Limitations of Neoseiulus baraki and Proctolaelaps bickleyi as control agents of Aceria guerreronis

Several predatory mites have been found in association with the coconut mite, Aceria guerreronis Keifer, in northeast Brazil. However, the latter still causes damage to coconut in that region. The objectives of this work were to compare the frequencies of occurrence of Neoseiulus (Phytoseiidae) and Proctolaelaps (Melicharidae) species on standing and aborted coconuts in coastal Pernambuco State, northeast Brazil and to analyze their possible limitations as control agents of the coconut mite, based on evaluations of the restrictions they may have to access the microhabitat inhabited by the pest and their functional and reproductive responses to increasing densities of the latter. Neoseiulus baraki (Athias-Henriot) was found mostly on standing coconuts whereas Proctolaelaps bickleyi (Bram) was found mostly on aborted coconuts. Measurements of the entrance to the microhabitat occupied by the coconut mite, between the bracts and the subjacent fruit surface, showed that this different pattern of predator prevalence could be related to predator sizes, although other environmental factors could not be disregarded. Progressively higher predation rate of N. baraki was observed up to an experimental density that corresponded to 1,200 coconut mites per fruit, which is close to the average number determined in northeast Brazil, reducing slightly afterwards. Predation rate of P. bickleyi reduced consistently but slightly with increasing prey densities, but in absolute values, rates were always much higher than determined for N. baraki. The excessively high killing capacity of P. bickleyi, probably related to its high feeding requirement, may be detrimental in terms of stability. In fact, such high requirement for food suggests that P. bickleyi might not have a strong relation with the coconut mite and that the latter may not be its main food source under natural conditions. It is concluded that body sizes of both predators and the exceedingly high feeding requirement of P. bickleyi may limit their performance as control agents of the coconut mite.

Characterization of a Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae) - derived chitinase and its potential for pest control

The larval endoparasitoid Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae) has a toolbox of biological weapons to secure for host colonization and the successful parasitization of its host Heliothis virescens (F.) (Lepidoptera: Noctuidae). The cDNA of a putative chitinase has been previously isolated and initially characterized from teratocytes of this parasitoid among the plethora of molecules available in the venom and calyx fluids injected by females, oral and/or anal secretions released by the parasitoid larvae and/or produced by the expression of genes of the symbiotic associated polydnavirus. This putative chitinase has been initially associated with the host cuticle digestion to allow for parasitoid egression and with the asepsis of the host environment, acting as an antimicrobial. As chitinases are commonly expressed in plants against plant pathogens, the chitinase derived from the teratocytes of T. nigriceps is a potential tool for the development of insect pest control methods based on the disruption of the perithrophic membrane of herbivores. Therefore, we aimed to characterize the activity of the putative chitinase from teratocytes of T. nigriceps (Tnchi) produced using the Escherichia coli expression system and its potential to control H. virescens larvae when expressed into transgenic tobacco plants. The purified E. coli-produced Tnchi protein showed no chitinolitic activity, but was active in binding with colloidal and crystalline chitins in water and with colloidal chitin in buffered solution (pH = 6.74). Transgenic tobacco plants showed no enhanced chitinolitic activity relative to control plants, but survival of three-day old larvae of H. virescens was severely affected when directly fed on transgenic tobacco leaves expressing the recombinant Tnchi protein. Some properties of the Tnchi protein and the potential use of Tnchi-transgenic plants to control plant pests are discussed. (c) 2012 Elsevier Inc. All rights reserved.

How promising is Lasioseius floridensis as a control agent of Polyphagotarsonemus latus?

The blattisociid mite Lasioseius floridensis Berlese was found associated with the broad mite, Polyphagotarsonemus latus (Banks), on gerbera leaves in Mogi das Cruzes, State of Sao Paulo, Brazil. Blattisociid mites are not common on aerial plant parts, except under high air humidity levels. Some Lasioseius species have been mentioned as effective control agents of rice pest mites, but nothing is known about the biology of L. floridensis. The objective of this study was to evaluate whether the observed co-occurrence of L. floridensis and P. latus was just occasional or whether the latter could be important as food source for the former, assumed by laboratory evaluation of the ability of the predator to maintain itself, reproduce and develop on that prey. Biological parameters of L. floridensis were compared when exposed to P. latus and to other items as food. The study showed that mating is a pre-requisite for L. floridensis to oviposit and that oviposition rate was much higher on the soil nematode Rhabditella axei (Cobbold) (Rhabditidae) than on P. latus. Ovipositon on the acarid mite Tyrophagus putrescentiae (Schrank) was about the same as on P. latus, but it was nearly zero when the predator was fed the fungi Aspergillus flavus Link or Penicillium sp., or cattail (Typha sp.) pollen. Survivorship was higher in the presence of pollen and lower in the presence of A. flavus or Penicillium sp. than in the absence of those types of food. Life table parameters indicated that the predator performed much better on R. axei than on P. latus. To evaluate the potential effect of L. floridensis as predator of P. latus, complementary studies are warranted to determine the frequency of migration of L. floridensis to aerial plant parts, when predation on P. latus could occur.

