Biological Control Of Insects Research Articles

Behavior and demography in an urban colony of <i>Tadarida brasiliensis</i> (Chiroptera: Molossidae) in Rosario, Argentina

Con el objetivo de incrementar el conocimiento de la ecología de los murciélagos en las urbanas, se muestrearon colonias en la ciudad de Rosario. Fueron registradas siete especies, de las cuales tres son nuevos registros. Se seleccion.ó una colonia que se consideró más representativa, para realizar un intensivo estudio ecológico. Se realizaron conteos poblacionales, que arrojaron aproximadamente 64 000 Tadarida brasiliensis formando una colonia maternal en el ático de un antigüo edificio. Se hicieron registros de comportamiento (fechas de arribo y partida, patrones diarios de actividad, pariciones, etc.). Los adultos arrivan al refugio a mediados de septiembre y lo abandonan en febrero. Las pariciones ocurren entre mediados de noviembre y mediados de diciembre. Las crías se ubicaron en grupos compactos en

Regional-Scale Spatio-Temporal Analysis of Anastrepha ludens (Diptera: Tephritidae) Populations in the Citrus Region of Santa Engracia, Tamaulipas, Mexico.

Large citrus areas in Tamaulipas are affected by Anastrepha ludens (Loew) populations. Here we report the findings of a spatio-temporal analysis of A. ludens on an extended citrus area from 2008-2011 aimed at analyzing the probabilities of A. ludens infestation and developing an infestation risk classification for citrus production. A Geographic Information System combined with the indicator kriging geostatistics technique was used to assess A. ludens adult densities in the spring and fall. During the spring, our models predicted higher probabilities of infestation in the western region, close to the Sierra Madre Oriental, than in the east. Although a patchy distribution of probabilities was observed in the fall, there was a trend toward higher probabilities of infestation in the west than east. The final raster models summarized the probability maps using a three-tiered infestation risk classification (low-, medium-, and high risk). These models confirmed the greater infestation risk in the west in both seasons. These risk classification data support arguments for the use of the sterile insect technique and biological control in this extended citrus area and will have practical implications for the area-wide integrated pest management carried out by the National Program Against Fruit Flies in Tamaulipas, Mexico.

Predatory hoverflies increase oviposition in response to colour stimuli offering no reward: Implications for biological control

There are increasing efforts worldwide to engineer agroecosystems to enhance ecosystem services such as carbon storage, minimisation of erosion, and biological control of pests. A key group of insect biological control agents is the hoverflies (Diptera: Syrphidae). While adult Syrphidae are pollen and nectar feeders, the larvae of many species are aphidophagous, thus demonstrating life-history omnivory and their potentially important role in the biological control of aphids and other pests. Several experiments have been conducted to assess whether the presence of flowers in or near crops has an effect on oviposition by syrphids, but the results have often been inconclusive. This paper describes a large-scale field experiment carried out over two years, in which standardised model flowers were placed in field margins and oviposition rates monitored near them. Statistically significantly more eggs were laid on broad bean (Vicia faba) infested with the pea aphid, Acyrthosiphon pisum, near yellow model flowers with and without pollen and honey resources than at positions with no model flowers nearby. These results suggest strongly that the presence of model flowers increases hoverfly oviposition and that colour may be more important than food resources in enhancing this behaviour. This work indicates that biological control of pests by hoverflies can be enhanced by simple, non-floral agroecological interventions.

Drosophila melanogaster brain invasion: pathogenic Wolbachia in central nervous system of the fly.

The pathogenic Wolbachia strain wMelPop rapidly over-replicates in the brain, muscles, and retina of Drosophila melanogaster, causing severe tissue degeneration and premature death of the host. The unique features of this endosymbiont make it an excellent tool to be used for biological control of insects, pests, and vectors of human diseases. To follow the dynamics of bacterial morphology and titer in the nerve cells we used transmission electron microscopy of 3-d-old female brains. The neurons and glial cells from central brain of the fly had different Wolbachia titers ranging from single bacteria to large accumulations, tearing cell apart and invading extracellular space. The neuropile regions of the brain were free of wMelPop. Wolbachia tightly interacted with host cell organelles and underwent several morphological changes in nerve cells. Based on different morphological types of bacteria described we propose for the first time a scheme of wMelPop dynamics within the somatic tissue of the host.

