Mattesia oryzaephili (Neogregarinorida: Lipotrophidae), a Pathogen of Stored-Grain Insects: Virulence, Host Range and Comparison with Mattesia dispora

The neogregarine, Mattesia oryzaephili (Neogregarinorida: Lipotrophidae) has only been reported from the sawtoothed grain beetle, Oryzaephilus surinamensis. The pathogen's presence in cadavers of the rusty grain beetle, Cryptolestes ferrugineus, in collapsed colonies prompted studies of its potential to control stored-product insects. Respective mortality rates in fourth instar C. ferrugineus and C. pusillus were 15.3 and 17.7% at 10² oocysts/g of diet and 89.4 and 80.5% at 10⁵ oocysts/g. The mortality of fourth instar O. surinamensis exposed to 10⁵ oocysts/g was only 12%. For C. ferrugineus larvae, there were no significant differences in mortality and infection between exposure to Mattesia dispora and exposure to M. oryzaephili (P>0.05), but for C. pusillus larvae, both responses were significantly higher for M. oryzaephili than M. dispora. Adult C. ferrugineus and O. surinamensis were similar in their responses to M. oryzaephili, with mortality not exceeding 20%, but differed in their responses to M. dispora, with O. surinamensis being more susceptible. The median lethal doses for larval Mediterranean flour moths, Ephestia kuehniella, were 7.9×10⁷M. oryzaephili oocysts/g of diet and 2.7×10³M. dispora oocysts/g of diet. In single dose assays of M. oryzaephili physiological host range, greater than 75% infection was achieved for Rhyzopertha dominica and Plodia interpunctella. More than half of oocysts germinated during passage through the guts of susceptible and resistant insects. Second and third instar Galleria mellonella were highly susceptible to M. oryzaephili infection, but fifth instars were not. Infection percentages in fifth instars exposed to 10⁶ oocysts/g were significant only when boric acid or the stilbene, Blankophor®RHK were incorporated into the diet. Host range and general morphology confirm the identity of Mattesia oryzaephili.     

Detection of Mattesia oryzaephili (Neogregarinorida: Lipotrophidae) in grain beetle laboratory colonies with an enzyme-linked immunosorbent assay

An indirect sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of the neogregarine Mattesia oryzaephili was developed with monoclonal antibodies. It was used to screen laboratory colonies of Oryzaephilus surinamensis, Cryptolestes ferrugineus, C. pusillus, and C. turcicus from the United States, Canada, and Australia. All of the colonies except C. turcicus had larvae that tested positive with the percent of positives ranging from 0.2 to 83.9, but only colonies that tested positive had reported population declines. This assay will make possible epizootiological studies to assess the impact of M. oryzaephili on pest populations.     

Diapause in a Glasgow strain of the flour moth, Ephestia kuehniella

ABSTRACT. The incidence of diapause in Ephestia kuehniella Zeller from an unhealed granary in Scotland was influenced by both photoperiod and temperature. At 25°C, nearly 50% of larvae entered diapause when reared in continuous darkness (DD) and up to 30% did so in short photoperiods. Little diapause was detected around LD 14:10 but a second, smaller peak of about 20% occurred at LD 16:8 and LD 18:6, falling away again to nearly zero in continuous light. More larvae entered diapause when reared continuously at 15 or 20°C than at 25 and 30°C. However, when larvae reared from hatch at 25°C in LD 16:8 were transferred after 1 week to 15°C in LD 9:15, almost twice as many entered diapause as did those reared at 15°C throughout. The sensitive phase for diapause induction occurred near the start of the final instar. The mean duration of diapause was between 2 and 3 months in most photoperiods at 20 and 25°C, and was shorter at 15°C. However, in DD at 25°C, it lasted about 7 months. Termination of diapause was hastened in larvae reared at 25°C in DD by transferring them to LD 14:10, and also by chilling them at 7.5°C for 6 weeks before returning to 25°C in DD. In an unhealed store in southern England, viable adults emerged from May to July and originated from larvae which terminated diapause relatively late. It would appear from the results of transferring larvae back to the laboratory at various times during the winter that some phases of diapause development were completed quite early after exposure to low temperatures, although no further development took place in the store until temperatures rose again in April.     

