Locusta Migratoria Migratorioides Research Articles

Quantitative analysis of behavioural phase difference in Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) (Orthoptera, Acrididae) from the examination of spatial distribution patterns

Quantitative analysis of behavioural phase difference in Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) (Orthoptera, Acrididae) from the examination of spatial distribution patterns

Invasions and Local Outbreaks of Four Species of Plague Locusts in South Africa: A Historical Review of Outbreak Dynamics and Patterns.

The current paper provides a detailed review of the historical outbreaks of each of the four plague locust species found in South Africa, namely the brown locust, the African migratory locust, the red locust, and the southern African desert locust. The history and dynamics of the plague infestations and the major local outbreaks are summarized. The typical patterns of the outbreaks of the different species are described, and the threat of these locusts to agriculture in South Africa is defined. The brown locust produces regular outbreaks in the semi-arid Karoo, with large-scale eruptions of plague proportions occurring about once per decade. Patterns of outbreaks often repeat themselves, but the sheer size of the plague outbreaks is almost impossible to stop, and the brown locust has the potential to threaten food security throughout southern Africa. The African migratory locust produces outbreaks in some of the main maize and wheat cropping areas where it is difficult to control. This locust has taken advantage of the man-made crop environment to produce an extra generation per year that was not previously possible in the original grasslands. The coastal area of KwaZulu Natal Province in South Africa was a prime reception and breeding area for plague invasions of the red locust in the past, and the country, therefore, relies on the successful control of outbreaks in east and central Africa to prevent the recurrence of the plague invasions. The southern African desert locust occurs in the Kalahari Desert area, and outbreaks requiring chemical control are rare.

Farklı Yemlerin (Teke Karidesi (Palaemon serratus Pennant, 1777), Morio Kurdu (Zophobas morio Fabricius, 1776) ve Afrika Göçmen Çekirgesi (Locusta migratoria L. 1758)) Olta Balıkçılığında Av Verimliliğine Etkilerinin Karşılaştırılması

Olta balıkçılığında hedef balık türlerine ve habitatlara göre canlı, cansız ve yapay yemler kullanılmaktadır. Bu çalışmada, Hexapoda türlerinden Morio Kurdu (Zophobas morio Fabricius, 1776) ve Afrika Göçmen Çekirgesi (Locusta migratoria L. 1758)’nin denizde olta balıkçılığında kullanılabilirliği ve av verimlilikleri Teke Karidesi (Palaemon serratus Pennant, 1777) ile karşılaştırmalı olarak test edilmiştir. Çalışma, Yelkoma Dalyanı’nda (Adana-Türkiye), toplam 420 olta operasyonu gerçekleştirilmiş ve 80 adet balık (72 adet çipura, 8 adet levrek) yakalanmıştır. Çipuraların % 45’i Teke Karidesi ile %33’ü Afrika Göçmen Çekirgesi ile ve %22’si Morio Kurdu ile, Levrek balığının da %75’i Afrika Göçmen Çekirgesi ile %25’i de Morio Kurdu ile yakalanmıştır. Oltaların ortalama CPUE değeri 0,003 (iğne/balık/saat) ve YPUE değeri de 0,327 (iğne/g/saat) olarak belirlenmiştir. Balıkların toplam ağırlıkları üzerinden yapılan Birim Maliyet Hesabına göre, en düşük maliyete sahip olan yemin Afrika Göçmen Çekirgesi olduğu belirlenmiştir.

Entomopathogenic bacteria Photorhabdus luminescens as natural enemy against the African migratory locust, Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) (Orthoptera: Acrididae)