Stress tolerance and virulence of insect-pathogenic fungi are determined by environmental conditions during conidial formation.

The virulence to insects and tolerance to heat and UV-B radiation of conidia of entomopathogenic fungi are greatly influenced by physical, chemical, and nutritional conditions during mycelial growth. This is evidenced, for example, by the stress phenotypes of Metarhizium robertsii produced on various substrates. Conidia from minimal medium (Czapek's medium without sucrose), complex medium, and insect (Lepidoptera and Coleoptera) cadavers had high, moderate, and poor tolerance to UV-B radiation, respectively. Furthermore, conidia from minimal medium germinated faster and had increased heat tolerance and were more virulent to insects than those from complex medium. Low water-activity or alkaline culture conditions also resulted in production of conidia with high tolerance to heat or UV-B radiation. Conidia produced on complex media exhibited lower stress tolerance, whereas those from complex media supplemented with NaCl or KCl (to reduce water activity) were more tolerant to heat and UV-B than those from the unmodified complex medium. Osmotic and nutritive stresses resulted in production of conidia with a robust stress phenotype, but also were associated with low conidial yield. Physical conditions such as growth under illumination, hypoxic conditions, and heat shock before conidial production also induced both higher UV-B and heat tolerance; but conidial production was not decreased. In conclusion, physical and chemical parameters, as well as nutrition source, can induce great variability in conidial tolerance to stress for entomopathogenic fungi. Implications are discussed in relation to the ecology of entomopathogenic fungi in the field, and to their use for biological control. This review will cover recent technologies on improving stress tolerance of entomopathogenic fungi for biological control of insects.

Symptoms shown by late-stage larvae of the West Indian sweet potato weevil Euscepes postfasciatus (Coleoptera: Curculionidae) infected with Farinocystis sp. (Neogregarinida: Lipotrophidae)

Pathogen outbreaks often represent a major issue when mass rearing target insects for biological control, even when applying sterile insect techniques (SIT). Here, we aimed to improve existing screening techniques used to detect a neogregarine Farinocystis sp. that infects the West Indian sweet potato weevil Euscepes postfasciatus Fairmaire (Coleoptera: Curculionidae) mass reared under the SIT program. Our results revealed that infected late-instar larvae exhibited swelling symptoms, and that their body weight and head width significantly increased compared to uninfected larvae. The head width to body weight ratio differed between infected and uninfected larvae; yet, head width was highly correlated with body weight in both cases. Visual diagnosis based on the appearance of the late-instar larvae showed concordance of almost 90 % with the current diagnostic methods of optical microscopy and PCR. Thus, the swelling symptoms observed in late-instar larvae were directly noticeable. Therefore, visual diagnosis, based on larval appearance, represents a feasible, low-cost technique for the early detection of Farinocystis sp. infection of the West Indian sweet potato weevil.

Modifying soil to enhance biological control of belowground dwelling insects in citrus groves under organic agriculture in Florida

An emerging organic citrus industry in Florida could benefit greatly from effective, non-conventional methods to mitigate losses from pests and diseases. We studied part of a soil food web in an organic orchard to learn ways to conserve and enhance biological control of insect pests by native entomopathogenic nematodes (EPNs). We evaluated two OMRI (Organic Materials Review Institute) approved cultural practices: (i) a mulch of commercially pelleted chicken manure, (ii) a commercial formulation of Purpureocillium lilacinus, and (iii) an un-amended control. Several soil nutrients (i.e. nitrogen, phosphate, and potassium) were affected by the amendments, but initial equilibrium values (T0) were restored by the last sampling time (T12). The plant parasitic nematode Tylenchulus semipenetrans increased in both treatments compared to the untreated control at T3 (P<0.05). The oomycete Phytophthora nicotianae increased in the P. lilacinus plots at T1, marginally at T12, but decreased at T6 and T9. Steinernema diaprepesi, Heterorhabditis indica and Heterorhabditis zealandica were the only EPNs regularly detected in the orchard. Mulch increased numbers of H. zealandica at T6 and T9 (P<0.05) and free living nematodes at T12 (P<0.01). The nematophagous fungus (NF) P. lilacinus persisted in plots where it was augmented (P<0.05), reaching a maximum level at T3 that was 17.5-fold greater than that in controls. Numbers of Paenibacillus sp. were directly related to both those of S. diaprepesi and Acrobeloides-group nematodes (P<0.01), but inversely to the FLN counts (P<0.05). The application of these two amendments did not produce strong changes in the EPN community but decreased the emergence from soil of adult Diaprepes abbreviatus, a root weevil pest. Thus, both amendments might contribute to citrus pest management under organic production.

