Laboratory studies were conducted to compare duration of feeding and super icial and in-depth damage to soybean (Glycine max) seeds by the Southern green stink bug, Nezara viridula (L.), the Neotropical brown stink bug, Euschistus heros (F.), the red-banded stink bug, Piezodorus guildinii (Westwood), and the green-belly stink bug, Dichelops melacanthus (Dallas). Results indicated that feeding time was signi icantly longer for N. viridula (≈ 133 min) compared to E. heros and D. melacanthus (≈ 70 min), but not different from P. guildinii (≈ 103 min). There was a positive correlation between feeding time and the resulting damage for E. heros, N. viridula and P. guildinii (R 2 > 0.80, P < 0.0001), but not for D. melacanthus (R 2 = 0.1011, P = 0.1493). The deepest seed damage (2.0 mm) was made by P. guildinii and the shallowest (0.5 mm) by D. melacanthus. The depth of the seed damage by E. heros and N. viridula (0.8, 1.2 mm, respectively) was intermediate in comparison to the other species studied. Feeding damage to the seed endosperm caused variable cell disruption and protein body dissolution, particularly when P. guildinii fed on seeds, suggesting that the deleterious action of salivary enzymes was greater for this bug compared to the others.

Neotropical Entomology 34(4): 601-606 (2005) ABSTRACT -The compatibility of a commercial formula of emulsible neem oil (Azadirachta indica A. Juss.) and of aqueous extracts of neem seeds and leaves with Beauveria bassiana (Bals.) Vuill. was evaluated in vitro. Three experiments were conducted to evaluate the effect of each product on the fungus vegetative growth and on conidia production and viability. The products were incorporated to a culture medium (BDA+E) and distributed into petri dishes, in the following concentrations: 0.15%; 1.5% and 15% (leaf aqueous extract), 1%; 2% and 4% (seed aqueous extract) and 0.5%; 1% and 1.5% (emulsible oil). Vegetative growth and conidia production were the basis for characterization of the aqueous extracts of seeds and leaves and of the emulsible oil, using the T classification model for compatibility of products. Seed and leaf extracts were less harmful to B. bassiana than the emulsible oil. Under the tested concentrations, the oil was not compatible with B. bassiana, inhibiting conidia vegetative growth significantly and decreasing production and viability of conidia, particularly at higher concentrations. Neem seed and leaf extracts were compatible with the entomopathogen in all concentrations. The seed extracts reduced conidia vegetative growth and production, but it did not affect the viability of spores. Leaf extract at 15% had a small negative impact on vegetative growth, and on production and viability of conidia, but it was still compatible with the fungus B. bassiana, according to the T model.

Greenhouse and laboratory studies were conducted to evaluate feeding activity and superficial damage to soybean seed by the brown-winged stink bug, Edessa meditabunda (F.), and the Neotropical brown stink bug, Euschistus heros (F.). Soybean plants (cv. BRS 282), at R6 stage of development were used. Thirty pairs of each species were used individually for 48 h. Two daily observations (9:00 AM and 3:00 PM) were taken to record the number of bugs (feeding/resting) on plant parts. Harvested seeds imbibed in tetrazolium solution were photographed for measurement of the damaged surface. Adult E. meditabunda significantly preferred soybean stems (19.7 bugs) to pods (2.7). Feeding/resting was similar at 9:00 AM (mean number of 28.0 bugs) and 3:00 PM (24.3). Euschistus heros equally fed/stayed on stems (7.3 bugs) and pods (6.9), although most bugs (12.3) remained on the cage net; feeding/resting on all plant structures amounted to 13.7 bugs at 9:00 AM and 17.7 bugs at 3:00 PM. Amylase activity was greater for E. heros (41.61 ± 0.89 U/mg) and almost none for E. meditabunda (2.35 ± 0.14 U/mg). The superficial damage to seeds was significantly greater for E. meditabunda (22. 9 mm(2)) compared to E. heros (12.5 mm(2)). However, E. meditabunda caused less shrinkage of the seed tegument, while E. heros damage was deeper and seeds showed reduction in size.

ABSTRACT. 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.KEYWORDS. Electron microscopy; mouth parts morphology; teneral adults.RESUMO. Comprimento do rostro, dentição mandibular, e áreas dos canais alimentar e salivar de espécies selecionadas de percevejos (Heteroptera, Pentatomidae). Comparou-se em laboratório o comprimento do rostro, a morfologia da dentição mandibular e as áreas dos canais de alimento e de saliva de Dichelops melacanthus (Dallas) (Dm), Euschistus heros (F.) (Eh), Nezara viridula (L.) (Nv) e Piezodorus guildinii (Westwood) (Pg) (Heteroptera: Pentatomidae). Nv apresentou comprimento do rostro mais longo (5,9 mm) e Pg o mais curto (3,5 mm); Dm e Eh apresentaram comprimentos intermediários. O comprimento e largura da região da ponta das mandíbulas que apresentam os dentes foram maiores em Nv (106,0 e 30,2 µm, respectivamente) e menores em Pg (71,1 e 23,7 µm), com todas as espécies possuindo quatro dentes centrais e três pares de dentes laterais. A superfície interna das mandíbulas apresentou superfície com textura escamosa. Secção transversal dos canais de alimento e de saliva (Fc e Sc) indicou áreas maiores em Nv e Dm e menores em Eh e Pg; entretanto, a razão Fc/Sc, apresentou valor relativo maior para Pg.PALAVRAS-CHAVE. Adultos teneral; microscopia eletrônica; morfologia do aparelho bucal.

-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 (Chapman 1964, Gangwere 1965, Gangwere et al 1976, Kaufmann 1971, caterpillars (Djamin & Pathak 1967), and beetles (both phytophagous and carnivores) (Raupp 1985, Wallin 1988. Even insects feeding on "soft" food, such as fungi, show mandibular teeth wear (Welton 1988). Damage to mandibles and other mouthparts structures is widespread amongst aquatic insect larvae that graze on algae (Arens 1990), and it is probably a widespread phenomenon in longer-lived mandibulated insects.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 Roitberg et al (2005), who compared stylet wear of old and young adults of the zoophytophagous Dicyphus hesperus Knight (Heteroptera: Miridae). They found that feeding on plant tissue increased mandibular stylets wear compared to feeding on animal (softer) prey.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 MethodsInsect 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 ...