Extra-oral Digestion Research Articles

Salivary Proteins ofLygus hesperus(Hemiptera: Miridae)

ABSTBACTLygus hesperus Knight (Hemiptera: Miridae) causes economic damage to a wide range of crops in the western United States. While stylet-probing, L. hesperus discharge saliva consisting of lytic enzymes that facilitate extraoral digestion of host tissues. L. hesperus saliva primarily consists of polygalacturonases, α-amylases, and proteases, but salivary constituents other than these enzymes have not been documented. Improved knowledge of L. hesperus salivary proteins could lead to a better understanding of Lygus-host interactions, and aid in the development of crops that are resistant or tolerant to injury caused by Lygus spp. The objective of our study was to use mass spectrometry to identify salivary proteins of L. hesperus adults. Multiple polygalacturonases and proteases were identified from diet that was stylet-probed and fed upon by L. hesperus. Laccase, alkyl hydroperoxide reductase-like protein, glucose dehydrogenase, and xanthine dehydrogenase were identified in styletprobed diets by using mass spectrometry, and laccase activity was confirmed using a colorimetric assay. This is the first study to identify laccase, glucose dehydrogenase, and xanthine dehydrogenase from L. hesperus saliva; we propose these enzymes target plant-defense compounds. Nearly 100 proteins from the bacterial plant pathogen, Pantoea ananatis and nine proteins from Serratia spp. were identified in stylet-probed diets. These results suggest L. hesperus may vector these plant pathogens. Our study adds to the list of documented L. hesperus salivary proteins, and provides information that will be useful for the further study of L. hesperus saliva and Lygus-microbe interactions.

PROTEOME ANALYSIS OF GUT AND SALIVARY GLAND PROTEINS OF FIFTH‐INSTAR NYMPH AND ADULTS OF THE SUNN PEST, Eurygaster integriceps

In the digestive system of the sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), the salivary gland has a key role in extra oral digestion and the gut is the main site for digestion of food. In this study, proteomics was used to study the role of proteins involved in digestion. The amount of feeding on wheat grain by adult insects increased by comparison to fifth-instar nymphs. Proteins of the gut and salivary gland in adults and fifth-instar nymphs were analyzed 1 day after feeding. The proteins related to digestion, metabolism, and defense against toxins were accumulated in the gut of adult insects. Three plant proteins including serpin, dehydroascorbate reductase, and β-amylase were accumulated in guts of adults. In the salivary gland, phospholipase A2 and arginine kinase were increased in adults. Heat shock protein 70 increased in the gut of fifth-instar nymphs. Proteomic analysis revealed that most of changed proteins in digestive system of sunn pest were increased in adults. This study provided more targets derived from gut and salivary gland for pest management.

Role of Proteases in Extra-Oral Digestion of a Predatory Bug,Andrallus spinidens

Roles of salivary proteases in the extra-oral digestion of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae) were studied by using 2% azocasein as a general substrate and specific protease substrates, as well as synthetic and endogenous inhibitors. It was found that salivary glands of A. spinidens have two anterior, two lateral, and two posterior lobes. Azocasein was used to measure the activity of general proteases in the salivary glands using different buffer solutions. The enzyme had the highest activity at pH 8. General protease activity was highest at 40 °C and was stable for 6–16 hours. The use of specific substrates showed that trypsin-like, chymotrypsin-like, aminopeptidase, and carboxypeptidase are the active proteases present in salivary glands, by the maximum activity of trypsin-like protease in addition to their optimal pH between 8–9. Ca2+ and Mg2+ increased proteolytic activity about 216%, while other ions decreased it. Specific inhibitors including SBTI, PMSF, TLCK, and TPCK significantly decreased enzyme activity, as well as the specific inhibitors of methalloproteases including phenanthroline, EGTA, and TTHA. Extracted endogenous trypsin inhibitors extracted from potential prey, Chilo suppressalis, Naranga aenescens, Pieris brassicae, Hyphantria cunea, and Ephestia kuhniella, had different effects on trypsin-like protease activity of A. spinidens salivary glands. With the exception of C. suppressalis, the endogenous inhibitors significantly decreased enzyme activity in A. spinidens.

