No abstract

Euschistus heros is an important pest in Brazilian agriculture growing importance in the general Neotropical realm. Its reproductive potential is the key factor for its characterization as a pest in major crops such as soybean and cotton. The aims of this study were to characterize morphometric parameters of testicles and testicular accessory cells-TACs nuclei of adults E. heros treated with chitin biosynthesis inhibitors (CBIs). The insecticides lufenuron (Match® 50 EC) and buprofezin (Applaud® 250 WP) were applied individually in 4th instar nymphs, remained in controlled conditions until the emergence of adult males. The testicles were identified and removed 72 h after emergency, fixed, photographed for anatomic analysis, and processed for morphometric analyses of the TACs nuclei. It was possible to observe that lufenuron and buprofezin decreased the testicular area. Buprofezin decreased the mean nuclear area analyzed in the TACs, and nuclear hypertrophy can indicate an activity on support and nutrition of germ line cells, presenting a possible effect on protein synthesis. The intense reaction for Fast green in control compared to buprofezin treatment may indicate that total protein (histones and non-histones) has been altered. The tested insecticides, with special focus on buprofezin may affect the final stages of reproductive development of E. heros, with potential to be used in field to the control of this pest.

No abstract

Infestations of Dichelops melacanthus (Dallas; Hemiptera: Pentatomidae) in corn and wheat in Brazil, and the subsequent damage, have increased in recent years, mainly owing to this insect’s ability to survive the off-season. The control of this insect is mainly carried out with chemical insecticides, but the development of alternative methods, such as biological control, can contribute to a more sustainable management. Thus, the objective of this study was to evaluate the potential of entomopathogenic nematodes (EPNs) for the control of D. melacanthus. A selection test was performed with 15 isolates of genera Steinernema and Heterorhabditis regarding their pathogenicity and virulence on adults of D. melacanthus. Concentration (10, 20, 40, 50, and 100 infective juveniles (IJs)/cm2) and greenhouse tests were carried out only with the Steinernema feltiae isolate (IBCB-n 47). All experiments were conducted in a completely randomized design. The selection test data were submitted to the Scott-Knott averages test (P ? 0.05), and those from the greenhouse test to the Student's t-test. The results of the concentration assay were subjected to regression analysis. All isolates showed pathogenicity and virulence in adults of D. melacanthus. The isolates GL (Heterorhabditis amazonensis), IBCB-n27 (Steinernema sp.), and RSC05 (H. amazonensis) were the most virulent (80.0, 82.0, and 88.0% mortality, respectively). The higher concentrations of S. feltiae (50 and 100 IJs/cm²) were responsible for the highest mortality rates of green belly stink bug (88.0 and 86.0%, respectively). In the greenhouse test, S. feltiae caused higher mortality (38%) than the control.

The effects of alternative treatments on the oviposition and viability of Leucoptera coffeella eggs and larvae were evaluated. Under controlled conditions, coffee sprouts cv. IAPAR-59, eight months old, were sprayed with brown propolis extract (1%), pyroligneous extract with pepper and garlic (PEPG) (2%), silicate clay (2%), kaolin (5%), lime sulfur (2%), neem oil (1%) and kaolin + neem oil (5% + 1%), distilled water and no treatment. In a first no-choice bioassay, coffee sprouts were sprayed before oviposition and kept in cages, where adult insects within three days after emergence were released. Adults remained in the cages for 24 hours. Eggs were then counted. 10 eggs per sprout were preserved to verify larval mortality. The number of eggs when treated with propolis extract, neem oil, kaolin + neem oil and PEPG decreased in the evaluations. Treatments with neem oil caused greater larval hindrance. Eggs laid on leaves were also sprayed with the treatments. Egg viability was reduced by treatments containing neem oil and lime sulfur. Neem oil treatments resulted in slim adult emergence; intermediate viability with lime sulfur and slight hindrance with silicate clay. Finally, treatments were also sprayed on leaves, hosting first or third instar larvae. Neem treatment caused high mortality for 1st and 3 rd instar larvae, however, this effect was reduced when mixed with kaolin. Nonetheless, these negative effects disappeared when considering the adult survival ratio. Results indicated that propolis extract, PEPG and neem oil treatments are suitable for reducing egg deposition, neem oil considerably diminished larvae survival and adult emergence.