Evaluation of the Adenanthera pavonina seed proteinase inhibitor (ApTI) as a bioinsecticidal tool with potential for the control of Diatraea saccharalis

Diatraea saccharalis, is a major sugarcane pest, causing damage to the stalks of sugarcane plants. In this study, a trypsin inhibitor (ApTI) was purified from Adenanthera pavonina seeds and was tested for its insect growth regulatory effect. ApTI showed a dose-dependent effect on average larval weight and survival. 0.1% ApTI produced approximately 67% and 50% decreases in weight and survival larval, respectively. The results from dietary utilization experiments with D. saccharalis larvae showed a reduction in the efficiency of conversion of ingested food and digested food, and an increase in approximate digestibility and metabolic cost. The level of trypsin was significantly decreased (ca. 55%) in the midgut of larvae reared on a diet containing 0.05% ApTI and the trypsin activity in ApTI-fed larvae demonstrated sensitivity to ApTI. The action of ApTI on the development of D. saccharalis larvae shows that this protein may have great toxic potential. (C) 2011 Elsevier Ltd. All rights reserved.

ASSESSING Bemisia tabaci (GENN.) BIOTYPE B RESISTANCE IN SOYBEAN GENOTYPES: ANTIXENOSIS AND ANTIBIOSIS

Since it was first reported in Brazil in the 1990s, the B biotype of silverleaf whitefly (Bemisia tabaci [Genn.], Hemiptera: Aleyrodidae) has been recognized as an important pest in soybeans (Glycine max L.), reducing the productivity of this legume species in some areas of the country. As an alternative to chemical control, the use of resistant genotypes represents an important tool for integrated pest management (IPM). This study evaluated the performance of 10 soybean genotypes prior to whitefly infestation, by testing attractiveness and preference for oviposition in the greenhouse and antibiosis in the laboratory. In a multiple-choice test, 'IAC-17' was the least attractive to insects. In a no-choice test, 'IAC-17' was the least attractive for, egg deposition, indicating the occurrence of non-preference for oviposition on this genotype. Trichome density was positively correlated with the oviposition site and may be associated with the resistance of 'IAC-17' to infestation. The genotypes 'IAC-PL1', 'IAC-19', 'Conquista', 'IAC-24' and 'IAC-17' extended the insect's life cycle, indicating the occurrence of a small degree of antibiosis and/or non-preference for feeding.

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.

Description of the Pupa and Redescription of the Imagines of Geyeria decussata and their Association with Bromeliads in Southern Brazil (Lepidoptera: Castniidae)

ALBERTONI F F [Fed Univ, Florianopolis, Brazil], MORAES S S [Mus Zool USP, Sao Paulo, Brazil], STEINER J [Fed Univ. Florianopolis, Brazil] & ZILLIKENS A [Univ Tubingen, Germany]: Description of the Pupa and Redescription of the Imagines of Geyeria decussata and their Association with Bromeliads in Southern Brazil (Lepidoptera: Castniidae). - Entomol Gener 34 (1-2): 061-074: Stuttgart 2012-09. - [Article] Bromeliads can serve as a resource for numerous arthropods, especially insects. Caterpillars of the moth Geyeria decussata (Godart 1824) were recorded in the leaf rosettes of the bromeliads Wittrockia superba, Vriesea philippocoburgii and Aechmea nudicaulis. The larvae were feeding on the leaf bases, eventually killing the plants. In addition to life history data a description of the pupa and a re-description of the imagines are provided here. These findings constitute new records of larval hosts for this species and confirm a close association of castniid moths and bromeliads.

Molecular cloning and insecticidal effect of Inga laurina trypsin inhibitor on Diatraea saccharalis and Heliothis virescens

Native Inga laurina (Fabaceae) trypsin inhibitor (ILTI) was tested for anti-insect activity against Diatraea saccharalis and Heliothis virescens larvae. The addition of 0.1% ILTI to the diet of D. saccharalis did not alter larval survival but decreased larval weight by 51%. The H. virescens larvae that were fed a diet containing 0.5% ILTI showed an 84% decrease in weight. ILTI was not digested by the midgut proteinases of either species of larvae. The trypsin levels were reduced by 55.3% in the feces of D. saccharalis and increased by 24.1% in the feces of H. virescens. The trypsin activity in both species fed with ILTI was sensitive to the inhibitor, suggesting that no novel proteinase resistant to ILTI was induced. Additionally, ILTI exhibited inhibitory activity against the proteinases present in the larval midgut of different species of Lepidoptera. The organization of the ilti gene was elucidated by analyzing its corresponding genomic sequence. The recombinant ILTI protein (reILTI) was expressed and purified, and its efficacy was evaluated. Both native ILTI and reILTI exhibited a similar strong inhibitory effect on bovine trypsin activity. These results suggest that ILTI presents insecticidal properties against both insects and may thus be a useful tool in the genetic engineering of plants. (c) 2012 Elsevier Inc. All rights reserved.

