The side-effects of 21 pesticides were tested on the Hymenoptera egg parasitoid Trichogramma cacoeciae, using four different types of laboratory methods. The methods combined: (a) adult parasitoid exposure to fresh pesticide residue on glass plates ~ initial toxicity worse case to select harmless preparations, (b) direct spray of host eggs enclosing the parasitoid pupae (less susceptible life stage), (c) duration of harmful activity (persistence) on adultsselect preparations that are less persistent and (d) dose-response exposures LD,, -to assess the risk margin. The results showed that the preparations (used at the highest recommended dose) greatly differed in their initial toxicity as well as in their persistence. The fungicide Topsin M@ (thiophanat-methyl) and the herbicides Pyramin@ (chloridazon), Butisan' S (metazachlor) and Banvel" 70 WG (dicamba) were harmless to T. cacoeciae. The insecticides Match" (lufenuron) and Admirals, (pyriproxifen), the fungicides Bavistin" (carbendazim), AlietteE (fosetyl) and Captan" 83 W (captan) as well as the herbicides Duplosan% 600 KV (mecoprop-p) and Focuss; (cycloxydim) were slightly harmful. The fungicide Scala@ (pyrimethanil) was moderately harmful. TeImion% (rape oil), Vertimec@ (abamectin) and Scala were harmful in the initial toxicity test but only slightly persistent. These less persistent preparations are likely to have less impact on the natural enemy in the field. In the persistence test, Zolone Flow@ (phosalon), Polo@ (difenthiuron), Euparen@ M (tolylfluanid), Dithane@ M 45 (mancozeb), KumulusLR, (sulphur) constantly reduced parasitism by between 90 and 100% and were rated as persistent. The direct spray of parasitized host eggs showed that Zolone Flow, Polo, Eupareum M, Dithane M 45, Scala and Touchdown" were harmless to the parasitoid pupae within the egg, that Telmion, Thiram@ 80 WG and Kumulus were slightly harmful and Vertimec was moderately harmful. The dose-response test indicated a risk quotient (dose in g or ml product per ha/LDSo value) of spray drift for off-field parasitoids for the chemicals in the order of increasing risk as follows: Polo (1.33) followed by Thiram (3.62), Touchdown (7.54), Scala (10.39), Dithane M 45 (13.94), Telmion (27.04) and Zolone Flow (39.34).

In Brazil, the Neotropical brown stink bug, Euschistus heros (F.) (Hemiptera: Pentatomidae), commonly disperses from soybeans to cotton fields. The establishment of an economic treatment threshold for this pest on cotton crops is required. Infestation levels of adults of E. heros were evaluated on cotton plants at preflowering, early flowering, boll filling, and full maturity by assessing external and internal symptoms of injury on bolls, seed cotton/lint production, and fiber quality parameters. A completely randomized experiment was designed to infest cotton plants in a greenhouse with 0, 2, 4, 6, and 8 bugs/plant, except at the full-maturity stage in which only infestation with 8 bugs/plant and uninfested plants were evaluated. Results indicated that the preflowering, early-flowering, and full-maturity stages were not affected by E. heros. A linear regression model showed a significant increase in the number of internal punctures and warts in the boll-filling stage as the population of bugs increased. The average number of loci with mottled immature fibers was significantly higher at 4, 6, and 8 bugs compared with uninfested plants with data following a quadratic regression model. The seed and lint cotton was reduced by 18 and 25% at the maximum level of infestation (ca. 8 bugs/plant) in the boll-filling stage. The micronaire and yellowing indexes were, respectively, reduced and increased with the increase of the infestation levels. The economic injury level of E. heros on cotton plants at the boll-filling stage was determined as 0.5 adult/plant. Based on that, a treatment threshold of 0.1 adult/plant can be recommended to avoid economic losses.