BackgroundThe African Migratory Locust, Locusta migratoria migratorioides (Reiche & Fairmaire, 1849) (Orthoptera: Acrididae), is a major threat to agricultural crops and food security on a worldwide scale; hence, maintaining control over it is crucial. Photorhabdus luminescens bacteria can accomplish the efficient biocontrol agent criteria. As a result, the aim of this study was to assess the efficacy of the P. luminescens (EGAP3) strain and its cell-free filtrate against L. migratoria migratorioides, as well as to investigate changes in the activity of carbohydrates hydrolyzing enzymes, amylase, invertase, and trehalase in whole-body homogenates of the 5th nymphal instar under laboratory conditions and to investigate the histopathological changes in the midgut of the locust.ResultsThe virulence of entomopathogenic bacteria was determined at different densities of 4 × 107, 4 × 106, 4 × 105, and 4 × 104 colony-forming units (CFU)/ml at different exposure times as well as different concentrations of its cell-free filtrate, undiluted cell-free filtrate (100, 50, 25, and 12.5%). The results indicated that higher-density cell suspension up to 4 × 107 cells.ml−1 and undiluted cell-free filtrate (100%) were the most effective insecticidal fluids, reaching up to 76.7 and 80%, respectively, after 7 days. The estimated LC50 value was 2.7 × 106 cells.ml−1 for bacteria, and the estimated LC50 value for cell-free filtrate was the 2nd dilution (50%).ConclusionsThe data clarified the toxicological and histopathological effects and carbohydrate hydrolyzing enzyme activities of the host insect L. migratoria migratorioides, following bacteria and cell-free filtrate infection; that provides an overview of the efficiency of bacteria and their cell-free filtrate on the host. In conclusion, P. luminescens (EGAP3) and its toxins can be an optimal option for bio-controlling of L. migratoria migratorioides.

NEEM, Azadirachta indica L. (A. Juss): AN ECO-FRIENDLY BOTANICAL INSECTICIDE FOR MANAGING FARMERS’ INSECTS PEST PROBLEMS - A REVIEW

The search for reducing risks associated with the use of chemicals has necessitated use of pest control using plant products. Neem is perhaps one of the most useful medicinal plant in the tropics. Each part of the tree has huge insecticidal property. Apart from the chemistry of the neem compounds, considerable progress has been achieved regarding the biological activity and insecticidal uses of neem. It is now considered as a valuable source of unique natural product for botanical insecticides against various pests. Farmers in tropical countries commonly used its leaves, seed kernels and its oil in various forms. Neem is utilized in form of powders, extracts or as an emulsifiable oil. Researches had shown that neem consists of pesticidal ingredients called triterpenes (limonoids). Trials conducted on the effect of neem products revealed secondary metabolites affect metabolic processes that include feeding and oviposition deterrence; metamorphosis inhibition, protein synthesis, changes in biological fitness, impaired sexual communication and chitin synthesis. Azadirachtin in particular interferes with chemoreception and exerts direct negative effects on many insect tissues such as muscles and digestive epithelial cells as well as insect mortality. Neem derived biopesticides are cheap, available in all ecological zone, posed no hazard to applicator and the environment as it is biodegradable. Insects such as Aphids, African migratory locust, legume pod-borer, coreid bugs and storage insect pests such as cowpea seed bruchid were controlled using neem. Sustainable insect pest control can be achieved with the use of neem based biopesticides.

Edible Insects and Toxoplasma gondii: Is It Something We Need To Be Concerned About?

Novel foods, such as edible insects and food products on the basis of insects, could play an important role in both human and animal nutrition in the future. The identification of dangers associated with insect consumption is fundamental to guarantee consumer safety and adequate regulatory guidelines for operators of the food sector. Although former studies have focused on the microbiological contamination of fresh or processed edible insects, so far little information is available about the occurrence of foodborne parasites, such as Toxoplasma gondii, whose life cycles make them candidates for potential insect breeding substrate contamination. Hence, we investigated the presence of contaminating T. gondii in farmed edible insects to rule out this further hazard for consumers. Four species of insects most commonly used as food for human consumption were analyzed: mealworm; African migratory locust, house cricket, and silkworm. Samples included live specimens but also minimally (dehydrated) and highly processed edible insects. Traces of T. gondii DNA were detected in samples of dehydrated mealworm. These results highlight the need for implementing good farming and processing practices with particular care paid to safe storage and handling of feed and substrates used for edible insects to reduce the chance of T. gondii entering the human food chain.

A Proteomic- and Bioinformatic-Based Identification of Specific Allergens from Edible Insects: Probes for Future Detection as Food Ingredients.

The increasing development of edible insect flours as alternative sources of proteins added to food and feed products for improving their nutritional value, necessitates an accurate evaluation of their possible adverse side-effects, especially for individuals suffering from food allergies. Using a proteomic- and bioinformatic-based approach, the diversity of proteins occurring in currently consumed edible insects such as silkworm (Bombyx mori), cricket (Acheta domesticus), African migratory locust (Locusta migratoria), yellow mealworm (Tenebrio molitor), red palm weevil (Rhynchophorus ferrugineus), and giant milworm beetle (Zophobas atratus), was investigated. Most of them consist of phylogenetically-related protein allergens widely distributed in the different groups of arthropods (mites, insects, crustaceans) and mollusks. However, a few proteins belonging to discrete protein families including the chemosensory protein, hexamerin, and the odorant-binding protein, emerged as proteins highly specific for edible insects. To a lesser extent, other proteins such as apolipophorin III, the larval cuticle protein, and the receptor for activated protein kinase, also exhibited a rather good specificity for edible insects. These proteins, that are apparently missing or much less represented in other groups of arthropods, mollusks and nematods, share well conserved amino acid sequences and very similar three-dimensional structures. Owing to their ability to trigger allergic responses in sensitized people, they should be used as probes for the specific detection of insect proteins as food ingredients in various food products and thus, to assess their food safety, especially for people allergic to edible insects.