Isolation and identification of cuticular compounds from the mediterranean flour moth,Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), their antibacterial activities and biological functions

Cuticular analysis of Ephestia kuehniella females by gas chromatography-mass spectrometry revealed the presence of four groups of chemical compounds including alkane, alcohol, aldehyde and fatty acid. The cuticular n-alkanes ranged from 12 to 18, 20, 23, 24 and 29 carbon atoms in the chain. The most abundant n-alkanes detected in the cuticular extracts were C₁₄ (14.98%) and C₁₈ (8.15%). Cuticular fatty acids included hexadecenoic acid, 9-octadecenoic acid and 9,12-octadecenoic acid. Two types of alcohol including, 2-methyl-Z,Z-3,13-octadecadienol and 9-methyl-Z-10-tetradecen-1-ol acetate, were found in the cuticular lipids of the females. Two aldehyde components, (E)-11-hexadecenal and 9,17-octadecadienal, were identified in the cuticular extract of E. kuehniella. Antibacterial activity of the cuticular compounds was tested against Bacillus subtilis, Bacillus thuringiensis and Escherichia coli. These compounds from the moths inhibited the growth of Gram-positive bacteria. The functional characteristics of the cuticular compounds operating as pheromones, species-associated compounds and host-resistant compounds to bacterial infection are discussed.     

Der Feinbau des Auges der Mehlmotte,Ephestia kuehniella Zeller (Lepidoptera,Pyralididae)

Zusammenfassung Die Retinula im Ommatidium der Mehlmotte besteht aus einer wechselnden Anzahl (9–12, meist 11) langgestreckter, prismatischer Sinneszellen. Außerdem enthält jede Retinula nahe der Basalmembran im Zentrum zwischen diesen distalen Retinulazellen noch eine basale Retinulazelle. Die Längsachse der Retinula wird von der Achsenstruktur eingenommen, die aus Mikrovilli besteht. Ihr distaler Teil ist der Achsenfaden, der breitere, proximale Teil bildet das Rhabdom. Dieses erscheint im Querschnitt meist vierstrahlig gelappt, da seine Außenseite in Längsrichtung tief gekehlt ist. Der Rhabdomquerschnitt gliedert sich in mehrere Schöpfe parallel angeordneter Mikrovilli (Rhabdomsektoren); jeder Rhabdomsektor besteht aus 1 oder 2 Rhabdomeren. Die basale Retinulazelle entsendet einen kleinen Schopf von Mikrovilli in die proximale Spitze des Rhabdoms. Die distalen Retinulazellen setzen sich proximal in Neuriten fort, welche sich in Einkehlungen der basalen Retinulazelle bzw. der Tracheenendzelle einschmiegen. Jeweils eine Tracheole durchbricht zusammen mit dem Neuritenstrang einer Retinula die Basalmembran; sie verzweigt sich distal zu ca. 30 Tracheolen, die die Retinula umhüllen.Die Kristallkegelzellen grenzen distal an die Cornea; proximal laufen die Kristallkegelzellen eines Ommatidiums in einen gemeinsamen Fortsatz aus, der zwischen den Retinulazellen unmittelbar am Achsenfaden endet. — Nur das helladaptierte Auge wurde untersucht. Hierbei erscheint im distalen Teil der Retinula nur der Achsenfaden lichtdurchlässig, das Cytoplasma der Retinulazellen hingegen von Pigmentgrana durchsetzt und für Licht undurchlässig.

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Fine structure of the eye of the meal moth, Ephestia kuehniella Zeller (Lepidoptera, Pyralididae)

