Coconut rhinoceros beetle digestive symbiosis with potential plant cell wall degrading microbes

Coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is an invasive palm pest whose larvae eat wood, yet lack the necessary digestive enzymes. This study confirmed endogenous CRB cellulase is inactive, suggesting microbial fermentation. The inner lining of the CRB hindgut has tree-like structures covered with a conspicuous biofilm. To identify possible symbionts, 16 S rRNA amplicon sequencing was used on individuals from across Taiwan. Several taxa of Clostridia, an anaerobic class including many cellulolytic bacteria, were highly abundant in most individuals from all locations. Whole metagenome sequencing further confirmed many lignocellulose degrading enzymes are derived from these taxa. Analyses of eggs, larvae, adults, and soil found these cellulolytic microbes are not transmitted vertically or transstadially. The core microbiomes of the larval CRB are likely acquired and enriched from the environment with each molt, and enable efficient digestion of wood.

A practical guide to collections-based research on ecogeographic rules

Ecogeographic research into how species' forms vary across space, time, and climate has taken on new urgency due to contemporary global climate change. Research using museum specimens and other records to study biological rules like Bergmann's, Allen's, and Gloger's Rules has a long history and continues to generate publications and robust scientific debates. Despite the prevalence and history of the field, however, no simple guide on how to carry out such work has ever been published. To lower the barriers of entry for new researchers, this review was created as a practical guide on how to perform ecogeographic research. The guide consolidates disparately published methodologies into a single, convenient document that reviews the history and present of the field of ecogeographic rule research, and describes how to generate appropriate hypotheses, design experiments, gather, and analyze biotic and geographic data, and interpret the results in an ecologically meaningful manner. The result is a semi-standardized guide that enables scientists at all levels from any institution to carry out an investigation from start to finish on any biological rule, taxon, and location of their choice.

Anatomical changes of the beetle digestive tract during metamorphosis correspond to dietary changes

During pupation, the tissues of holometabolous insects change in preparation for the adult lifestyles, although little literature exists examining this hidden process in detail. Using beetles as a model, we hypothesized that species where the adult and larva have the same diets will show less pronounced changes of the digestive tract during metamorphosis than species where the adults diets differ. We also wanted to observe these changes and document them at a level of detail missing from the current record. We compared the structure of the digestive tracts of scarab beetles Oryctes rhinoceros, Thaumastopeus shangaicus, and Protaetia spp. (Coleoptera: Scarabaeidae)-where the larvae eat wood, soil, or compost while the adults feed on soft plant matter, tree sap, and rotting fruits-with the tortoise beetle, Cassida circumdata (Coleoptera: Chrysomelidae), which feeds on leaves as both larva and adult. In the scarab beetles we observed considerable changes in the digestive tracts during the pupal stage, which we could divide into distinct stages, while in the leaf beetle pupae, the gut did not change. This information can provide new insight into metamorphosis, and the illustrations of what occurs during pupation are novel contributions to this field that will facilitate future work.

Chryseobacterium oryctis sp. nov., isolated from the gut of the beetle Oryctes rhinoceros, and Chryseobacterium kimseyorum sp. nov., isolated from a stick insect rearing cage