Endophytic fungi from Vitis labrusca L. ('Niagara Rosada') and its potential for the biological control of Fusarium oxysporum

We investigated the diversity of endophytic fungi found on grape (Vitis labrusca cv. Niagara Rosada) leaves collected from Salesopolis, SP, Brazil. The fungi were isolated and characterized by amplified ribosomal DNA restriction analysis, followed by sequencing of the ITS1-5.8S-ITS2 rDNA. In addition, the ability of these endophytic fungi to inhibit the grapevine pathogen Fusarium oxysporum f. sp herbemontis was determined in vitro. We also observed that the climatic factors, such as temperature and rainfall, have no effect on the frequency of infection by endophytic fungi. The endophytic fungal community that was identified included Aporospora terricola, Aureobasidium pullulans, Bjerkandera adusta, Colletotrichum boninense, C. gloeosporioides, Diaporthe helianthi, D. phaseolorum, Epicoccum nigrum, Flavodon flavus, Fusarium subglutinans, F. sacchari, Guignardia mangiferae, Lenzites elegans, Paraphaeosphaeria pilleata, Phanerochaete sordida, Phyllosticta sp, Pleurotus nebrodensis, Preussia africana, Tinctoporellus epiniltinus, and Xylaria berteri. Among these isolates, two, C. gloeosporioides and F. flavus, showed potential antagonistic activity against F. oxysporum f. sp herbemontis. We suggest the involvement of the fungal endophyte community of V. labrusca in protecting the host plant against pathogenic Fusarium species. Possibly, some endophytic isolates could be selected for the development of biological control agents for grape fungal disease; alternatively, management strategies could be tailored to increase these beneficial fungi.

Parasitoids (Braconidae) associated with Anastrepha (Tephritidae) in host fruits on the Southern coast of Bahia, Brazil

Among the organisms acting in the natural biological control of tephritids, members of the family Braconidae are the most active form of natural parasite, and in Neotropical regions, members of Opiinae are the main control agents of Anastrepha. The objective of this work was to discover the percentage of parasitism and the species of braconid associated with fruit trees growing in cities on the southern coast of Bahia. During the period of August, 2005 to March, 2008, hosts fruits of fruit flies from several plant species were collected and from the fruits the following species of Anastrepha were obtained: A. fraterculus, A. obliqua, A. bahiensis, A. serpentina, A. sororcula and A. zenildae. Of the total of 838 specimens of braconids, 21.36% were of the species Utetes anastrephae (Viereck), obtained from yellow mombin, carambola, guava, mango and pitanga; 4.42% were of the species Asobara anastrephae (Muesebeck) obtained from the fruits of the yellow mombin, carambola and guava, and only one example of Opius bellus Gahan (0.12%) that came from a guava sample. The species Doryctobracon areolatus (Szepligeti) (74.10%) was predominant and emerged from puparia from all the host fruits collected, probably due to the greater efficiency of this species in locating tephritid larvae. The mean percentage of parasitism by Anastrepha spp. was 4.45%.

Identification of Aspergillus flavus isolates as potential biocontrol agents of aflatoxin contamination in crops

Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops

Insecticidal Activity of the Granulosis Virus in Combination with Neem Products and Talc Powder Against the Potato Tuberworm Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