Phylogenetic diversity of Brazilian Metarhizium associated with sugarcane agriculture

Biological control of spittlebugs with Metarhizium (Hypocreales: Clavicipitaceae) in Brazilian sugarcane is an example of effective pest management. However, little is known about the richness, distribution and ecology of Metarhizium species in Brazilian agroecosystems. We investigated Metarhizium diversity within a collection of 96 Brazilian isolates from spittlebugs and other insects, strains used for spittlebug control and soil isolates from sugarcane and other field crops and pristine habitats. A multilocus phylogenetic analysis of 5′-TEF and nuclear intergenic loci MzFG543igs and MzIGS3 yielded robust support for current species limits of the two most abundant taxa, Metarhizium anisopliae and Metarhizium robertsii, and the resolution of two lineages that lie beyond currently recognized species limits in this complex. With a single exception, all isolates from insects belong to a single subclade of M. anisopliae. These data will serve as resources about Metarhizium biodiversity for insect biological control initiatives in South America.

Genetic Diversity Study of Locally Isolated Bacillus thuringiensis Strains from Kuwait Using Random Amplified Polymorphic DNA Analysis

Introduction: Bacillus thuringiensis (Bt) is significant bacteria in the field of insect biological control due to their insecticidal properties and its importance in agriculture. Aim: The objective of this study was to analyze genetic variation of 15 native isolates of Bacillus thuringiensis and four reference strains (total 19) using the random amplified polymorphic DNA (RAPD) technique, this allowed the analysis the genetic diversity of this species in the microbial populations from different soil samples of Kuwait. Methodology: We isolated 109 Bacillus thuringiensis strains, out of which, 15 strains were subspecies thuringiensis, using culture and serological method. A rapid typing method of Bacillus thuringiensis local isolates from Kuwait soil was established using the RAPD technique. A single Original Research Article Qasem et al.; BMRJ, 7(4): 193-201, 2015; Article no.BMRJ.2015.111 194 decamer primer was used to study and characterize Bacillus Spp, Bacillus thuringiensis var. thuringiensis, to differentiate the isolated species. Based on RAPD pattern, data were subjected to cluster analysis using Alpha Ease software. Results: We found three groups each, with two strains that had a similar pattern of DNA and one group that had three subspecies that have a similar DNA pattern. The rest of the eight isolates each had a unique pattern of DNA. These isolates were classified according to the same chemical and physical characterization, but were different genetically. Conclusion: In conclusion, using molecular methods for comparison of genomic DNA between different bacterial species of the same genus is a good measurement of genetic relations between different species, which could lead to discovery of new species unique to the local environment.

Improving mycoinsecticides for insect biological control.

The desire for decreased reliance on chemical pesticides continues to fuel interest in alternative means for pest control including the use of naturally occurring microbial insect pathogens. Insects, as vectors of disease causing agents or as agricultural pests, are responsible for millions of deaths and significant economic losses worldwide, placing stresses on productivity (GDP) and human health and welfare. In addition, alterations in climate change are likely to affect insect ranges, expanding their access to previously constrained geographic areas, a potentially worrisome outcome. Metarhizium anisopliae and Beauveria bassiana, two cosmopolitan fungal pathogens of insects found in almost all ecosystems, are the most commonly applied mycoinsecticides for a variety of insect control purposes. The availability of the complete genomes for both organisms coupled to robust technologies for their transformation has led to several advances in engineering these fungi for greater efficacy and/or utility in pest control applications. Here, we will provide an overview of the fungal-insect and fungal-plant interactions that occur and highlight recent advances in the genetic engineering of these fungi. The latter work has resulted in the development of strains displaying (1) increased resistance to abiotic stress, (2) increased cuticular targeting and degradation, (3) increased virulence via expression of insecticidal protein/peptide toxins, (4) the ability to block transmission of disease causing agents, and (5) the ability to target specific insect hosts, decrease host fecundity, and/or alter insect behaviors.