Two strains of Chryseobacterium identified from different experiments are proposed to represent new species. Strain WLa1L2M3T was isolated from the digestive tract of an Oryctes rhinoceros beetle larva. Strain 09-1422T was isolated from a cage housing the stick insect Eurycantha calcarata. Sequence analysis of the 16S rRNA and rpoB genes found both strains to be similar but not identical to other Chryseobacterium species. Whole-genome sequencing suggested the isolates represent new species, with average nucleotide identity values ranging from 74.6 to 80.5 %. Genome-to-genome distance calculations produced values below 25.3 %, and digital DNA-DNA hybridization values were 13.7-29.9 %, all suggesting they are distinct species. The genomic DNA G+C content of WLa1L2M3T is approximately 32.53 %, and of 09-1422T is approximately 35.89 %. The predominant cellular fatty acids of strain WLa1L2M3T are C15 : 0 iso, summed feature 9 (C16 : 0 10OH or C17 : 1 iso ω6c), C17 : 0 iso 3OH, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C15 : 0 iso 3OH, C15 : 0 anteiso and C13 : 0 iso, and those of strain 09-1422T are C15 : 0 iso, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C17 : 0 iso 3OH, C15 : 0 anteiso, C15 : 0 iso 3OH, C16 : 1 ω7c, C17 : 0 2OH and C18 : 0. In addition, physiological and biochemical tests revealed phenotypic differences from related Chryseobacterium type strains. These cumulative data indicate that the two strains represent novel species of the genus Chryseobacterium for which the names Chryseobacterium oryctis sp. nov. and Chryseobacterium kimseyorum sp. nov. are proposed with WLa1L2M3T (=BCRC 81350T=JCM 35215T=CIP 112035T) and 09-1422T (=UCDFST 09-1422T=BCRC 81359T=CIP 112165T), as type strains, respectively.

Cytochrome P450 Genes Expressed in Phasmatodea Midguts

Cytochrome P450s (CYPs) are xenobiotic detoxification genes found in most eukaryotes, and linked in insects to the tolerance of plant secondary chemicals and insecticide resistance. The number and diversity of CYP clans, families, and subfamilies that an organism produces could correlate with its dietary breadth or specialization. This study examined the CYP diversity expressed in the midguts of six species of folivorous stick insects (Phasmatodea), to identify their CYP complement and see if any CYPs correlate with diet toxicity or specialization, and see what factors influenced their evolution in this insect order. CYP genes were mined from six published Phasmatodea transcriptomes and analyzed phylogenetically. The Phasmatodea CYP complement resembles that of other insects, though with relatively low numbers, and with significant expansions in the CYP clades 6J1, 6A13/14, 4C1, and 15A1. The CYP6 group is known to be the dominant CYP family in insects, but most insects have no more than one CYP15 gene, so the function of the multiple CYP15A1 genes in Phasmatodea is unknown, with neofunctionalization following gene duplication hypothesized. No correlation was found between CYPs and diet specialization or toxicity, with some CYP clades expanding within the Phasmatodea and others likely inherited from a common ancestor.

Increasing Body Sizes in Anomala expansa expansa (Coleoptera: Scarabaeidae) Populations in Response to Rising Temperatures Over Time

Many insects have been studied over wide geographical areas to determine whether they follow Bergmann's Rule, which predicts that animal clades or populations should have smaller body sizes in warmer climates. While this ecogeographic rule is well supported in mammals and birds, insect latitudinal sizes can show Bergmann, converse Bergmann, or no size clines at all. Museum collections are typical sources of data for insect clines, and long-term collections should reflect rising global temperatures and shifting climates, possibly producing temporal size clines along with any geographical clines. We hypothesize that insects with Bergmann clines geographically will show Bergmann-like clines temporally as well, and that the converse and inverse of this rule are also true. By looking at museum samples going back a century, we tested whether Anomala expansa expansa (Bates, 1866), a species of Scarabaeidae beetle common in lowland Taiwan, was experiencing long-term changes in body size in response to rising temperatures. We found that overall, the size of these beetles increased over time. Within Taipei populations, this increase was correlated with rising average yearly temperatures. The impact of this pest species' rising size with time will need to be monitored, and temporal size clines in other pests need to be investigated.

