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PubMed2026

Genetic inference in social insects: The continued utility of microsatellites in the sociogenomic era.

Social insects differ from many other biological systems because colonies function as integrated reproductive, ecological, and evolutionary units, often conceptualized as superorganisms. This organization makes genetic inference inherently hierarchical, often requiring genotyping across multiple biological levels: the colony, the population, the individual, and, in some cases, the cellular level. Although whole-genome sequencing and single-nucleotide polymorphism (SNP)-based approaches are now widely used in population genomics, microsatellites or short tandem repeats (STRs) remain a useful approach for cost-effective, low-input, and highly replicated genotyping, particularly in the hierarchical sampling designs common in social insect studies. Here, we review the utility and limitations of microsatellites in social insect research using a three-tiered framework spanning colony-, population-, and individual- or cellular-level analyses. Across these scales, microsatellites are especially valuable for colony delimitation, kinship inference, diagnostic screening of known reproductive systems, and low-input genotyping. By comparing the suitability of microsatellites with that of SNP-based and broader genomic approaches across these applications, this review links marker choice to biological scale, sampling design, and inferential goal in studies of social insects.

Journal Article↗
PubMed2026

The Adaptive Roles of Active Transposable Elements in Insect Hosts.

Active transposable elements (TEs) are capable of generating new insertions in genomes and have historically been viewed as genomic parasites due to their largely detrimental or neutral effects. However, emerging evidence suggests that these elements also play a crucial role in driving adaptive evolution in insects. This mini-review synthesizes recent findings on how active TEs contribute to insect adaptation through various mechanisms, including regulation of gene expression, structural variation, and epigenetic effects. Notable examples of adaptation driven by active TEs include their roles in insecticide resistance, morphological adaptations, tolerance to harsh climates, and antiviral immune responses. We argue that while host silencing mechanisms, such as the piRNA pathway, tightly regulate TE activity to minimize harmful effects, the context-dependent activation of active TEs can generate beneficial genetic variation that enhances insect adaptations to anthropogenic and climatic pressures. Future research that integrates long-read sequencing, single-cell omics, and gene editing techniques will provide a robust mechanistic foundation for understanding the adaptive significance of active TEs in insects, with important implications for pest management, pollinator protection, and evolutionary biology.

Journal Article↗
PubMed2004

Ice nucleation in solutions and freeze-avoiding insects-homogeneous or heterogeneous?

This article challenges the common view that solutions and cold-hardy freeze-avoiding insects always freeze by heterogeneous nucleation. Data are presented to show that the nucleation temperatures of a variety of solutions and freeze-avoiding insects are a function of the water volume as described by the data previously published by Bigg in 1953. The article also points out that the relationships between melting point depression and depression of nucleation temperature are different for samples undergoing homogeneous nucleation and those undergoing heterogeneous nucleation. Aqueous solutions and freeze-avoiding insects display a relationship like that of homogeneously nucleated samples. It is also argued that the identity of the "impurities" assumed to cause heterogeneous nucleation in aqueous solutions and insects is obscure and that the "impurities" have features which make their existence rather unlikely.

Acclimatization↗
PubMed2004

Exploiting the potential of insects for in vivo pathogenicity testing of microbial pathogens.

Conventional assays for quantifying the virulence of microbial pathogens and mutants have traditionally relied upon the use of a range of mammalian species. A number of workers have demonstrated that insects can be used for evaluating microbial pathogenicity and provide results comparable to those that can be obtained with mammals since one component of the vertebrate immune system, the innate immune response, remains similar to that found in insects. Larvae of the Greater Wax Moth Galleria mellonella have been used to evaluate the virulence of a range of bacterial and fungal pathogens and a correlation with the virulence of these microbes in mice has been established. This review highlights the similarities of the vertebrate and insect innate immune responses to infection and identifies the potential use of insects for the in vivo evaluation of the microbial pathogenicity.

Animals↗
PubMed2006

Baculovirus-mediated gene silencing in insect cells using intracellularly produced long double-stranded RNA.