Efficiency of Agroecosystem Compounds against the desert locust Schistocerca gregaria (Forskal) and the African migratory locust Locusta migratoria migratorioides (Reiche and Fairmaire)

The efficacy of Agroecosystem Compounds, fipronil, spinosad and chlorantraniliprole as alternatives to the conventional insecticides on the mortality rates and haemolymph protein, lipid and carbohydrate contents were assessed in Schistocerca gregaria and Locusta migratoria migratorioides. One day old 5th nymphal instars of each of the mentioned species were treated by various concentrations of tested compounds by the feeding technique. The results indicated that Locusta migratoria migratorioides is more sensitive to all tested insecticides than Schistocerca gregaria. In both species, fipronil was the most effective followed by spinosad, and chlorantraniliprole was the least effective. LC30 concentrations of the three compounds were used to treat the 5th instar hoppers of both species to examine the effects of sub lethal concentrations of the mentioned insecticides on the haemolymph total proteins, total lipids and total carbohydrates. It was found that haemolymph proteins, lipids and carbohydrates contents were dramatically reduced for the treated hoppers when compared to the untreated ones of both species. Malformed hopper and wrinkled winged adult were seen in insects treated by sub lethal concentrations of fipronil and spinosad.

English

Gomaa KFS, Bashir MO. 2017. Evaluation of five pearl millet ecotypes susceptibility to the nymphal instars of migratory locust. Trop Drylands 1: 57-63. The present study was carried out biological control unit of Insectary Laboratory, Department of Crop Protection, Faculty of Agriculture, University of Khartoum, Shambat, Sudan. The study lasted from during the beginning of May 2014 to January 2015. The experiments were undertaken under semi-field (cage-experiment) conditions. The primary objective of the study was to detect the most preferred food variety on the development of nymphal instars (3rd & 4th instars) of the locust. Five different experiments with five ecotype varieties of Pearl millet Pennisetum glaucum var. were setup. Each experiment with three replications was applied topically on the 3rd and 4th nymphal instars. Each experiment lasted for four days. We grew the Millet in ground basin and plastic cup to feed the locusts and for experiment application techniques. Observed variables were recorded daily after 24 hours from the start of experiments until the fourth day. The food preference and ecotype susceptibility evaluation were based on the amount of food intake in gram, weight of food ingested and digested in gram, percentages, and amount of weight of feces in gram. The results showed a significant difference of susceptibility of five ecotypes of pearl millet. The susceptibility of feeding by 3rd and 4th nymphal instars was observed in all ecotypes. The study results showed that the preference of ecotypes by nymphs was increased according to increasing of application time. The highest one was Bayouda-late maturing compared to four other ecotypes. During the experiments, we noticed that the preferences of five ecotypes were elevated in the first and third readings of experiments. However, we discovered in the study that the susceptibility of five pearl millet ecotypes was according to the remaining amount of feces in any ecotype variety. The least amount of reminder feces was in Bayouda-late maturing ecotype, which means that most of the food intake was ingested, digested and assimilated as with the four other ecotypes. The greater percentages of ingested amount of food consumption for five ecotypes of pearl millet, with 3rd and 4th instars of African migratory locust, ranked as mentioned above. The research concludes that further works on evaluation of susceptibility of pearl millet varieties with different pest, particularly in migratory locust is recommended to detect the palatable target variety as a trap in pest management control.

