Use In Insect Control Research Articles

Biosynthesis of Silver Nanoparticles Mediated by Entomopathogenic Fungi: Antimicrobial Resistance, Nanopesticides, and Toxicity.

Silver nanoparticles are widely used in the biomedical and agri-food fields due to their versatility. The use of biological methods for the synthesis of silver nanoparticles has increased considerably due to their feasibility and high biocompatibility. In general, microorganisms have been widely explored for the production of silver nanoparticles for several applications. The objective of this work was to evaluate the use of entomopathogenic fungi for the biological synthesis of silver nanoparticles, in comparison to the use of other filamentous fungi, and the possibility of using these nanoparticles as antimicrobial agents and for the control of insect pests. In addition, the in vitro methods commonly used to assess the toxicity of these materials are discussed. Several species of filamentous fungi are known to have the ability to form silver nanoparticles, but few studies have been conducted on the potential of entomopathogenic fungi to produce these materials. The investigation of the toxicity of silver nanoparticles is usually carried out in vitro through cytotoxicity/genotoxicity analyses, using well-established methodologies, such as MTT and comet assays, respectively. The use of silver nanoparticles obtained through entomopathogenic fungi against insects is mainly focused on mosquitoes that transmit diseases to humans, with satisfactory results regarding mortality estimates. Entomopathogenic fungi can be employed in the synthesis of silver nanoparticles for potential use in insect control, but there is a need to expand studies on toxicity so to enable their use also in insect control in agriculture.

Occurrence of persistent organic pollutants in air at different sites in the province of Córdoba, Argentina.

The occurrence of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of six sites with different emission sources in the province of Córdoba, Argentina, was analyzed. The sites included urban, industrial, agricultural, and mountain areas. Samples were collected using passive air samplers (PAS) consisting of polyurethane foam disks (PUF). Samples were analyzed for 12 PAHs, 31 polychlorinated biphenyls (PCBs), 12 organochlorine pesticides (OCPs), and 11 polybrominated diphenyl ethers (PBDEs). The concentrations of PAHs in the atmosphere were elevated at urban sites and were even higher at the industrial site. With respect to OCPs, it was observed that the concentrations of endosulfan were greater at the agricultural site (AGR) (416 ± 4pgm-3). For hexachlorocyclohexanes (HCHs), only the alpha isomer was detected and there were minimal differences between the different sampling sites (5.9-13.3pgm-3). In the case of dieldrin, the highest concentrations (33.6pgm-3) were found at the mountain site, which may have been due to its use for insect control. Although heptachlor epoxide was not detected, the concentration of heptachlor was significantly higher at the agricultural and downtown sites (∼3.6pgm-3). Regarding DDTs, the isomers p,p'-DDT and p,p'-DDE showed the highest concentrations at the mountain site (ΣDDT 120 ± 12pgm-3) and downtown site (ΣDDT 157 ± 62pgm-3). The relationship between the isomers suggested that at the downtown site, the contribution of this pesticide to the environment was recent, probably for the control of diseases vectors. The congener pattern of PBDEs was dominated by BDE-47, and BDE-99 at all sites, with the downtown site having the highest concentrations of compound esters (ΣPBDEs 118 ± 38pgm-3). Finally, high concentrations of PCBs were found at the industrial site (ΣPCBs 1677 ± 134pgm-3), and the predominating homologs were 5-Cl and 6-Cl, in contrast to the other sites where PCBs were dominated by 3-Cl and 4-Cl. This is the first study of POPs carried out in the province of Córdoba.

