Adult Locusta Migratoria Research Articles

Comparison of the Virulence of Space Mutants of Aspergillus oryzae XJ-1 against Adult Locusta migratoria

Biological control methods provide a sustainable approach for reducing agricultural losses caused by locust plagues. Space mutagenesis can generate high numbers of mutations using satellites and spacecrafts, including beneficial and stable mutants. Aspergillus oryzae XJ-1 was recently reported to show high virulence against locusts. We subjected this fungal pathogen to space mutagenesis to obtain more effective strains. Pathogen conidia powder was mutated in the China Space Station for 6 months. We obtained five mutants of A. oryzae XJ-1, TQ201, TQ238, TQ302, TQ549, and TQ555, and all mutants were identified as A. oryzae by molecular techniques. TQ549 showed the highest virulence against adult L. migratoria (LT50: 4.97 ± 0.21 days); the LT50 of A. oryzae XJ-1 was 5.67 ± 0.06 days. Both TQ549 and A. oryzae XJ-1 grew most rapidly at 33 °C on potato dextrose agar (PDA) plates. There was no significant difference in the growth rate of TQ549 and A. oryzae XJ-1 at 24 °C. The colony morphological characteristics of the five mutants on PDA plates differed from that of A. oryzae XJ-1. The space mutant TQ549, which showed high virulence against adult locusts, could be used as a biological control agent for the control of locust infestations.

Virulence of the fungal pathogen, Aspergillus oryzae XJ-1 in adult locusts (Orthoptera: Acrididae) in both laboratory and field trials.

Locusts and grasshoppers are pests of many agricultural crops, and their frequent outbreaks worldwide threaten food security. Microbial control agents are currently used to suppress the early (nymphal) stages of pests, but they are often less effective against adults, which are primarily responsible for locust plagues. The fungal pathogen Aspergillus oryzae XJ-1 has high pathogenicity in locust nymphs. To assess its potential for controlling locust adults, we evaluated the virulence of A. oryzae XJ-1 (i.e., locust Aspergillus, LAsp) in locust adults using laboratory, field-cage experiments, and a field trial. The lethal concentration of LAsp in adult Locusta migratoria was 3.58±0.09×105 conidia/ml 15 days after inoculation in the laboratory. A field-cage experiment showed that the mortalities of adult L. migratoria were 92.0±4.6% and 90.1±3.2% 15 days after inoculation with 3×105 and 3×103 conidia/m2 of LAsp, respectively. A large-scale field trial of 666.6 ha was conducted, in which a LAsp water suspension was applied at a concentration of 2×108 conidia/ml in 15 L/ha by aerial spraying via drones. The densities of mixed populations of L. migratoria and Epacromius spp. were significantly reduced by 85.4±7.9%-94.9±5.1%. In addition, the infection rates of surviving locusts collected from the treated plots were 79.6% and 78.3% on the 17th and 31st day after treatment, respectively. These results indicate that A. oryzae XJ-1 is highly virulent in adult locusts and that it has high potential for the control of locusts.

Effect of Substrates' Compliance on the Jumping Mechanism of Locusta migratoria.

Locusts generally live and move in complex environments including different kind of substrates, ranging from compliant leaves to stiff branches. Since the contact force generates deformation of the substrate, a certain amount of energy is dissipated each time when locust jumps from a compliant substrate. In published researches, it is proven that only tree frogs are capable of recovering part of the energy that had been accumulated in the substrate as deformation energy in the initial pushing phase, just before leaving the ground. The jumping performances of adult Locusta migratoria on substrates of three different compliances demonstrate that locusts are able to adapt their jumping mode to the mechanical characteristics of the substrate. Recorded high speed videos illustrate the existence of deformed substrate's recoil before the end of the takeoff phase when locusts jump from compliant substrates, which indicates their ability of recovering part of energy from the substrate deformation. This adaptability is supposed to be related to the catapult mechanism adopted in locusts' jump thanks to their long hind legs and sticky tarsus. These findings improve the understanding of the jumping mechanism of locusts, as well as can be used to develop artifact outperforming current jumping robots in unstructured scenarios.