Summary In each ommatidium of the meal moth a retinula is formed from a varying number (9–12, mostly 11) of elongated, prismatic sense cells. In addition, a basal retinular cell is situated near the basement membrane in the center of the other (distal) retinular cells. The axis of the retinula is occupied by many microvilli forming the axial structure, the distal section of which is the slender axial thread. Proximally, the axial structure widens (to 8.5 m instead of 1 m in diameter) and is now called rhabdom. Cross sections of the rhabdom mostly look like a petaloid with four petals; this figure is due to longitudinal infoldings along the length of the rhabdom surface. The rhabdom cross section is subdivided into several brushes of microvilli (rhabdom sectors), each one being characterized by an approximately parallel arrangement of its microvilli. One rhabdom sector may be composed of one or two rhabdomeres respectively.The basal retinular cell participates in rhabdom formation through a small brush of microvilli at the proximal end of the rhabdom. Proximally, the distal retinular cells taper into slender neurites which are embedded in grooves at the surface of the basal retinular cell and the tracheal end cell respectively. One tracheole piercing the basement membrane together with the neurites of one retinula branches into about 30 tracheoles surrounding the retinula.The crystalline cone cells touch the cornea; proximally, their cytoplasm forms a point which eventually terminates amongst the distal tips of the retinular cells, immediately at the axial thread.—Our work was restricted to light adapted eyes; in this condition, light transmission in the distal part of the retinula seems to be blocked by retinular cell pigment except inside the axial thread.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Connections between adjacent retinula cell columns in the eye of Ephestia kuehniella Zeller (Lepidoptera,Pyralididae)

Summary Connections were found between retinula cells of adjacent retinula cell columns in the eye of Ephestia. The connections occur most frequently at the level of the retinula cell nuclei and may involve two or more retinula columns simultaneously. The absence of specialized structural modifications of the membranes and the presence of pigment granules at the level of the connections or distal to them indicates that these connections are probably not involved in selective chemical or electrical communication nor in light transmission. It is suggested that the connections may serve tactily to coordinate cytoplasmic movement in adjacent retinula columns during light-dark adaptation.Senior U. S. Scientist Awardee of the Alexander von Humboldt Foundation. Thanks to Prof. Dr. A. Fischer for his suggestions and assistance.     

Tolerance to Bacillus thuringiensis endotoxin in immune-suppressed larvae of the flour moth Ephestia kuehniella

Tolerance to Bacillus thuringiensis crystal endotoxins (Bt-toxins) is correlated with an elevated immune status in larvae of the flour moth Ephestia kuehniella. To gain more specific information about the effector pathways involved in the protection against the toxin, we studied the effects of Bt-toxin formulations in susceptible (non-induced) and tolerant (immune-induced) larvae after natural (parasitism-mediated) and chemical (tropolone-mediated) suppression of defence reactions. Although melanization in hemolymph was significantly reduced, there was no significant effect on susceptibility to the toxin in parasitised or tropolone-treated larvae. This suggests that melanization of hemolymph is correlated with an elevated immune status but not responsible for the observed tolerance to Bt-toxin. To examine whether hemolymph proteins exist in the gut lumen and function as pro-coagulants, we compared gut and plasma proteins of immune-induced with those of non-induced larvae. Here we show that the lipid carrier lipophorin represents a major component in the gut lumen and interacts with mature Bt-toxin to form a complex.     

Long-term pheromone-mediated mating disruption of the Mediterranean flour moth, Ephestia kuehniella, in a flourmill

Several studies have indicated that mating disruption (MD) successfully reduces population densities of stored product moths, for example, the Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae). However, practical issues, such as finding control plots, replication, and lack of similarity between replicates, often incur problems in full-scale investigations and often draw focus from the added results. We here present results from long-term monitoring of E. kuehniella populations in two similar flourmills in Poland, one treated with pheromone for MD and one left untreated and used as control. Pheromone-mediated MD was applied during 2 years. Thirty pheromone dispensers (one per 100 m³ factory volume), each releasing about 2 mg ( Z,E )-9,12-tetradecadienyl acetate per day, were used. Pheromone-baited traps were used to monitor the moth populations in the MD mill and in a nearby untreated mill. The reduction in trap catch during the MD treatment was about 90% or more, compared with the untreated mill or pre-treatment periods of the MD mill. The reduction was larger during the 2nd year of MD than during the 1st year. These results contribute to the picture that MD is an effective method to control moth species infesting stored products.     

Inheritance of a temperature-modified phenotype of the short antennae (sa) mutation in a moth, Ephestia kuehniella (Lepidoptera: Pyralidae).