Selection, assessment of virulence to Alphitobius diaperinus, and Pr1 enzyme production of Beauveria bassiana (Bals.) Vuill. isolates cultured at stress temperatures

The entomopathogenic fungus Beauveria bassiana is a promising agent for use in insect control. Its pathogenic activity, as well as other factors such as temperature that can interfere with its development, should be assessed, thus, establishing the foundations for B. bassiana use in biological control programs. The objective of this study was to select and induce tolerance of B. bassiana isolates to high and low temperatures and to assess their virulence before and after exposure to those temperatures. A pre-selection test was performed, in which the tolerance of isolates to stress temperatures was tested and compared to the ideal growth temperature of 25 °C for this organism. For the isolates/temperature combinations resulting in growth, conidia germination and colony-forming units (CFUs) were assessed. The isolates Unioeste 4 and Unioeste 40 exhibited >95% germinated conidia at 16 and 31 °C. Thereafter, they underwent four consecutive passages at maximum and minimum tolerated temperatures (10 and 37 °C). A significant difference in germination was observed between the two isolates at all temperatures tested. More CFUs were observed for Unioeste 4 compared to Unioeste 40 at all temperatures, and in the case of the latter, there was no difference in CFU formation at 10 and 25 °C. For both isolates, decreased vegetative growth was observed at 37 °C. Recovery of virulence was observed in both isolates, as determined by insect mortality. No relationship was observed between production of the enzyme Pr1 and the virulence of the isolates.

Structure–activity relationship study of trifluoromethylketones: inhibitors of insect juvenile hormone esterase

The juvenile hormone esterase (JHE) regulates juvenile hormone titre in insect hemolymph during its larval development. It has been suggested that JHE could be targeted for use in insect control. This enzyme can also be considered as involved in the phenomenon of endocrine disruption by xenobiotics in beneficial insects. Consequently, there is a need to know the characteristics of the molecules able to act on the JHE. Trifluoromethylketones (TFKs) are the most potent JHE inhibitors found to date and different quantitative structure–activity relationships (QSARs) have been derived for this group of chemicals. In this context, a set of 181 TFKs (118 active and 63 inactive compounds), tested on Trichoplusia ni for their JHE inhibition activity and described by physico-chemical descriptors, was split into different training and test sets to derive structure–activity relationship (SAR) models from support vector classification (SVC). A SVC model including 88 descriptors and derived from a Gaussian kernel was selected for its predictive performances. Another model computed only with 13 descriptors was also selected due to its mechanistic interpretability. This study clearly illustrates the difficulty in capturing the essential structural characteristics of the TFKs explaining their JHE inhibitory activity.

Pheromone Use for Insect Control: Present Status and Prospect in Bangladesh

The insect’s world is filled with many odors. Insects use these odors to cue them in a variety of complex social behaviors, including courtship, mating, and egg laying. Scientists and pest control specialists have known about these complex communication systems for decades. The main aim of this study was to visualize the availability, trends and differences in the sources of pheromone control in agricultural growth of Bangladesh. It also concerned on constrains and present use of pheromone and their possible recommendation on behalf of Bangladesh agriculture. It concentrated on the data during last three decades (1980-2010), comprising status of pheromone use in Bangladesh agriculture and its future. Review revealed that Bangladesh has been enormously successful in increasing pheromone use in agricultural production (especially for vegetables). Understanding of the nature of pheromones and their potential for pest control along with the future prospective of pheromone technique in agriculture were stated. Since the pheromone, technologies for control of major crop pests in Bangladesh are still limited. So that this review emphasized on more attention to the authority to increase the research works and project facilities related to develop and promote pheromone techniques. It is highly recommended to increase availability of pheromone in market, more investment in research and development, introduction of newly identified pheromone for specific pest, to assist government and nongovernment organizations to work with farmers to reduce harmful insecticide use and promote pheromone tactics as one part of integrated crop management (ICM). DOI: http://dx.doi.org/10.3329/ijarit.v2i1.14005 Int. J. Agril. Res. Innov. & Tech. 2 (1): 47-55, June, 2012

Transfer and fate of seminal fluid molecules in the beetle, Diaprepes abbreviatus: Implications for the reproductive biology of a pest species

Molecules transferred from males to females via seminal fluids are important to the study of insect reproduction because they affect female physiology, reproductive behavior, and longevity. These molecules (seminal fluid molecules or SFMs) interest applied entomologists because of their potential use in insect control. SFMs are also interesting because of their relatively rapid evolution and important role in post-mating sexual selection. We studied SFMs in Diaprepes abbreviatus, a major pest of numerous plant species of economic importance. Using radiolabeled-methionine ( 35S), we found that D. abbreviatus males synthesized proteins de novo in their reproductive tissues after mating. Males that were fed radiolabeled methionine transferred radioactivity to females beginning within the first 10 min of mating. Male-derived substances are absorbed from the female's reproductive tract into the hemolymph and circulated throughout the body, but are found primarily in the eggs and ovaries. As a result, SFMs may be a useful means of both horizontal (to mates) and vertical transfer (to offspring) of control agents between conspecifics.

