Área do dano causado pelo percevejo marrom em sementes de soja com diferentes porcentagens de lignina.

A lignina no tegumento das sementes de soja reduz a incidência de danos mecânicos durante a colheita. Todavia, pouco se conhece sobre seu efeito na alimentação dos percevejos. O objetivo dos experimentos foi avaliar a área do dano causado pelo percevejo marrom, Euschistus heros, na fase adulta, em sementes de soja contendo diferentes porcentagens de lignina, em laboratório e em casa de vegetação. Em laboratório, foram usadas sementes de soja dos cultivares Doko (6,20% de lignina), BRS-255 RR (5,09%), BRS-284 (3,15%) e BRS-232 (1,65%) hidratadas por 16 h, e submetidas individualmente ao ataque do percevejo, em delineamento inteiramente casualizado com quatro repetições (50 sementes/repetição). A atividade dos insetos foi monitorada durante seis horas, para registro do tempo de alimentação e da quantidade de insetos que atacaram as sementes. As sementes atacadas foram submetidas ao teste de tetrazólio para a obtenção de imagens fotográficas do dano causado pelos percevejos, e posterior medição da área danificada no programa Photop (IAPAR). Em casa de vegetação, legumes de cada cultivar no estágio R5/R6 foram individualizados no interior de gaiolas contendo um percevejo. Foram utilizadas cinco plantas por cultivar, com cada planta contendo quatro gaiolas. As vagens ficaram disponíveis ao ataque dos insetos durante 48 horas. As sementes foram colhidas após a secagem natural das plantas, e submetidas ao teste de tetrazólio para obtenção de imagens fotográficas dos danos causados pelos percevejos em 30 sementes por cultivar, para medição das áreas dos danos. As sementes de cultivares com menor porcentagem de lignina no tegumento apresentaram áreas de danos significativamente maiores (Tukey, P?0,05) que as com maiores porcentagens de lignina

Rostrum length, mandible serration, and food and salivary canals areas of selected species of stink bugs (Heteroptera, Pentatomidae)

Laboratory studies were conducted to compare rostrum length morphology of mandible serration and area of food and salivary canals of Dichelops melacanthus (Dallas) (Dm), Euschistus heros (F.) (Eh), Nezara viridula (L.) (Nv), and Piezodorus guildinii (Westwood) (Pg) (Heteroptera: Pentatomidae). Nv showed the longest (5.9 mm) and Pg the shortest (3.5 mm) rostrum length; Dm and Eh were intermediate. Length and width of mandible tip areas holding serration was bigger for Nv (106.0 and 30.2 µm, respectively) and smaller for Pg (71.1 and 23.7 µm), with all species having four central teeth and three pairs of lateral teeth. The inner mandible surface showed squamous texture. Cross-section of food and salivary canals (Fc and Sc) indicated greater area for Nv and Dm compared to Eh and Pg; however, the ratio Fc/Sc, yielded the highest relative area for Pg

Aging and Food Source Effects on Mandibular Stylets Teeth Wear of Phytophagous Stink Bug (Heteroptera: Pentatomidae)

ABSTRACT -Studies were conducted to test the effect of age and food sources on wear of the mandibular teeth of the phytophagous pentatomid, Euschistus heros (F.). The total length (μm) of the area bearing the mandibular teeth, the length of the 1st tooth, and the height of the 2nd tooth for teneral (< 1 day-old) adults were signifi cantly greater than that of adults fed on natural [green bean, Phaseolus vulgaris pods, raw shelled peanuts, Arachis hypogaea, and mature soybean, Glycine max seeds] for 30 or 60 days. Adults fed on artifi cial dry diet showed, in general, similar results to those of teneral adults. Force (Newtons) required penetrating the natural foods was signifi cantly greater than that required penetrating the artifi cial diet. The greater hardness of the natural foods caused increased mandibular serration wear. KEY WORDS: Euschistus heros, mouthpart, morphology, penetration resistance, diet Insect feeding on tough plant parts often results in considerable wear of mandibles (Chapman 1995). Despite their highly sclerotized nature, which can be increased with the addition of zinc or manganese to the cuticle (Schofi eld et al 2002), this phenomenon does occur. Variable degrees of wear to the mandibles have been recorded in several insect groups with chewing mouthparts, such as grasshoppers Regarding insects with piercing/sucking mouthparts, little is know about the effect of food and/or age on the wear of mandibular stylets. The only report found is by To date, no study was made to measure mandibular wear of phytophagous stink bugs of different ages feeding on natural and artifi cial diets. To test this, we selected females of the pentatomid Euschistus heros (F.) of known ages, and offered them different types of food sources. We wanted to test the hypothesis that aging and tougher food source will increase mandibular wear. Material and Methods Insect colony. Adults of E. heros were fi eld-collected using a sweep on soybean, Glycine max cultivated at Embrapa Soja, in Londrina, PR, Brazil (latitude 23º 18' S) during October 2008. A colony was established in the laboratory. Bugs were fed on fresh green bean pods (Phaseolus vulgaris), raw shelled peanuts (Arachis hypogaea), and mature soybean seeds, which were replaced every two days. Pairs (n = 30) were placed in each of three clear plastic boxes (25 x 20 x 20 cm), and provided with the above mentioned foods. Boxes were kept in a walk-in chamber at 25 ± 1°C temperature, 65 ± 5% RH and a photoperiod of 14:10h (L:D). Food was replaced every other day and nymphs obtained were raised to adults. Cotton balls were offered as oviposition substrates Sample preparation and measurements taken. Less than 1 day-old (teneral) adult females of E. heros were selected from the laboratory established colony and were fed on natural diet (diet composed of the plant structures previously referred) for 30 (n = 5) and 60 days (n = 5), and on artifi cial diet (dry exposed diet -a square piece 0.5 cm was used

Feeding activity, salivary amylase activity, and superficial damage to soybean seed by adult Edessa meditabunda (F.) and Euschistus heros (F.) (Hemiptera: Pentatomidae).

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Hypothalamic disconnection caudal to paraventricular nucleus affects cardiovascular and drinking responses to central angiotensin II and carbachol

The paraventricular nucleus of the hypothalamus (PVN) is an important area of the brain involved in the control of cardiovascular system and fluid-electrolyte balance. In the present study we evaluated the effects of hypothalamic disconnection (HD) caudal to PVN in the pressor and dipsogenic responses induced by intracerebroventricular (icy) injections of angiotensin II (ANG II) or carbachol (cholinergic agonist). Male Holtzman rats (280-320 g) with a stainless steel cannula implanted into the lateral ventricle and submitted to sham or D surgery were used. HD (2 or 15 days) reduced the pressor responses to ANG II (50 ng/1 mu l) icy (8 +/- 3 and 11 +/- 3 mm Hg, respectively, vs. sham: 23 +/- 3 and 21 +/- 2 mm Hg) or carbachol (4 nmol/1 mu l (8 +/- 2 and 21 +/- 3 mm Hg, respectively, vs. sham: 33 +/- 3 and 33 +/- 3 mm Hg), without changing baseline arterial pressure. Acutely (2-4 days), HD also reduced water intake to icy ANG II (3.3 +/- 2.2 vs. sham: 14.2 +/- 3.0 ml/60 min) or carbachol (4.4 +/- 1.8 vs. sham: 11.4 +/- 1.6 ml/60 min); however, chronically (15-17 days), HD produced no change on ANG II-and carbachol-induced water intake, in spite of the increased daily water intake and urinary volume. The results suggest that medial projections caudal to PVN are important for pressor and dipsogenic responses to central angiotensinergic and cholinergic activation. (C) 2011 Elsevier B.V. All rights reserved