Emergência, longevidade e fecundidade de Trissolcus basalis e Telenomus podisi após estocagem no estágio pupal

Pupae of Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae) were stored at 12ºC and 15ºC for 120-210 days, after different periods of parasitism at 18ºC in order to evaluate adult emergence, longevity and ovipositional capacity. There was no emergence of adults at 12ºC. The rate of emergence of parasitoids transferred to 15ºC at the beginning of the pupal stage was 1.5% and 26.3%, for T. basalis and T. podisi respectively, whereas those parasitoids transferred one day before the expected date of emergence at 18ºC showed 86.4% of emergence for T. basalis and 59.9% for T. podisi. Mean adult longevity was also significantly lower when pupae were transferred to 15ºC at the beginning of the pupal stage. Female semerged after storage and maintained for 120 to 210 days at 15ºC parasitized host eggs after transference to 25ºC; however, fecundity of T. podisi was reduced in about 80% after cold storage.Pupas de Trissolcus basalis (Wollaston) e Telenomus podisi Ashmead (Hymenoptera: Scelionidae) armazenadas a 12ºC e 15ºC por 120 a 210 dias, após diferentes períodos de parasitismo a 18ºC, foram avaliadas quanto à emergência, longevidade e capacidade de parasitismo dos adultos. Não houve emergência de adultos a 12ºC. Os índices de emergência de parasitóides transferidos a 15ºC no início do estágio pupal foram 1,5% e 26,3%, em T. basalis e T. podisi, respectivamente, enquanto os transferidos um dia antes da data prevista para a emergência dos adultos a 18ºC apresentaram índices de emergência de 86,4% em T. basalis e 59,9% em T. podisi. De forma semelhante, a longevidade média dos adultos foi significativamente menor quando a transferência para 15ºC foi realizada no início do estágio pupal. Fêmeas emergidas após estocagem das pupas e mantidas por 120 a 210 dias a 15ºC parasitaram ovos hospedeiros após transferência para 25ºC; no entanto, a fecundidade de T. podisi foi reduzida em cerca de 80% quando mantida em baixa temperatura

Quantitative and qualitative damage caused by Oebalus poecilus (Hemiptera, Pentatomidae) to upland rice cultivated in new agricultural frontier of the Amazon rainforest (Brazil)

ABSTRACT Oebalus poecilus (Dallas 1851) is one of the stink bug species of great economic importance for rice producers in Brazil of irrigated, flood and upland cropping systems. These pentatomids are known as stink bugs of panicles, because both nymphs and adults feed mainly on panicles. Stink bug attacks result in pecky (spots) seeds, lower mass, germinative reduction and deformed grains. Bearing these factors in mind, the aim of this study was to evaluate the quantitative and qualitative losses in commercial cultivars of upland rice (Cambará variety), submitted to different population levels of stink bugs of panicles, O. poecilus, at different reproductive growth stages. The results show that in upland rice (Cambará variety), the rice grains are susceptible to quantitative (number and weight) and qualitative (pecky, atrophy, chalky and broken grains) damage during all panicle development. However, when the insects feed during anthesis/caryopsis and milky stage cause significantly greater percentage of empty grains (up to 83%) than when they feed of grains during later phases of panicle development. This characteristic was also observed for the reduction in grain weight. This information may benefit producers and other researchers, allowing them to focus on the monitoring efforts of O. poecilus in most susceptible phases of the attack of this insect. This will enable decision-making about what control measures should be taken, and when, in order to control stink bugs of panicles

Toxicity of essential oils from leaves of Piperaceae species in rice stalk stink bug eggs, Tibraca limbativentris (Hemiptera: Pentatomidae)

