The chemical composition of essential oils from three species of plants belonging to the Eucalyptus genus was determined and, their insecticidal effects on egg, larva and adult phases of Lutzomyia longipalpis were assessed. The insects were collected in the municipality of Sobral in the State of Ceará, Brazil. Five treatments with different concentrations were performed along with two negative controls, distilled water and Tween 80 (3%), and a positive control, cypermethrin (0.196mg/ml). The tests were carried out in plastic pots internally coated with sterile plaster and filled with a substrate made of rabbit feces and crushed cassava leaves. The eggs, larvae and adults were sprayed with the oils. The hatched larvae were counted for 10 consecutive days and observed until pupation. Insect mortality was observed after 24, 48 and 72h. E. staigeriana oil was the most effective on all three phases of the insect, followed by E. citriodora and E. globulus oils, respectively. The major constituents of the oils were Z-citral and alpha-citral (E. staigeriana), citronellal (E. citriodora) and 1,8-cineole (E. globulus). The Eucalyptus essential oils constitute alternative natural products for the control of L. longipalpis since the median effective concentration (EC(50)) values revealed relevant action as compared with other natural products, some of their chemical constituents are already known for their insecticidal activity and these oils are produced in commercial scale in Brazil.

Neotropical Entomology 37(4): 457-462 (2008) PALAVRAS-CHAVE: Ácaro do coqueiro, ácaro predador, controle biológico, PhytoseiidaeABSTRACT -Aceria guerreronis Keifer can cause severe damage to coconuts in several countries around the world. Rare studies have been conducted to determine the predatory mites associated with A. guerreronis in Brazil. The study evaluated the prevalence of A. guerreronis and associated predators on the bracts and on the surface of the fruits underneath the bracts, for 12 months, on coconut palms grown along the coast of the States of Alagoas, Paraíba and Pernambuco, Northeastern Brazil. Mites of 10 families were found, but by far the most abundant species was A. guerreronis, corresponding to 99.5% of the mites collected. The prevailing species amongst the predators were the Phytoseiidae mites Neoseiulus baraki (AthiasHenriot) and Neoseiulus paspalivorus (De Leon). These are fl at mites that have short limbs, characteristics that allow them to invade the main habitat occupied by A. guerreronis. Other predators were found, but in low numbers, due mainly to their diffi culty in reaching the fruit areas most inhabited by A. guerreronis. However, these mites could prey on that pest when it leaves its preferred habitat to disperse. No signifi cant correlations were observed between the levels of abiotic factors and the population levels of A. guerreronis or of the phytoseiids associated with it. This probably occurred due to the simultaneous and confl icting effects of those factors on the mites in the fi eld, or to signifi cant differences between the climatic factors measured in the environment and those prevailing in the habitat occupied by A. guerreronis.

The occasional feeding on plants by Podisus nigrispinus (Dallas) has produced different responses on its biology according to the plant species available. This study was undertaken to determine the development and reproduction of P. nigrispinus when confined on Gossypium hirsutum cv. Precocious CNPA1 and processing tomato Lycopersicum esculentum cv. IPA5 plants, using Tenebrio molitor (L.) pupa as prey. Nymphs and adults of P. nigrispinus were provided with prey and plants of cotton, prey and plant of tomato, prey and water, and only the prey. The predator could access the plants by caging nymphs and prey on plant leaves cultivated in pots. Nymphs caged on cotton or tomato plants with prey showed shorter duration of second and fifth ínstars. However, the shortest development period was observed for nymphs caged on cotton plants with prey. Nymphs fed on prey alone had lower survival within each ínstar and for the whole stage when compared to nymphs accessing plant, prey and water. The availability of cotton plants to nymphs produced heavier individuals compared to tomato plants, prey and water, and only prey. The adult weight at emergence was similar between plants and prey plus water, and superior to the treatment with prey alone. However, females of P. nigrispinus with access to the prey and cotton plant and prey and water showed significant body weight increase at the beginning of the reproductive activity, while females confined on tomato plants and only on prey did not range their weight during their lives. The availability of cotton and tomato plants to P. nigrispinus increased the number of eggs produced and adult longevity; moreover the former plant promoted higher oviposition frequency. Based on the results on net reproduction rate, intrinsic rate of increase and generation time, calculated for P. nigrispinus, the populations improved according to the plant species available and showed better response when confined with prey on cotton plants, followed by tomato plants. Also, insects fed on water plus prey developed better than those fed only on the prey.