Double-stranded RNA-mediated interference (RNAi) has recently emerged as a powerful reverse genetics tool to silence gene expression in multiple organisms, including plants, nematodes and insects. In this study, DNA vectors capable of promoting the synthesis of long hairpin dsRNAs in vivo from a DNA template to suppress gene expression in insect cells have been successfully constructed. The inhibition of the expression of a gene encoding enhanced green fluorescent protein (eGFP) in insect cells was demonstrated by using plasmid or baculovirus vectors. Both plasmid and baculovirus vectors were able to inhibit eGFP expression in a dose dependent manner. Complete inhibition was obtained when co-transfection ratios of target plasmid to inhibition plasmid were 1:1 and 1:0.1. Eighty percent suppression was still maintained even when the ratio of eGFP plasmid to 'hairpin' plasmid was as high as 1:0.01. When the hairpin dsRNAs were encoded in a baculovirus, the suppression was about 50% when the ratio of 'target' baculovirus to 'inhibition' baculovirus reached 1:10. Therefore, the designed plasmid and baculovirus vectors are useful to induce RNAi in insect cell systems.

Animals↗
PubMed2004

How the choice of method influence on the results in electrophysiological studies of insect olfaction.

In identifying the volatiles that insects use to locate suitable host plants, electrophysiological recordings of olfactory responses to plant volatiles may give important information. However, divergent results may be obtained with different recording techniques. To illustrate these differences, the results of a previous investigation using single cell recordings linked to a gas chromatograph (SCR-GC) are compared with the results obtained with an electroantennogram linked to a gas chromatograph (EAG-GC). Testing insects of the same species (Hylobius abietis) for the same test sample, 30 potent volatile compounds were identified by SCR-GC and 18 by EAG-GC. Of the 34 different compounds, 14 were identified by both techniques. Furthermore, when the same compound elicited detectable responses by both techniques, the response strength was usually not the same relative to the strongest response recorded by each technique. This shows that both EAG-GC and SCR-GC are important techniques in the identification of potent plant volatiles for insects. However, by using SCR-GC more information was obtained, information that can be crucial for understanding the insect-plant relationship.

Animals↗
PubMed2006

Exploring the role of insect host factors in the dynamics of Trypanosoma cruzi-Rhodnius prolixus interactions.

Members of the subfamily Triatominae, family Reduviidae, comprise a large number of insect species of which some are vectors of Trypanosoma cruzi, the causative agent of Chagas' disease. This article outlines research on the process of transformation and the dynamics of developmental stages of Trypanosoma cruzi in the triatomine insect hosts. Special attention is given to the interactions of parasites with gut molecules, and the gut environment, and with host developmental physiology and intestinal organization. The vector insect's permissiveness to Trypanosoma cruzi, which develops in the vector gut, largely depends on the host nutritional state, the parasite strain, trypanolytic compounds, digestive enzymes, lectins, resident bacteria in the gut and the endocrine system of the insect vector. Finally, the mechanisms of these interactions and their significance for Trypanosoma cruzi transmission are discussed.

Animals↗
PubMed2004

The extracellular constitutive production of chitin deacetylase in Metarhizium anisopliae: possible edge to entomopathogenic fungi in the biological control of insect pests.

The possible contribution of extracellular constitutively produced chitin deacetylase by Metarhizium anisopliae in the process of insect pathogenesis has been evaluated. Chitin deacetylase converts chitin, a beta-1,4-linked N-acetylglucosamine polymer, into its deacetylated form chitosan, a glucosamine polymer. When grown in a yeast extract-peptone medium, M. anisopliae constitutively produced the enzymes protease, lipase, and two chitin-metabolizing enzymes, viz. chitin deacetylase (CDA) and chitosanase. Chitinase activity was induced in chitin-containing medium. Staining of 7.5% native polyacrylamide gels at pH 8.9 revealed CDA activity in three bands. SDS-PAGE showed that the apparent molecular masses of the three isoforms were 70, 37, and 26 kDa, respectively. Solubilized melanin (10microg) inhibited chitinase activity, whereas CDA was unaffected. Following germination of M. anisopliae conidia on isolated Helicoverpa armigera, cuticle revealed the presence of chitosan by staining with 3-methyl-2-benzothiazoline hydrazone. Blue patches of chitosan were observed on cuticle, indicating conversion of chitin to chitosan. Hydrolysis of chitin with constitutively produced enzymes of M. anisopliae suggested that CDA along with chitosanase contributed significantly to chitin hydrolysis. Thus, chitin deacetylase was important in initiating pathogenesis of M. anisopliae softening the insect cuticle to aid mycelial penetration. Evaluation of CDA and chitinase activities in other isolates of Metarhizium showed that those strains had low chitinase activity but high CDA activity. Chemical assays of M. anisopliae cell wall composition revealed the presence of chitosan. CDA may have a dual role in modifying the insect cuticular chitin for easy penetration as well as for altering its own cell walls for defense from insect chitinase.