ABSTRACT Tibraca limbativentris to is an important rice pest and occurs in all rice-growing regions of Latin America. The control this insect is accomplished with synthetic chemical insecticides, however, new approaches are needed to reduce risks to the environment, to the natural enemies and also to avoid the onset of insecticides resistance. This study was designed to assess the toxicity of essential oils (EOs) from leaves of Piper aduncum, P. gaudichaudianum, P. malacophyllum, P. marginatum and P. tuberculatum (Piperaceae) on rice stalk stink bug eggs, T. limbativentris. Essential oils were extracted with steam distillation and dilutions were made for bioassays at concentrations of 0.25; 0.5; 1.0; 2.0 and 4.0%. Essential oils from all species of Piperaceae displayed ovicidal activity. The LC50 values indicated that both younger and older eggs were susceptible to these oils. Ovicidal activity is related to the potential toxicity of several compounds, especially dilapiolle, myristicin, cubebene, α-guaiene, longifolene, prezizane, spathulenol, sabinene and δ-2-carene. Thus, EOs tested showed promising results for use as biorational botanical insecticides

Biotic factors are more important than abiotic factors in regulating the abundance of Plutella xylostella L., in Southern Brazil

ABSTRACT The serious economic loss caused Plutella xylostella L., 1758 in several regions of the world has prompted a demand for alternative management strategies. In this context, understanding the key factors governing the population dynamics of the pest is important for development of management strategies. This study aimed to identify the larval parasitoids associated with P. xylostella and investigate the biotic (crop subspecies, plant age and parasitism) and abiotic factors (minimum and maximum temperatures, rainfall, relative humidity and planting season) affecting the population dynamics of the pest in organic crops located in Southern Paraná State, Brazil. Despite the continuous and abundant availability of host plants throughout the year, P. xylostella occurred between June and November, and the largest peaks of abundance were observed between August and September, when low temperatures and rainfall were recorded. According to the stepwise regression analysis, P. xylostella was more abundant in broccoli during winter. Neither temperature, nor rainfall significantly influenced pest abundance. Four species of larval parasitoids were identified associated with the pest, of which Diadegma leontiniae (Brèthes) (Hymenoptera: Ichneumonidae), Apanteles piceotrichosus Blanchard (Hymenoptera: Braconidae) and Siphona sp. Meigen (Diptera: Tachinidae) were abundant, while Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) was rarely found. Parasitism was the major factor influencing population dynamics of P. xylostella, contributing to 48% of the variation in pest abundance. These results show the importance of larval parasitoids complex in regulating P. xylostella population and that the temperature and rainfall recorded during field experiments did not influenced pest abundance

Biotic factors are more important than abiotic factors in regulating the abundance of Plutella xylostella L., in Southern Brazil

ABSTRACT The serious economic loss caused Plutella xylostella L., 1758 in several regions of the world has prompted a demand for alternative management strategies. In this context, understanding the key factors governing the population dynamics of the pest is important for development of management strategies. This study aimed to identify the larval parasitoids associated with P. xylostella and investigate the biotic (crop subspecies, plant age and parasitism) and abiotic factors (minimum and maximum temperatures, rainfall, relative humidity and planting season) affecting the population dynamics of the pest in organic crops located in Southern Paraná State, Brazil. Despite the continuous and abundant availability of host plants throughout the year, P. xylostella occurred between June and November, and the largest peaks of abundance were observed between August and September, when low temperatures and rainfall were recorded. According to the stepwise regression analysis, P. xylostella was more abundant in broccoli during winter. Neither temperature, nor rainfall significantly influenced pest abundance. Four species of larval parasitoids were identified associated with the pest, of which Diadegma leontiniae (Brèthes) (Hymenoptera: Ichneumonidae), Apanteles piceotrichosus Blanchard (Hymenoptera: Braconidae) and Siphona sp. Meigen (Diptera: Tachinidae) were abundant, while Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) was rarely found. Parasitism was the major factor influencing population dynamics of P. xylostella, contributing to 48% of the variation in pest abundance. These results show the importance of larval parasitoids complex in regulating P. xylostella population and that the temperature and rainfall recorded during field experiments did not influenced pest abundance

The potential of Mythimna sequax Franclemont eggs for the production of Trichogramma spp. after cryopreservation in liquid nitrogen

