E. R. Sujii

Field responses of stink bugs to the natural and synthetic pheromone of the Neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae)

Abstract.The synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a component of the male produced pheromone of Euschistus heros (F.) (Heteroptera, Pentatomidae), was attractive to pentatomid species in a field test, using homemade pheromone trap designs. The pentatomid Piezodorus guildinii was caught in high numbers in field traps, during two field experiments, indicating a consistent response of this species to the E. heros pheromone. A correlation was found between the range of insects caught in the pheromone‐baited traps and a random sampling method. The synthetic stereoisomeric mixture of methyl 2,6,10‐trimethyldodecanoate, a minor component of E. heros pheromone, was also field tested and caught no pentatomids. Egg parasitoids were caught in traps baited with E. heros pheromone, indicating that this pheromone can be exploited as a kairomone. A synchrony in the periodicity of trap catch, between the egg parasitoids and their host, was also recorded.

Semiochemical and physical stimuli involved in host recognition by Telenomus podisi (Hymenoptera: Scelionidae) toward Euschistus heros (Heteroptera: Pentatomidae)

The egg parasitoid, Telenomus podisi, was shown to recognize its host, Euschistus heros, through both chemical and physical cues. These were determined in short‐range bioassays. The cues comprised fertile and infertile host eggs, egg extracts, crude extracts of adult males and females and successive dilutions of the synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a male‐produced pheromone of E. heros.

Monitoring the Neotropical brown stink bug Euschistus heros (F.) (Hemiptera: Pentatomidae) with pheromone‐baited traps in soybean fields

The effectiveness of the synthetic sex pheromone of the Neotropical brown stink bug, Euschistus heros, was evaluated both in laboratory and in field assays. Lures loaded with 1 mg of methyl 2,6,10‐trimethyltridecanoate (TMTD) continuously attracted female bugs for more than 30 days to pheromone‐baited traps in field trials. The pheromone‐baited traps were effective in field tests even at low bug population densities, as compared with the usual monitoring technique, shake cloth sampling. Traps around borders or in the centre of soybean fields caught similar numbers of bugs. Trap captures showed a positive relationship with field populations, as monitored with the shake cloth technique, during the reproductive phase of the soybean crop, i.e. from the R1–R5 developmental stage (pod formation to pod fill). The physiological state of the trapped migrating insects was determined. The first insects arriving in the field had fewer eggs in the reproductive tract compared to later arrivals. Some cross‐attraction was also observed, with Piezodorus guildinii and Edessa meditabunda also being caught in pheromone‐baited traps, suggesting that these insects respond to the sex pheromone or to the defensive compounds released by E. heros captured in traps. In brief, the results showed that traps baited with 1 mg of the sex pheromone efficiently caught bugs, that the lures lasted for more than 1 month under field conditions and that placement of traps around the borders of the crop area was as effective as placement inside the crop area. Border‐placed traps were effective at a density of one trap every 200 m.

Behavioural evidence of methyl-2,6,10-trimethyltridecanoate as a sex pheromone of Euschistus heros (Het., Pentatomidae)

Abstract: Males of the Neotropical brown stink bug, Euschistus heros, were attractive to conspecific females in bioassays. A synthetic stereoisomeric mixture of methyl‐2,6,10‐trimethyltridecanoate, previously identified and presumed as the male‐produced pheromone, was confirmed to attract females. A 24 h bioassay showed the presence of a diel periodicity, where the females respond to males from noon to midnight. A still‐air olfactometer assembled from commercially available food containers was used to test the attractants from E. heros.

Does Cry1Ac Bt‐toxin impair development of worker larvae of Africanized honey bee?

The western honey bee (Apis mellifera L.) is a widespread pollinator species. The present study aimed to test if Africanized honey bee larvae are negatively affected by the ingestion of diet contaminated with the Bacillus thunringiensis toxin Cry1Ac, which is expressed in GM cotton plants. The toxin activity was confirmed in bioassays with the velvetbean caterpillar (Anticarsia gemmatalis), a soybean pest species susceptible to Cry1Ac. The honey bee larvae were subjected to ingestion of either pure larval diet (control), diluted larval diet (diluted control) or larval diet diluted in a Cry1Ac solution at a concentration compatible with the maximum possible field exposure. Although diluted diet slightly increased larval mortality, Cry1Ac ingestion did not affect survival, developmental time, and neither adult body mass nor size, indicating that GM plants are unlikely to significantly impair the development of honey bee larvae. The larval‐rearing system reported here was suitable to assess the lethal and sub‐lethal effects of GM expressed toxins against honey bee larvae.

Selection of bee species for environmental risk assessment of GM cotton in the Brazilian Cerrado

The objective of this work was to list potential candidate bee species for environmental risk assessment (ERA) of genetically modified (GM) cotton and to identify the most suited bee species for this task, according to their abundance and geographical distribution. Field inventories of bee on cotton flowers were performed in the states of Bahia and Mato Grosso, and in Distrito Federal, Brazil. During a 344 hour sampling, 3,470 bees from 74 species were recovered, at eight sites. Apis mellifera dominated the bee assemblages at all sites. Sampling at two sites that received no insecticide application was sufficient to identify the three most common and geographically widespread wild species: Paratrigona lineata, Melissoptila cnecomola, and Trigona spinipes, which could be useful indicators of pollination services in the ERA. Indirect ordination of common wild species revealed that insecticides reduced the number of native bee species and that interannual variation in bee assemblages may be low. Accumulation curves of rare bee species did not saturate, as expected in tropical and megadiverse regions. Species-based approaches are limited to analyze negative impacts of GM cotton on pollinator biological diversity. The accumulation rate of rare bee species, however, may be useful for evaluating possible negative effects of GM cotton on bee diversity.

Economic and productivity incentives to produce organically in Brazil: Evidence from strawberry production in the Federal District

Brazil has the largest market for organic products in Latin America, but only 1.04% of its agricultural land is utilized for organic production (OP). We compared organic and conventional production (CP) in economic and productivity terms using data from a randomized survey of 86 organic and conventional strawberry growers (response rate 85.2%) in Brazlândia, Federal District, Brazil. Probit model selection estimates showed that the use of technical assistance from rural extension and producer gender had no effect, but growers with greater age, higher indebtedness, smaller strawberry production area, more education and less experience on growing strawberries were more likely to produce organically. For growers with more than 5.6 years of education and less than 13.54 years of experience, more education and experience make them less likely to produce strawberry organically. Thus, we expect growers’ probabilities of conversion for strawberry OP will remain about the same over time in the study area. The average treatment effect for the treated (ATT) was estimated using nearest neighbor/propensity score matching and endogenous switching regression (ESR). These showed that producing strawberry organically had no effect on productivity or total cost per box, but increased revenue and profit per box, probably as a result of the price premium for organic strawberries. As only 4.8% of farmers had converted to organic production, conversion costs and non-economic factors, such as psychological factors and social capital, may be barriers to conversion.