Amidohydrolases↗
PubMedDate not supplied

Leishmania parasites (Kinetoplastida: Trypanosomatidae) reversibly inhibit visceral muscle contractions in hemimetabolous and holometabolous insects.

Female sand flies can acquire protozoan parasites in the genus Leishmania when feeding on an infected vertebrate host. The parasites complete a complex growth cycle in the sand fly gut until they are transmitted by bite to another host. Recently, a myoinhibitory peptide was isolated from Leishmania major promastigotes. This peptide caused significant gut distension and reversible, dose-dependent inhibition of spontaneous hindgut contractions in the enzootic sand fly vector, Phlebotomus papatasi. The current study further characterizes myoinhibitory activity in L. major and other kinetoplastid parasites, using the P. papatasi hindgut and other insect organ preparations. Myoinhibitory activity was greatest in cultured promastigotes and in culture medium in late log-phase and early stationary-phase, coinciding with development of infective Leishmania morphotypes in the sand fly midgut. L. major promastigote lysates inhibited spontaneous contractions of visceral muscle preparations from hemimetabolous (Blattaria and Hemiptera) and holometabolous (Diptera) insects. Inhibition of visceral muscle contractions in three insect orders indicates a conserved mode of action. Myoinhibitory activity was detected also in Leishmania braziliensis braziliensis, a Sudanese strain of Leishmania donovani, and the kinetoplastid parasite Leptomonas seymouri. Protozoan-induced myoinhibition mimics the effect of insect myotropins. Inhibiting host gut contractions protects Leishmania parasites from being excreted after blood meal and peritrophic matrix digestion, allowing development and transmission of infective forms.

Animals↗
PubMed2005

The influence of Conidiobolus coronatus on phagocytic activity of insect hemocytes.

An essential component of the insect cellular response is phagocytosis. Analyses of the in vitro phagocytosis could be useful for the studies of the relationship between insects and their pathogens. Fungal metabolites are known to inhibit phagocytosis whereas components of the fungal cell wall stimulate phagocytosis. To achieve a better understanding of fungal pathogenesis in insects, haemocyte populations of two insect species susceptible to Conidiobolus coronatus infection (Galleria mellonella, Dendrolimus pini ) were compared with haemocytes of the resistant species (Calliphora erythrocephala ). Fungal infection increased phagocytic activity of G. mellonella plasmatocytes 3.3 times and this of D. pini plasmatocytes 2.1 times. Analysis of infected C. erythrocephala larvae did not reveal any influence of C. coronatus upon phagocytic activity.

Animals↗
PubMed2006

Tethered stick insect walking: a modified slippery surface setup with optomotor stimulation and electrical monitoring of tarsal contact.

A modified and improved setup based on Epstein and Graham [Epstein S, Graham D. Behaviour and motor output of stick insects walking on a slippery surface. I. Forward walking. J Exp Biol 1983;105: 215-29] to study straight and curve walking in the stick insect was developed and applications for its use are described. The animal is fixed on a balsa stick and walks freely on a slippery surface created with a thin film of a glycerin/water solution on a black, Ni-coated, polished brass plate. The glycerine/water ratio controls the viscosity of the lubricant and thereby the forces necessary to move the legs of the stick insect. A small amount of NaCl is added to ensure electric conductivity. Walking is induced through an optomotor stimulus given by two stripe-projectors producing rotatory and translatory stimuli to influence walking direction. The walking pattern is monitored in two ways: (1) tarsal contact with the slippery surface is measured electrically using a lock-in-amplifier. The tarsal contact signal allows correlation with the activity in different muscles of the stick insect leg recorded with EMG electrodes; (2) leg kinematics in the horizontal plane is monitored using synchronized high speed video. This setup allows us to determine the coupling of activity in different leg muscles to either swing or stance phase during straight and curve walking in the intact animal or the reduced single-leg preparation with a high time resolution.

Animals↗
PubMed2006

Curvature facilitates prey fixation in predatory insect claws.

