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At least 199 records · Page 11Linked to original sources
PubMed2005

A amylase activity of nymphal stages of sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae).

Wheat production in Iran has changed substantially over the past one or two decades with development of higher-yielding cultivars and improved methods of planting. Sunn pest, Eurygaster integriceps (Heteroptera: Pentatomidae), is the most important cereal pest in Iran. Sunn pest like other insect pests of wheat lives on a polysaccharide-rich diet and depends to a large extent on effectiveness of their alpha-amylases for survival. alpha-amylase (1-4-alpha-D-glucan glucanohydrolase) hydrolyses starch, and related polysaccharides by randomly cleaving internal alpha-1,4-glucosidic linkages and has a major role in the utilization of polysaccharides. The recent increase in study of insect digestive enzymes seems to make sense in the realization that the gut is the major interface between the insect and its environment. Hence, an understanding of digestive enzyme function is essential when developing methods of insect control such as the use of enzyme inhibitor's and transgenic plants to control phytophagous insects. The aim of the current study is to identify and characterize alpha-amylase activity in order to gain a better understanding of its digestive physiology, which hopefully will lead to new strategies of the insect control. In order to analyze a-amylase activity adult and different nymphal stages were collected from wheat field from Karaj area and midgut complex from these individuals were dissected under a light microscope in ice-cold saline buffer (0.006M NaCl). After homogenization in buffer, homogenate was centrifuged at 15000 g for 20 min at 4 degrees C. The supernatant was pooled and stored at -20 degrees C for subsequent analysis. alpha-amylase activity was assayed by the dinitrosalicylic acid (DNS) procedure using soluble starch as substrate (starch 1%). Our result showed that enzyme activities in different nymphal stages (first, second, third, fourth and fifth stadium) were 0.19, 0.78, 1.21, 1.23, 1.25 units/mg protein, respectively.

Animals↗
PubMed1976

Control and management of insect populations by chemosterilants.

Chemosterilants, i.e., chemical compounds that interfere with the reproduction potential of sexually reproducing organisms, can be used in three new approaches to insect control. In the sterile-insect release technique, the principal problem is to develop compounds and methods for their application that would not result in introducing harmful residues into the environment. Because of the unusual and often unique circumstances connected with releasing large numbers of sterilized insects, the residue problem and its cost-benefit aspects must be examined individually for each intended control or eradication program. In the direct application technique, chemosterilants must meet the same efficiency and safety standards required from approved insecticides. Combined insecticidal and sterilizing activity is characteristic for some compounds now being investigated. In the genetic technique, chemosterilants may be used for inducing heritable changes in the insect's genome under laboratory conditions, and such procedures would not present any residue problems. Only the first two chemosterilant techniques are approaching practical application, and their safety aspects require detailed evaluation and assessment.

Chemosterilants↗
PubMed2003

A test bed for insect-inspired robotic control.

Flying insects are remarkable examples of sophisticated sensory-motor control systems. Insects have solved the fundamental challenge facing the field of mobile robots: robust sensory-motor mapping. Control models based on insects can contribute much to the design of robotic control systems. We present our work on a preliminary robotic control system inspired by current behavioural and physiological models of the fruit fly, Drosophila melanogaster. We designed a five-degrees-of-freedom robotic system that serves as a novel simulation/mobile robot hybrid. This design has allowed us to implement a fly-inspired control system that uses visual and mechanosensory feedback. Our results suggest that a simple control scheme can yield surprisingly robust fly-like robotic behaviour.

Adaptation, Physiological↗
PubMed1975

Control of insects by sexual sterilization.

The control of insect populations by restricting their birth rate offers several advantages over methods based on increasing the death rate. The sterile-male technique scored practical success in the control of the screwworm, Cochliomyia hominivorax (Coquerel), but more general applications of the sterility procedure may be expected in conjunction with the development of integrated procedures for pest insect management.

Animals↗
PubMedDate not supplied

Controlled release effect of insecticide microcapsules and their results in common household insect pest control.

Since 1978 we have prepared microencapsulated insecticides by complex coacervation and interfacial polymerization for household insect pest control, fenthion being the main core element. A series of tests have been conducted against mosquitoes (Culex pipiens quinquefasciatus), cockroaches (Periplaneta americana) and bedbugs (Cimex lectularius), and the results indicate that microencapsulation can prolong persistent effects by 2-12 times, enhance safety and subdue offensive odour. Furthermore, the production cost is comparatively low.

Animals↗
PubMed1994

Digestive enzymes, haemolysins and symbionts in the search for vaccines against blood-sucking insects.