ABSTRACT The cryopreservation of noctuid eggs in liquid nitrogen has proved be a promising tool in the mass production of Trichogramma, however studies into this technique have only just begun. This study evaluated the response of different densities of the female of Trichogramma pretiosum Riley to the parasitism of Mythimna sequax eggs stored and not stored in liquid nitrogen, and the performance of females reared only in cryopreserved eggs. The study evaluated the influence of the number of T. pretiosum females (4, 8 and 12) released to parasitise 40 M. sequax eggs, stored and not stored for 15 days in liquid nitrogen, as well as the performance of T. pretiosum females reared in eggs stored for three generations and females reared in non-stored eggs. Parasitism by T. pretiosum in stored eggs was 84%, twice the value obtained in previous studies. The emergence of parasitoids was greater than 95% in both experiments. The performance of females raised in stored eggs did not differ from that of females raised in non-stored eggs. The data show that the technique of cryopreservation of M. sequax eggs may be a viable alternative in the mass production of T. pretiosum

Efeito da temperatura no desenvolvimento de Euplectrus ronnai (Brethes) (Hymenoptera, Eulophidae) parasitando Pseudaletia sequax Franclemont (Lepidoptera, Noctuidae) e impacto do parasitismo no consumo alimentar do hospedeiro

Estudou-se em laboratório o efeito de cinco temperaturas constantes (15 ° C, 17 ° C, 21° C, 25 ° C e 29 ° C) na duração das fases imaturas de Euplectrus ronnai (Brétlies) sobre lagartas de Pseudaletia sequax Franclcmont. O Parasitóide completou o desenvolvimento em todas as temperaturas. A menor mortalidade (13 %) a 25 ° C e a maior (48,5 %) a 1 5 ° C. Obteve-se uma relação linear entre o tempo de desenvolvimento de E. ronnai e a temperatura na faixa entre 15 e 29 ° C. A temperatura base (Tl) e a constante térmica (

The potential of Mythimna sequax Franclemont eggs for the production of Trichogramma spp. after cryopreservation in liquid nitrogen

<div><p>ABSTRACT The cryopreservation of noctuid eggs in liquid nitrogen has proved be a promising tool in the mass production of Trichogramma, however studies into this technique have only just begun. This study evaluated the response of different densities of the female of Trichogramma pretiosum Riley to the parasitism of Mythimna sequax eggs stored and not stored in liquid nitrogen, and the performance of females reared only in cryopreserved eggs. The study evaluated the influence of the number of T. pretiosum females (4, 8 and 12) released to parasitise 40 M. sequax eggs, stored and not stored for 15 days in liquid nitrogen, as well as the performance of T. pretiosum females reared in eggs stored for three generations and females reared in non-stored eggs. Parasitism by T. pretiosum in stored eggs was 84%, twice the value obtained in previous studies. The emergence of parasitoids was greater than 95% in both experiments. The performance of females raised in stored eggs did not differ from that of females raised in non-stored eggs. The data show that the technique of cryopreservation of M. sequax eggs may be a viable alternative in the mass production of T. pretiosum.</p></div

First phytochemical description of essential oils from Piper cachimboense (Piperales, Piperaceae)

<div><p>ABSTRACT Piper cachimboense is recorded only for the Amazon region of Brazil and Colombia, and the objective of this study was to report the first phytochemical assessment of the composition of the essential oils (EOs) from this species collected in the Amazon rainforest, in Novo Progresso, Pará State, Brazil. Samples of leaves were subjected to hydrodistillation in a Clevenger-type apparatus. The chemical identification was carried out by gas chromatography. The yield of oils was of 11.03 ± 5.94% for fresh leaves, and 1.07 ± 0.27% for dry leaves. The analysis showed 36 volatile compounds from fresh leaves and 49 from dried leaves. Main constituents in EOs of both fresh and dried leaves from P. cachimboense were (E)-caryophyllene, germacrene-D, γ-amorfene, δ-cadinene and apiole.</p></div