Insects show a large variety in prey capture strategies, with a correspondingly large diversity in predatory adaptations. We studied a specific type of predatory claws, these can for example be found in praying mantis species. The claw is closeable over its entire length and the prey is fixed between the femur (upper arm) and the tibia (lower arm) of the insect leg. The morphology of these predatory claws is diverse. Some species have straight claws covered with spines, while other species have smooth, curved claws. We have studied the mechanics of this femur-tibia type of predatory insect claws, by making a physical model, eventually trying to explain why in some insect species the claws are curved instead of straight. The main results are (1) when comparing curved claws to straight claws, curvature leads to a strong reduction of forces driving the prey away from the pivoting point, thereby reducing the need for friction generating structures. (2) In the curved claw model a position exists where the resulting force on the prey is exactly zero. This is because the normal forces on the femur and tibia are opposed, and in line. At this position the prey is perfectly clamped and not driven out of the claw. This feature does not exist in straight claws. (3) In the curved claw, the prey cannot be placed at a position further than a certain maximum distance from the pivoting point. Near this maximum position, the resulting force on the prey reaches high values because moment arms are near zero. (4) Between the zero position and the maximum position the resulting force is directed toward the pivoting point, which stabilizes prey fixation.

Adaptation, Physiological↗
PubMed2006

Angiotensin-converting enzyme as a target for the development of novel insect growth regulators.

Insect angiotensin converting enzyme (ACE) is a zinc metallopeptidase capable of inactivating a variety of small to medium size peptide hormones by cleavage of C-terminal dipeptides and dipeptideamides. High levels of ACE activity are found in the hemolymph and in reproductive tissues of insects, where the enzyme is considered to have an important role in the metabolism of bioactive peptides. Therefore, inhibiting ACE activity is expected to interfere with the peptidergic endocrine system and to have detrimental effects on growth, development and reproduction. We will review the studies showing that ACE inhibitors do indeed disrupt growth and reproduction in various insect species. We will also present some new genetic and pharmacological data that strengthens our conclusion that ACE should be considered as a potential target for the development of new insect growth regulators.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2004

Insect growth inhibition by tocotrienols and hydroquinones from Roldana barba-johannis.

The methanol extract from the aerial parts of Roldana barba-johannis (Asteraceae) afforded sargachromenol, sargahydroquinoic acid, and sargaquinoic acid. These natural products and their corresponding acetylated and methylated derivatives showed insecticidal and insect growth regulatory activities against the Fall Armyworm [Spodoptera frugiperda J.E. Smith, (Lepidoptera: Noctuidae)], an important insect pest of corn. The most active compounds were sargachromenol and its acetylated derivative; sargahydroquinoic acid and its acetylated derivative; and a mixture of sargachromenol, sargahydroquinoic acid, and sargaquinoic acid (6:3:1) and the acetylated form of this mixture. All these compounds and mixtures had significant inhibitory effects between 5.0 and 20.0 ppm in diets. Most compounds were insecticidal to larvae, with lethal doses between 20 and 35 ppm. In addition, these substances also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl radical in TLC autographic and spectrophotometric assays. These compounds appear to have selective effects on the pre-emergence metabolism of the insect. The results from these compounds were fully comparable in activity to those known natural insect growth inhibitors such as gedunin and methanol extracts of Cedrela salvadorensis and Yucca periculosa. These substances may be useful as natural insecticidal agents.

Animals↗
PubMed2005

Insect growth regulatory effects of some extracts and sterols from Myrtillocactus geometrizans (Cactaceae) against Spodoptera frugiperda and Tenebrio molitor.

A methanol extract from the roots and aerial parts of Myrtillocactus geometrizans (Cactaceae) yielded peniocerol 1, macdougallin 2, and chichipegenin 3. The natural products 1, 2 their mixtures, MeOH and CH(2)Cl(2) extracts showed insecticidal and insect growth regulatory activity against fall armyworm [Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae)], an important insect pest of corn, and [Tenebrio molitor (Coleoptera)], a pest of stored grains in Mexico. The most active compounds were 1, 2, and a mixture (M(2)) of 1 and 2 (6:4). All these extracts, compounds and the mixture had insect growth regulating (IGR) activity between 5.0 and 50.0 ppm and insecticidal effects between 50 and 300 ppm in diets. The extracts were insecticidal to larvae, with lethal doses between 100 and 200 ppm. These compounds appear to have selective effects on the pre-emergence metabolism of Coleoptera, because in all treatments of the larvae of T. molitor, pupation were shortened and this process show precociousness in relation to controls. In contrast to S. frugiperda larvae, onset of pupation was noticeably delayed. Emergence in both cases was drastically diminished. In both pupae and in the few adults that were able to emerge, many deformations were observed. The results of these assays indicated that the compounds were more active than other known natural insect growth inhibitors such as gedunin and methanol extracts of Cedrela salvadorensis and Yucca periculosa. Peniocerol, macdougallin and chichipegenin, as well as mixtures of these substances, may be useful as natural insecticidal agents.