Thiamine (vitamin B1) as an insect repellent: a scoping review

While the desire for systemic repellents is high, ineffective repellents put one at risk of insect-vectored pathogens. Vitamin B1, or thiamine, has been touted as a systemic insect repellent since 1943, and denounced as an ineffective placebo for just as long. This paper presents a scoping review of 104 relevant case reports, research studies, and review articles to trace the evolution of this idea and identify an evidence-based, scientific consensus. Reports of thiamine's systemic repellency are primarily anecdotal and based on uncontrolled trials and/or used bite symptoms as a proxy for reduced biting. Controlled experiments on insect landing and feeding found no evidence of repellency. Of the 49 relevant review papers, 16 insect bite prevention guidelines, and 4 government documents, none after the 1990s claimed thiamine is a repellent. The findings of this review are that thiamine cannot repel arthropods in any dosage or route of administration. Due to limited available evidence, the possibility that thiamine reduces the subjective symptoms of insect bites cannot currently be ruled out. Unfortunately, many medical professionals and travelers today still believe thiamine may be effective despite the evidence stating otherwise. Continued promotion of debunked repellents on the commercial market poses a serious risk in countries with the endemic, mosquito-vectored disease.

Pseudomonas schmalbachii sp. nov., isolated from the gut of a millipede (Trigoniulus corallinus) from a coconut tree

During an investigation of microbes associated with arthropods living in decaying coconut trees, a Pseudomonas isolate, Milli4^T, was cultured from the digestive tract of the common Asian millipede, Trigoniulus corallinus. Sequence analysis of 16S rRNA and rpoB genes found that Milli4^T was closely related but not identical to Pseudomonas panipatensis Esp-1^T, Pseudomonas knackmussi B13^T and Pseudomonas humi CCA1^T. Whole genome sequencing suggested that this isolate represents a new species, with average nucleotide identity (OrthoANIu) values of around 83.9-87.7% with its closest relatives. Genome-to-genome distance calculations between Milli4^T and its closest relatives also suggested they are distinct species. The genomic DNA G+C content of Milli4^T was approximately 65.0 mol%. Phenotypic and chemotaxonomic characterization and fatty acid methyl ester analysis was performed on Milli4^T and its related type strains. Based on these data, the new species Pseudomonas schmalbachii sp. nov. is proposed, and the type strain is Milli4^T (=BCRC 81294^T=JCM 34414^T=CIP 111980^T).

Syzygium samarangense Leaf Infusion as Aedes albopictus (Diptera: Culicidae) Ovitrap Bait

Adding lures can improve the efficiency of mosquito ovitraps used for monitoring or in attract-and-kill pest management. Easily produced, low-to-no cost bait would be ideal for remote field sites and community-run vector management. Plant infusions are popular ovitrap baits for their low cost and potent attractiveness, attributed either to the plants or their microbiomes. We tested fermented leaf infusions of the wax apple tree, Syzygium samarangense (Blume) Merr. & Perry, as bait in lethal ovitraps in urban Taipei with Bti larvicide. All trapped insects were inferred to be Asian tiger mosquito, Aedes albopictus (Skuse). The bait significantly increased the yield of the traps, with no negative interactions with the larvicide in either direction. Syzgium samarangense leaves are readily available across Taiwan, making their infusion an easy bait to greatly improve ovitrap efficiency.

Evolution of CP2 transcription factors in Hexapoda

The CP2 transcription factors are highly conserved in metazoans, where they are divided into two groups: grainyhead and late SV40 factor (LSF). We traced their evolutionary history in the Hexapoda using over 500 insect transcriptomes, to test the hypothesis that the evolution of holometaboly involved novel isoforms of these genes. All insects appear to express at least one grainyhead and one LSFlike gene, regardless of life cycle, as in most known metazoa. No major evolutionary events in these gene families occurred during the evolution of insects.

Culturing-Enriched Metabarcoding Analysis of the Oryctes rhinoceros Gut Microbiome

Simple Summary

The coconut rhinoceros beetle is a pest of palm trees, which may have symbiotic gut microbes that help it digest its food. These microbes may produce enzymes like cellulase, which have uses in human industry. If the microbes are essential for the beetle’s survival, then finding ways to attack the microbes could help fight the pest. We sampled microbes from the guts of larval beetles collected in coconut trees in southern Taiwan, and identified the microbes both by culturing and with molecular biology methods. We found several species of bacteria and a yeast, Candida xylanolytica, with potential digestive functions for the beetle. Some of these microbes had been reported in these beetles before while others are new. Broader surveys of the beetle microbiome are needed to determine whether or not they have a conserved microbiome.