The potato tuberworm Phthorimaea operculella (Zeller) is an important agricultural pest that causes significant economic losses to potato growers worldwide. The addition of an effective method of biological control for the potato tuberworm is greatly needed, and is currently unavailable in Brazil. The granulosis virus (Baculoviridae) is a promising biological control agent to protect post-harvest potatoes and in storage from the potato tuberworm. However, the control measure must be economically feasible. Liquid suspensions of a granulosis virus applied alone or in mixture with two commercial neem oil-based products (DalNeem (TM) and NeemAzal (TM)), and a dry powder formulation of viral granules were evaluated for control of potato tuberworm larvae by treating potato tubers under laboratory conditions. High larval mortality (86.7%) was achieved when DalNeem and virus were applied together at 4 mg of azadirachtin/L and 10(4) occlusion bodies (OBs)/mL, respectively. This combination resulted in a parts per thousand yen50% efficacy in relation to their counterparts alone. Conversely, NeemAzal did not enhance virus effectiveness against larvae of the potato tuberworm. The talc-based virus formulation was used for dusting seed tubers at different concentrations and resulted in 100% larval mortality at 5 x 10(8) OBs/g. Formulated and unformulated virus provided 50% mortality at 166 OBs/g and at 5.0 x 10(5) OBs/mL, respectively. As a result, talc-based virus formulation had a better control efficiency on potato tuberworm than the aqueous virus suspension. The granulosis virus combined with DalNeem at low rates or formulated with talc powder is a viable option to control the potato tuberworm under storage conditions.

Biochemical Analysis of a Castor Bean Leaf Extract and its Insecticidal Effects Against Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)

Plant extracts represent a great source of molecules, with insecticidal activity, which are used for pest control in several crop production systems. This work aimed to evaluate the toxicity of an aqueous extract of leaves of castor bean against larvae of Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) in search for different classes of molecules with insecticidal activities by using in vitro assays. The effects of the castor bean leaf extract on the food utilization, development, and survival of S. frugiperda larvae was evaluated by feeding the larvae an artificial diet supplemented with different concentrations of the extract (0%, 1%, 2.5%, 5%, and 10% w/v). The effects observed were dose-dependent, and the highest concentration evaluated (10% w/v) was the one the most affected food utilization by altering the nutritional indices, as well as larval weight gain, development time, and survivorship. In vitro assays to detect saponins, lectins, and trypsin inhibitors in the castor bean leaf extract were performed, but only trypsin inhibitors were detected. No preference for the diet source was detected in S. frugiperda by feeding the larvae in choice experiments with diets containing different concentrations of the castor bean extract tested. The data obtained indicate the existence of a potential molecule in the tested extract of castor bean to be used as an alternative insecticide to be integrated in the management of S. frugiperda.

FRUGIVORY OF NEOSILBA SPECIES (DIPTERA: LONCHAEIDAE) AND THEPYTUS ECHELTA (LEPIDOPTERA: LYCAENIDAE) ON PSITTACANTHUS (SANTALALES: LORANTHACEAE) IN ECOTONAL CERRADO-SOUTH PANTANAL, BRAZIL

This paper presents a survey of the insects that feed on fruits of Psittacanthus Martius (Santalales: Loranthaceae), a hemiparasitic mistletoe genus that infects trees in Brazil and other neotropical countries. The aim of the study was to identify candidate insects for biological control of Psittacanthus mistletoes. Unripe and mature fruits were collected in several localities of Cerrado, bordering South Pantanal, Southwestern Brazil, from 29 Apr 1998 to 30 Jul 2000. A total of 24,710 fruits (54 samples) of Psittacanthus acinarius infecting 15 species from 10 plant families were evaluated. Psittacanthus acinarius (Mart.) was the most abundant and frequent species of mistletoe parasitizing trees in the ecotonal Cerrado-Pantanal. From 24,710 fruits of Psittacanthus acinarius were obtained 1,812 insect larvae including 1,806 Neosilba McAlpine (Diptera: Lonchaeidae) species and 6 Thepytus echelta (Hewitson) (Lepidoptera: Lycaenidae). From these emerged 1,550 Neosilba spp. adults and 6 T. echelta. Neosilba pantanense Strikis was described from this research. Larvae of T. echelta occurred in fruits of P. acinarius parasitizing Cecropia pachystachya Trecul (Urticaceae) and Anadenanthera colubrina (Vellozo) Brenan (Fabaceae). Larvae of Neosilba caused no adverse effects on the germination of infected fruits of Psittacanthus, because they do not eat the embryo or viscin tissues. This differs from the larvae of T. echelta that interrupted the germination of seeds by feeding on those tissues. Thepytus echelta may be a promising insect for the biological control of P. acinarius in the ecotonal Cerrado-Pantanal, although its abundance and frequency were low throughout the sampling period.

