Variegated Grasshopper Zonocerus Variegatus Research Articles

Nutritive value of variegated grasshopper Zonocerus variegatus (L.)

The act of eating insects (entomophagy) has been on the increase due to their medicinal and nutritional importance. This study examines the gender differences in the nutritive value of adult variegated grasshopper Zonocerus variegatus (L.). The proximate (crude protein, fibre ash, fat and carbohydrate), mineral (Na+, Ca2+, Mg2+ and Fe2+), vitamin (A, B1, B2 and C), anti-nutrients (flavonoids, tannin, saponin, alkaloid and antraguinone) assays and heavy metals compositions (Pb, Cu, Zn, Cd and Ni) of newly emerged male and female adults were analyzed by standard methods. Adult female Z.variegatus had significantly higher (p<0.05) crude protein, ash, fibre and carbohydrate than the male. Similar trend was observed for mineral composition and vitamins assay of the adults. Anti-nutrients and heavy metal composition of the adults varied from 0.210–8.82% and 0.113–1.264 mg/100g, respectively with the female showing higher values. Adult female Z.variegatus is thus more nutritious than the male.

Sexual differences in destructive capability and midgut enzyme activities in adult variegated grasshoppers Zonocerus variegatus (LINNAEUS, 1758) (Orthoptera: Pyrgomorphidae)

AbstractThe variegated grasshopper Zonocerus variegatus is a polyphagous insect, feeding on numerous food and cash crops. The present study aimed to investigate the sexual variations in the destructive capability of the adult insects and the composition of leaves damaged by them, as well as in the levels of midgut microbial flora and digestive enzymes (cellulase, amylase and α-glucosidase). The results showed that females consumed and caused more damage to cassava leaves than their male congeners. The leaves damaged by males contained more nutrients than those damaged by females. The gut microbial flora and enzyme assay showed that females had significantly larger colony forming units and a non-significant difference in enzyme activities. It can thus be concluded that adult females are more destructive than males.

Detoxification of cyanide in insects. I. Purification and some properties of rhodanese from the gut of the variegated grasshopper Zonocerus variegatus (Orthoptera: Pyrgomorphidae)

The purification and characterization of rhodanese, an enzyme that catalyses the detoxification of cyanide, from the gut of the variegated grasshopper ( Zonocerus variegatus L.) were carried out to understand the biochemical basis of the survival of this grasshopper living on cyanogenic plants such as cassava. All experiments, including enzyme assay, were carried out at room temperature and all buffers contained 10 m m sodium thiosulphate to stabilize the enzyme. Grasshoppers were caught alive from a cassava farm within the locality and kept frozen until analysis. Each grasshopper was dissected and the gut was removed quickly. Approximately 102 g of the gut were homogenized in three volumes of 0.1 m acetate glycine buffer (pH 7.8) containing ɛ-amino- n -caproic acid. The supernatant was collected by centrifugation at 12,000 rpm, for 30 min at 40 °C. The enzyme was purified to homogeneity by a combination of procedures such as ammonium sulphate precipitation, ion-exchange chromatography (CM-Sephadex and DEAE-Sephadex), gel filtration (Sephadex G-75) and Agarose-Blue affinity chromatography. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) and non-SDS–PAGE were used to ascertain the purity of the enzyme. The native and subunit molecular weights of the enzyme were determined by gel filtration on a Bio-Gel P-200 column and SDS–PAGE, respectively. Kinetic parameters were determined by using varying concentrations of one of the substrates at a fixed concentration of the other, and vice versa. Furthermore, the effects of temperature, pH and cations on the activity of the enzyme were investigated. The purified enzyme had a specific activity of 51.7 μmol thiocyanate formed/ml/min/mg protein (U/mg protein) with a yield of about 29%. The apparent molecular weight of the enzyme estimated by Sephadex G-75 gel filtration was 35,400 ± 482 Da and its subunit molecular weight determined by SDS–PAGE was 33,000 ± 212 Da. The K m values of KCN and Na 2 S 2 O 3 were found to be 29.63 ± 02.87 and 26 ± 03.04 m m , respectively. An optimum pH and temperature of 7.0 and 35 °C, respectively, were obtained for the enzyme. The results of enzyme inhibition showed that the activity of the enzyme was not affected by NH 4 Cl, MgCl 2 , CoCl 2 , CaCl 2 , MnCl 2 , NiCl 2 and SnCl 2 , but inhibited by ZnCl 2 and BaCl 2 . In conclusion, these results suggest that the survival of Z. variegatus depends on the presence of the enzyme rhodanese, which shows high activity and has suitable kinetic properties in the gut of the grasshopper that feeds mainly on cassava leaves which are cyanogenic.