The autosomal recessive mutation short antennae (sa) causes considerable shortening of antennae in male and female Mediterranean flour moths (Ephestia kuehniella Zeller). However, the sa phenotype can be suppressed by several physical factors, making sa moths indistinguishable from wild-type moths (sa(WT)). This can be done by subjecting larva and pupa to a higher temperature (25 degrees C), to lithium ions, or to an alternate electric field. The first half of pupal development was found to be the sensitive period for the sa(WT) phenotype. The sa(WT) phenotype is stable and cannot be reverted to the original sa type by physical or chemical factors. The sa(WT) phenotype is transmitted to future generations. When crossed with typical sa moths, the sa(WT) phenotype is inherited either as a dominant character if carried by males or a semidominant character if carried by females. We compared proteins of the ejaculate, accessory gland secretions, and spermatophore in sa, sa(WT), and wild-type males and found considerable differences between sperm proteins of sa(WT), sa, and wild-type males. The sa(WT) phenotype influences the mating success of males: sa(WT) males mated successfully with any females, whereas typical sa males were less successful in mating and then mainly with females of the same phenotype.     

Visualization of polyfusomes in gonads of a moth,Ephestia kuehniella Z. (Lepidoptera : Pyralidae), by a microspreading technique and electron microscopy

Microspreads of gonads are usually employed to analyse the behaviour of the synaptonemal complexes during meiosis. We show in the present report that microspread preparations can be used for the study of polyfusomes as well. Polyfusomes are bridge systems which, as a result of incomplete cleavage, interconnect germ cells in both sexes of higher insects. In spread preparations using gonads of both sexes of a moth, Ephestia kuehniella (Lepidoptera : Pyralidae), the polyfusomes appear as threads of material of medium electron density. The threads are branched when later developmental stages are observed. Remnants of the electron-dense contractile rings are visible and signal the position of a preceding cleavage. The comparison of a branched spread polyfusome with the reconstruction of a fully differentiated serially sectioned polyfusome from a moth ovary, shows that spread preparations, while more rapid and less costly, visualize the bridge system properly. Polyfusomes interconnecting male germ cells show numerous ramifications. It appears difficult to preserve them in their full size in whole-mount preparations. Large polyfusomes probably fragment during the spreading procedure. Nevertheless, visualization of polyfusomes and associated contractile rings in spread preparations opens new inroads for the study of the composition and the behaviour of these components.     

Insecticidal action of Annona coriacea lectin against the flour moth Anagasta kuehniella and the rice moth Corcyra cephalonica (Lepidoptera: Pyralidae)

Annona coriacea lectin (ACLEC) was tested for insecticidal activity against larvae of two pyralid moths, Anagasta kuehniella and Corcyra cephalonica. ACLEC produced approximately 50% mortality and mass loss in A. kuehniella larvae when incorporated into an artificial diet at levels of 1.5% and 1.0% (w/w), respectively. In contrast, the inclusion of up to 2% ACLEC in the diet did not significantly decrease the survival or weight of C. cephalonica larvae. The nutritional indices for A. kuehniella and C. cephalonica suggested that ACLEC had a multi-mechanistic mode of action and was an antifeedant for both insects. The toxicity in A. kuehniella apparently resulted from a change in the gut membrane environment and consequent disruption of digestive enzyme recycling mechanisms. Affinity chromatography showed that ACLEC bound to midgut proteins of A. kuehniella and C. cephalonica. However, the 14 kDa subunit of ACLEC was not digested by midgut proteases of A. kuehniella, but was degraded by the corresponding C. cephalonica proteases within a few hours. These findings suggest the possibility of using ACLEC to engineer crop plants.     

Transfection of Wolbachia in Lepidoptera: the feminizer of the adzuki bean borer Ostrinia scapulalis causes male killing in the Mediterranean flour moth Ephestia kuehniella

