fruit fly, Ceratitis capitata

Three developmental stages of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), can be found in the soil (late third instar larvae, pupae, and teneral adults). These stages are susceptible to predation by generalist ground-dwelling predators. Our objectives have been to investigate the association between ground cover management (bare soil, a seeded cover of Festuca arundinacea and a mulch of straw), the emergence success of C. capitata, and the activity density of the most important groups of ground-dwelling predators (spiders, beetles, ants and earwigs). As expected, C. capitata emergence was lower in a seeded cover of Festuca arundinacea (FA) and a mulch of straw (M) (10.2%) relative to bare soil (BS) (13.2%). This was related to higher diversity and activity density of ground-dwelling predators in FA and M compared to BS. The contribution of the ground-dwelling predators considered in this study to this reduction highlights the key role of beetles, earwigs and, to a lesser extent, ants, while the contribution of the most abundant group of ground-dwelling predators, spiders, remains unclear. Ground covers appear as a strong and sustainable conservation biological control method that should be taken into consideration for the management of C. capitata populations.

Characteristics of environmental RNAi in potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psylloidea: Triozidae).

RNA interference (RNAi) has potential to become a major tool for integrated management of insect pests of agricultural crops based on sequence-specificity and low doses of rapidly biodegradable dsRNA. Deploying 'environmental RNAi' for control of insect vectors of plant pathogens is of increasing interest for combatting emerging plant diseases. Hemipteran insect vectors, including psyllids, are vascular feeders, making their development difficult to control specifically by targeting with pesticidal chemistries. Psyllids transmit "Candidatus Liberibacter solanacearum" the causal organism of potato zebra chip and tomato vein greening diseases, transmitted, respectively, by the potato or tomato psyllid (PoP). Until now, the optimal effective concentration(s) of double-stranded RNA (dsRNA) required for significant gene knockdown and RNAi persistence in PoP have not been determined. The objective of this study was to optimize RNAi in young PoP adults and 3rd instars for screening by oral delivery of dsRNAs. The minimal effective dsRNA concentrations required for robust knockdown and persistence were evaluated by delivering seven concentrations spanning 0.1ng/μL to 500ng/μL over post ingestion-access periods (IAP) ranging from 48h to 12days. The PoP gene candidates evaluated as targets were vacuolar ATPase subunit A, clathrin heavy chain, and non-fermenting protein 7, which were evaluated for knockdown by qPCR amplification. The minimum and/or the second most effective dsRNA concentration resulting in effective levels of gene knockdown was 100ng/μL for all three targets. Higher concentrations did not yield further knockdown, indicating potential RISC saturation at the higher doses. Gene silencing post-IAP of 100ng/μL dsRNA persisted for 3-5days in adults and nymphs, with the PoP 3rd instar, followed by teneral and mature adults, respectively, exhibiting the most robust RNAi-response.

Bioaccumulation and bioamplification of pharmaceuticals and endocrine disruptors in aquatic insects

Environmental fate of emerging contaminants such as pharmaceuticals and endocrine disrupting compounds at the aquatic terrestrial boundary are largely unexplored. Aquatic insects connect aquatic and terrestrial food webs as their life cycle includes aquatic and terrestrial life stages, thus they represent an important inter-habitat linkage not only for energy and nutrient flow, but also for contaminant transfer to terrestrial environments. We measured the concentrations of pharmaceuticals and endocrine disrupting compounds in the larval and adult tissues (last larval stages and teneral adults) of five Odonata species sampled in a wastewater-impacted river, in order to examine their bioaccumulation and bioamplification at different taxonomic levels. Twenty different compounds were bioaccumulated in insect tissues, with majority having higher concentrations (up to 90% higher) in aquatic larvae compared to terrestrial adults (reaching 88 ng/g for 1H-benzotriazole). However, increased concentration in adults was observed for seven compounds in at least one suborder (41% of the accumulated), confirming contaminants bioamplification across the metamorphosis. Both, bioaccumulation and bioamplification differed at various taxa levels; the order (Odonata), suborder (Anisoptera and Zygoptera) and species level. Highest variability was observed between Anisoptera and Zygoptera, due to the underlying differences in their ecology. Generally, Zygoptera had higher concentrations of contaminants in both larvae and adults. Additionally, we aimed at predicting effects of contaminant properties on bioaccumulation and bioamplification patterns using the commonly used physicochemical and pharmacokinetic descriptors on both order and suborder levels, however, neither of the two processes could be consistently predicted with simple linear models. Our study highlights the importance of taxonomy in studies aiming at advancing the understanding of contaminant exchange between aquatic and terrestrial food webs, as higher taxonomic categories include ecologically diverse groups, whose contribution to “the dark side of subsidies” could substantially differ.