Biologia di Tuta absoluta (Lepidoptera: Gelechiidae), interazioni con l’ambiente e valutazione di tecniche di contenimento ecocompatibili

Tuta absoluta (Meyrick) è un lepidottero originario dell’America meridionale, infeudato a pomodoro e ad altre solanacee coltivate e spontanee. Con l’attività trofica le larve causano mine fogliari e gallerie nei frutti, con conseguenti ingenti danni alle colture. T. absoluta è stato segnalato per la prima volta in Italia nel 2008 e in Piemonte nel 2009. Pertanto le ricerche sono state condotte per rilevarne la distribuzione in Piemonte, studiarne l’andamento di popolazione in condizioni naturali e controllate, e valutare l’efficacia di differenti mezzi di lotta al fine di definire le strategie di difesa. Il monitoraggio, condotto nel 2010, ha evidenziato come T. absoluta sia ormai largamente diffuso sul territorio regionale già pochi mesi dopo la segnalazione. L’insetto ha mostrato di prediligere condizioni climatiche più miti; infatti è stato ritrovato con maggiore frequenza nelle aree più calde. Il fitofago ha raggiunto densità di popolazione elevate a partire dalla seconda metà dell’estate, a ulteriore dimostrazione che, in una regione a clima temperato come il Piemonte, T. absoluta dà origine a infestazioni economicamente rilevanti solo dopo il culmine della stagione estiva. Per definire le strategie di lotta, sono state condotte prove in laboratorio, semi-campo e campo volte a valutare la tossicità nei confronti del lepidottero di preparati a base di emamectina benzoato, rynaxypyr, spinosad e Bacillus thuringiensis Berliner. In campo è stata verificata anche l’efficacia del miride dicifino Macrolophus pygmaeus (Rambur), reperibile in commercio. In tutte le prove, è stata riscontrata una maggiore efficacia di rynaxypyr ed emamectina benzoato. In campo M. pygmaeus ha mostrato difficoltà d’insediamento ed è stato in grado di contenere efficacemente il fitofago soltanto con bassi livelli d’infestazione. Per contro è stata costantemente osservata la presenza naturale di un altro miride dicifino Dicyphus errans (Wolff), che in laboratorio ha mostrato di non essere particolarmente disturbato dalle sostanze saggiate.

Untersuchungen zur biologischen Bekämpfung der Kleidermotte Tineola bisselliella (Hummel 1823) und anderer tineider Textilschädlinge (Lepidoptera: Tineidae) mit parasitoiden Hymenopteren