Abstract

Wood-feeding insects should have a source of enzymes like cellulases to digest their food. These enzymes can be produced by the insect, or by microbes living in the wood and/or inside the insect gut. The coconut rhinoceros beetle, Oryctes rhinoceros, is a pest whose digestive microbes are of considerable interest. This study describes the compartments of the O. rhinoceros gut and compares their microbiomes using culturing-enriched metabarcoding. Beetle larvae were collected from a coconut grove in southern Taiwan. Gut contents from the midgut and hindgut were plated on nutrient agar and selective carboxymethylcellulose agar plates. DNA was extracted from gut and fat body samples and 16S rDNA metabarcoding performed to identify unculturable bacteria. Cellulase activity tests were performed on gut fluids and microbe isolates. The midgut and hindgut both showed cellulolytic activity. Bacillus cereus, Citrobacter koseri, and the cellulolytic fungus Candida xylanilytica were cultured from both gut sections in most larvae. Metabarcoding did not find Bacillus cereus, and found that either Citrobacter koseri or Paracoccus sp. were the dominant gut microbes in any given larva. No significant differences were found between midgut and hindgut microbiomes. Bacillus cereus and Citrobacter koseri are common animal gut microbes frequently found in Oryctes rhinoceros studies while Candida xylanilytica and the uncultured Paracoccus sp. had not been identified in this insect before. Some or all of these may well have digestive functions for the beetle, and are most likely acquired from the diet, meaning they may be transient commensalists rather than obligate mutualists. Broader collection efforts and tests with antibiotics will resolve ambiguities in the beetle–microbe interactions.

Identification of a Novel Picorna-like Virus in Coconut Rhinoceros Beetles (Oryctes rhinoceros)

A novel Picorna-like virus, tentatively named Oryctes rhinoceros Picorna-like virus 1 (OrPV1), was identified in coconut rhinoceros beetle (Oryctes rhinoceros) larvae in Taiwan. The complete genome sequence consisted of 9,665 nucleotides with a polyA tail and included one open reading frame. Conserved structural domains such as Picornavirus capsid protein, RNA helicase, Peptidase and RNA-dependent RNA polymerase (RdRp) were identified through Pfam domain searches. The genome shares approximately 27-28% identity with other unclassified Picornavirales that infect honey bees (Darwin bee virus 2, Bundaberg bee virus 5, and Sacbrood virus) and a recently reported virus from Asian lady beetle (Harmonia axyridis virus 1). We did not detect this virus in any other geographical populations of O. rhinoceros collected from the South Pacific Islands and the Philippines. Analysis of the deduced RdRp amino acid sequences showed that the virus clustered with other Picorna-like viruses and separated from other members of family Dicistroviridae and Iflaviridae.

Microbes Associated With Black Soldier Fly (Diptera: Stratiomiidae) Degradation of Food Waste

Black soldier fly (Hermetia illucens L.) larvae are capable of valorizing waste by converting it into insect biomass that can be used as animal feed, leaving undigested residue that can be used as soil enrichment. Evidence is conflicting over whether larvae fed substrate containing pathogenic microbes emerge uncontaminated. Studies also differ on which clades comprise the species' gut microbiome, and on whether and how diet affects these microbes. Using culturing and metabarcoding, the bacterial microbiota of black soldier fly larvae reared on two different kinds of food waste (postproduction soy pulp and postconsumer cafeteria waste) were analyzed, along with the microbes of their substrates. Little to no overlap was found between the wastes, the larvae, and the residues, but the larvae fed different foods had a significant percentage of their microbes in common. The data, in line with other works on this species, suggest the larvae have a conserved microbiota whose components vary geographically.