Allosteric interactions among pyrethroid, brevetoxin, and scorpion toxin receptors on insect sodium channels raise an alternative approach for insect control

Intensive pyrethroid use in insect control has led to resistance buildup among various pests. One alternative to battle this problem envisions the combined use of synergistically acting insecticidal compounds. Pyrethroids, scorpion α- and β-toxins, and brevetoxins bind to distinct receptor sites on voltage-gated sodium channels (NaChs) and modify their function. The binding affinity of scorpion α-toxins to locust, but not rat-brain NaChs, is allosterically increased by pyrethroids and by brevetoxin-1. Brevetoxin-1 also increases the binding of an excitatory β-toxin to insect NaChs. These results reveal differences between insect and mammalian NaChs and may be exploited in new strategies of insect control.

Mutations and their use in insect control.

Traditional chemically based methods for insect control have been shown to have serious limitations, and many alternative approaches have been developed and evaluated, including those based on the use of different types of mutation. The mutagenic action of ionizing radiation was well known in the field of genetics long before it was realized by entomologists that it might be used to induce dominant lethal mutations in insects, which, when released, could sterilize wild female insects. The use of radiation to induce dominant lethal mutations in the sterile insect technique (SIT) is now a major component of many large and successful programs for pest suppression and eradication. Adult insects, and their different developmental stages, differ in their sensitivity to the induction of dominant lethal mutations, and care has to be taken to identify the appropriate dose of radiation that produces the required level of sterility without impairing the overall fitness of the released insect. Sterility can also be introduced into populations through genetic mechanisms, including translocations, hybrid incompatibility, and inherited sterility in Lepidoptera. The latter phenomenon is due to the fact that this group of insects has holokinetic chromosomes. Specific types of mutations can also be used to make improvements to the SIT, especially for the development of strains for the production of only male insects for sterilization and release. These strains utilize male translocations and a variety of selectable mutations, either conditional or visible, so that at some stage of development, the males can be separated from the females. In one major insect pest, Ceratitis capitata, these strains are used routinely in large operational programs. This review summarizes these developments, including the possible future use of transgenic technology in pest control.

Recent developments in our knowledge of steroids.

Annually, the American Chemical Abstracts has some 3 000 references to plant steroids or related compounds. This is a review of 34 selected papers mainly from the literature of 1984-1985. Plant steroids as raw material for the pharmaceutical industry; tissue culture for steroids; horticultural trials of species for sapogenins; the in vitro use of enzymes to increase the yield of sapogenins from plant material. New furostanol precursors of diosgenin; the cytotoxic activity of these and related compounds; their possible role in plant mineral metabolism. Microorganisms in the biotransformation of steroids; the exploitation of waste material as a source of sterols; the use of fungal spores on diatomaceous particles; the use of fungal protoplasts; hydrophobic resin as a product reservoir in such transformations. Brassinosteroids, their distribution as plant growth hormones; their microquantitative bioassay; physiological studies towards their use for enhancement of crop production; patented analogues obtained by partial synthesis. Ecdysones, their wide distribution in plants; their possible functions: effect on photosynthetic and respiratory rates; root protection against soil nematodes; dietary value in animal nutrition; their use in insect control. 29-Fluorophytosterols as pro-insecticides; fungal pregnanes as insecticides. Cardiac glycosides; ecological significance in plant-insect-bird relationships; new cardenolides, naturally occurring and those obtained by partial synthesis; the use of mesophyll cells in tissue culture; crossbreeding of Digitalis species. Steroidal alkaloids: reference to their annual review and to a Steroidal antibiotic; the types of alkaloids now defineable in the Buxaceae and their chemotaxonomic significance for the new ones from the single genus family, Didymelaceae.