Structures, properties, and energy-storage mechanisms of the semi-lunar process cuticles in locusts.

Locusts have excellent jumping and kicking abilities to survive in nature, which are achieved through the energy storage and release processes occurring in cuticles, especially in the semi-lunar processes (SLP) at the femorotibial joints. As yet, however, the strain energy-storage mechanisms of the SLP cuticles remain unclear. To decode this mystery, we investigated the microstructure, material composition, and mechanical properties of the SLP cuticle and its remarkable strain energy-storage mechanisms for jumping and kicking. It is found that the SLP cuticle of adult Locusta migratoria manilensis consists of five main parts that exhibit different microstructural features, material compositions, mechanical properties, and biological functions in storing strain energy. The mechanical properties of these five components are all transversely isotropic and strongly depend on their water contents. Finite element simulations indicate that the two parts of the core region of the SLP cuticle likely make significant contributions to its outstanding strain energy-storage ability. This work deepens our understanding of the locomotion behaviors and superior energy-storage mechanisms of insects such as locusts and is helpful for the design and fabrication of strain energy-storage devices.

Locust primary neuronal culture for the study of synaptic transmission

We have designed a cell culture system for thoracic neurons of adult Locusta migratoria that enables the establishment of functional synapses in vitro. Patch-clamp recordings revealed three different neuron classes. About half of the neurons (47%) had unexcitable somata with outward and no inward conductance. The other half generated either single (37%) or multiple action potentials (18%) and differed mainly in lower outward conductance. Selectively stained motor neurons were analyzed to demonstrate varied physiological properties due to culture conditions. Using paired patch clamp recordings we demonstrate directly synaptic transmission in morphologically connected neurons in vitro. Presynaptic stimulation resulted in postsynaptic potentials in 42 pairs of neurons tested, independent of the type of neuron. According to pharmacological experiments most of these synapses were either glutamatergic or GABAergic. In addition to these chemical synapses, electrical synapses were found. With the demonstration of synapse formation in cell culture of adult locust neurons, this study provides the basis for the future analysis of more defined insect neuronal circuits in culture.

Interactions between the endocrine and immune systems in locusts

Abstract. The prophenoloxidase cascade in the haemolymph of mature adult Locusta migratoria migratorioides (R & F) is activated in response to injection of laminarin, a β‐1,3 glucan. Co‐injection of adipokinetic hormone‐I (Lom‐AKH‐I) and laminarin prolongs the activation of the enzyme in a dose‐dependent manner. However, injections of bacterial lipopolysaccharide (LPS) do not activate prophenoloxidase unless AKH is co‐injected, when there is a dose‐dependent increase in the level of phenoloxidase that persists in the haemolymph for several hours. Even when AKH is co‐injected, the highest levels of phenoloxidase activity are always greater after injection of laminarin than after LPS, and these two immunogens must activate the prophenoloxidase cascade by quite distinct pathways. In the present study, interactions between the endocrine and immune systems were examined with respect to activation of prophenoloxidase and the formation of nodules: injection of LPS induces nodule formation in adult locusts. With LPS from Pseudomonas aeruginosa, nodules form exclusively in dense accumulations in the anterior portion of the abdomen on either side of the dorsal blood vessel associated with the dorsal diaphragm. However, with LPS from Escherichia coli, fewer nodules are formed but with a similar distribution, except that occasionally some nodules are aligned additionally on either side of the ventral nerve cord. Co‐injection of Lom‐AKH‐I with LPS from either bacteria stimulates greater numbers of nodules to be formed. This effect of coinjection of AKH on nodule formation is seen at low doses of hormone with only 0.3 or 0.4 pmol of Lom‐AKH‐1, respectively, increasing the number of nodules by 50%. Injections of octopamine or 5‐hydroxytryptamine do not mimic either of the actions of Lom‐AKH‐I described here. Co‐injection of an angiotensin‐converting enzyme inhibitor, captopril, reduces nodule formation in response to injections of LPS but has no effect on the activation of phenoloxidase. Co‐injection of an inhibitor of eicosanoid synthesis, dexamethasone, with LPS influences nodule formation (with or without AKH) in different ways according to the dose of dexamethasone used, but does not affect activation of prophenoloxidase. Eicosanoid synthesis is important for nodule formation, but not for the activation of the prophenoloxidase cascade in locust haemolymph.