The developmentally dynamic microRNA transcriptome of Glossina pallidipes tsetse flies, vectors of animal trypanosomiasis.

MicroRNAs (miRNAs) are single stranded gene regulators of 18-25 bp in length. They play a crucial role in regulating several biological processes in insects. However, the functions of miRNA in Glossina pallidipes, one of the biological vectors of African animal trypanosomosis in sub-Saharan Africa, remain poorly characterized. We used a combination of both molecular biology and bioinformatics techniques to identify miRNA genes at different developmental stages (larvae, pupae, teneral and reproductive unmated adults, gravid females) and sexes of G. pallidipes. We identified 157 mature miRNA genes, including 12 novel miRNAs unique to G. pallidipes. Moreover, we identified 93 miRNA genes that were differentially expressed by sex and/or in specific developmental stages. By combining both miRanda and RNAhybrid algorithms, we identified 5550 of their target genes. Further analyses with the Gene Ontology term and KEGG pathways for these predicted target genes suggested that the miRNAs may be involved in key developmental biological processes. Our results provide the first repository of G. pallidipes miRNAs across developmental stages, some of which appear to play crucial roles in tsetse fly development. Hence, our findings provide a better understanding of tsetse biology and a baseline for exploring miRNA genes in tsetse flies. Raw sequence data are available from NCBI Sequence Read Archives (SRA) under Bioproject accession number PRJNA590626. Supplementary data are available at Bioinformatics Advances online.

Mating marks on museum specimens reveal breeding patterns in species of Pterostichus Bonelli (Carabidae, Pterostichini).

We found distinct and consistently placed, species- and sex-specific abrasions of the cuticle on museum specimens of 14 species of the Pterostichus Bonelli, 1810 (Carabidae, Pterostichini) subgenusHypherpes Chaudoir, 1838. We deduced that these marks are generated during mating and, therefore, can be used to distinguish between preserved specimens of beetles that had previously mated at the time of capture and those that had not mated. In addition to describing and detailing the occurrence of the marks and providing evidence that they are the result of mating, we demonstrate their utility for inferring life history using a museum voucher collection. By scoring these indications of mating from pinned specimens, we describe life cycle patterns in two similar, relatively closely related and sympatric species of the subgenus Hypherpes, P.vicinus Mannerheim, 1843 and P.californicus (Dejean, 1828). Both were sampled during a pitfall trap study in Contra Costa, California, USA from 2014–2019 and deposited in the Essig Museum of Entomology, UC Berkeley. Both species had very low adult activity through the drought and end of drought period prior to the spring of 2017 and are significantly more abundant in the post-drought period. Based on mating marks, both species responded to accumulated precipitation ending the drought by the emergence of an active, mostly unmated cohort of adults. The spring activity peak, following the end of the drought, was dominated by unmarked and presumably unmated beetles, but samples from subsequent springs included a nearly equal mix of beetles showing mating marks and apparently unmated beetles. The beetle activity appears to correspond more with the accumulated rainfall of the preceding rainy season than with the rains of the sample year. Beetles sampled in autumn and winter (rainy season) predominantly show mating marks. The occurrence throughout the year of beetles that are marked as having mated is consistent with iteroparous beetles with a lifespan of more than one year and also consistent with dynamic phenotypic polyvariance in which the adult activity period is synchronised by adjusting development time. The dominant pattern fits with a life cycle that is typically annual univoltine, or possibly biennial semivoltine in dry years, rainy season breeding (autumn-winter) iteroparous, with adult summer aestivation and possibly facultative larval hibernation. However, unmarked and so apparently unmated individuals and teneral adults were captured during peak activity periods regardless of the season, suggesting that either the beetles diapause as teneral adults that then complete development and become active at various points during the year and/or there are multiple periods of breeding and oviposition each year in at least some portion of the population.