-The effects of aqueous extracts of different plant species on the development of Plutella xylostella (L.) were studied. Leaf discs of kale cultivar Portuguesa, Brassica oleracea var. acephala, were dipped in each plant extract per 30 seconds. Twelve neonate P. xylostela larvae (<12h) were fed on treated leaf discs and kept in petri dishes. The leaf discs were replaced at two-day intervals by fresh leaf discs treated with the plant extracts. Larvae of P. xylostella which fed on leaf discs treated with Melia. azedarach L. and Cissampelos aff. glaberrima St. Hil. delayed their development by 3.5 and 1.7 days, respectively. However, the other plant extracts studied did not affect larva development. Extracts of Aspidosperma pyrifolium Mart., Azadirachta indica A. Juss., and A. indica oil formulation caused 100% mortality of P. xylostella larvae, while, the extracts of M. azedarach, C. aff.glaberrima, Laurus nobillis L., Prosopis juliflora DC, Croton sp. and Eugenia uniflora L. caused larval mortality of 96.7, 93.3, 83.3, 66.7, 63.3 and 60%, respectively. The other studied extracts did not cause significant larval mortality. Duration of pupae stage was not affected by the studied plant extracts, however, the extracts of M. azedarach, L. nobillis, C. aff. Glaberrima and Croton sp. caused 100, 90, 66.7 and 65% of pupae mortality, respectively. KEY WORDS: Insecta, diamondback moth, plant insecticide, cabbage pest.RESUMO -Avaliou-se o efeito de extratos aquosos de diferentes espécies de plantas no desenvolvimento de Plutella xylostella (L.). Discos de couve, Brassica oleracea var. acephala, 'Portuguesa' foram imersos em cada extrato e, após secos ao ar livre, foram inoculados com 12 larvas recém-eclodidas (<12h) de P. xylostella e então mantidos em placas de Petri. As avaliações foram realizadas, a cada dois dias, e os discos foliares foram substituídos por outros, submetidos aos mesmos tratamentos e procedimentos descritos acima. A duração da fase larval de P. xylostella foi alongada pelos extratos aquosos de Melia azedarach L. Cissampelos aff. glaberrima St. Hil. em 3,5 e 1,7 dias, respectivamente. Os extratos de Aspidosperma pyrifolium Mart., Azadirachta indica A. Juss. e a formulação de A. indica ocasionaram mortalidade total das larvas, o que não permitiu o cálculo da duração da fase larval. O restante dos extratos aquosos não afetou esse parâmetro. Para os extratos de M. azedarach, C. aff. glaberrima, Laurus nobillis L., Prosopis juliflora DC, Croton sp. e Eugenia uniflora L., a mortalidade das larvas foi de 96,7; 93,3; 83,3; 66,7; 63,3 e 60%, respectivamente. Os demais extratos não afetaram a viabilidade da fase larval de P. xylostella. A duração da fase pupal de P. xylostella não foi afetada pelos extratos, entretanto a viabilidade dessa fase foi afetada pelos extratos de M. azedarach, L. nobillis, C. aff.. glaberrima e Croton sp. com 100; 90; 66,7 e 65% de pupas das quais não emergiram adultos, respectivamente.PALAVRAS-CHAVE: Insecta, traça-das-crucíferas, planta inseticida, repolho.

Many aspects of a parasitoid’s biology may be affected by its host. Host size, for example, could affect parasitoid fitness, especially in gregarious parasitoids, in which the resource is used by multiple siblings. Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) is a gregarious larval–pupal endoparasitoid of the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), a major pest of crucifers worldwide, and is able to superparasitize the host. This study focuses on the hypothesis that because resource availability is higher in larger hosts, parasitoids developing in larger hosts will fare better. However, superparasitized hosts are expected to yield larger numbers of parasitoid offspring of smaller body size. Results showed that superparasitism increased the number of parasitoid offspring produced per host and increased offspring longevity, but decreased offspring body size. However, developmental time and sex ratio of parasitoid offspring was similar among hosts parasitized once, twice, or three times. Regardless of superparasitism, parasitoids emerging from larger hosts that were fed honey solution lived longer than similarly fed progeny from smaller hosts (36.4 vs. 22.1 days). The results partially support the hypothesis that Oomyzus gained fitness from an increase in host size; moreover, superparasitism seems advantageous for Oomyzus due to increased offspring numbers and longevity.

