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.

-The objective of this work was to study the toxicity of pymetrozine and thiamethoxam to the cotton aphid parasitoid Aphelinus gossypii Timberlake and to the whitefly predator Delphastus pusillus (LeConte). Cotton leaves containing mummies of the parasitoid A. gossypii were collected and treated with seven concentrations of both insecticides. Parasitoid emergence was not affected by pymetrozine and ranged from 59.9% to 75.0%, but decreased with the increase of thiamethoxam concentrations ranging from 30.2% to 69.6%. Cotton leaves infested by whitefly and treated with recommended rates of both insecticides were collected three hours, three days and six days after spraying and colonized with larvae and adults of D. pusillus. Predators released on thiamethoxamtreated leaves experienced mortality from 70% to 100%, while those released on pymetrozine-treated leaves showed mortality from 0% to 20%. Topical toxicity from both insecticides was studied on larvae, pupae and adults of D. pusillus. The survival of predator after six days of exposure to 400, 600 and 800 mg/L of pymetrozine a.i. was higher than 69.6%, and to 25, 100 and 200 mg/L of thiamethoxam a.i. was lower than 8.7%. The toxicity data for A. gossypii and D. pusillus characterize the pymetrozine as harmless for both species, and thiamethoxam of low to moderate toxicity for A. gossypii treated mummies, and high toxicity for D. pusillus.Index terms: Gossypium, infestation, parasitoids, insecticide selectivity. Toxicidade de pimetrozine e tiametoxam a Aphelinus gossypii e Delphastus pusillusResumo -O objetivo deste trabalho foi estudar a toxicidade de pimetrozine e tiametoxam ao parasitóide do pulgão-do-algodoeiro Aphelinus gossypii Timberlake e ao predador da mosca-branca Delphastus pusillus (LeConte). Folhas de algodoeiro contendo múmias do parasitóide A. gossypii foram coletadas e tratadas com sete concentrações de ambos inseticidas. A emergência do parasitóide não foi afetada pelo pimetrozine e variou de 59,9% a 75%, enquanto as múmias tratadas com tiametoxam produziram emergência de A. gossypii variando de 30,2% a 69,6%. Plantas infestadas por mosca-branca e tratadas com três concentrações recomendadas de ambos inseticidas foram coletadas três horas, três dias e seis dias após tratamento e colonizadas com larvas e adultos de D. pusillus. Os predadores liberados em folhas tratadas com tiametoxam apresentaram mortalidades de 70% a 100%, enquanto aqueles liberados em folhas tratadas com pimetrozine apresentaram mortalidade de 0% a 20%. Seis dias após tratamento tópico de larvas, pupas e adultos de D. pusillus com pimetrozine (i.a.) a 400, 600 e 800 mg/L, a população viva era acima de 69,6%, enquanto os tratados com tiametoxam (i.a.) a 25, 100 e 200 mg/L, apresentaram sobrevivência abaixo de 8,7%. O pimetrozine foi inócuo para A. gossypii e D. pusillus, e o tiametoxam mostrou toxicidade de baixa a moderada para múmias de A. gossypii e foi altamente tóxico a D. pusillus.Termos para indexação: Gossypium, infestação, parasitóide, seletividade de insetic...

-The objectives of this work were to study the insecticides espinosad, lambdacyhalothrin and monocrotophos on the control of Alabama argillacea (Hübner), the compatibility of these insecticides with the predatory stinkbug Podisus nigrispinus (Dallas), and the effects of the insecticides and acaricides methiocarb, pymetrozine, thiamethoxam, abamectin, diafenthiuron, dicofol and propargite on the predatory stinkbug behavior preying upon A. argillacea under field conditions. More than 90% of cotton leafworm control was obtained at the day 0 of application with all insecticides. Control of A. argillacea by lambdacyhalothrin (20 g a.i./ha) and monocrotophos (240 and 320 g a.i./ha) was observed up to day 3 after application; while spinosad (30 and 60 g a.i./ha) prolonged control up to day 5. Monocrotophos and lambdacyhalothrin were significantly more toxic to P. nigrispinus compared to spinosad. Toxicity of monocrotophos and lambdacyhalothrin to P. nigrispinus was evident up to day 3 after application. Survival of P. nigrispinus was affected by methiocarb, thiamethoxam, diafenthiuron, abamectin and sulfur one day after application and only under thiamethoxam treatment after three days. Pymetrozine, dicofol and propargite did not affect P. nigrispinus survival compared to untreated plants. Podisus nigrispinus at the day of application did not prey on A. argillacea under methiocarb treatment, and the predation rate was affected under thiamethoxam, abamectin, diafenthiuron and sulfur treatments at the day of application and after three days. The insecticides pymetrozine and spinosad, and the acaricides dicofol and propargite were compatible to P. nigrispinus and should be considered within a cotton pest management program.KEY WORDS: Integrated pest management, pymetrozine, spinosad, methiocarb, thiamethoxam.RESUMO -Os objetivos deste trabalho foram estudar a ação dos inseticidas espinosade, lambdacialotrina e monocrotofós no controle do curuquerê-do-algodoeiro Alabama argillacea (Hübner), sua compatibilidade com o percevejo predador Podisus nigrispinus (Dallas), e os efeitos dos inseticidas e acaricidas metiocarbe, pimetrozine, tiametoxam, abamectim, diafentiurom, dicofol e propargite na predação de A. argillacea por P. nigrispinus no campo. Inseticidas e concentrações utilizadas proporcionaram controle de A. argillacea acima de 90% no dia da aplicação. O controle de A. argillacea por lambdacialotrina (20 g i.a./ha) e monocrotofós (240 e 320 g i.a./ha) foi observado até três dias após aplicação, enquanto espinosade (30 e 60 g i.a./ha) prolongou o controle acima de 90% até cinco dias. Monocrotofós e lambdacialotrina foram significativamente mais tóxicos para P. nigrispinus comparado a espinosade. O efeito residual de monocrotofós e lambdacialotrina para P. nigrispinus foi evidente até três dias após a aplicação. A sobrevivência de P. nigrispinus foi afetada por metiocarbe, tiametoxam, diafentiurom, abamectim e enxofre após um dia, e apenas por tiametoxam após três dias da aplicação. Pimetrozine, dicofol e proparg...