Entomopathogenicity of Simplicillium lanosoniveum Isolated in Korea

Fruiting bodies similar to those of the ascomycete fungi Podostroma cornu-damae and Cordyceps militaris were collected from Mt. Seunghak in Busan, Korea on August 21, 2012. The fruiting bodies were cylindrical, with tapered ends and golden red in color. The fruiting bodies contained abundant conidiophores bearing single-celled conidia, but no perithecia or asci. Pure culture of the fungal isolates was obtained through single-spore isolation. Analyses of morphological characteristics, including conidia shape, and phylogenetic traits, using internal transcribed spacer sequences, showed that these isolates belonged to the species Simplicillium lanosoniveum. Although this fungal species is known to be mycoparasitic, the isolates obtained in this study were unable to infect fungi. However, silkworms (Bombyx mori) inoculated with the fungal isolates died during the larval or pupal stages, as has been shown for the strongly entomopathogenic fungus Beauveria bassiana. This study is the first report of the entomopathogenicity of S. lanosoniveum and indicates its potential for use in biological control of insects.

Characterization of Wheat Germ Oil Particles Formed by Gas-Saturated Solutions Process with Polyethylene Glycol

Wheat germ oil is a unique source of highly concentrated nutrient; its beneficial active ingredients could have a substantial impact on human health considering the amount that is used in cooking. In this study, wheat germ oil was micronized with polyethylene glycol using particles from gas-saturated solutions (PGSS) process and investigated functional materials content in particle changing different parameters. PGSS was carried out at temperatures of 40–50C, pressures of 10–30 MPa and at different ratios (10:1, 5:1). The average particle size was found from 0.6330 ± 0.004 to 1.3506 ± 0.011 μm at a ratio of 10:1 and from 1.1776 ± 0.011 to 3.7680 ± 0.016 μm at a ratio of 5:1. In fatty acid compositions, linoleic acid was present and had the highest amount in all conditions after particle formation. Total phenolic compound and antioxidant capacity were also found in particles. Practical Application Wheat germ is mainly produced as a by-product in the wheat milling industry. This by-product is generally used as animal feed; however, it contains oil that contains high amounts of functional materials like polyunsaturated fatty acids and phenolic compounds that have practical uses in life. These have great health benefits for humans and can be used in products such as foods, biological insect control agents, pharmaceuticals and cosmetic formulations. But for protection from oxidation, preservation of bioactivity and because of control release and dose measurement, particle formation is the best way. Small particles of pharmaceuticals with a narrow particle size distribution play a vital role in the design of conventional drug delivery systems like tablets, capsules, injections and biphasic drug delivery systems.

Isolation of entomopathogenic bacteria in the Southwest region of Paraná state in Brazil

Background The use of entomopathogenic bacteria to control harmful insects has increased the interest and researches about spore forming bacteria. Species from genus Bacillus are described as rod-shaped cells, sometimes in chains, and mostly capable of producing endospore. Although hundreds of bacteria species are known to be associated with insects, there is only a few which can be used as biological control for agricultural pests as well as, for vectors of tropical diseases. Several agricultural pests seem to be resistant to both chemical pesticides and known toxins produced by entomopathogenic bacteria. Therefore, the goal of this study was to describe the isolation of an entomopathogenic bacteria contributing with researches for new potentially toxic isolates in biological control of insects.