Two species of Lepidoptera, Ostrinia scapulalis and Ephestia kuehniella, harbour Wolbachia, which are maternally transmitted intracellular bacteria that often cause reproductive abnormalities in arthropods. While the infection in O. scapulalis causes conversion of genetic males into functional females (feminization), that in E. kuehniella induces cytoplasmic incompatibility. In the present study, we investigated the relative importance of host and Wolbachia factors in the differential expression of reproductive alterations in these insects. We transferred the Wolbachia harboured by O. scapulalis to E. kuehniella in which the original infection had been cured by tetracycline treatment. The transfected strain of E. kuehniella expressed a maternally inherited, female-biased sex ratio. Unexpectedly, two lines of evidence suggested that the sex ratio distortion was due to male killing. First, higher mortality of young larvae was observed. Second, the removal of the transferred Wolbachia resulted in the recovery of a 1:1 sex ratio, whereas the removal of a feminizer should result in a male-biased sex ratio among offspring. To the authors' knowledge, this is the first report that a single Wolbachia strain can cause two distinct sexual abnormalities in different hosts. Our observations highlighted the importance of host-Wolbachia interactions in determining the phenotype of reproductive alterations.     

Effect of diallyl disulfide on physiological performance of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

Ephestia kuehniella Zeller is a key pest by severe deficiencies on quantity and quality of stored products. Due to concerns made by synthetic insecticides, use of natural products (like botanical insecticides) is of great importance as an alternative pest management. In the current study, the effect of diallyl disulfide was determined on digestive enzymes and those involved in intermediary metabolism of E. kuehniella. Concentration of 0.31% was obtained as LC₅₀ of diallyl disulfide followed by bioassay experiments. Activities of α-amylase, proteases, alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase significantly decreased in the treated larvae, while the adverse effects were observed in case of triacylglyceride-lipase, aspartate aminotransferase, γ-glutamyl transferase, aldolase and acid phosphatase. Results confirmed that diallyl disulfide interrupted larval digestion by lower activities of digestive enzymes indicating significant effect on intermediary metabolism.     

The structure of Verson's cells in Ephestia kuehniella Z. (Pyralidae,Lepidoptera)

Summary Testis follicles of Lepidoptera contain a large somatic cell termed Verson's cell. The present study focuses on the structure of Verson's cells and neighbouring germ cells in the Mediterranean mealmoth, Ephestia kuehniella (Pyralidae), using electron microscopy, antitubulin immunofluorescence, and phalloidin incubation for the visualization of microfilaments. Verson's cells of young larvae are connected with the follicle boundary and show large areas containing packages of glycogen particles, whereas Verson's cells of pupae lie freely within the testis follicle and are largely devoid of glycogen. Both developmental stages of Verson's cells have in common the presence of a dense cytoplasmic network of microtubules. A juxtanuclear subset of the cytoplasmic microtubule array is recognized by an antibody against acetylated microtubules. This indicates that more stable microtubules exist in this region. Microfilaments are arranged parallel to the cytoplasmic microtubules. The microtubule-microfilament-complex forms a cytoskeleton that may keep larger organelles, such as mitochondria and lysosomes, in a juxtanuclear position. Chromatin within the nuclei of Verson's cells is largely decondensed and nuclear pores are abundant. This indicates a high synthetic activity within the cells. The development of cells directly attached to Verson's cells, viz. prespermatogonia, may be controlled by the Verson's cells. Prespermatogonia, which differ in cytoplasmic density from spermatogonia further away from Verson's cells, may represent stem cells that give rise to spermatogonia and somatic cyst cells upon detachment from Verson's cells. This suggestion is compatible with the low division rate of prespermatogonia.     

Mattesia geminata sp. n. (Neogregarinida: Ophrocystidae) a Parasite of the Tropical Fire Ant,Solenopsis geminata (Fabricius)*

SYNOPSIS. A new species of neogregarine, Mattesia geminata sp. n., that infects immature stages of the tropical fire ant, Solenopsis geminata (Fabricius), is described. The parasite, which develops in the hypodermis, causes disruption of the developing eyes, melanization of the cuticle, and death of pupae. lntracolonial infection rates are usually less than 2±, but may exceed 90±. Attempts to transmit the infection were unsuccessful.     