A single allatostatin-immunoreactive neuron innervates skeletal muscles of several segments in the locust

In the nervous system of embryos and adult Locusta migratoria, somata, neurites within the ganglia, and axons leaving the thoracic ganglia show allatostatin immunoreactivity. The immunoreactive efferent axons divide to follow different nerve branches and form varicose terminals on skeletal muscles. In the adult locust, one pair of motor neurons is particularly prominent among the allatostatin-immunoreactive neurons. The somata are located symmetrically in a lateral position in the first abdominal neuromere of the fused metathoracic ganglion. Each neuron gives rise to five axon branches projecting into ipsilateral nerves. Three axons project posteriorly and exit through the dorsal nerves of the abdominal neuromeres A1, A2, and A3. One axon extends into the metathoracic neuromere and exits through metathoracic nerve 1 (N1). The fifth axon extends anteriorly through the connective into the mesothoracic ganglion, where it leaves through the mesothoracic N1. The targets of this neuron, among them the mesothoracic and metathoracic muscles M87, M88, M116 and the dorsal longitudinal muscles M81 and M112, are located in five different segments. In addition to supplying skeletal muscles, the neuron forms neurohaemal-like structures in the sheath of nerve branches. The authors call this neuron the common lateral neuron (CLN). The innervation of several muscles by Diploptera allatostatin 7-immunoreactive axon branches with a common cellular origin and the anatomy of one of the corresponding motor neurons in adults, the CLN, suggest that allatostatin acts as a modulator of neuromuscular parameters in insects by multisegmental direct innervation of skeletal muscles.

A single allatostatin‐immunoreactive neuron innervates skeletal muscles of several segments in the locust

In the nervous system of embryos and adult Locusta migratoria, somata, neurites within the ganglia, and axons leaving the thoracic ganglia show allatostatin immunoreactivity. The immunoreactive efferent axons divide to follow different nerve branches and form varicose terminals on skeletal muscles. In the adult locust, one pair of motor neurons is particularly prominent among the allatostatin-immunoreactive neurons. The somata are located symmetrically in a lateral position in the first abdominal neuromere of the fused metathoracic ganglion. Each neuron gives rise to five axon branches projecting into ipsilateral nerves. Three axons project posteriorly and exit through the dorsal nerves of the abdominal neuromeres A1, A2, and A3. One axon extends into the metathoracic neuromere and exits through metathoracic nerve 1 (N1). The fifth axon extends anteriorly through the connective into the mesothoracic ganglion, where it leaves through the mesothoracic N1. The targets of this neuron, among them the mesothoracic and metathoracic muscles M87, M88, M116 and the dorsal longitudinal muscles M81 and M112, are located in five different segments. In addition to supplying skeletal muscles, the neuron forms neurohaemal-like structures in the sheath of nerve branches. The authors call this neuron the common lateral neuron (CLN). The innervation of several muscles by Diploptera allatostatin 7-immunoreactive axon branches with a common cellular origin and the anatomy of one of the corresponding motor neurons in adults, the CLN, suggest that allatostatin acts as a modulator of neuromuscular parameters in insects by multisegmental direct innervation of skeletal muscles. J. Comp. Neurol. 413:507–519, 1999. © 1999 Wiley-Liss, Inc.

Effects of Deltamethrin on Glucose Catabolic Pathways in the Isolated Fat Body of Adult Male Locusta migratoria

