Plant extract have been recognized as important natural source of insecticide. Herein, we assessed the toxicity of leaves-extract and seeds-extract of Annona mucosa (Annonaceae) against brown stink bug, Euschistus heros (F.) (Hemiptera: Pentatomidae), a soybean pest in Neotropical America. For this, bioassays with nymphs and adults were conducted using the concentrations of 5, 10, 20, 40 and 80 mg.mL -1 of leaves and seeds extract of A. mucosa and DMSO (10%), as control. Ten replicates were conducted by treatment, with five nymphs (3 rd instar) by replicate (bioassay with nymphs) and one couple of adults (< 24h of old) by replicate (bioassay with adults). The number of nymphs death (mortality) and survival of adults were assessed. For adults the fecundity (number of eggs) and fertility (number of nymphs hatched) of females also were assessed. The nymphs bioassay has promising results in seeds extract, when compared to leaves extract. The mortality of nymphs treated with seeds extract was dependent-concentration, with increased in mortality in concentrations > 5.0mg.mL -1 , while nymphs treated with leaves extract do not exhibit difference between treatments. In adults the survival was reduced, when were treated with seed extract of A. mucosa at concentrations higher than 20mg.mL -1 , with reduction up to 92 days in contrast to control. A drastic reduction in the fecundity and fertility was observed, which highlight deleterious action of seed extract against reproductive potential of E. heros. This is the first report about toxicity A. mucosa (leaves and seed) on E. heros, and our results suggest that seeds extract of A. mucosa is promising for control of nymphs and adults of brown stink bug.
Sowing is a fundamental stage in crops’ cultivation process. If performed improperly, it can compromise the entire crop development. Seeding speed stands out as a key factor which can affect seeding quality. The objective of this study was to assess the effects of variation of working speed in maize initial establishment and in direct seeding’s’ quality parameters. The experiment was carried out in the municipality of Tangará da Serra – MT. Four seeding speeds were used V1 equal 1.11 (4.0), V2 equal 1.39 (5.0), V3 equal 1.67 (6.0) and V4 equal 1.94 m s-1 (7.0 km h-1). The assessed parameters were emergence speed index, emergence rate, seed deposition depth, plant spacing, and initial plant population. No interference of seeding speed variation was observed in seed deposition depth, emergence speed index and initial plant population. However, seeding speed influenced in plant spacing, in which speed increase was proportional to plant spacing increase.
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