Animals↗
PubMed2006

Ebola virus-like particles produced in insect cells exhibit dendritic cell stimulating activity and induce neutralizing antibodies.

Recombinant baculoviruses (rBV) expressing Ebola virus VP40 (rBV-VP40) or GP (rBV-GP) proteins were generated. Infection of Sf9 insect cells by rBV-VP40 led to assembly and budding of filamentous particles from the cell surface as shown by electron microscopy. Ebola virus-like particles (VLPs) were produced by coinfection of Sf9 cells with rBV-VP40 and rBV-GP, and incorporation of Ebola GP into VLPs was demonstrated by SDS-PAGE and Western blot analysis. Recombinant baculovirus infection of insect cells yielded high levels of VLPs, which were shown to stimulate cytokine secretion from human dendritic cells similar to VLPs produced in mammalian cells. The immunogenicity of Ebola VLPs produced in insect cells was evaluated by immunization of mice. Analysis of antibody responses showed that most of the GP-specific antibodies were of the IgG2a subtype, while no significant level of IgG1 subtype antibodies specific for GP was induced, indicating the induction of a Th1-biased immune response. Furthermore, sera from Ebola VLP immunized mice were able to block infection by Ebola GP pseudotyped HIV virus in a single round infection assay, indicating that a neutralizing antibody against the Ebola GP protein was induced. These results show that production of Ebola VLPs in insect cells using recombinant baculoviruses represents a promising approach for vaccine development against Ebola virus infection.

Animals↗
PubMed2006

Why do highly polarizing black burnt-up stubble-fields not attract aquatic insects? An exception proving the rule.

Horizontal black surfaces are usually very attractive to polarotactic aquatic insects, since they generally reflect highly and horizontally polarized light, and thus imitate water surfaces. We monitored highly polarizing black burnt-up stubble-fields, but surprisingly never found aquatic insects or their carcasses in the ash, although flying polarotactic insects were abundant in the area, which we showed by attracting them to horizontal black plastic sheets. To explain this observation, we measured the reflection-polarization characteristics of burnt-up stubble-fields in the red (650 nm), green (550 nm) and blue (450 nm) parts of the spectrum at three directions of view relative to the solar meridian. We established that (i) the degree of linear polarization p of light reflected from the black ash is high; (ii) p is the higher, the darker the ash; (iii) the direction of polarization of reflected light is nearly horizontal only towards the solar and antisolar meridians, and it is tilted in other directions of view; (iv) the standard deviation of both the degree and the direction of polarization of reflected light is large. The latter two characteristics explain why burnt-up stubble-fields are unattractive to aquatic insects. These results may be important in the study of the wider environmental effects of post-harvest burning.

Animals↗
PubMed2006

even-skipped has gap-like, pair-rule-like, and segmental functions in the cricket Gryllus bimaculatus, a basal, intermediate germ insect (Orthoptera).

Developmental mechanisms of segmentation appear to be varied among insects in spite of their conserved body plan. Although the expression patterns of the segment polarity genes in all insects examined imply well conserved function of this class of genes, expression patterns and function of the pair-rule genes tend to exhibit diversity. To gain further insights into the evolution of the segmentation process and the role of pair-rule genes, we have examined expression and function of an ortholog of the Drosophila pair-rule gene even-skipped (eve) in a phylogenetically basal insect, Gryllus bimaculatus (Orthoptera, intermediate germ cricket). We find that Gryllus eve (Gb'eve) is expressed as stripes in each of the prospective gnathal, thoracic, and abdominal segments and as a broad domain in the posterior growth zone. Dynamics of stripe formation vary among Gb'eve stripes, representing one of the three modes, the segmental, incomplete pair-rule, and complete pair-rule mode. Furthermore, we find that RNAi suppression of Gb'eve results in segmentation defects in both anterior and posterior regions of the embryo. Mild depletion of Gb'eve shows a pair-rule-like defect in anterior segments, while stronger depletion causes a gap-like defect showing deletion of anterior and posterior segments. These results suggest that Gb'eve acts as a pair-rule gene at least during anterior segmentation and also has segmental and gap-like functions. Additionally, Gb'eve may be involved in the regulation of hunchback and Krüppel expression. Comparisons with eve functions in other species suggest that the Gb'eve function may represent an intermediate state of the evolution of pair-rule patterning by eve in insects.

Amino Acid Sequence↗