The effects of various doses (non-lethal, LD 15, LD 25, LD 50, LD 75) of the pyrethroid insecticide deltamethrin were investigated on glucose catabolism pathways in the isolated fat body of starved 25-day-old male adult Locusta migratoria. Two methods of poisoning with deltamethrin were used. In the first case, the insecticide was injected into the locust in vivo and then the fat body was dissected either 30 min or 1hr after injection. The orientation of glucose with respect to its catabolic pathways was estimated in isolated fat body by means of radio-respirometric method using [1- 14C]glucose and [6- 14C]glucose. Deltamethrin reduced the relative participation of the pentose pathway, and this effect was maximal 1hr after insecticide treatment. Glucose degradation in the glycolysis-Krebs cycle was increased only 30 min after treatment. Deltamethrin significantly modified the orientation of glucose between the catabolic pathways. In the second case, deltamethrin was added directly into the fat body incubation medium after its sampling in in vitro conditions. Labeled glucose was added either simultaneously or 30 min after the insecticide dose. In both cases, deltamethrin diverted glucose from the pentose cycle; this effect was larger with simultaneous injections. The relative participation of the glycolysis-Krebs cycle was slightly increased, and this effect was observed only when the injections were separated by 30 min. A direct dose-dependent response was observed only on the pentose cycle. An indirect action of deltamethrin on glucose catabolism pathways in fat body might be the most probable explanation, but we cannot eliminate the possibility of a direct effect on these catabolic pathways.

Recovery of the flight system following ablation of the tegulae in immature adult locusts

The capacity of the flight system to recover from ablation of the tegulae was studied in immature adult Locusta migratoria and compared with recovery in mature adults. We ablated the hindwing tegulae or all tegulae in adult locusts either 1 day after the imaginal moult (immature locusts) or 2 weeks after the imaginal moult (mature locusts). We monitored recovery throughout the recovery period by using a stroboscope to measure the wingbeat frequency of tethered locusts. In addition, we measured other parameters of the flight motor pattern using electromyographic electrodes implanted into recovered locusts. Both methods of monitoring recovery yielded the same results. There was no reduction, during adult maturation, in the capacity of the locust flight system to recover from the loss of these proprioceptors. Plasticity of the locust flight system was therefore maintained in the mature adult locust. This suggests that the flight system is not fixed and simply implemented when the locust reaches adulthood, but that the circuitry can be remodelled throughout the animal's life to produce behaviour adapted to the needs and constraints of the individual.

The combined effects of the fungusMetarhizium flavovirideGams & Rozsypal and the insecticide cypermethrin onLocusta migratoria migratorioides(Reiche & Fairmaire) in the laboratory

Abstract A problem in the use of the fungus Metarhizium flavoviride Gams & Rozsypal to control locusts is that the locust continues eating for the first few days after the fungus has been applied. Applying a dose of 13 000 spores per locust to adult Locusta migratoria migratorioides (Reiche & Fairmaire) in 10 ppm cypermethrin (approximately LC10, even 7 days after dosing) inhibited feeding by 50% on day 1 after treatment and advanced the onset of locust mortality from the fungus by 48 h. A similar inhibition of feeding from the cypermethrin also occurred in combination with doses of fungus as low as 375 spores per locust, but the earlier locust mortality was not then observed. It was also determined that cypermethrin was not toxic to M. flavoviride in in vitro tests.

Inhibition of RNA synthesis by adipokinetic hormones and brain factor(s) in adult fat body of Locusta migratoria

Extracts of brains and corpora cardiaca from adult Locusta migratoria inhibit total RNA synthesis in vitro in the fat body of Locusta migratoria. Adipokinetic hormones (AKHs) appear to be responsible for the inhibitory activity in extracts of corpora cardiaca, but these peptides are not the active factor(s) in the brain. Locusta adipokinetic hormones-I, -II and -III (AKH-I, AKH-II and AKH-III) inhibit RNA synthesis in vitro in both females and in males. In males, the responses are dose-dependent with their potencies decreasing in the order: AKH-III > AKH-II > AKH-I. All three AKHs are equally efficacious, suppressing RNA synthesis to levels similar to those measured when actinomycin D is added to the incubations of fat body tissue. Mature adults (25 days old of either sex) are the most sensitive, while younger insects show practically no inhibition of RNA synthesis in response to injected adipokinetic peptides. At supramaximal doses, however, the peptides cease to be effective in females, while they retain their efficacy in males. The chemical nature of the active material in the extracts of brain remains to be determined, but its mechanism of action in inhibiting RNA synthesis differs from that of the AKHs: the latter require extracellular Ca 2+ for their action, while extracts of brain do not. Neither mechanism appears to involve cAMP.