Activity of digestive enzymes in Zonocerus variegatus (Orthoptera: Pyrgomorphidae) gut homogenates during post-embryonic development

The activity of five enzymes - amylase, a-glucosidase, cellulase, proteinase and lipase - present in the foregut, midgut and hindgut of the African variegated grasshopper Zonocerus variegatus (L.) was studied in the post-embryonic stages of the insect. The activities of all the enzymes increased with age of the insect, with the adult stage having significantly higher (P , 0.05) activity than the lower instars. The midgut had the highest activity for all the enzymes except for amylase. Proteinase activity was the highest, and cellulase the lowest in the gut regions. These findings indicate that the adult stage of the polyphagous insect has higher digestive capacity than the immature stages.

A Study on the Feeding and Growth Patterns of the Variegated Grasshopper Zonocerus Variegatus (L) in the Laboratory

The feeding and growth patterns of the variegated grasshopper, Zonocerus variegatus (L) were studied in the laboratory to ascertain the amount of food intake, food assimilated and faeces excreted by its nymph and adult stages on a mixed diet of Cassava (Manihot esculenta) and Siam weed (Chromolaena odorata) leaves. Also, the length and weight of the nymph and adult insects were determined separately while the behavioural patterns of food selection were observed. Although temperature and relative humidity affected the activities of the insects, and were not regulated in the experimental room, these did not affect their feeding pattern and as such, could not be the main factors’ affecting the insect’s feeding and growth patterns. Results obtained from the analysis of data obtained showed that the nymphal stages of the grasshoppers consumed and utilized more feed for growth and development than their adult stages. Consequently, it could be inferred that the nymphal stages would constitute more serious pest problems on the vegetation they attack than the adults. Therefore, significant management of this pest can be achieved when control measures are aimed more at the nymphal stages than the adults.

Extracellular enzyme production by microflora from the gut region of the variegated grasshopper Zonocerus variegatus (Orthoptera: Pyrgomorphidae)

Microbial isolates from the gut region of larvae and adults of the variegated grasshopper Zonocerus variegatus (Linnaeus) were screened for extracellular production of the enzymes lipase, amylase, esterase, protease, linamarase and cellulase. Using the pour-plate culture technique, 15 bacterial, 4 yeast and 5 mould isolates were tested. None of the bacterial isolates showed lipase activity, but virtually all showed esterase and protease activities. Many bacterial isolates demonstrated linamarase and cellulase activities, and a few of them amylase activity. Of the yeast isolates, a few had amylase activity. None of the mould isolates showed enzyme activity except Aspergillus sp., which showed lipase activity. Evidently, the gut of Z. variegatus contains micro-organisms that are able to produce digestive enzymes. Of significance is the biosynthesis of linamarase (β-d-glucosidase) by the grasshopper’s gut bacteria, which probably contributes to the insect’s neutralization of the toxic effects of cyanogenic glycosides present in cassava (Manihot esculenta), one of its major food plants.

Morphometrics and enzyme activities in the femoral muscles of variegated grasshopper Zonocerus variegatus (Orthoptera: Pyrgomorphidae) during post-embryonic development

The measurements of the hind femur and activities of five enzymes (α-glucosidase, amylase, cellulase, proteinase and lipase) were determined in the femoral muscles of all post-embryonic developmental stages of Zonocerus variegatus (Linnaeus). The length, width and weight of the hind femur increased during the post-embryonic developmental stages. The enzymatic activities in the femoral muscles of the adult stage were significantly (P < 0.05) higher than the lower instar stages. Proteinase and lipase activities were higher than the carbohydrases (a-glucosidase, amylase and cellulase), reflecting the nature and composition of the food plants consumed.

A soluble β-cyanoalanine synthase from the gut of the variegated grasshopper Zonocerus variegatus (L.)

β-Cyanoalanine synthase ( β-cyano- l-alanine synthase; l-cysteine: hydrogen sulphide lyase (adding hydrogen cyanide (HCN)); EC 4. 4.1.9) was purified from the cytosolic fraction of the gut of grasshopper Zonocerus variegatus (L.) by ion-exchange chromatography on DEAE-Cellulose and gel filtration on Sephadex G-100 columns. The crude enzyme had a specific activity of 2.16 nmol H 2S/min/mg. A purified enzyme with a specific activity, which was seventeen times higher than that of the crude extract, was obtained. A molecular weight of about 55.23±1.00 Kd was estimated from its elution volume on Sephadex G-100. The fraction when subjected to sodium dodecyl sulphate–polyacrylamide elel electrophoresis revealed the presence of a protein band with M r of 23.25±0.25 Kd. The enzyme exhibited Michaelis–Menten kinetics having K m of 0.38 mM for l-cysteine and K m of 6.25 mM for cyanide. The optimum temperature and pH for activity were determined to be at 30 °C and pH 9.0, respectively. This enzyme might be responsible for the ability to detoxify cyanide in this insect pest and hence its tolerance of the cyanogenic cassava plant. Biophysical, biochemical and kinetic properties of this enzyme, which will reveal how this ability can possibly be compromised by enzyme inhibition, may lead, in the long term, to the potential use of this enzyme as drug target for pest control.