No abstract

The neotropical brown stink bug, Euschistus heros (F.), is a phytophagous pentatomid that causes considerable economic losses in soybean crop, but it has been recently reported using cotton as a new host plant. Nymphs and adults of E. heros were raised on six different food sources composed of the reproductive structures of cotton and soybean plants: a standard diet (green-bean pods + raw peanuts + privet fruits), soybean seeds, soybean pods, cotton seeds, cotton bolls, and cotton floral buds. The following biological parameters were evaluated: nymph developmental time, instar duration, and survivorship; adult weight at emergence; male and female longevity; duration of pre-oviposition and oviposition periods; and female fecundity and fertility. Nymphal development time and survival, as well as the adult weight and fecundity of E. heros fed on cotton bolls and seeds were reduced if compared to those fed on soybean pods. The cotton floral buds did not support the immature development nor the reproduction of adults of E. heros. Most of the cotton plant structures fed to E. heros caused high nymph mortality and low adult fertility. Cotton, therefore, appeared to be an unsuitable host for the development and reproduction of E. heros. Therefore, our data may allow us to suggest that the occurrence of E. heros on cotton may be due to occasional dispersion in search for shelter.

Este texto é uma revisáo bibliográfica que abrange 30 anos de ocorrência do bicudo-do-algodoeiro, Anthonomus grandisBoheman, 1843 (Coleoptera: Curculionidae), no Brasil. O bicudo é considerado uma das pragas mais prejudiciais à agricultura pelos danos que causa e pelas dificuldades de seu controle. Originário do México, esse inseto foi constatado pela primeira vez no Brasil em 1983 e duas safras após seu surgimento já estava disseminado nas principais áreas produtoras de algodão no país, onde se mantém até a atualidade. Quando não controlado, esse inseto pode destruir completamente a produção de um algodoal, já quando controlado os prejuízos variam de 3 a 75% da produtividade esperada. Os principais danos causados pelo bicudo são resultantes de orifícios promovidos nas estruturas reprodutivas da planta durante a alimentação e oviposição dos adultos, sendo os botões florais as estruturas preferencialmente atacadas pelo inseto. O período de ataque do bicudo às plantas de algodoeiro se inicia por volta dos 30 dias após a emergência, no estabelecimento vegetativo da cultura, passando pelo florescimento e frutificação e chegando até a fase de maturação, sendo que durante esse período vários métodos podem ser adotados visando ao seu controle. Para controle de A. grandis, no Brasil, são citados métodos de controle comportamental, controle cultural, resistência de plantas, controle biológico (predadores, parasitoides e patógenos), produtos naturais, controle legislativo e manejo integrado, além de iniciativas de programas de supressão populacional do inseto. O controle químico não é discutido neste artigo.

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) causes economically significant damage to soybeans Glycine max (L.) Merrill (Fabaceae: Phaseoleae). The genetically modified soybean expressing the Cry1Ac protein of Bacillus thuringiensis Berliner, which is toxic to lepidopterans, is a potential alternative tool to manage this pest. Bioassays with H. armigera larval instars were conducted with Bt (Cry1Ac) and non-Bt soybean plants in order to evaluate the efficacy of control with the modified cultivar. Bt soybean affected the mean time of mortality in each larval instar, but its efficacy was not affected by the larval stage. Mortality was 100% in all six instars, indicating that the Bt soybean expressing the Cry 1Ac protein is an efficient control tactic for this pest.

No abstract

The boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the most important cotton pest in Brazil. A large-scale field-testing of a Boll Weevil Suppression Program (BWSP) was implemented to assess its technical and operational feasibility for boll weevil suppression in the state of Goiás, Brazil. The pilot plan focused on 3,608 ha of cotton during the 2006/2007 and 6,011 ha in the 2007/2008 growing seasons; the areas were divided into four inner zones with an outer buffer zone. We analyzed data on boll weevil captures using pheromone traps installed in the BWSP fields, on the detection of the first insect and the first damaged floral bud, greatest damage, and number of insecticide applications. The nonparametric Mann-Whitney U test was used to evaluate the differences between presuppression and suppression years. Fourteen pheromone-baited trapping evaluations were used to compare the weevil populations from 2006/2007 and 2007/2008 growing seasons. The BWSP regime reduced in-season boll weevil captures from 15- to 500-fold compared to presuppression levels in the preceding year. The low capture rates were related to delays in infestation and damage by weevils. The smaller population size measured by trapping and field monitoring reduced the number of required insecticide treatments. The BWSP strategy was efficient in suppressing populations of this pest and is a viable program for cotton production in subtropical and tropical regions, with long-term economic and environmental benefits.