Alterations in Carbohydrate Metabolism Induced in Locusta migratoria after Poisoning with the Pyrethroid Insecticide Deltamethrin

The effects of ethanolic solutions of deltamethrin injected at LD50 and LD75 doses on circulating and stored carbohydrates in 20- to 25-day-old male adult Locusta migratoria have been investigated. First, the impact of the use of either fed or starved locusts for this study was addressed. Starved insects appeared to be more homogeneous in relation to their hydromineral metabolism and nycthemeral cycles. Deltamethrin effects on trehalosemia showed two different phases: the first phase which took place during the first hour after the injection of deltamethrin characterized by a significant hypertrehalosemia ( + 50% for LD75). Subsequently, a second phase appeared, characterized by a significant decrease of trehalose for a period of 24 hr (−60% for LD50 and LD75 at 24 hr). Deltamethrin at the LD75 dose induced a very large decrease in fat body glycogen stores (−100% at 15 min and 6 hr after the injection of deltamethrin); then glycogen decreased in controls and virtually disappeared in treated locusts. Simultaneously, fat body glycogen phosphorylase was activated by deltamethrin at the LD75 dose. The glycogen stores of flight muscles were only slightly affected by the treatment at early times while a significant decrease was observed after 6 and 24 hr of drug action. The activity of flight muscle glycogen phosphorylase was not modified. Hemolymphatic peptide extracts from locusts previously treated with deltamethrin (LD75) show hypertrehalosemic activity.

Omega AGA toxin IVA blocks high-voltage-activated calcium channel currents in cultured pars intercerebralis neurosecretory cells of adult locusta migratoria

Using the whole cell patch-clamp technique, calcium (Ca) channel currents from cultured medial neurosecretory cells (MNSCs) of Locusta migratoria (Rössler and Bickmeyer, 1993) were investigated. The calcium channel blocker omega AGA toxin IVA (AGA IVA) blocks a fraction of these calcium channel currents in ∼30% of MNSCs, without a shift in the I– V relationship. The block can be at least partially reversed by strong depolarizing voltage pulses as described for vertebrate neurones from Mintz et al. (1992). The existence of probably more than three calcium channel types in insects is discussed.

Neurotensin-like immunoreactivity in locust supraesophageal ganglion and optic lobes

A substance immunoreactive to antibodies directed against bovine neurotensin (NT) was localized in neurons in the supraesophageal ganglion (SEG) and optic lobes of larval and adult Locusta migratoria L. Two large somata were located in the caudal cortex, ventral to the calyces and symmetrical to the medium of the SEG. Four smaller somata also in the caudal cortex were located as two symmetrical pairs at the level of the central body. These somata formed a diffuse network of varicose fibers from the superior lateral to the ventro-lateral protocerebrum between the pedunculi and frontal cortical region. Some fibers crossed the median to the contralateral sides of the SEG. Another pair of immunoreactive somata whose terminating processes remained unclear was found at the level of the antennal lobes. Intrinsic networks of fibers were labeled in the accessory medulla and in layer 4/5 of the medulla. These fibers originated from 8–10 small somata near the dorso-frontal rim of the medulla. All larval stages contained these NT-like immunoreactive structures. Results from isoelectric focusing and press-blot analysis of SEG homogenates, synthetic neurotensin and neurotensin fragments indicate that this substance is similar to bovine neurotensin(1–13).

Foregut Morphology of Locusta migratoria (L.) (Orthoptera: Acrididae)

ABSTRACTThe role of the foregut of adult Locusta migratoria in feeding was evaluated using light and scanning electron microscopy. the intima of the foregut possesses many spines, different regions of the foregut bearing spines with different morphologies. Crop and proventricular spines with multiple prongs were observed. Wear was observed on spines from month‐old locusts, revealing that considerable mechanical interaction with plant material occurs within the gut. Morphological evidence does not support a grinding or crushing function for the spines of the foregut. the foregut spines are most likely used to regulate the passage of food through the foregut.