Anatomy and ultrastructure of the salivary (prosomal) glands in unfed water mite larvae Piona carnea (C.L. Koch, 1836) (Acariformes: Pionidae)

Anatomy and ultrastructure of prosomal salivary glands in the unfed water mite larvae Piona carnea (C.L. Koch, 1836) were examined using serial semi-thin sections and transmission electron microscopy. Three pairs of alveolar salivary glands shown are termed lateral, ventro-lateral and medial in accordance with their spatial position. These glands belong to the podocephalic system and are situated on the common salivary duct from back to forth in the above mentioned sequence. The arrangement of the medial glands is unusual because they are situated one after another on the medial (axial) body line, therefore they are termed anterior and posterior medial glands. The secretory duct of the anterior medial gland mostly turns right, and the duct of the posterior gland turns left. The salivary glands are located in the body cavity partly inside the gnathosoma and in the idiosoma in front of the brain (synganglion). Each gland is represented by a single acinus (alveolus) and is composed of several cone shaped secretory cells arranged around the large central (intra-acinar) cavity with the secretory duct base. The cells of all glands are filled with secretory vesicles of different electron density. The remaining cell volume is occupied by elements of rough endoplasmic reticulum, and the membrane enveloping vesicles may have ribosomes on its external surface. Large nuclei provided with large nucleoli occupy the basal cell zones. The pronounced development of the prosomal salivary glands indicates their important role in extra-oral digestion of water mite larvae.

Protein patterns in the salivary gland of the sunn pest, Eurygaster integriceps (Put.) (Hemiptera: Scutelleridae)

Summary Salivary glands of the members of the Order Hemiptera contain proteins which are involved in extra oral digestion and insect-plant interactions. Identification of proteins and determination of their physiological roles in the salivary gland is an essential step to elucidate sunn pest-wheat interactions. In this study, proteomic techniques were used to compare protein patterns in the salivary gland of fifth-instar nymphs and adults of the sunn pest, Eurygaster integriceps. Among 139 detected spots, 31 spots were selected for protein identification. Thirteen spots were differentially expressed between the two life stages. Trypsin, arginine kinase and phospholipase A2 levels were higher in the adult stage whereas chymotrypsin, arginine methyltransferase and salivary endonuclease levels were greater in fifth-instar nymphs. The remaining eighteen spots were selected for protein mapping of the salivary gland. Serine protease ssp3, alpha-amylase, glucose dehydrogenase, vacuolar H+ATPase and thrombostasin-3 were expressed at similar levels in fifth-instar nymphs and adults

A Molecular Approach to Identifying the Natural Prey of the African Creeping Water BugNaucoris, A Potential Reservoir ofMycobacterium ulcerans

The extra-oral digestion of creeping water bugs (Naucoridae: Hemiptera) hinders the study of their diet using the standard method of identifying prey body parts in the gut. Genetic methods are available, but rely on PCR tests or similar diagnostics to confirm suspected prey. Where the potential prey is unknown and a broad search for all possible prey is desirable, methods that can potentially capture any prey item are required. Naucoris sp. is known to harbor Mycobacterium ulcerans (Actinomycetales: Mycobacteriaceae), the causative bacterium of Buruli ulcer. Outbreaks of Buruli ulcer have been associated with disturbed freshwater habitats, but the mode of transmission to humans remains unclear. Here we examine the diet of Naucoris sp., a dominant aquatic predator in water bodies in Ghana where the prevalence of Buruli ulcer is high. We cloned and sequenced 576 PCR products (mtDNA rrnL, cox1) isolated from the gut of 60 Naucoris sp. individuals to determining diet composition as broadly as possible. Using phylogenetic analysis of newly sequenced clones and 6 potential prey taxa collected from the site, sequences isolated from Naucoris sp. guts matched locally collected Coleoptera (Hydrophilidae). Blastn queries to GenBank of other clone sequences produced matches to (Anura) (n = 1), Rotifera (n = 5), and fungi (n = 4) as additional components of the diet. Our results suggest that sp. in this Buruli ulcer-endemic area feeds on a wide range of prey and body sizes, and that the approach could be successfully applied to studies of aquatic food webs where morphological identification of prey is impossible and where little or no a priori knowledge is available.