PALAVRAS-CHAVE: Insecta, parasitóide, hospedeiro alternativo, razão sexual, plasticidade do desenvolvimento ABSTRACT -The development of Melittobia australica Girault and M. digitata Dahms were studied parasitizing blow fly puparia Neobellieria (=Sarcophaga) bullata (Parker) using from one to five foundress females per host. Aspects of parasitoids biology such as number of descendents produced, longevity, and progeny body size can be affected as the number of foundress increases per host. The percentage of puparia parasitized was higher overall for M. digitata than for M. australica. Regardless of foundress numbers, the average total number of descendents produced was significantly higher for M. digitata (66.5 -158.0) than for M. australica (10.9 -55.5). The number of descendents produced per female was inversely proportional to the number of foundresses on a host for both species. Developmental time increased for M. australica and decreased for M. digitata, as the number of foundresses increased. Life spans of adult progeny of both species, deprived of host and food, were longer for progeny derived from fewer foundresses. Body size as measured by forewing and hind-tibia lengths of descendents showed significant reduction as number of foundresses increased for both species, except for the forewing of M. digitata. Changing foundress number did not affect offspring sex ratios (0.95 -0.98 for M. australica, and 0.95 -0.97 for M. digitata). These results indicated that M. digitata achieved better performance parasitizing N. bullata compared to M. australica, and both parasitoid species had their performance affected by increasing the parasitoid densities per host, suggesting that progeny competition occurred.

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-We report the occurrence of natural enemies of Plutella xylostela (L.) in organically farmed kale in Pernambuco, Brazil. Seven natural enemies were observed parasitizing or preying on larvae and pupae of P. xylostella -three parasitoids: Cotesia plutellae Kurdjumov (Hym.: Braconidae), Conura pseudofulvovariegata (Becker) (Hym.: Chalcididae) and Tetrastichus howardi (Olliff) (Hym.: Eulophidae), and four predators: Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), Pheidole sp.Westwood (Hym.: Formicidae), nymphs and adults of Podisus nigrispinus (Dallas) (Hem.: Pentatomidae), and one unidentified species of solitary wasp. Beyond recording these natural enemies, data on predation of P. xylostella larvae in the field and laboratory by C. inclusum are presented.KEY WORDS: Natural biological control, Cotesia, Conura, Tetrastichus, Cheiracanthium, Podisus, PheidoleThe diamondback moth (DBM), Plutella xylostella (L.), is the most destructive pest of crucifers worldwide. The estimated average control cost for DBM is greater than one billion dollars per year (Talekar 1992, Haseeb et al 2004. Intensive insecticide use continues to be the primary method of control against P. xylostella (Barros et al 1993, França & Medeiros 1998, Cheng et al 2008. As a result of biological and behavioral traits of DBM (e.g., great ability to disperse, high fecundity and short life cycle) and conditions offered by the environmental sites (e.g., availability of various crucifers in neighbor fields and throughout the year), P. xylostella has been considered as difficult to control. Thus, use of biological control methods is important for the management of this pest, and augmentation of biological control agents already present is prominent because it has minimum or no cost to growers.In this work we report natural enemies of P. xylostella on an organic farm of kale crop (~90 days old) located in Chã Grande, Pernambuco State, Brazil (08 o 15'14.4''S and 35 o 30'0.3''W with an altitude of 505 m). To sample the natural enemies we exposed sentinel 3 rd -instar DBM larvae at the rate of 30 larvae per kale plant in the field. The exposure system consisted of 15 plants distributed along two transects marked in the study area. Selected plants were eight meters apart and distributed throughout the kale field. Eight out of 15 plants monitored were confined using cylindrical cages (50 cm diameter x 80 cm high) made with 4 mm mesh nylon fastened with wood sticks. Three days after infestation, all remaining DBM larvae were collected, and held for rearing until either an adult DBM or a parasitoid emerged. Predators observed directly preying on larvae or pupae in the field were noted.Because there were significantly fewer P. xylostella larvae recovered in the uncaged plants, and the caged plants excluded spiders and predatory wasps, a study was conducted in the field and in the laboratory to measure the predation rates of the spider species on DBM larvae. The spider species found preying upon DBM larvae in the field was identified as Cheiracanth...

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