Aging and food source effects on mandibular stylets teeth wear of phytophagous stink bug (Heteroptera: Pentatomidae)

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 significantly 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 artificial dry diet showed, in general, similar results to those of teneral adults. Force (Newtons) required penetrating the natural foods was significantly greater than that required penetrating the artificial diet. The greater hardness of the natural foods caused increased mandibular serration wear.

Redução da sobrevivência da broca-do-café, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), e do seu ataque aos frutos de café pela pulverização com nim em laboratório / Reduced survival and infestation of coffee borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), on coffee fruits, in response to neem sprays in laboratory

Aqueous solutions of neem oil and aqueous extracts of neem seeds and leaves were sprayed on coffee fruits for laboratory evaluation of their efficiency in reducing infestation of the coffee borer, Hypothenemus hampei (Ferrari), in multi-choice preference assays in laboratory. Neem oil and extracts reduced infestation of fruits in a dose-dependent manner, acting as a repellent. At 0.5 percent, 1 percent and 1.5 percent, the oil reduced fruit infestation by 30.2 percent, 42.5 percent (P > 0.05), and 58.6 percent (P < 0.05), respectively, as compared with the control. Seed extracts at 1 percent, 2 percent and 4 percent (w/v) reduced infestation by 30.9 percent, 38.3 percent (P > 0.05) and 70.2 percent (P < 0.05), respectively; seed extracts at 0.15 percent, 1.5 percent and 15 percent (w/v) reduced fruit infestation by 16.5 percent, 38.5 percent (P > 0.05) and 56.9 percent (P < 0.05), respectively. Spraying the emulsifiable oil at 1 percent on coffee fruits and adult borers was compared with spraying on fruits or adults only. Adult-only spraying caused low mortality (P > 0.05) and low reduction on the number of damaged fruits (P > 0.05). Fruit-only spraying significantly reduced insect survival rates and the number of damaged fruits (P < 0.05). However, spraying on adults and fruits caused the greatest reduction in adult survival (55.6 percent; P < 0.05) and in fruit infestation (78.7 percent; P < 0.05), probably due to insect mortality and neem oil repellence acting together.

Rostrum length, mandible serration, and food and salivary canals areas of selected species of stink bugs (Heteroptera, Pentatomidae) / Comprimento do rostro, dentição mandibular, e áreas dos canais alimentar e salivar de espécies selecionadas de percevejos (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.

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.

Compatibility of the fungus Beauveria Bassiana (Bals.) Vuill. (Deuteromycetes) with extracts of neem seeds and leaves and the emulsible oil / Compatibility of the fungus Beauveria Bassiana (Bals.) Vuill. (Deuteromycetes) with extracts of neem seeds and leaves and the emulsible oil

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 percent; 1.5 percent and 15 percent (leaf aqueous extract), 1 percent; 2 percent and 4 percent (seed aqueous extract) and 0.5 percent; 1 percent and 1.5 percent (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 percent 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.

A compatibilidade de uma formulação comercial de óleo emulsionável de nim (Azadirachta indica A. Juss.), do extrato aquoso de sementes e do extrato aquoso de folhas de nim com Beauveria bassiana (Bals.) Vuill., foi avaliada in vitro. Foram conduzidos três experimentos para avaliar o efeito de cada um dos produtos no crescimento vegetativo do fungo, e na produção e viabilidade dos conídios. Os produtos foram incorporados ao meio de cultura (PDA+E) e distribuídos em placas de Petri, nas concentrações, 0,15; 1,5 e 15 por cento (extrato aquoso de folhas), 1; 2 e 4 por cento (extrato aquoso de sementes) e 0,5; 1 e 1,5 por cento (óleo emulsionável). Com base no crescimento vegetativo e na produção de conídios, os extratos aquosos de sementes e de folhas e o óleo emulsionável de nim foram caracterizados segundo o modelo T para classificação de compatibilidade de produtos. Os extratos de sementes e de folhas mostraram-se menos prejudiciais a B. bassiana que o óleo emulsionável. Esse produto, nas concentrações testadas, não foi compatível com B. bassiana, inibindo significativamente o crescimento vegetativo e reduzindo a produção e a viabilidade dos conídios com efeitos mais acentuados nas concentrações mais altas. Os extratos de sementes e de folhas de nim foram compatíveis com o entomopatógeno em todas as concentrações testadas. O extrato de sementes reduziu o crescimento vegetativo e a produção de conídios, mas não afetou a viabilidade dos esporos produzidos. Embora o extrato de folhas a 15 por cento tenha reduzido um pouco o crescimento vegetativo e a produção e viabilidade dos conídios, ainda se manteve compatível com o fungo B. bassiana, segundo o modelo T.