Hemolymph phenol oxidases in Drosophila melanogaster, Locusta migratoria, and Austropotamobius pallipes

The early enzyme-mediated reaction sequence in the biosynthesis of melanin from L-tyrosine involves an initial hydroxylation (monophenol oxidase activity, MPO) of the aromatic amino acid precursor to form L-dopa (3,4-dihydroxyphenylalanine), and the ensuing oxidation (diphenol oxidase activity, DPO) of the resultant diphenol to form dopaquinone. By means of high pressure liquid chromatography with electrochemical detection (HPLC-ED) both phenol oxidase activities were observed in the blood (hemolymph) of two species of insect, third-stage larvae of Drosophila melanogaster and adult Locusta migratoria, and in an adult fresh-water crayfish, Austropotamobius pallipes. These results establish that in each species MPO and DPO can be detected readily without the use of exogenous activators.

Effects of methoprene and juvenile hormone on the oxidative metabolism of isolated mitochondria from flight muscle ofLocusta migratoria L.

In vitro applications of juvenile hormone III and a juvenile hormone analogue, methoprene, were made to mitochondria isolated from dorsal longitudinal flight muscles of adultLocusta migratoria L. Both compounds completely inhibited oxygen consumption at the highest concentrations used. At lower concentrations, state 3 respiration and respiratory control were reduced but the ADP/O ratio was largely unaffected.

Different isoforms of an apoprotein (apolipophorin III) associate with lipoproteins in Locusta migratoria

Insects transport lipid for flight in the form of diacylglycerol-rich low-density lipoproteins (low-density lipophorin, LDLp), which in the hemolymph are produced from high-density lipophorin (HDLp) by reversible association with several molecules of an apolipoprotein, apolipophorin III (apoLp-III, Mr approximately 18,000-20,000) during lipid loading. Two isoforms of apoLp-III (a and b) were purified both from adult Locusta migratoria migratorioides hemolymph and LDLp, which have identical apparent Mr but differ in amino acid composition, NH2-terminal amino acid sequence, and isoelectric points (5.35 +/- 0.01 for apoLp-IIIa, 5.10 +/- 0.01 for apoLp-IIIb). The NH2-terminal sequence of apoLp-IIIb is identical to the primary structure of apoLp-III deduced from cloned cDNA [Kanost et al. (1988) J. Biol. Chem. 263, 10,568-10,573], whereas the NH2-terminal sequence of apoLp-IIIa is identical to that of apoLp-IIIb but preceded by Arg-Pro-, which is the C-terminal of the putative signal peptide coded by cDNA upstream from that coding for apoLp-IIIb. The ratio apoLp-IIIa apoLp-IIIb free in hemolymph is identical to that in LDLp (5:9); since 14 molecules of apoLp-III appear to be bound in one molecule of LDLp, an average of 5 molecules of apoLp-IIIa and 9 of apoLp-IIIb are involved in formation of each LDLp particle. In vivo studies using 35S-labeled apoLp-IIIa and b demonstrate that each of the isoforms can associate with HDLp to produce LDLp reversibly; in an in vitro system, production of LDLp containing exclusively apoLp-IIIa or apoLp-IIIb demonstrates independent participation of each isoform in LDLp formation.

Cytodifferentiation and maturation in the male accessory glands of Locusta migratoria migratorioides (R. and F.) (Orthoptera : Acrididae)

The male accessory glands of adult Locusta migratoria migratorioides (R. and F.) (Orthoptera : Acrididae) lie on each side of the ejaculatory duct. Each gland contains 15 tubules derived from the wall of the 10th coelomic vesicle. There are 3 types of tubules: white, hyaline and opalescent. They remain identical until the 5th instar, and then differentiate during the first 15 days of imaginal life. During this period, the glandular epithelium differentiates and secretion begins. The secretion of each tubule type is distinctive. The lumen of the opalescent gland contains a homogeneous material, which is not packed by the Golgi, and paracrystalline material, which originates as a clear secretion in the Golgi, and crystallizes in the lumen. The lumen of the white tubules contains granular material produced in the Golgi apparatus. Finally, the endoplasmic reticulum of the hyaline tubules contains only homogeneous material. These morphological differences are reflected in different acrylamide electrophoresis patterns.