Nach den Ergebnissen der vorliegenden Arbeit ist eine biologische Bekämpfung von Kleider- und Pelzmotten durch die gezielte Freilassungen von parasitoiden Hymenopteren als deren natürliche Gegenspieler möglich. Es wurden erstmalig ausführliche Versuche zur Parasitierung der Kleider- und Pelzmotte, insbesondere durch Eiaparasitoide der Gattung Trichogramma, durchgeführt. Für die braconide Schlupfwespe Apanteles carpatus wurde eine Zucht- und Freilassungsmethode entwickelt. Sie kann nun als neuer Nützlinge gegen textilschädigende Mottenlarven eingesetzt werden. Eine natürliche Parasitierung textilschädigender Motten durch Eiparasitoide ist bislang nicht nachgewiesen worden. Die Tineiden erwiesen sich im Laborversuch für Trichogramma als gut geeignete Wirte. Hinsichtlich der praktischen Anwendung von Eiparasitoiden der Gattung Trichogramma konnte aus einer Auswahl von 29 Arten und Stämmen aus einer Laborzucht mit T. piceum (Stamm: PIC M 91) eine besonders geeignete Art selektiert werden. Dieser Stamm zeigte die höchste Parasitierungsrate mit über 80 Eiern bei Temperaturen von 20-25°C und einer Lebensdauer von bis zu 17 Tagen. Im Präferenztest wurden sowohl Eier der Kleidermotte als auch der Getreidemotte, dem Massenzuchtwirt, von allen Stämmen mit Abstand am besten parasitiert. Das Geschlechterverhältnis von T. piceum lag bei über 80%. Der untersuchte Stamm von Apanteles carpatus zeigte bei 25°C eine durchschnittliche Nachkommenzahl von 55 pro Weibchen. Die Parasitoide erreichten jedoch nur unter optimalen Bedingungen eine Lebensdauer von bis zu 14 Tagen. In den Käfigversuchen ohne zusätzliche Nahrungsquellen wurden die Tiere nicht älter als 4 Tage. Es war nicht möglich, für A. carpatus Ersatzwirte für eine Massenzucht zu finden, da sie offensichtlich auf Tineiden spezialisiert sind, jedoch konnte ein Zuchtsystem mit Kleidermotten als Zuchtwirte etabliert werden. Die ausgewählten Trichogramma-Arten wurden in Käfigversuchen ausführlich untersucht und im Hinblick auf ihre Suchleistung auf verschiedenen Stoffoberflächen geprüft. Es wurde festgestellt, dass die getesteten Arten sehr unterschiedlich geeignet sind, um Textilien nach Eiern abzusuchen. Die Arten T. evanescens (Stamm: Lager) und T. piceum (PIC M 91) erwiesen sich als in der Suchleistung als am besten geeignet. Im Vergleich dazu zeigte T. cacoeciae (CAC D 90 O) sehr wenig Suchleistugsvermögen auf Textilien. Die geeigneten Arten durchdrangen außer verschiedenen Textilien auch grobe Schafwolle bis zu 0,4 m vom Freilassungsort. Das Ködern von Larvalparasitoiden von tineiden Motten im Freiland erwies sich als nicht erfolgreich. Trotzdem in der Literatur eine Reihe parasitoider Hymenopteren als Gegenspieler von Tineiden beschrieben sind und in Innenräumen beobachtet wurden, war es nicht möglich, weitere freilebende Arten zu ködern. Sowohl für das Ködern im Freiland als auch für die Rückköderung in Lagern wurden Ködermethoden getestet und optimiert. Nebenwirkungstests haben ergeben, dass die Nützlinge ergänzend zum Einsatz von Niem-Präparaten an schlecht zugänglichen Befallsstellen eingesetzt werden können. Ebenso wurde ermittelt, dass eine Kombination des Nützlingseinsatzes mit Repellents möglich ist. Bei zu hoher Konzentration der Wirkstoffe, den reinen Niem-Öl und konzentriertem Lavendel-Öl, in geschlossenen Glaskäfigen, wurden starke Nebenwirkungen auf Trichogramma festgestellt. In größerem Raumvolumen oder geringerer Dosierung der Wirkstoffe parasitierte Trichogramma allerdings auch Ködereier, die sich auf Niem-behandeltem Stoff befanden. Erste Freilassungsversuche in der Praxis ergaben unterschiedliche Erfolge. Nach einer Freilassung von Apanteles carpatus in einem Wohnhaus, das mit Schafwolle gedämmt wurde, reduzierte sich Fang von adulten Motten auf Pheromon-Klebfallen deutlich. In einem Textillager hingegen war es mit einer einmaligen Freilassung jedoch nicht möglich, die Gegenspieler zu etablieren und den Mottenbefall zu kontrollieren. Die mehrwöchige Freilassung von Trichogramma in einem Textillager konnte dazu beitragen, einen Pelzmottenbefall zu reduzieren. Hier zeigten sich Möglichkeiten und Grenzen des Einsatzes von parasitoiden Schlupfwespen gegen Textilmotten gleichermaßen.

Herbivore-Induced Plant Volatiles Can Serve as Host Location Cues for a Generalist and a Specialist Egg Parasitoid

Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and similarly, insect oviposition might elicit the release of plant volatiles functioning as host finding cues for egg parasitoids. We hypothesized that egg parasitoids also might utilize HIPVs of emerging larvae to locate plants with host eggs. We, therefore, assessed the olfactory response of two egg parasitoids, a generalist, Trichogramma pretiosum (Tricogrammatidae), and a specialist, Telenomus remus (Scelionidae) to HIPVs. We used a Y-tube olfactometer to tests the wasps’ responses to volatiles released by young maize plants that were treated with regurgitant from caterpillars of the moth Spodoptera frugiperda (Noctuidae) or were directly attacked by the caterpillars. The results show that the generalist egg parasitoid Tr. pretiosum is innately attracted by volatiles from freshly-damaged plants 0–1 and 2–3 h after regurgitant treatment. During this interval, the volatile blend consisted of green leaf volatiles (GLVs) and a blend of aromatic compounds, mono- and homoterpenes, respectively. Behavioral assays with synthetic GLVs confirmed their attractiveness to Tr. pretiosum. The generalist learned the more complex volatile blends released 6–7 h after induction, which consisted mainly of sesquiterpenes. The specialist T. remus on the other hand was attracted only to volatiles emitted from fresh and old damage after associating these volatiles with oviposition. Taken together, these results strengthen the emerging pattern that egg and larval parasitoids behave in a similar way in that generalists can respond innately to HIPVs, while specialists seems to rely more on associative learning.

Temperature-dependent phenology of Plutella xylostella (Lepidoptera: Plutellidae)

Temperature-dependent population growth of diamondback moth (DBM) Plutella xylostella (L.), a prolific insect pest of crucifer vegetables, was studied under six constant temperatures in the laboratory. The objective of the study was to predict the impacts of temperature changes on the population of DBM at high-resolution scales along altitudinal gradients and under climate change scenarios. Non-linear functions were fitted on the data for modeling the development, mortality, longevity and oviposition of the pest. The best-fitted functions for each life stage were compiled for estimating the life table parameters of the species by stochastic simulations. To quantify the impacts on the pest, three indices (establishment, generation and activity) were computed using the estimates of life table parameters and temperature data obtained at local scale (current scenario 2013) and downscaled climate change data (future scenario 2055) from the AFRICLIM database. To measure and represent the impacts of temperature change along the altitude on the pest; the indices were mapped along the altitudinal gradients of Kilimanjaro and Taita Hills, in Tanzania and Kenya, respectively. Potential impact of the changes between climate scenarios 2013 and 2055 was assessed. The data files included in this database were utilized for the above analysis to develop temperature dependent phenology of Plutella xylostella to assess current and future distribution along eastern African Afromontanes.

Actividad insecticida de Ricinus Communis L. sobre Plodia Interpunctella Hbn. (Lepidoptera: Phycitinae).

La aplicación de insecticidas sintéticos como principal sistema de control de plagas de granos y productos almacenados ha originado el desarrollo de poblaciones de insectos resistentes a dichos químicos, la contaminación del medio ambiente y la acumulación de sustancias tóxicas en los alimentos. En este trabajo se evaluaron los efectos de la aplicación de molido de hojas de ricino sobre larvas de la «polilla de las harinas» (Lepidoptera: Phycitinae). Los molidos vegetales se obtuvieron a partir de hojas de Ricinus communis L. secadas en estufa a 40 ± 2 °C durante 48 horas y posteriormente molidas hasta lograr un polvo de textura similar a la harina de maíz, material con el que se mezcló a fin de lograr concentraciones de 5, 10 y 15 % y un testigo sin ricino. Las unidades experimentales consistieron en cajas de Petri con seis larvas de primer y segundo estadio y se efectuaron cinco repeticiones por tratamiento (n=120). Se registró el número de larvas, pupas y adultos vivos, cada cuatro días, hasta que las larvas sobrevivientes llegaron al estado adulto. Se calcularon los porcentajes de eficacia mediante la fórmula de Abbott. Los resultados se evaluaron por ANVA y test de Tukey. Se determinaron el tiempo efectivo medio (TE50) y concentración efectiva media (CE50) por el método Probit. Los resultados de mortalidad indicaron que la concentración al 15 % superó significativamente al resto de los tratamientos y al testigo.

Evaluación de los efectos de la composición de la dieta artificial para la cría de Diatraea saccharalis (Lepidoptera: Crambidae) y Cotesia flavipes (Hymenoptera: Braconidae)

El control biológico aumentativo de Diatrae saccharalis Fabricius (Lepidoptera: Crambidae) requiere la cría masiva del parasitoide Cotesia flavipes Cameron (Braconidae: Microgastrinae) y por ello, es necesario el desarrollo de dietas artificiales eficientes. El objetivo fue examinar los efectos de distintos tipos de dieta sobre parámetros biológicos de D. saccharalis y su impacto en la producción de cocones de C. flavipes. Se sembraron 46136 huevos de D. saccharalis en once combinaciones de dietas artificiales, con dos tipos de harinas y tres tipos de antibióticos. Los resultados mostraron que la composición de la dieta afectó los parámetros biológicos de ambas especies. La mayor eficiencia en la cría se obtuvo con el empleo de combinaciones de harina de poroto y ampicilina. Sin embargo, si se considera la relación entre costos de producción y parámetros biológicos, la dieta con harina de poroto, oxitetraciclina y estreptomicina resulta más adecuada para la cría masiva.