Isolation, Expression Profiling, and Regulation via Host Allelochemicals of 16 Glutathione S-Transferases in the Chinese White Pine Beetle, Dendroctonus armandi.

The Chinese white pine beetle (Dendroctonus armandi) is undoubtedly one of the most important pests causing ecological damage in the Qinling Mountains. When bark beetles invade conifers, they must overcome host tree defenses, including primary resistance and induced resistance responses. Moreover, this induced resistance occurs following herbivory by bark beetles. Bark beetles have a corresponding defense mechanism for degrading toxic compounds, and glutathione S-transferases (GSTs) can catalyze the binding of endogenous substances that reduce glutathione (GSH) to various harmful electrophilic substrates, increasing their solubility and facilitating their excretion from cells. In this experiment, we successfully obtained sixteen full-length sequences of D. armandi, which belonged to four GST categories (delta, epsilon, sigma, and theta). The transcript levels of sixteen GSTs in D. armandi were compared at four developmental stages (larvae, pupae, teneral adults, and adults), three different tissues (antennae, gut, and reproductive organs), and under various levels of terpenoid stimuli during feeding on phloem tissue to evaluate the various relevant modes of action. This study aids in the understanding of the interaction between monoterpenes and beetles, and beetles’ detoxification through GSTs.

Cuidado maternal en Omaspides bistriata Boheman (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini)

Maternal care (subsociality): characterization of the different stages of maternal care and its efficiency as a strategy. Maternal care and larval development of Omaspides bistriata Boheman, 1862 (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini) are described; including characteristics and manner in which maternal care is given across the different stages of development of the specie (eggs, larvae, pupae and teneral adults). We report the oviposition of eggs, the duration to hatch the eggs, and the duration of larval period, pupal stage, and emergence. A life table and survival curve is presented covering all life stages. Changes in the behavior and feeding habits are also noted for the immatures and the attending mother.

Assessment of the toxicity of Carica papaya plant powders against Sitophilus zeamais (Mots) (Coleoptera: Curculionidae) on maize seeds during storage

The toxicity of Carica papaya plant parts powder (leaf, stem bark, root and flower) at different dosages (0.5, 1.0, 1.5, 2.0 and 2.5 g) against Sitophilus zeamais infesting stored maize grains were assessed at the Biology Laboratory of the Federal College of Agriculture, Ibadan. Treatments were admixed with 30 g of maize grains, infested with 10 teneral adults of S. zeamais and stored in 3.0 mm petri dishes. The experiment was laid out in completely randomized design (CRD) and replicated four times each. Data were collected on adult mortality, oviposition and percentage weight loss of the grain in each of the replicate. Data collected were analyzed using analysis of variance, while sample means were separated with the aid of least significant difference (LSD) at 5%. There were significant differences in adult mortality of S. zeamais treated with different dosages of the plant parts powder. The flower powder of the plant recorded the highest mean adult mortality (10) compared to the lowest adult mortality of 0.1 obtained at the control experiment. The flower part powder also revealed the lowest mean eggs laid (oviposition) (7.1) and the lowest grain damage loss (1.4%) when compared with the values of 18.7 and 40.0 obtained for mean eggs laid and percentage weight loss obtained with stem bark and control treatments respectively. This clearly showed that the powder of the flower of C. papaya showed good potential as bio-insecticide for protecting stored maize grains.

Biometry of the large dragonfly Anax imperator (Odonata: Aeshnidae): A study of traits from larval development to adults

Insect larval development affects adult traits but the biometric relationships are usually poorly understood, including large odonates. In this study, measurements of morphological traits of larvae, exuviae and adults of Anax imperator were recorded. They were used to investigate the effects of early development on adult morphology. Results showed an increase in larval length during the final instar and the length of its exuviae significantly exceeded that of the larva. Length and body mass of teneral adults were strongly related to the length of their exuviae. Adult males were significantly longer than adult females, while both had the same body mass at emergence. Length of teneral adults was negatively related to the date of emergence in both sexes. During maturation, body mass of males only increased slightly whereas that of females increased greatly. Mature specimens were also significantly longer than teneral individuals. Body mass of mature males and length of mature females were both associated with the date of capture. Wing length did not differ between sexes or from data available from Great Britain. This study underscores the importance of taking into account larval growth in order to better understand the adult traits of odonates.