Insect Pest Management in Stored Pulses: an Overview

Pulses, which constitute an important part in the daily diet of mostly the vegetarian population, suffer a great damage by insects during storage. In this review, different control measures such as chemical treatment, physical treatment, and biological control of insects in stored pulses are discussed in brief. Chemicals like methyl bromide, malathion, and dichlorvos are being phased out. In these circumstances, new age chemicals like carbonyl sulfide and sulfuryl fluoride are gaining acceptance. Carbon dioxide and biogas generated from cow dung can be used as fumigation measures. Natural products like vegetable oil, inert dusts, plant extracts like essential oils, lectins, proteins, and leaf powders, which have insecticidal and antimicrobial activity, have been used as fumigants for traditional storage worldwide. Simple technologies like sun drying and repeated sieving can be adopted by small-scale farmers and traders. Maintaining low oxygen, high carbon dioxide, or pure nitrogen atmosphere in the storage environment is also proving to be beneficial preventive methods. Hot air and irradiation are being used, while dielectric heating is still in the stage of development in many of the developed countries for insect control. Developing countries are beginning to consider the use of these methods to control stored product insects.

Selectivity of Metarhizium anisopliae and Beauveria bassiana (Hypocreales: Clavicipitaceae) on adults of Cotesia flavipes (Hymenoptera: Braconidae).

Understanding mortality patterns and interactions between entomopathogenic fungi and parasitoids is important to improve insect biological control programs. The aim of this study was to evaluate the effect of Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1833 and Beauveria bassiana (Balsamo) Vuillemin, 1912 (Hypocreales: Clavicipitaceae) on adults of Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) with biological insecticides Biometha WP Plus (M. anisopliae), Biovéria G (B. bassiana), Boverril WP (B. bassiana), Metarril WP (M. anisopliae), and Metie WP (M. anisopliae) at concentrations of 1 x 10(9) conidia (con).mL(-1), 5 x 10(9) con.ml(-1), and 10 x 10(9) con.ml(-1). In the experimental, 10 females of C. flavipes were packed in disposable cups capped with a contact surface (filter paper, 9 cm2) treated with commercial product. The experimental design was completely randomized, with 16 treatments and five replicates of 10 females each. Mortality was assessed at 24, 48, 72, 96, and 120 hours after exposition (HAE) of the products. In general, B. bassiana and M. anisopliae in the concentrations of 1 x 10(9) con.ml(-1), 5 x 10(9) con.ml(-1), and 10 x 10(9) con.ml(-1) can't affect C. flavipes females because the peak of mortality in treatments with bioinsecticides was similar to the control and this demonstrated the selectivity of fungi B. bassiana and M. anisopliae on C. flavipes females.

Penetration of a Single Domain of Bacillus thuringiensis Cry1Ie-Domain I to a Lipid Membrane In vitro

Domain I of the activated Crystal protein from Bacillus thuringiensis has a seven α-helix bundle structure, which is responsible for membrane channel formation in its insecticidal mechanism. Cry1Ie is toxic to Asian corn borer, Ostrinia furnacalis (Guenée), and plays important roles in insect biological control. The domain I from Cry1Ie has been expressed and purified in its normal conformation, as embedded in the full length homologous toxin structure. The membrane insertion ability of this single domain was compared with the full length homologous toxin using a monolayer insertion experiment. The results indicated that the Cry1Ie-domain I had the ability to insert into the lipid monolayer, and this ability is greater than that of the IE648 toxin. However, the state of insertion is not stable and remains for only a short period of time. The Cry1Ie-domain I plays no role in receptor binding as it had a nonspecific binding with the brush border membrane vesicles of the Asian corn borer.