Who's afraid of DEET? Fearmongering in papers on botanical repellents

DEET (N,N-Diethyl-meta-toluamide) is considered the gold standard in mosquito repellents, not only for its effectiveness, but also for its safety. DEET has been more extensively studied for safety than any other repellent, and is accepted as completely safe when used correctly (i.e. not consumed or bathed in). Researchers studying botanical repellents, however, often paint DEET as far more toxic than it really is, falsely claiming it is a menace to the public health or even the environment. These claims are unfounded, and often the only evidence given by such publications are references to other publications also studying botanical repellents. Such publications are biased, and may be attacking DEET’s excellent safety record to justify their existence and the need for their research. The inconvenient yet undisputable fact is that no botanical repellent has been proven to be as safe as DEET, and the majority never had any safety testing whatsoever. The automatic assumption that botanical repellents are safer than DEET is the ‘appeal to nature fallacy,’ which also drives most of the market for “natural” repellents, yet natural repellents have side effects and even a body count. Finding a botanical repellent that works as well as DEET and is equally safe is a legitimate research goal on its own, and need not be justified by fear-mongering and irrational chemophobia. Researchers studying these alternatives should strive for integrity, raising the real issue of the lack of safety testing for botanical repellents rather than denying the proven safety of DEET.

Multifunctional cellulase enzymes are ancestral in Polyneoptera

Many hemimetabolous insects produce their own cellulase enzymes from the glycoside hydrolase family 9, first observed in termites and cockroaches. Phasmatodea have multiple cellulases, some of which are multifunctional and can degrade xylan or xyloglucan. To discover when these abilities evolved, we identified cellulases from the Polyneoptera sampled by the 1000 Insect Transcriptome and Evolution (1KITE) project, including all cockroach and termite transcriptomes. We hoped to identify what role enzyme substrate specificities had in the evolution of dietary specification, such as leaf-feeding or wood-feeding. Putative cellulases were identified from the transcriptomes and analysed phylogenetically. All cellulases were amplified from an exemplar set of Polyneoptera species using rapid amplification of cDNA ends PCR and heterologously expressed in an insect cell line, then tested against different polysaccharides for their digestive abilities. We identified several multifunctional xyloglucanolytic enzymes across Polyneoptera, plus a large group of cellulase-like enzymes found in nearly all insect orders with no discernible digestive ability. Multifunctional xylanolytic cellulases remain unique to Phasmatodea. The presence or absence of multifunctional enzymes does not impact dietary specification, but rather having multiple, multifunctional cellulase genes is an ancestral state for Polyneoptera and possibly Insecta. The prevalence of multifunctional cellulases in other animals demands further investigation.

The unique antimicrobial peptide repertoire of stick insects

The comparative analysis of innate immunity across different insect taxa has revealed unanticipated evolutionary plasticity, providing intriguing examples of immunity-related effector gene expansion and loss. Phasmatodea, the stick and leaf insects, is an order of hemimetabolous insects that can provide insight into ancestral innate immunity genes lost by later insect clades. We injected the stick insect Peruphasma schultei with a mixture of microbial elicitors to activate a strong immune response, followed by RNA-Seq analysis to screen for induced immunity-related effector genes. This revealed a highly diverse spectrum of antimicrobial peptides (AMPs) belonging to the attacin, coleoptericin, defensin, thaumatin, and tachystatin families. In addition, we identified a large group of short, cysteine-rich putative AMPs, some of which were strongly elicited. The immunity-related effector gene repertoire also included c-type and i-type lysozymes and several pattern-recognition proteins, such as proteins that recognize Gram-negative bacteria and peptidoglycans. Finally, we identified 45 hemolymph lipopolysaccharide-binding protein sequences, an unusually large number for insects. Taken together, our results indicate that at least some phasmids synthesize a broad spectrum of diverse AMPs that deserve further in-depth analysis.