Functional morphology of the mouthparts in the scorpionfly Sinopanorpa tincta (Mecoptera: Panorpidae)

The feeding mechanism of insects can be deduced from the morphology of their mouthparts. The mouthpart morphology of the scorpionfly Sinopanorpa tincta (Navás) was investigated using light and scanning electron microscopy. The mandibulate mouthparts of S. tincta are situated at the distal end of the rostrum, which is formed from the elongation of clypeus and subgenae. The blade-shaped mandible terminates in two inwardly curved sharp teeth. The paired maxillae each consist of a triangular cardo, an elongated stipes, a hirsute galea, a spiny lacinia, and a five-segmented palpus. Rows-arranged claw-like spines are first found to occur on the mesal side of the lacinia. The labium is composed of a basal elongated membranous submentum, a central vase-shaped mentum, and a short distal prementum, which distally carries a pair of two-segmented labial palpi. The proximal labial palpomere is very hirsute on mesal side and well sclerotized at the basal part of the lateral side. On the baso-mesal side of the distal labial palpomere is a triangular area, which is densely furnished with long microtrichia. Various sensilla are concentrated on the epipharynx, maxillary and labial palpi. The pattern of thick basiconic sensilla at the apex of epipharynx exhibits distinct sexual dimorphism. The feeding mechanism is conjectured from the ultramorphology of the mouthparts. We suggest that scorpionflies are likely to feed on liquid food of their prey after extra-oral digestion. Hair brushes on the hirsute epipharynx, galeae, laciniae, labial palpi, and hypopharynx might serve to filtrate large particles.

Paralytic activity of lysophosphatidylcholine from saliva of the waterbugBelostoma anurum

Lysophosphatidylcholine (LPC) is a major bioactive lipid that is enzymatically generated by phospholipase A(2) (PLA(2)). Previously, we showed that LPC is present in the saliva of the blood-sucking hemipteran Rhodnius prolixus and modulates cell-signaling pathways involved in vascular biology, which aids blood feeding. Here, we show that the saliva of the predator insect Belostoma anurum contains a large number of lipids with LPC accounting for 25% of the total phospholipids. A PLA(2) enzyme likely to be involved in LPC generation was characterized. The activity of this enzyme is 5-fold higher in Belostoma saliva than in other studied hemipterans, suggesting a close association with the predator feeding habits of this insect. Belostoma employs extra-oral digestion, which allows for ingestion of larger prey than itself, including small vertebrates such as amphibians and fish. Therefore, prey immobilization during digestion is essential, and we show here that Belostoma saliva and B. anurum saliva purified LPC have paralytic activity in zebrafish. This is the first evidence that lysophospholipids might play an important role in prey immobilization, in addition to contributing to blood feeding, and might have been an evolutionary acquisition that occurred long before the appearance of hematophagy in this animal group.

Mechanical damage to pollen aids nutrient acquisition in Heliconius butterflies (Nymphalidae).

Neotropical Heliconius and Laparus butterflies actively collect pollen onto the proboscis and extract nutrients from it. This study investigates the impact of the processing behaviour on the condition of the pollen grains. Pollen samples (n = 72) were collected from proboscides of various Heliconius species and Laparus doris in surrounding habitats of the Tropical Research Station La Gamba (Costa Rica). Examination using a light microscope revealed that pollen loads contained 74.88 ± 53.67% of damaged Psychotria pollen, 72.04 ± 23.4% of damaged Psiguria/Gurania pollen, and 21.35 ± 14.5% of damaged Lantana pollen (numbers represent median ± first quartile). Damaged pollen grains showed deformed contours, inhomogeneous and/or leaking contents, or they were empty. Experiments with Heliconius and Laparus doris from a natural population in Costa Rica demonstrated that 200 min of pollen processing behaviour significantly increased the percentage of damaged pollen of Psychotria compared to pollen from anthers (P = 0.015, Z = -2.44, Mann-Whitney U-test). Examination of pollen loads from green house reared Heliconius butterflies resulted in significantly greater amounts of damaged Psiguria pollen after 200 min of processing behaviour compared to pollen from flowers (P < 0.001, Z = -4.583, Mann-Whitney U-test). These results indicate that pollen processing functions as extra oral digestion whereby pollen grains are ruptured to make the content available for ingestion.