Trade-offs between developmental parameters of two endoparasitoids developing in different instars of the same host species

Trade-offs amongst life history traits is a major theme in evolutionary biology. Parasitoid wasps are important biological control agents and make excellent organisms to examine trade-offs in fitness related traits such as size, development rate and survival. Here, we examined trait-related trade-offs in 2 solitary endoparasitoids developing in different stages (or instars) of the same caterpillar host, the cabbage moth Mamestra brassicae. Microplitis mediator is a small specialist parasitoid that attacks first (L1) to third (L3) instars of M. brassicae; Meteorus pulchricornis is a larger highly generalized parasitoid that attacks L1–L4 instars of the same host species. When developing in early host instars (e.g. L1–L2), both parasitoids differently traded-off size against development time. In M. mediator, adult body mass was smaller in wasps developing in L1 than in L2 and L3 hosts, whereas development time was unaffected by instar. By contrast, adult body mass in M. pulchricornis was smaller and development time longer when developing in L1 and L2 than in L3 and L4 instars. Periodic starvation of M. brassicae caterpillars parasitized by M. pulchricornis further reduced adult mass and extended development time of wasps in L2 (but not L4) hosts. Maximum egg load in M. pulchricornis (but not M. mediator) was correlated with adult female body size. Our results imply that rapid development time is more important than body size for fitness in both species, although in M. pulchricornis both development time and adult size are traded off in determining the optimal phenotype. Developing a better understanding of association-specific patterns of development in parasitoids can assist in the optimization of mass rearing of these insects for biological control.

Biological insect control using Metarhizium anisopliae: morphological, molecular, and ecological aspects

Microbial control of insects is based on the rational use of pathogens to maintain environmentally balanced pest population levels, and Metarhizium anisopliae has been the most studied and most utilized fungal species for that purpose. The natural genetic variability of entomopathogenic fungi is considered one of the principal advantages of microbial insect control. The inter- and intraspecific variability and the genetic diversity and population structures of Metarhizium and other entomopathogenic fungi have been examined using ITS-RFLP, ISSR, and ISSP molecular markers. The persistence of M. anisopliae in the soil and its possible effects on the structures of resident microbial communities must be considered when selecting isolates for biological insect control.

Genetic Differentiation among Maruca vitrata F. (Lepidoptera: Crambidae) Populations on Cultivated Cowpea and Wild Host Plants: Implications for Insect Resistance Management and Biological Control Strategies

Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a polyphagous insect pest that feeds on a variety of leguminous plants in the tropics and subtropics. The contribution of host-associated genetic variation on population structure was investigated using analysis of mitochondrial cytochrome oxidase 1 (cox1) sequence and microsatellite marker data from M. vitrata collected from cultivated cowpea (Vigna unguiculata L. Walp.), and alternative host plants Pueraria phaseoloides (Roxb.) Benth. var. javanica (Benth.) Baker, Loncocarpus sericeus (Poir), and Tephrosia candida (Roxb.). Analyses of microsatellite data revealed a significant global FST estimate of 0.05 (P≤0.001). The program STRUCTURE estimated 2 genotypic clusters (co-ancestries) on the four host plants across 3 geographic locations, but little geographic variation was predicted among genotypes from different geographic locations using analysis of molecular variance (AMOVA; among group variation −0.68%) or F-statistics (F ST Loc = −0.01; P = 0.62). These results were corroborated by mitochondrial haplotype data (φSTLoc = 0.05; P = 0.92). In contrast, genotypes obtained from different host plants showed low but significant levels of genetic variation (F ST Host = 0.04; P = 0.01), which accounted for 4.08% of the total genetic variation, but was not congruent with mitochondrial haplotype analyses (φSTHost = 0.06; P = 0.27). Variation among host plants at a location and host plants among locations showed no consistent evidence for M. vitrata population subdivision. These results suggest that host plants do not significantly influence the genetic structure of M. vitrata, and this has implications for biocontrol agent releases as well as insecticide resistance management (IRM) for M. vitrata in West Africa.

If and when successful classical biological control fails

Classical biological control of insects has a long history of success, with high benefit–cost ratios. However, most attempts to introduce a biological control agent have been unsuccessful, largely because the agent does not establish in the new environment. This perspectives paper discusses the possibility that even successful biological control may eventually fail, although records show that this is far from a common event. A documented example of eventual biological control failure is discussed and the prospect for future failures analyzed. Part of this analysis is based on an introduced weevil pest in New Zealand and its successful parasitoid biological control agent. The potential fragility of this host–parasitoid relationship is considered, as well as why it may indeed be starting to show signs of instability; this is particularly from the point of view of New Zealand’s often species-poor agricultural ecosystems.