Genetic control of pest Lepidoptera: construction of a balanced lethal strain in Ephestia kuehniella

A genetic method for the suppression of Lepidopteran pests has been investigated in the Mediterranean flour moth, Ephestia kuehniella Zeller. The method is based on the release of males trans-heterozygous for two sex-linked recessive lethal mutations (SLRLMs). In this paper, characteristics of 16 new SLRLMs are presented. The construction of a balanced lethal strain, BL-2, which was the last step to develop the method, is reported. Males of the strain are balanced for two non-allelic SLRLMs, sl-2 and sl-15. Females carry either sl-2 or sl-15 in their Z chromosome and the T(W;Z)2 translocation on their W chromosome. The translocation includes wild-type alleles of both lethal loci so that the females are viable. Matings between males of the BL-2 strain and normal females of the wild-type strain gave 99.74% male progeny. Exceptional females were due to recombination between the sl-2 and sl-15 loci. Thus, males of the BL-2 strain have a potential to suppress wild populations of the pest. Another envisaged use of this method is for an effective sexing technique.     

Distribution of gamma-tubulin differs in primary and secondary oocytes of Ephestia kuehniella (Pyralidae,Lepidoptera)

In a previous study, barrel-shaped spindles were found in metaphase I oocytes of Ephestia kuehniella (Pyralidae, Lepidoptera). Aster microtubules (MTs) were missing (Wolf, 1993: Cell Motil Cytoskeleton 24:200-204). This points to an acentriolar organization of the spindle apparatus. The present study was aimed at the question of whether gamma-tubulin, a newly detected member of the tubulin superfamily that has often been identified in microtubule-organizing centers, plays a role in the nucleation of MTs in meiotic spindles of the moth. To this end, the distribution of gamma tubulin was examined in oocytes of E. kuehniella using an antibody against gamma-tubulin in combination with indirect immunofluorescence. The antibody evenly decorated spindle MTs in metaphase I oocytes of the moth. Enhanced staining of the spindle poles was not detectable In subsequent stages of meiosis, gamma-tubulin was gradually lost from spindle MTs and was then found at the surface of the so-called elimination chromatin. Female meiosis in Lepidoptera is achiasmatic. The elimination chromatin, i.e., modified and persisting synaptonemal complexes, is believed to keep homologous chromosomes linked until the onset of anaphase I. In meiosis I of female Lepidoptera, the elimination chromatin persists at the spindle equa or between the segregating chromatin masses. It is plausible to assume that gamma-tubulin is involved in spindle organization in the absence of canonical centrosomes. In MTs of metaphase II spindles of E. kuehniella, gamma-tubulin was no longer detectable with our immunological approach. This points to a far-reaching change in spindle organization during transition from meiosis I to meiosis II. © 1996 Wiley-Liss, Inc.     

Mattesia bombi n. sp. (Neogregarinida: Ophrocystidae), a parasite of Bombus (Hymenoptera: Apidae)

The fat bodies of queen, male, and worker bumble bees were found to harbor a parasite, Mattesia bombi n. sp. (Neogregarinida: Ophrocystidae). The life cycle of this protozoan includes micronuclear and macronuclear schizogonies, gametogony, and sporogony. Sporocysts are predominantly oval in shape and measured 27 × 5.4 μm when mature. The life cycle of the parasite is described and the mode of infection discussed.     

Effect of temperature and humidity on insecticidal effect of SilicoSec against Ephestia kuehniella (Lepidoptera: Pyralidae) larvae

Laboratory experiments were carried out to assess the insecticidal effect of the diatomaceous earth formulation SilicoSec against larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), in stored wheat (Triticum durum Desf.). Larvae were exposed to wheat treated with SilicoSec at 400 and 800 ppm and held at 20, 25, and 30 degrees C and 55 and 75% RH. Larval mortality was assessed after 24 h, 48 h, 7 d, and 14 d of exposure in the treated wheat. At both dose rates, mortality increased with temperature, but this increase varied with the exposure interval. At short (< or = 48-h) exposures, larval mortality was significantly higher at 30 degrees C than at the other two temperatures. In contrast, no significant differences were noted between 20 and 25 degrees C. At longer exposures (> or = 7 d), the increase of temperature increased mortality at 800 ppm, but no significant differences were noted between 25 and 30 degrees C at 400 ppm. Furthermore, significant differences in larval mortality were noted between the two humidity levels, but only at exposures > or = 7 d. After 14 h of exposure, at both dose rates examined, the increase of temperature significantly decreased mortality. The results of the current study indicate that E. kuehniella is susceptible to SilicoSec, but temperature and relative humidity should be taken into consideration.