Ultramorphology of the proventriculus in Panorpidae and Bittacidae (Mecoptera)

The proventriculus is a specialized part of the foregut in the alimentary canal in some insects, varying greatly in its structure across different insect groups. The ultramorphology of the proventriculus in Mecoptera was investigated in eight species of Panorpidae and one of the Bittacidae using light microscopy and scanning electron microscopy. The proventriculus consists of the outer circular muscles, the inner longitudinal muscles, an epithelium, and a sclerotized intima with dense acanthae. The proventricular acanthae could be divided into three categories: the anterior acanthae (AA), the main acanthae (MA), and the posterior acanthae (PA). In Panorpidae the AA are rounded in cross section and could be subdivided into two subtypes, the long AA with a polytomy apiculus and the short AA with a V-shaped or spine-like apiculus. The MA, covering the majority of the proventricular inner surface, are dense, uniform, and hollow rectangular structures in cross section with forked apiculi. Each hollow base of the MA was first found to be inserted with a cone-shaped process of the corresponding epithelial cell. The PA are very thin, with a spine-like apiculus. In Bittacidae the proventriculus is specialized by a ring of cuticular thickening within its anterior orifice, and the AA are shaped like a ring of thin spines. Six cardiac valves were observed in Panorpidae and ten in Bittacidae. The functions of the various types of acanthae in digestion and extra-oral digestion and their significance in insect systematics are briefly discussed.

Characterization and expression analysis of a gene encoding a secreted lipase-like protein expressed in the salivary glands of the larval Hessian fly, Mayetiola destructor (Say)

In a salivary gland transcriptomics study we identified a cDNA with a full-length open reading frame for a gene ( MdesL1) encoding a lipase-like protein expressed in the salivary glands of the larval Hessian fly, Mayetiola destructor (Say). Fluorescent in situ hybridization on salivary polytenes positioned MdesL1 on the long arm of Autosome 1. BLASTp and conserved domain searches revealed the deduced amino acid sequence contained a lipase superfamily domain with similarity to lipases and phospholipases from other insects. A secretion signal peptide was identified at the amino terminus of the deduced amino acid sequence. Analysis of the transcript of MdesL1 in larval Hessian fly tissues by quantitative real-time PCR (qPCR) revealed the greatest abundance was in salivary glands. Analysis of transcript levels during development showed the greatest level was detected in feeding 1st-instar and early 2nd-instar larvae. Transcript levels increased dramatically over time in larvae feeding on susceptible wheat but were detected at low levels in larvae feeding on resistant wheat. These data suggest the protein encoded by MdesL1 is likely secreted into host-plant cells during larval feeding and could be involved in extra-oral digestion and changes in host-cell permeability or in generating a second messenger in a host-cell-signaling cascade.

Viable algae released by the seastar Dermasterias imbricata feeding on the symbiotic sea anemone Anthopleura elegantissima

Echinoderms are major predators of anemones in temperate ecosystems. The fate of two algae, zooxanthellae and zoochlorellae, after their host anemone (Anthopleura elegantissima Brandt) was consumed by the leather star Dermasterias imbricata Grube was determined in experiments conducted in July and August 2004. Productivity, photosynthetic pigments, and mitotic index (percent of cells dividing) were used as indicators of algal health; algae released after leather stars consumed their host were compared with algae freshly isolated from anemones. Two types of waste products contained algae: pellets resulting from extraoral digestion, and feces. Zooxanthellae and zoochlorellae isolated from these waste products were photosynthetic, although to different extents. For algae from feces and pellets, light-saturated photosynthetic rates (Pmax) were 85 and 13%, respectively, of Pmax of freshly isolated zooxanthellae; and were 20 and 46%, respectively, for zoochlorellae. The photosynthetic pigments and mitotic index (percent of dividing cells) were not altered by the feeding activities of the leather star. These results show that algae released by seastar predation on their hosts remain viable, and are hence available for establishing symbioses in A. elegantissima and other potential hosts.

Morphology and preliminary enzyme characterization of the salivary glands from the predatory bug &lt;I&gt;Podisus nigrispinus&lt;/I&gt; (Heteroptera: Pentatomidae)