Control of blood-sucking insects by vaccination of the host is an appealing possibility. In this overview the potential of digestive enzymes, haemolysins and symbionts as targets for vaccines are discussed. Blood-sucking insects are largely dependent on proteases for digestion. This is advantageous in the search for a vaccine as there is a considerable fund of biochemical knowledge for this group of molecules. Also there are a range of inhibitors available which can be used to mimic the effects of a vaccine providing a useful guide to the potential usefulness of such a vaccine before the considerable investment needed in producing one. Weighing against this, proteolytic enzymes by their nature will attack antibodies approaching them making it questionable if antibodies ingested by the insect could succeed before they themselves are destroyed by their target. Proteolytic enzymes are also poor immunogens, probably because they attack the antibody making machinery approaching them and because the complexes formed between the abundant vertebrate antiproteolytic molecules and proteases provide a different antigenic target to the native enzymes. Despite their relative paucity, evidence suggests that lipid digesting enzymes deserve attention as potential vaccine targets. Because about 80% of the nutrients in blood are locked up in its formed elements haemolysins are a strong potential target of a vaccine. The obligate haematophages rely on symbionts to provide essential nutrients and in consequence these are also potential vaccine targets in these insects.

Animals↗
PubMed1964

ESTERASE INHIBITORS AS PESTICIDES.

Thirty years of testing has yielded over 120 esterase inhibitors in current use for pest control. Several hundred million pounds of these organophosphates and carbamates are employed each year as insecticides and acaricides and, to a much lesser extent, as anthelmintic agents, nematocides, and herbicides. Systemics or chemotherapeutic agents for control of insect pests of plants and animals first became practical with the organophosphates. Compounds of lower mammalian toxicity and other favorable biological properties continue to appear and displace established compounds and broaden the use areas. Problems of resistance and residues in certain areas of insect control by chlorinated hydrocarbons will result in a further shift to esterase-inhibitors for pest control. Interpretation of the potential hazards of pesticides to man is dependent on the availability of fundamental information on their modes of action combined with use experience; this knowledge is available for the organophosphates and carbamates that act as acetylcholinesterase inhibitors.

Animals↗
PubMed2006

Recent developments and future prospects in insect pest control in transgenic crops.

The adoption of insect-resistant transgenic crops has been increasing annually at double-digit rates since the commercial release of first-generation maize and cotton expressing a single modified Bacillus thuringiensis toxin (Bt) nine years ago. Studies have shown that these Bt crops can be successfully deployed in agriculture, which has led to a decrease in pesticide usage, and that they are environmentally benign. However, the sustainability and durability of pest resistance continues to be discussed. In this review, we focus on the science that underpins second- and third-generation insect-resistant transgenic plants and examine the appropriateness and relevance of models that are currently being used to determine deployment strategies to maximize sustainability and durability. We also review strategies that are being developed for novel approaches to transgenic insect pest control.

Bacterial Toxins↗
PubMed1990

Insect resistant cotton plants.

We have expressed truncated forms of the insect control protein genes of Bacillus thuringiensis var. kurstaki HD-1(cryIA(b) and HD-73 (cryIA(c) in cotton plants at levels that provided effective control of agronomically important lepidopteran insect pests. Total protection from insect damage of leaf tissue from these plants was observed in laboratory assays when tested with two lepidopteran insects, an insect relatively sensitive to the B.t.k. insect control protein, Trichoplusia ni (cabbage looper) and an insect that is 100 fold less sensitive, Spodoptera exigua (beet armyworm). Whole plants, assayed under conditions of high insect pressure with Heliothis zea (cotton bollworm) showed effective square and boll protection. Immunological analysis of the cotton plants indicated that the insect control protein represented 0.05% to 0.1% of the total soluble protein. We view these results as a major step towards the agricultural use of genetically modified plants with insect resistance in this valuable, high acreage crop.

Amino Acid Sequence↗
PubMed1998

Toxicity and Pathogenicity Testing of the Insect Pest Control Fungus Metarhizium anisopliae

Renewed interest in the use of Metarhizium anisopliae and its toxins for insect control prompted the following safety assessment. A neutral extract (methylene chloride, pH 7.2), derived from M. anisopliae cultures, was evaluated for toxicity and mutagenicity using aquatic animal bioassays and the Ames test. The average LC50 of the neutral extract obtained in static, acute 96-h tests conducted with </=24-h-old Mysidopsis bahia was 2.41 mg L-1. By partially purifying destruxins from the neutral extract, it was shown that destruxins alone were not responsible for the observed toxicity in mysids. The neutral extract was fetotoxic to developing grass shrimp, Palaemonetes pugio, and frog, Xenopus laevis, embryos; the LC50 values were 52 and 32 mg L-1, respectively. Eye spot abnormalities were observed in shrimp and frog embryos exposed to the neutral extract. In extract-exposed frog embryos, moderate to severe cranial, facial, and gut malformations were also observed. The neutral extract was toxic to juvenile mosquito fish, Gambusia affinis, at an LC50 value of 141 mg L-1. Adult female G. affinis surviving a 24-h exposure to 200 µg ml-1 of the neutral extract produced healthy broods. After 3 months, no mortalities or adverse effects were observed in adult G. affinis fed a diet partially composed of a freeze-dried M. anisopliae culture. The neutral extract did not show mutagenicity in the Ames test using strains TA98 and TA100 with and without metabolic activation by rat liver S9. Significant (p </= 0.05) mortalities were obtained when embryos of grass shrimp and inland silverside fish, Menidia beryllina, were exposed to the same lot of M. anisopliae conidiospores. Exposure of frog embryos to M. anisopliae conidiospores did not cause significant (p > 0.05) mortalities or malformations.

Journal Article↗