Joint action of Beauveria bassiana and the insect growth regulators diflubenzuron and novaluron, on the migratory locust, Locusta migratoria

Beauveria bassiana (Balsamo) Vuillemin and sublethal concentrations of the insect growth regulators (IGR) diflubenzuron and novaluron were applied simultaneously and sequentially to second-instar Locusta migratoria migratorioides (Sauss.) to determine the interaction between these materials and an entomopathogenic fungus. Nymphs were fed on corn leaf disks treated with several concentrations of each IGR, and a constant dose of B. bassiana was applied topically. Additive interaction was demonstrated in all instances when second-instar nymphs were exposed to diflubenzuron or novaluron simultaneously with B. bassiana treatment, and when the fungus was applied first and IGR after 48 h. Additive interaction was also exhibited when novaluron was applied first and B. bassiana after 48 h. Antagonism was demonstrated when nymphs were fed diflubenzuron-treated corn leaves first, then after 48 h were treated with B. bassiana. The additive interaction that was observed in our experiments could still be useful to achieve efficacious levels of acridid control at low rates of an IGR along with a biological control agent such as an entomopathogenic fungus.

Investigation of the histological development of the frontal ganglion in Locusta migratoria L. 1758 (Orthoptera, Acrididae)

The frontal ganglion plays a critical role in insect feeding and molting-related behaviors. It is present in all insect orders at all developmental stages. In this study, the histological development of the frontal ganglion of Locusta migratoria, the African migratory locust, was investigated. Ganglia were dissected at 3 distinct developmental stages and their histological structure was evaluated at the light microscope level. The development of the cells generating the ganglion in the first and fifth nymphal stages and in adults was determined using the variance analysis method. Total width and length of the ganglion cells as well as width and length of the nucleus were measured. A significant expansion of the cell and nucleus diameter was observed during development from the youngest stage toward adulthood.

The role of the twin-arginine translocation pathway in Escherichia coli K1 pathogenicity in the African migratory locust, Locusta migratoria

Escherichia coli K1 infection is a major cause of neonatal meningitis, with high rates of mortality and disability. Despite years of research, only a small number of factors contributing to E. coli K1 virulence have been identified. The Tat (twin-arginine translocation) protein export system is found in the cytoplasmic membrane of E. coli and is involved in the transport of folded proteins. In vivo and ex vivo models using the African migratory locust, Locusta migratoria, were employed to explore the role of Tat pathway in E. coli K1 virulence using tat-deletion mutants. Groups of locusts were infected and mortality was recorded at 24-h intervals. The findings revealed that ΔtatA, ΔtatAC and Δtat produced levels of mortality similar to wild-type E. coli K1, with >78% mortality recorded within 72 h. Bacteraemia was determined from haemolymph obtained 3 and 24 h postinfection. Again, wild-type and ΔtatA produced similar levels of bacteraemia. In contrast, ΔtatAC and Δtat produced lower levels of bacteraemia. Following injection of bacteria into isolated head capsules ex vivo, all mutants invaded the CNS. Overall, these studies showed no evidence of involvement of the Tat pathway in locust mortality but suggest its possible role in bacteraemia.

Functional analysis of a pancreatic secretory trypsin inhibitor-like protein in insects: Silencing effects resemble the human pancreatic autodigestion phenotype

Introduction In mammalian pancreatic cells, the pancreatic secretory trypsin inhibitor (PSTI) prevents the premature activation of digestive enzymes and thus plays an important role in a protective mechanism against tissue destruction by autophagy, a process which may ultimately cause diseases such as pancreatitis and pancreatic cancer. Insects, however, lack a pancreas and so far no PSTI-like peptides are functionally characterized. Results In several insect species protease inhibitors that structurally resemble the mammalian PSTI were predicted in silico. A putative PSTI-like protein (LmPSTI) was cloned and sequenced in the African migratory locust, Locusta migratoria. For the first time the expression of an insect derived PSTI-like inhibitor was shown to be restricted to the digestive enzyme-producing organs in insects (midgut and caeca). LmPSTI was produced via a bacterial expression system and was found to be a potent inhibitor of bovine trypsin as well as endogenous locust gut enzymes. In the caeca, RNAi-mediated knockdown of LmPSTI resulted in a significantly upregulated expression (2-fold) of locust ATG8 transcripts (an ubiquitin-like protein crucial for autophagosome formation). These findings were confirmed by an ultrastructural study on caeca, revealing the presence of autophagy-related structures in RNAi-treated animals. Conclusion The results of this study lead us to believe that LmPSTI plays an important role in controlling the proteolytic activity in the digestive system of L. migratoria. These findings provide new evidence for the existence of an ancient protective mechanism in metazoan digestive systems and open new perspectives for the study of autophagy-related diseases in the digestive tract.