Effects of sublethal doses of methoxyfenozide on the development, survival and reproduction of Spodoptera frugiperda.

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to ϐifth instars until pupation in doses corresponding to the LC 10 and LC 25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC 10 and 60% for the LC 25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a signiϐicant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from ϐifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm

Adaptation of Spodoptera exigua larvae to plant proteinase inhibitors by induction of gut proteinase activity insensitive to inhibition.

Tobacco plants were transformed with a cDNA clone of chymotrypsin/trypsin-specific potato proteinase inhibitor II (PI2) under the control of a constitutive promoter. Although considerable levels of transgene expression could be demonstrated, the growth of Spodoptera exigua larvae fed with detached leaves of PI2-expressing plants was not affected. Analysis of the composition of tryptic gut activity demonstrated that only 18% of the proteinase activity of insects reared on these transgenic plants was sensitive to inhibition by PI2, whereas 78% was sensitive in insects reared on control plants. Larvae had compensated for this loss of tryptic activity by a 2.5-fold induction of new activity that was insensitive to inhibition by PI2. PI2-insensitive proteolytic activity was also induced in response to endogenous proteinase inhibitors of tobacco; therefore, induction of such proteinase activity may represent the mechanism by which insects that feed on plants overcome plant proteinase inhibitor defense.

Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae): adequação de uma dieta artificial e avaliação do seu controle biológico com Trichogramma pretiosum Riley em tomateiro

Tuta absoluta (Meyrick, 1917) é uma das pragas-chave da cultura do tomate e outras solanáceas na América do Sul e atualmente também na Eurásia e África. Devido aos grandes prejuízos que causa à cultura, são principalmente usados inseticidas para o seu controle. Entretanto, na busca de estratégias mais sustentáveis, cada dia adquire maior importância o uso do controle biológico, como uma das estratégias do manejo integrado de pragas. Para o desenvolvimento destas estratégias é fundamental desenvolver um método de criação de T. absoluta em laboratório, em dieta artificial, sem necessitar do hospedeiro natural, muitas vezes difícil de ser obtido e mantido em laboratório, e, de grande importância para produzir parasitoides específicos para esta praga. Dentre os parasitoides mais usados para ovos de lepidópteros está Trichogramma pretiosum Riley 1879 que é usado no controle biológico aplicado desta praga. Tendo como foco principal T. absoluta, neste trabalho foram pesquisados 1) a seleção de uma dieta artificial para este lepidóptero baseando-se em características físicas e químicas, avaliando o seu desempenho por várias gerações em laboratório, e 2) avaliação de aspectos biológicos e reprodutivos de T. pretiosum parasitando ovos de T. absoluta e aspectos físicos da planta (tricomas) para compreender o controle biológico desta praga no tomateiro. Foi encontrado que uma dieta à base de germe-de-trigo, caseína e celulose é apropriada para a criação deste lepidóptero, já que o inseto mostrou adaptação à mesma no transcorrer das gerações com base em características biológicas e de tabela de vida; adicionalmente, os ovos provenientes de T. absoluta alimentada com dieta artificial são comparáveis aos da dieta natural, no parasitismo de T. pretiosum. Com relação ao controle biológico foi demonstrado que este parasitoide desenvolvido em ovos de T. absoluta, diminui seu tamanho e desempenho com o transcorrer das gerações, apresentando menor capacidade de voo do que os insetos produzidos em A. kuenhiella, sendo necessária a liberação de altas densidades de parasitoides por ovo da praga. Foi observado que, embora o parasitismo de T. pretiosum de ovos de T. absoluta seja melhor em variedades com poucos tricomas, uma alta densidade destas estruturas não impede o controle da praga alvo dependendo da disposição destas estruturas. O controle biológico de T. absoluta com T. pretiosum tem uma ação momentânea, sendo necessárias liberações frequentes devido ao fato de os parasitoides desenvolvidos na praga serem menos competitivos com aqueles provenientes do hospedeiro alternativo que apresenta ovos maiores do que T. absoluta.