Recombinant expression, localization and in vitro inhibition of midgut cysteine peptidase (Sl-CathL) from sugarcane weevil, Sphenophorus levis

A cDNA coding for a digestive cathepsin L, denominated Sl-CathL, was isolated from a cDNA library of Sphenophorus levis larvae, representing the most abundant EST (10.49%) responsible for proteolysis in the midgut. The open reading frame of 972 bp encodes a preproenzyme similar to midgut cathepsin L-like enzymes in other coleopterans. Recombinant Sl-CathL was expressed in Pichia pastoris, with molecular mass of about 42 kDa. The recombinant protein was catalytically activated at low pH and the mature enzyme of 39 kDa displayed thermal instability and maximal activity at 37 degrees C and pH 6.0. Immunocytochemical analysis revealed Sl-CathL production in the midgut epithelium and secretion from vesicles containing the enzyme into the gut lumen, confirming an important role for this enzyme in the digestion of the insect larvae. The expression profile identified by RT-PCR through the biological cycle indicates that Sl-CathL is mainly produced in larval stages, with peak expression in 30-day-old larvae. At this stage, the enzyme is 1250-fold more expressed than in the pupal fase, in which the lowest expression level is detected. This enzyme is also produced in the adult stage, albeit in lesser abundance, assuming the presence of a different array of enzymes in the digestive system of adults. Tissue-specific analysis revealed that Sl-CathL mRNA synthesis occurs fundamentally in the larval midgut, thereby confirming its function as a digestive enzyme, as detected in immunolocalization assays. The catalytic efficiency of the purified recombinant enzyme was calculated using different substrates (Z-Leu-Arg-AMC, Z-Arg-Arg-AMC and Z-Phe-Arg-AMC) and rSl-CathL exhibited hydrolysis preference for Z-Leu-Arg-AMC (k(cat)/K-m = 37.53 mM S-1), which is similar to other insect cathepsin L-like enzymes. rSl-CathL activity inhibition assays were performed using four recombinant sugarcane cystatins. rSl-CathL was strongly inhibited by recombinant cystatin CaneCPI-4 (K-i = 0.196 nM), indicating that this protease is a potential target for pest control. (C) 2011 Elsevier Ltd. All rights reserved.

Obtaining NiAl intermetallic compound using different milling devices

NiAl intermetallic compound was synthesized by mechanical alloying technique in planetary and attritor mills. The starting powders consisted of elemental mixtures of Ni and Al at Ni50Al50(at%) composition. In the planetary mill, compound formation occurred gradually during mechanical alloying, while the occurrence of a mechanically induced self-propagating reaction (MSR) can be suggested in the attritor mill. The NiAl obtained in both mill types was partially disordered with long-range order parameter not inferior to 0.66. Quantitative phase analysis using the Rietveld method was performed in as-milled samples, and this method was also employed to estimate changes in crystallite size and lattice strain of the NiAl produced during mechanical alloying. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Trichogramma pretiosum parasitism and dispersal capacity: a basis for developing biological control programs for soybean caterpillars

In order to succeed in biological control programs, not only is it crucial to understand the number of natural enemies to be released but also on how many sites per area this releasing must be performed. These variables might differ deeply among egg parasitoid species and crops worked. Therefore, these trials were carried out to evaluate the parasitism (%) in eggs of Anticarsia gemmatalis and Pseudoplusia includens after the release of different densities of the egg parasitoid Trichogramma pretiosum. Field dispersal was also studied, in order to determine appropriate recommendations for the release of this parasitoid in soybean fields. The regression analysis between parasitism (%) and densities of the parasitoid indicated a quadratic effect for both A. gemmatalis and P. includens. The maximum parasitism within 24 h after the release was reached with densities of 25.6 and 51.2 parasitoids per host egg, respectively, for the two pests. Parasitism of T. pretiosum in eggs of P. includens decreased linearly as the distance of the pest eggs from the parasitoid release sites increased. For P. includens, the mean radius of T. pretiosum action and the area of parasitoid dispersal in the soybean crop were 8.01 m and 85.18 m(2), respectively. We conclude that for a successful biological control program of lepidopteran pests using T. pretiosum in soybean fields, a density of 25.6 parasitoids per host egg, divided into 117 sites per hectare, should be used.