The female reproductive system and control of oviposition in Locusta migratoria migratorioidesThe present review is the first of a series of occasional review articles that have been invited by the Editors and will feature the broad range of disciplines and expertise represented in our Editorial Advisory Board.

The spermatheca acts as a repository for sperm deposited by the male and, in the African migratory locust ( Locusta migratoria migratorioides (Fairmaire and Reiche, 1849)), is situated dorsal to the lateral and common oviducts. In the locust, eggs mature in the ovaries and are ovulated into the lateral oviducts where they are held until a suitable oviposition site is found. At that time, a hole is dug in the soil by the locust and, aided by muscular contractions of the upper lateral oviducts, the eggs are propelled through the common oviduct and genital chamber and deposited in a pod in the soil. Contractions of the spermathecal sac lead to sperm release, resulting in fertilization of eggs in the genital chamber. Coordination of digging and of the oviducts and spermatheca is clearly critical to the production of viable eggs. The muscles responsible for digging and both reproductive structures are under central neuronal control, incorporating neurons that express an array of neuropeptide and amine phenotypes. Many of the phenotypes are common to both reproductive tissues. A neural loop ensures the coordinated release of sperm when an egg passes into the genital chamber. This review will discuss our understanding of the neural control of these reproductive tissues and their coordination with digging.

Peptidomic survey of the locust neuroendocrine system

Neuropeptides are important controlling agents in animal physiology. In order to understand their role and the ways in which neuropeptides behave and interact with one another, information on their time and sites of expression is required. We here used a combination of MALDI-TOF and ESI-Q-TOF mass spectrometry to make an inventory of the peptidome of different parts (ganglia and nerves) of the central nervous system from the desert locust Schistocerca gregaria and the African migratory locust Locusta migratoria. This way, we analysed the brain, suboesophageal ganglion, retrocerebral complex, stomatogastric nervous system, thoracic ganglia, abdominal ganglia and abdominal neurohemal organs. The result is an overview of the distribution of sixteen neuropeptide families, i.e. pyrokinins, pyrokinin-like peptides, periviscerokinins, tachykinins, allatotropin, accessory gland myotropin, FLRFamide, (short) neuropeptide F, allatostatins, insulin-related peptide co-peptide, ion-transport peptide co-peptide, corazonin, sulfakinin, orcokinin, hypertrehalosaemic hormone and adipokinetic hormones (joining peptides) throughout the locust neuroendocrine system.

Novel model for the in vivo study of central nervous system infection due to Acanthamoeba spp. (T4 genotype)

In this study it was shown for what is believed to be the first time that the African migratory locust can be used as a model for the study of Acanthamoeba pathogenesis. Mature adult locusts were injected intra-abdominally with 10 mul suspension of 10(6) Acanthamoeba (a clinical isolate of the T4 genotype) in culture medium, or with the same volume of sterile culture medium. Locusts injected with Acanthamoeba showed significant weight loss and reduced production of faeces compared with control locusts. Furthermore, injection of amoebae killed all of the locusts within 17 days at room temperature, although the speed of kill was temperature and dose dependent. When samples of faecal pellets and various tissues of infected locusts were cultured on non-nutrient agar plates containing bacterial lawns, live amoebae were recovered from haemolymph, flight muscle and fat body samples, but not from faeces. When brains dissected from locusts were incubated with an anti-amoebic drug (100 muM chlorhexidine) to kill extracellular amoebae, and then washed, homogenized and cultured on bacteria-seeded non-nutrient agar plates, only lysates from amoebae-infected locusts were positive for Acanthamoeba. This strongly suggests that amoebae invade the locust brain and, indeed, trophozoites of Acanthamoeba could be identified within the brain in histological sections of brains from infected locusts, but not from uninfected locusts. These findings support the view that locusts can be used as a model for the study of Acanthamoeba pathogenesis in vivo.

Identification of New Members of the (Short) Neuropeptide F Family in Locusts and Caenorhabditis elegans

Both the long and short neuropeptides F (NPF) represent important families of invertebrate neuropeptides that have been implicated in the regulation of reproduction and feeding behavior. In the present study, two short NPFs (SNRSPS(L/I)R(L/I)RFamide and SPS(L/I)R(L/I)RFamide) were de novo sequenced by mass spectrometry in two major pest insects, the desert locust Schistocerca gregaria and the African migratory locust Locusta migratoria. They are two of the most widespread peptides in the locust neuroendocrine system. A peptide that was previously reported to accelerate egg development in S. gregaria is shown to represent a truncated form of long NPF. This peptide is most likely derived by a novel processing mechanism involving cleavage at RY. In addition, an NPF peptide from the nematode Caenorhabditis elegans was isolated and sequenced by tandem mass spectrometry.