Podisus nigrispinus (Dallas) is a common predator in agricultural and natural systems in Neotropical America. Its feeding strategy involves extra-oral digestion and to better understand this process its salivary glands were extracted and subjected to morphological and preliminary enzyme characterization. The salivary glands of P. nigrispinus are formed by a pair of main and accessory gland complexes. The main salivary glands are further divided into an anterior and a posterior lobe. The compartmentalization of the salivary gland complex is likely to be important for the production, activation and release of the digestive enzymes used in the extra-oral digestion of prey items. Proteases and lipase, important digestive enzymes involved in zoophagy, were detected in the salivary glands of P. nigrispinus. The prevailing trypsin-like protease activity was characterized by using the serine-protease substrate N-alpha-benzoyl-L-Arg-p-nitroanilidine (L-BApNA) and the trypsin inhibitors tosyl-L-lysine chloromethyl ketone (TLCK) and benzamidine. The KM value obtained for trypsin-like activity was 1.57 mm and the different peaks of optimum pH and temperature activity suggest the presence of multiple forms of this enzyme in P. nigrispinus. Detection of amylase activity in the salivary glands of this predator suggests its ability to digest starch and obtain nutrients from plants, which may have adaptative value under prey scarcity.

Morphology and preliminary enzyme characterization of the salivary glands from the predatory bugPodisus nigrispinus(Heteroptera: Pentatomidae)

AbstractPodisus nigrispinus(Dallas) is a common predator in agricultural and natural systems in Neotropical America. Its feeding strategy involves extra-oral digestion and to better understand this process its salivary glands were extracted and subjected to morphological and preliminary enzyme characterization. The salivary glands ofP. nigrispinusare formed by a pair of main and accessory gland complexes. The main salivary glands are further divided into an anterior and a posterior lobe. The compartmentalization of the salivary gland complex is likely to be important for the production, activation and release of the digestive enzymes used in the extra-oral digestion of prey items. Proteases and lipase, important digestive enzymes involved in zoophagy, were detected in the salivary glands ofP. nigrispinus. The prevailing trypsin-like protease activity was characterized by using the serine-protease substrateN-α-benzoyl-L-Arg-p-nitroanilidine (L-BApNA) and the trypsin inhibitors tosyl-L-lysine chloromethyl ketone (TLCK) and benzamidine. The KMvalue obtained for trypsin-like activity was 1.57 mm and the different peaks of optimum pH and temperature activity suggest the presence of multiple forms of this enzyme inP. nigrispinus. Detection of amylase activity in the salivary glands of this predator suggests its ability to digest starch and obtain nutrients from plants, which may have adaptative value under prey scarcity.

The salivary gland and salivary enzymes of the giant waterbugs (Heteroptera; Belostomatidae)

The giant waterbugs are predators that utilize extra-oral digestion and are known to capture a wide variety of prey. Herein we describe the differences in salivary enzyme composition between large and small species of giant waterbug ( Lethocerus uhleri, Lethocerinae and Belostoma lutarium, Belostomatinae, respectively). The saliva of L. uhleri contains 3 proteolytic enzymes and no amylase, while the salivary gland of B. lutarium produces 2 proteolytic enzymes and amylase. This fundamental difference in salivary enzyme composition correlates with the difference in diet preference between the Lethocerinae and Belostomatinae. Furthermore, we describe the ultrastructure of the salivary gland complex of B. lutarium and present data on the division of labor with respect to compartmentalization of enzyme production. Proteolytic enzymes are produced in the accessory salivary gland and amylase is produced in the main salivary gland lobe. This is the first reported evidence of protease production in the accessory salivary gland in the Heteroptera.

Biological and ecological studies on Scymnus syriacus and Scymnus levaillanti (Coleoptera: Coccinellidae)

Both Scymnus syriacus Mars. and Scymnus levaillanti Muls. are aphidophagous coccinellids. In the laboratory they con- sumed and successfully reproduced on several species of aphids. Larvae suck the prey contents from aphid appendages, while adults consume the whole aphid, except for parts of the appendages. Extra-oral digestion is practiced during feeding. The mean number of aphids consumed by the larval stage of S. syriacus when reared at 25°C was 95, and 130 aphids at 30°C. For S. levaillanti it was 125 and 139 aphids at 25°C and 30°C, respectively. The mean number of eggs deposited daily by S. syriacus for the first three weeks of adult life was 19.5, with a range of 3-30 eggs at 25°C. Longevity of adults ranged from 3 to 4 months at 25°C and 2.5-3 months at 30°C.