Acoustic communication of insects and the use for insect control

Acoustic communication of insects and the use for insect control

Residues of carbon tetrachloride and 1,2‐dibromoethane in cereals and processed foods after liquid fumigant grain treatment for pest control

AbstractResidues of halogenated hydrocarbon ‘liquid’ fumigants occurring in cereals and their products as a result of use for insect control continue to be of concern in technologically advanced as well as developing countries. Carbon tetrachloride and ethylene dibromide residues remaining in wheat, maize, barley and sorghum shortly after fumigation, during storage for periods of up to 1 year and after processing have been determined, with the fumigants applied either as liquids or vapours. Amounts of residues occurring in bread made from wheat containing residual fumigants were also measured. Current methods of use of these fumigants are discussed with reference to the results of these experiments and interim recommendations are made for post‐ treatment handling of cereals.

Role of Phermones and Kairmones for Insect Suppression Systems and Their Possible Health and Environmental Impacts

Insects produce pheromones as a chemical communication system to facilitate reproduction. These highly active chemical attractants have been synthesized for some of the most important insect pests, including the boll weevil, gypsy moth, codling moth, tobacco budworm, European corn borer, and several bark beetles. While none of the synthetic sex attractants have yet been developed for use in insect control, they offer opportunities for the future both as control agents and to greatly improved insect detection. Investigations are underway on insect trapping systems employing the phermones and on air permeation techniques to disrupt insect reproduction. The pheromones are generally highly species-specific and are not likely to pose hazards to nontarget organisms in the environment. Toxicological studies indicate that they are low in toxicity to mammals, birds, and fish, but adequate toxicological data are necessary before they can be registered for use in insect control. Another new class of compounds called kaironomes has been discovered. These chemicals are involved in the detection of hosts or prey by insect parasites and predators. Kairomones may prove useful in manipulating natural or released biological agents for more effective biological control of insect pests. No information is yet available on the toxicology of these chemicals.

Role of phermones and kairmones for insect suppression systems and their possible health and environmental impacts.

Insects produce pheromones as a chemical communication system to facilitate reproduction. These highly active chemical attractants have been synthesized for some of the most important insect pests, including the boll weevil, gypsy moth, codling moth, tobacco budworm, European corn borer, and several bark beetles. While none of the synthetic sex attractants have yet been developed for use in insect control, they offer opportunities for the future both as control agents and to greatly improved insect detection. Investigations are underway on insect trapping systems employing the phermones and on air permeation techniques to disrupt insect reproduction. The pheromones are generally highly species-specific and are not likely to pose hazards to nontarget organisms in the environment. Toxicological studies indicate that they are low in toxicity to mammals, birds, and fish, but adequate toxicological data are necessary before they can be registered for use in insect control. Another new class of compounds called kaironomes has been discovered. These chemicals are involved in the detection of hosts or prey by insect parasites and predators. Kairomones may prove useful in manipulating natural or released biological agents for more effective biological control of insect pests. No information is yet available on the toxicology of these chemicals.

Studies on the Antifeedant Against the Caterpillars of Pericallia ricini F. (Arctiidae) and Spodoptera littoralis Boesd (Noctuidae: Lepidoptera) on Castor (Ricinus communis L.)

Organotin compounds have been recently known for their use in insect control as an antifeedant and chemosterilant (Ascher and Rones, 1964; Kenega, 1965). There are enough findings with different organotins proving their antifeeding efficacy and many compounds for moth proofing have been evolved based on their antifeeding properties rather than on insecticidal effects. The present observation was designed to study the effect of TTH (Triphenyl tin hydroxide) on feeding activity of castor bean leaf caterpillar Pericallia ricini F. and Spodoptera littoralis Boesd. (Prodenia litura).

Insect control by radiation sterilization in Australia

The use of radiation for the production of sterile male insects and their use in insect control or eradication is discussed. Results are reported from the use of sterile males in the control of the Queensland fruit fly, Dacus tyroni, and the sheep blowfly, Lucilia cuprina, in Australia, (C.H.)

New Organic Compounds for Use in Insect Control

New Organic Compounds for Use in Insect Control