Transcriptome and microbiome of coconut rhinoceros beetle (Oryctes rhinoceros) larvae

BACKGROUND

The coconut rhinoceros beetle, Oryctes rhinoceros, is a major pest of palm crops in tropical Asia and the Pacific Islands. Little molecular data exists for this pest, impeding our ability to develop effective countermeasures and deal with the species' growing resistance to viral biocontrols. We present the first molecular biology analyses of this species, including a metagenomic assay to understand the microbiome of different sections of its digestive tract, and a transcriptomics assay to complement the microbiome data and to shed light on genes of interest like plant cell wall degrading enzymes and immunity and xenobiotic resistance genes.

RESULTS

The gut microbiota of Oryctes rhinoceros larvae is quite similar to that of the termite gut, as both species feed on decaying wood. We found the first evidence for endogenous beta-1,4-endoglucanase in the beetle, plus evidence for microbial cellobiase, suggesting the beetle can degrade cellulose together with its gut microfauna. A number of antimicrobial peptides are expressed, particularly by the fat body but also by the midgut and hindgut.

CONCLUSIONS

This transcriptome provides a wealth of data about the species' defense against chemical and biological threats, has uncovered several potentially new species of microbial symbionts, and significantly expands our knowledge about this pest.

Ancestral gene duplication enabled the evolution of multifunctional cellulases in stick insects (Phasmatodea)

The Phasmatodea (stick insects) have multiple, endogenous, highly expressed copies of glycoside hydrolase family 9 (GH9) genes. The purpose for retaining so many was unknown. We cloned and expressed the enzymes in transfected insect cell lines, and tested the individual proteins against different plant cell wall component poly- and oligosaccharides. Nearly all isolated enzymes were active against carboxymethylcellulose, however most could also degrade glucomannan, and some also either xylan or xyloglucan. The latter two enzyme groups were each monophyletic, suggesting the evolution of these novel substrate specificities in an early ancestor of the order. Such enzymes are highly unusual for Metazoa, for which no xyloglucanases had been reported. Phasmatodea gut extracts could degrade multiple plant cell wall components fully into sugar monomers, suggesting that enzymatic breakdown of plant cell walls by the entire Phasmatodea digestome may contribute to the Phasmatodea nutritional budget. The duplication and neofunctionalization of GH9s in the ancestral Phasmatodea may have enabled them to specialize as folivores and diverge from their omnivorous ancestors. The structural changes enabling these unprecedented activities in the cellulases require further study.

Differential expression of endogenous plant cell wall degrading enzyme genes in the stick insect (Phasmatodea) midgut

BACKGROUND

Stick and leaf insects (Phasmatodea) are an exclusively leaf-feeding order of insects with no record of omnivory, unlike other "herbivorous" Polyneoptera. They represent an ideal system for investigating the adaptations necessary for obligate folivory, including plant cell wall degrading enzymes (PCWDEs). However, their physiology and internal anatomy is poorly understood, with limited genomic resources available.

RESULTS

We de novo assembled transcriptomes for the anterior and posterior midguts of six diverse Phasmatodea species, with RNA-Seq on one exemplar species, Peruphasma schultei. The latter's assembly yielded >100,000 transcripts, with over 4000 transcripts uniquely or more highly expressed in specific midgut sections. Two to three dozen PCWDE encoding gene families, including cellulases and pectinases, were differentially expressed in the anterior midgut. These genes were also found in genomic DNA from phasmid brain tissue, suggesting endogenous production. Sequence alignments revealed catalytic sites on most PCWDE transcripts. While most phasmid PCWDE genes showed homology with those of other insects, the pectinases were homologous to bacterial genes.