Development, characterization, and in vitro trials of chloroaluminum phthalocyanine-magnetic nanoemulsion to hyperthermia and photodynamic therapies on glioblastoma as a biological model

A glioblastoma multiforme (GBM) is the highest grade glioma tumor (grade IV) and is the most malignant form of astrocytomas. Grade IV tumors, which are the most malignant and aggressive, affect people between the ages of 45 and 70 years. A GBM exhibits remarkable characteristics that include excessive proliferation, necrosis, genetic instability, and chemoresistance. Because of these characteristics, GBMs are difficult to treat and have a poor prognosis with a median survival of less than one year. New methods to achieve widespread distribution of therapeutic agents across infiltrative gliomas significantly improve brain tumor therapy. Photodynamic therapy (PDT) and hyperthermia (HPT) are well-established tumor therapies with minimal side effects while acting synergistically. This study introduces a new promising nanocarrier for the synergistic application of PDT and magnetic hyperthermia therapy against human glioma cell line T98 G, with cellular viability reduction down to as low as 17% compared with the control. (C) 2012 American Institute of Physics. [doi:10.1063/1.3671775]

Biological and behavioral parameters of the parasitoid Cotesia flavipes (Hymenoptera: Braconidae) are altered by the pathogen Nosema sp (Microsporidia: Nosematidae)

A major issue for mass rearing of insects concerns sanitary conditions and disease. Microsporidian infection (Nosema sp.) in laboratory colonies of Diatraea saccharalis (Fabr.) (Lepidoptera: Crambidae), used in producing the parasitoid. Cotesia flavipes Cameron (Hymenoptera: Braconidae), is representative of the problems faced by growers and industry. Although C. flavipes has been produced for several years in Brazil for biological control of D. saccharalis, we have only recently observed that the parasitoid becomes infected when developing inside hosts infected with Nosema sp. We assessed the effects of Nosema sp. on C. flavipes, including the ability to locate and select hosts, and evaluated pathogen transmission. Third instar larvae of D. saccharalis were inoculated with Nosema sp. spores at different concentrations and were parasitized when larvae reached fifth instar. Heavily infected D. saccharalis larvae did not support parasitism. Parasitoids that developed in infected D. saccharalis larvae exhibited increased duration of larval and pupal stages, decreased adult longevity and number of offspring, and reduced tibia size compared to parasitoids developing in uninfected D. saccharalis larvae. Infection by Nosema sp. reduced the ability of the C. flavipes parasitoid to distinguish between volatiles released by the sugarcane infested by healthy larvae and pure air. Uninfected parasitoids preferred plants infested with uninfected hosts. But infected C. flavipes did not differentiate between uninfected hosts and those infected with Nosema sp. The pathogen is transmitted from host to parasitoids and parasitoids to hosts. Pathogenic effects of the microsporidium in C. flavipes are sufficiently severe to justify disease management efforts, particularly considering the importance of C. flavipes as a biological control agent in sugarcane. (C) 2012 Elsevier Inc. All rights reserved.

Status of Aceria guerreronis Keifer (Acari: Eriophyidae) as a Pest of Coconut in the State of Sao Paulo, Southeastern Brazil

The coconut mite, Aceria guerreronis Keifer, is one of the main pests of coconut palms (Cocos nucifera) in northeastern Brazil. The objective of this study was to evaluate the levels of the coconut mite and other mites on coconut palms in the state of So Paulo and to estimate the possible role of predatory mites in the control of this pest. The effect of cultivated genotypes and sampling dates on the mite populations was also estimated. We sampled attached fruits, leaflets, inflorescences, and fallen fruits. The coconut mite was the main phytophagous mite found on attached and fallen fruits, with average densities of 110.0 and 20.5 mites per fruit, respectively. The prevalent predatory mites on attached and fallen fruits were Proctolaelaps bulbosus Moraes, Reis & Gondim Jr. and Proctolaelaps bickleyi (Bram), both Melicharidae. On leaflets, the tenuipalpids Brevipalpus phoenicis (Geijsks) and Tenuipalpus coyacus De Leon and the tetranychid Oligonychus modestus (Banks) were the predominant phytophagous mites. On both leaflets and inflorescences, the predominant predatory mites belonged to the Phytoseiidae. Neoseiulus baraki (Athias-Henriot) and Neoseiulus paspalivorus (De Leon), predators widely associated with the coconut mite in northeastern Brazil and several other countries, were not found. The low densities of the coconut mite in So Paulo could be related to prevailing climatic conditions, scarcity of coconut plantations (hampering the dispersion of the coconut mite between fields), and to the fact that some of the genotypes cultivated in the region are unfavorable for its development.