Participatory development of a biological control strategy of the variegated grasshopper in the humid tropics in West Africa

The results of a participatory rural appraisal (PRA) in 3 villages in the Couffo district of Benin show that the variegated grasshopper Zonocerus variegatus L. is a major, but recent, crop pest. Farmers’ knowledge of grasshopper biology is limited and they have not yet developed indigenous control methods. Villagers were keen to collaborate in a participatory research, testing alternative control methods. A demonstration of biological control of grasshoppers was organized, followed by the training of a group of six farmers per village—the village brigade, who will be in charge of grasshopper control in their village. After the training, where grasshopper biology and the advantages and disadvantages of different control options were discussed, it was agreed to test a biological pesticide, an oil-based formulation of the entomopathogenic fungus Metarhizium anisopliae var . acridum, in a participatory research program. The village brigades chose to test two different strategies: preventive control by treating the young larval stages and curative control by treating adult grasshoppers, with two different sprayers (flit gun and spinning-disc sprayer). Both strategies were tested at three different doses (2, 20 and 50 g of spores/ha). Results show that the dose can be reduced to 20 g/ha without loss of efficacy, so the cost of the treatment (estimated at $20/100 g or $4/ha) is within the farmer's reach. Participatory testing also revealed that treating the uncultivated areas is not a practical strategy. Finally, although battery -powered spinning-disc sprayers are more expensive than the hand-powered flit gun sprayers, their higher efficacy justifies the extra expense. The villagers proposed that grasshopper biological control be organized by village brigades, in close collaboration with the village association of cotton growers, who will provide credit. For the 1998–1999 season, this strategy was proposed and accepted in 18 new villages, and each village organized a brigade, trained by the project. Women, who generally manage their own fields, preferred a separate brigade, and three female brigades have been trained so far.

The microbial flora of the different gut regions of the variegated grasshopper Zonocerus variegatus (L) (Orthoptera :Pyrgomorphidae)

The microbial flora of the gut regions and gut contents of the variegated grasshopper Zonocerus variegatus instars was studied using the pour plate technique. The gut sections (Fore-, mid-, and hind-gut) harboured a variety organisms mainly bacteria, fungi and mould. Yeasts species isolated were Candida, Saccharomyces and Pichia spp. Aspergilus, Penicillium, Fusarium and Rhizopus spp. Both gram positive and gram negative bacteria were isolated. The gram negative bacteria isolated were mainly rods and members of the family Enterobacteriaceae including Proteus, Alcaligenes, Escherichia and Serratia. These species were more widely distributed in and more frequently isolated from the gut regions and their contents than the gram positive bacteria which were represented by Sreptococcus, Lactobacillus and Staphylococcus species. Gram positive bacteria were isolated from the gut extracts of the 3rd and 4th instars but were found in some of the gut regions of the 6th and adult instars. Mould population decreased gradually as the grasshopper was moulting from the 3rd to adult instars. Ranking according to microbial load was adult> 6th >4th >3rd, a reflection of their gut capacity since the microbes were part of the diet. The number and types of microbes in the gut regions of these instars are similar but significantly different in terms of total microbial load (P>=0.05). The results of this study could provide a lead into the proper understanding of the physiological processes involved in the digestion of plant materials by the insect. Keywords: Z.variegatus, microbial, bacteria, mould, yeast ,gut. (Global Journal of Pure and Applied Sciences: 2002 8(4): 447-454)

Preliminary chemical analyses of the repellent secretion of the African variegated grasshopper Zonocerus variegatus

The chemical nature of the repellent secretion of the African grasshopper, Zonocerus variegatus (Orthoptera: Pyrgomorphidae) reared on Acalypha ivilkesiana L. and Manihot esculenta (Crantz) was analysed. It was found to contain alkaloids, glucose, proteins, free amino acids, trypsinlike proteinase, carbohydrases, lipase and the ions Ca2+, Mg2+ and K+ but not Na+ and (PO4)2−. Alkaloids were present in the secretion whether or not the insect was fed on plants containing alkaloids. Cyanide ions were absent in the secretion, even when Z. variegatus was fed exclusively on the cyanogenic Manihot esculenta. The amino acid and glucose contents were the same in grasshoppers reared on different plants. The protein content in the repellent secretion was constant, despite the fluctuations observed in the protein content of the haemolymph.