CONCLUSIONS

We identified a large and diverse PCWDE repertoire endogenous to the phasmids. If these expressed genes are translated into active enzymes, then phasmids can theoretically break plant cell walls into their monomer components independently of microbial symbionts. The differential gene expression between the two midgut sections provides the first molecular hints as to their function in living phasmids. Our work expands the resources available for industrial applications of animal-derived PCWDEs, and facilitates evolutionary analysis of lower Polyneopteran digestive enzymes, including the pectinases whose origin in Phasmatodea may have been a horizontal transfer event from bacteria.

Endogenous cellulase enzymes in the stick insect (Phasmatodea) gut

High cellulase (endo-beta-1,4-glucanase) activity was detected in the anterior midgut of the walking stick (Phasmatodea) Eurycantha calcarata. The enzyme was isolated and analyzed via mass spectrometry. RT-PCR revealed two endoglucanase genes, EcEG1 and EcEG2. Mascot analysis of the purified enzyme confirms it to be the product of gene EcEG1. Homologous cDNAs were also isolated from a distantly related species, Entoria okinawaensis, suggesting a general distribution of cellulase genes in phasmids. Phasmid cellulases showed high homology to endogenously-produced glycoside hydrolase family 9 (GH9) endoglucanases from insects, especially to those of termites, cockroaches, and crickets. The purified E. calcarata enzyme showed clear antigency against an anti-serum for termite GH9 cellulase, which, together with the sequence homology, further suggests an endogenous origin of the enzyme. This discovery suggests a possible nutritive value for cellulose in the leaf-feeding phasmids, unlike in herbivorous Lepidoptera.

Analysis of the gut microbiota of walking sticks (Phasmatodea)

BACKGROUND

Little is known about the Phasmatodea gut microbial community, including whether phasmids have symbiotic bacteria aiding in their digestion. While symbionts are near ubiquitous in herbivorous insects, the Phasmatodea's distinctively thin body shape precludes the gut enlargements needed for microbial fermentation. High-throughput sequencing was used to characterize the entire microbiota of the fat bodies, salivary glands, and anterior and posterior midguts of two species of walking stick.

RESULTS

Most bacterial sequences belonged to a strain of Spiroplasma (Tenericutes) found primarily in the posterior midgut of the parthenogenetic species Ramulus artemis (Phasmatidae). Beyond this, no significant differences were found between the R. artemis midgut sections or between that species and Peruphasma schultei (Pseudophasmatidae). Histological analysis further indicated a lack of bacteriocytes.

CONCLUSIONS

Phasmids are unlikely to depend on bacteria for digestion, suggesting they produce enzymes endogenously that most other herbivorous insects obtain from symbionts. This conclusion matches predictions based on phasmid anatomy. The role of Spiroplasma in insects warrants further study.

Mad scientist: the unique case of a published delusion

In 1951, entomologist Jay Traver published in the Proceedings of the Entomological Society of Washington her personal experiences with a mite infestation of her scalp that resisted all treatment and was undetectable to anyone other than herself. Traver is recognized as having suffered from Delusory Parasitosis: her paper shows her to be a textbook case of the condition. The Traver paper is unique in the scientific literature in that its conclusions may be based on data that was unconsciously fabricated by the author's mind. The paper may merit retraction on the grounds of error or even scientific misconduct "by reason of insanity," but such a retraction raises the issue of discrimination against the mentally ill. This article asks what responsibilities journals have when faced with delusions disguised as science, what right editors have to question the sanity of an author, and what should be done about the Traver paper itself. By placing higher emphasis on article content than author identity, scientific integrity is maintained and a balance is struck between avoiding discrimination against the mentally ill and not preventing patients from seeking needed treatment.

DEET (N,N-diethyl-meta-toluamide) induced delay of blowfly landing and oviposition rates on treated pig carrion (Sus scrofa L.)

The question of whether the insect repellent N,N-Diethyl-meta-toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers (p < 0.01 for all variables), with subsequently reduced decomposition (p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death.