The feeding behavior of Trichogramma brassicae: new evidence for selective ingestion of solid food

AbstractA descriptive study of the feeding behavior and structures of Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) was conducted. Based on direct observational and biochemical evidence, larvae feed predominantly on particulate materials, starting ca. 25 h post‐oviposition. Feeding lasted for ca. 9 h, at 25±1 °C. During this feeding period the shape of the larvae changed from vermiform to pyriform and then to sacciform, resulting in a ca. 40‐fold increase in body size. Larvae used elaborate feeding behaviors as they pulled solid food particles to their oral opening, broke small particles from larger ones, and took the particles into the stomodaeum, which is a powerful pump. In the stomodaeum, peristaltic movement further macerated the particles, which eventually passed through the cardiac valve into the midgut. As indicated by changes in fluorescently labeled casein, digestive enzymes aid in the extra‐oral chemical digestion of food. The contents of the gut, during and shortly after feeding, were almost entirely closely packed solid particles. The behavioral activity of feeding larvae centered almost exclusively on processing and ingesting solid food particles. The rapid larval growth is much more plausibly explained by their feeding on the highly concentrated nutrients found in solid foods, rather than the extensive concentration required if dilute liquids were the principal source of nutrients. The implications of these findings for the development of practical artificial diets are discussed.

A New Concept in Artificial Diets forChrysoperla rufilabris: The Efficacy of Solid Diets1

Abstract A semisolid artificial diet is described for rearing larvae of a green lacewing, Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae). Fifteen successive generations have been produced using this diet for larval development and a yeast, sucrose, and water mixture as the adult diet. The biological parameters of survival to the adult stage, mean egg production/female/day (= fecundity), duration of larval and pupal stages, and pupal weight measured 1 day after pupation were evaluated in generations 6–10. Survival from egg to pupa was about 87% on the larval diet and 89% on eggs from Ephestia kuehniella (Zeller) (Lepidoptera: Phycitidae). Fecundity was nearly identical in diet-produced C. rufilabris and those produced on eggs from E. kuehniella . Mean pupal weight for C. rufilabris fed diet was 9.40 (±0.19 SE) mg, and for those fed E. kuehniella eggs, it was 8.61 (±0.16) mg. Development time for larvae reared from newly emerged first instar larvae to onset of pupation was 10.85 (±0.15) days on the diet and 8.05 (±0.08) days on E. kuehniella eggs. Pupal duration was 9.41 (±0.07) days for diet-reared individuals and 10.08 (±0.11) for E. kuehniella -reared individuals. Diet-reared adults laid 21.5 eggs per female per day over a 5-day period compared to 19 eggs per C. rufilabris reared on E. kuehniella eggs. Larvae from the diet culture readily attacked and consumed cotton aphids, Aphis gossipyi Glover (Homoptera: Aphididae). The diet is a solid, stringy paste presented in stretched Parafilm membrane. The diet costs about $6.00 (U.S.) per kilogram, including packaging, compared with about $50 per kilogram for diets with protein hydrolysates and about $500 per kilogram for E. kuehniella eggs. We explain how solid diets accommodate, better than liquids, the feeding mechanisms of larval chrysopids and other predaceous arthropods that use extraoral digestion.

The effect of wounds on desiccation of prey: implications for a predator with extra-oral digestion.

Predators that inject prey with proteolytic enzymes, thereby breaking down their tissues for subsequent ingestion, run the risk that desiccation will hinder eventual retrieval of resources from these prey. Wounds made in capture might exacerbate this problem. However, desiccation rates of small syrphid flies Toxomerusmarginatus (Diptera: Syrphidae) killed by juvenile crab spiders Misumena vatia (Araneae: Thomisidae) and intact dead syrphid flies did not differ over the normal period of feeding, though desiccation rates in shade and sun differed several-fold. Neither the size of the spider (and presumably the size of the wounds it inflicted) nor the location of the wounds on the flies' bodies affected desiccation rates. Thus, this tactic of prey handling does not exact an added processing cost on Misumena.

Solid-to-Liquid Feeding: The Inside(s) Story of Extra-Oral Digestion in Predaceous Arthropoda

The study of extra-oral digestion is of general interest because it helps explain the success of over 80% of the predaceous families of the phylum Arthropoda (Cohen 1995), the phylum whose members comprise over three-quarters of the known animal species (Wilson 1992). Extra-oral digestion especially is interesting because it involves the integration of several levels of biological organization—biochemical, physiological, morphological, and behavioral adaptations—all within an ecological and evolutionary context. It also is fascinating because it is so alien to our way of eating that it challenges our world-view about what most of us feel is a mundane process.