RESUMOForam avaliados a CL 50 e o efeito de extratos aquosos de plantas na biologia, oviposição e período embrionário de Plutella xylostella L. (Lepidoptera: Plutellidae). Para determinação da CL 50 foram utilizadas concentrações entre 0,03 e 0,8 % para amêndoas de Azadirachta indica (A. Juss.) 0,5 e 7,0 % para casca de Aspidosperma pyrifolium (Mart.) e 0,5 e 12,5 % para frutos de Melia azedarach (L.), obtendo-se as CL 50 de 0,06; 2,17 e 2,90%, respectivamente. Verificou-se que os extratos aquosos de todas as espécies vegetais afetaram o desenvolvimento do inseto, principalmente na fase larval. Na fase de pupa, os extratos reduziram a massa e a viabilidade. Houve deformação de adultos para os extratos de A. pyrifolium e M. azedarach e o de A. indica causou maior porcentagem. Todos os extratos possuem efeito tóxico para ovos de P. xylostella, sendo dependente do aumento da concentração. Nos extratos da casca de A. pyrifolium, do fruto de M. azedarach e da amêndoa de A. indica observa-se ação ovicida quando usados na concentração letal de lagartas de primeiro ínstar da praga. Em observações do ovo de P. xylostella com auxílio de um microscópio eletrônico de varredura, verificou-se a existência de microporos onde pode ocorrer a penetração do produto ovicida, além da constatação da textura rugosa da casca do ovo que pode reter ou fixar os extratos.Palavras-chave: plantas inseticidas, traça-das-crucíferas, brássicas. ABSTRACT EFFECT OF AQUEOUS EXTRACTS OF AZADIRACHTA INDICA (A. JUSS), MELIA AZEDARACH (L.) AND ASPIDOSPERMA PYRIFOLIUM (MART.) ON THE DEVELOPMENT AND OVIPOSITION OFPLUTELLA XYLOSTELLA (L.) (LEPIDOPTERA: PLUTELLIDAE)The effects of aqueous extracts of plants on the biology, preference for oviposition and embryonic period of Plutella xylostella were evaluated. Concentrations between 0.03 and 0.8 % for kernel of Azadirachta indica, 0.5 and 7.0% for peel of Aspidosperma pyrifolium and 0.5 and 12.5% for fruits of Melia azedarach were used, with LC 50 values of 0.06; 2.17 and 2.90%, respectively, being obtained. It was verified that the aqueous extracts of all of the appraised vegetable species affected the development of the insect, mainly in the larval phase. In the pupae phase, the extracts reduced the weight and the viability. There was adults' deformation for the extracts of A. pyrifolium and M. azedarach, being it of A. indica what caused larger percentage. Toxics effects on the eggs of P. xylostella were observed for all extracts. The extracts from A. pyrifolium (peel); M. azedarach (fruit) and A. indica (kernel) presented ovicide action in the lethal concentration of caterpillars at first instar of the pest. Observations of P. xylostella eggs with the aid of an electronic microscope showed presence of microspore, revealing ovicide action, besides wrinkled texture of the eggs peel retaining the extracts.

Broad and indiscriminate use of Bt-based products has selected Brazilian P. xylostella populations to resistance. Larval movement appears to be a resistance-independent mechanism. Most populations of P. xylostella preferred to lay eggs on Bt-free surfaces, which might be a result of growers' practice of spraying the cabbage head. Reduced oviposition on treated surfaces correlated with physiological resistance, suggesting a behavioural response among the Bt-resistant colonies to Dipel®WP.

Estudou-se a capacidade de parasitismo de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), em ovos de Plutella xylostella (L.)(Leptoptera: Plutellidae) nas temperaturas de 18; 20; 22; 25; 28; 30 e 32ºC, avaliando-se número de ovos parasitados diariamente, porcentagem acumulada de parasitismo, número total de ovos parasitados por fêmea e longevidade de fêmeas. O ritmo de parasitismo durante as primeiras 24 horas, oscilou de 1,6 a 16 ovos parasitados por fêmea de T. pretiosum nas temperaturas entre 18 e 32ºC. O parasitismo acumulado de ovos de P. xylostella, nas temperaturas de 18; 20; 22; 25; 28; 30 e 32ºC, atingiu 80%, aos 2; 16; 11; 3; 5; 4 e 7 dias, por T. pretiosum. As maiores taxas de parasitismo ocorreram nas faixas térmicas de 25; 28 e 30ºC. A longevidade média de fêmeas de T. pretiosum nas faixas térmicas compreendidas entre 18 e 32ºC, variaram de 2,3 a 13,3 dias.