Susceptibility of immature stages of the locusts Schistocerca gregaria and Locusta migratoria migratorioides to the microsporidium Johenrea locustae and effects of infection on feeding and fertility in the laboratory

Second instar nymphs of African migratory locust, Locusta migratoria migratorioides, and desert locust, Schistocerca gregaria, were tested for their susceptibility to the microsporidium pathogen Johenrea locustae (Lange et al. 1996, Journal of Invertebrate Pathology, 68, 28) in the laboratory. Spores of J. locustae were produced from live L.m. migratorioides, a conspecific to L. migratoria capito. Locusta m. migratorioides and S. gregaria were exposed to wheat seedlings sprayed with 20 mL of three concentrations (106, 107 and 108 spores mL−1). Both second-instar nymphs of L.m. migratorioides and S. gregaria were susceptible to J. locustae infection at the three concentrations. There was no effect of concentration of the microsporidium on mortalities of S. gregaria (92–98%) 19 days postinfection. Adjusted mortality in L.m. migratorioides at 19 days post-exposure was 24, 43 and 80% at the corresponding treatment concentrations. The effect of infection on fecundity was tested on both L.m. migratorioides and S. gregaria. Spinach leaf discs were treated with different concentrations (0, 104, 105 and 106 spores mL−1) of J. locustae and presented to female insects for 24 h. Female L.m. migratorioides surviving infection as nymphs laid significantly fewer egg pods than untreated controls at all levels of exposure. The number of eggs per female was also significantly lower in treated lots than in the controls. Higher spore concentrations also adversely affected egg hatching rate. The effect of J. locustae infection on feeding was tested on S. gregaria. There was a significant decrease in food intake among S. gregaria nymphs treated only at the high concentration (106 spores mL−1).

Tyramine as a possible neurotransmitter/neuromodulator at the spermatheca of the African migratory locust, Locusta migratoria

Tyramine-like immunoreactivity was identified in neurons of the VIIIth abdominal ganglion and in axons projecting to the spermatheca of adult females of Locusta migratoria. Tyramine-like immunoreactive processes were also found throughout all regions of the spermatheca and tyramine-like immunoreactive bipolar or multipolar neurons were present on the spermathecal sac. HPLC coupled with electrochemical detection revealed more tyramine than octopamine present in spermathecal tissue. Electrical stimulation of the ventral ovipositor nerve resulted in a significant increase in calcium-dependent release of tyramine from the spermatheca. Both tyramine and octopamine increase the frequency and basal tonus of spermathecal contractions in a dose-dependent manner, with octopamine having a lower threshold. When tyramine is applied along with a half maximal octopamine dose, there is an additive effect on contractions of the spermatheca with slight synergistic effects at lower doses of tyramine. High concentrations of tyramine (10 −4 M) stimulated increases in cyclic AMP levels of the spermatheca; an effect blocked by phentolamine. Phentolamine has a higher affinity (and thus a lower IC 50 value ≅5.6 × 10 −8 M) than yohimbine (IC 50 ≅1.1 × 10 −4 M) in reducing tyramine-induced spermathecal contractions. Taken together, these results suggest that tyramine may be a co-transmitter with octopamine at the spermatheca, with both neuroactive chemicals acting on an octopamine receptor.

Development of a novel ex vivo insect model for studying virulence determinants of Escherichia coli K1

A key step in Escherichia coli K1 meningitis is the crossing of the blood-brain barrier by the bacteria in order to gain entry into the central nervous system (CNS). In this study, a novel ex vivo model to study E. coli K1 invasion of the CNS is described that uses the African migratory locust, Locusta migratoria. By injecting bacteria into isolated locust head capsules, it was demonstrated that E. coli K1 invade the locust brain within 2 h in numbers depending on the concentration of bacteria injected. Using several mutants derived from K1, it was shown that outer-membrane protein A is a critical bacterial determinant required for the E. coli K1 invasion. The isogenic gene-deletion mutants, DeltafimH, Deltacnf1, DeltaneuDB and a rough LPS mutant showed significantly reduced invasion of locust brain. This novel model for the study of E. coli K1 pathogenesis offers several advantages over existing mammalian models in relation to its relative ease of use, cost-effectiveness and ethical acceptability.