Sequential Sampling Plan of Anthonomus grandis (Coleoptera: Curculionidae) in Cotton Plants.

The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is one of the most important pests of cotton production worldwide. The objective of this work was to develop a sequential sampling plan for the boll weevil. The studies were conducted in Maracaju, MS, Brazil, in two seasons with cotton cultivar FM 993. A 10,000-m2 area of cotton was subdivided into 100 of 10- by 10-m plots, and five plants per plot were evaluated weekly, recording the number of squares with feeding + oviposition punctures of A. grandis in each plant. A sequential sampling plan by the maximum likelihood ratio test was developed, using a 10% threshold level of squares attacked. A 5% security level was adopted for the elaboration of the sequential sampling plan. The type I and type II error used was 0.05, recommended for studies with insects. The adjustment of the frequency distributions used were divided into two phases, so that the model that best fit to the data was the negative binomial distribution up to 85 DAE (Phase I), and from there the best fit was Poisson distribution (Phase II). The equations that define the decision-making for Phase I are S0 = -5.1743 + 0.5730N and S1 = 5.1743 + 0.5730N, and for the Phase II are S0 = -4.2479 + 0.5771N and S1 = 4.2479 + 0.5771N. The sequential sampling plan developed indicated the maximum number of sample units expected for decision-making is ∼39 and 31 samples for Phases I and II, respectively.

Spatial Distribution of Adult Anthonomus grandis Boheman (Coleoptera: Curculionidae) and Damage to Cotton Flower Buds Due to Feeding and Oviposition.

The cotton boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the main pest in cotton crop around the world, directly affecting cotton production. In order to establish a sequential sampling plan, it is crucial to understand the spatial distribution of the pest population and the damage it causes to the crop through the different developmental stages of cotton plants. Therefore, this study aimed to investigate the spatial distribution of adults in the cultivation area and their oviposition and feeding behavior throughout the development of the cotton plants. The experiment was conducted in Maracaju, Mato Grosso do Sul, Brazil, in the 2012/2013 and 2013/2014 growing seasons, in an area of 10,000 m2, planted with the cotton cultivar FM 993. The experimental area was divided into 100 plots of 100 m2 (10 × 10 m) each, and five plants per plot were sampled weekly throughout the crop cycle. The number of flower buds with feeding and oviposition punctures and of adult A. grandis was recorded throughout the crop cycle in five plants per plot. After determining the aggregation indices (variance/mean ratio, Morisita's index, exponent k of the negative binomial distribution, and Green's coefficient) and adjusting the frequencies observed in the field to the distribution of frequencies (Poisson, negative binomial, and positive binomial) using the chi-squared test, it was observed that flower buds with punctures derived from feeding, oviposition, and feeding + oviposition showed an aggregated distribution in the cultivation area until 85 days after emergence and a random distribution after this stage. The adults of A. grandis presented a random distribution in the cultivation area.

Transgenic Cotton-Fed Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Affects the Parasitoid Encarsia desantisi Viggiani (Hymenoptera: Aphelinidae) Development.

Cotton cultivars expressing Cry proteins are widely used to control lepidopteran pests. The effects of transgenic plants containing insecticidal Cry proteins on non-target species must be comprehended for a better and rational use of this technology for pest management. We investigated the influence of the Bt cotton cultivars NuOPAL and FM 975 on biological parameters of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), a non-target pest of Bt cotton cultivars and on its parasitoid Encarsia desantisi Viggiani (Hymenoptera: Aphelinidae). The experiments were conducted in a climatized room, and the non-transgenic near isolines were used for rearing whiteflies as control hosts. The effects of the Bt cotton cultivars on the period of embryonic and larval development and the percentage of adult emergence of B. tabaci were assessed. The period required for embryonic, larval, and pupal development and the percentage of emergence and longevity of E. desantisi females were determined using Bt cotton-fed and non-Bt cotton-fed B. tabaci as hosts. Both Bt cotton cultivars resulted in a decrease of approximately 20% of adult emergence of B. tabaci. Differently, an increase of approximately 10% of adult emergence of E. desantisi was observed for parasitoids that used hosts fed with both Bt cotton cultivars. However, female parasitoid longevity decreased when their hosts were fed on Bt cotton cultivars. Our data suggest that the use of Bt cotton cultivars in association with the biological control agent E. desantisi could be functional for the management of B. tabaci in Bt cotton crops.

Spatial distribution of Euschistus heros (F.) (Hemiptera: Pentatomidae) in soybean.

Soybean bugs are major crop pests that cause significant reduction in harvest yield and influence grain quality. The aim of this study was to verify the spatial distribution of Euschistus heros (F.) (Hemiptera: Pentatomidae) in conventional and transgenic soybean cultivars. The experiment was conducted during the 2010-2011 crop season in UNESP/FCAV, Jaboticabal, SP, Brazil, in two fields of 10,000-m(2) area that were subdivided into 100 plots (10 m × 10 m). The cultivars sown were M 7908 RR and its isoline M-SOY 8001. The number of the first to fifth instars and the number of adults were determined. To evaluate insect dispersion in the area, the following indices were used: variance/mean ratio, Morisita index, Green coefficient, and the k exponent of the negative binomial distribution. To study probabilistic models to describe the spatial distribution of the insects, the adjustments of the Poisson and negative binomial distributions were tested. The first to third instars showed aggregated spatial distribution, whereas the fourth and fifth instars, and adults, isolated or grouped, showed variation in the arrangement, ranging from moderately aggregated to randomly dispersed. During the adjustment of probability distributions, the negative binomial distribution model showed adjustment for the first to third instars, fourth and fifth instars, adults, and fourth and fifth instars plus adults.

Behavior of transgenic maize hybrids and their conventional isogenic counterparts in relation to infestation of spodoptera frugiperda (J. E. Smith, 1727) (lepidoptera: noctuidae) at two locations and sowing dates / Comportamento de híbridos de milho transgênicos e respectivos híbridos isogênicos convencionais em relação à infestação de Spodoptera Frugiperda (j. E. Smith,1727) (Lepidoptera: Noctuidae) em duas localidades e épocas de semeadura

The fall armyworm Spodoptera frugiperda is one of the most important pests of maize. Various studies are conducted for their management, integrating chemical and biological control tactics as well as resistant plants. In order to offer alternatives for an efficient management of this pest with minimal use of pesticides, the technology of genetically modified plants resistant to insects has been widely studied. The aim of the present study was to evaluate the natural infestation of larvae of S. frugiperda and their injuries under field conditions in transgenic maize hybrids compared to their conventional isogenic counterparts at two sowing dates and two regions. The hybrids were planted in the "off season" of 2010 in Jaboticabal, SP, Brazil, and the summer of 2010/2011 in Jaboticabal, and Pindorama, SP, in a randomized block with seven treatments (hybrids) and four replications. Different levels of infestation of larvae occurred throughout the phenological development of plants in conventional and genetically modified hybrids with significant differences between the two groups in most evaluations. The hybrid 2B710HX was the least infested with caterpillars and had the least damaged leaf area. It follows that the Cry1F toxin was the most effective in protecting the plant in relation to other toxic proteins expressed by the other Bt hybrids against infestation and damage promoted.

A lagarta-do-cartucho, Spodoptera frugiperda, é uma das mais importantes pragas do milho. Vários estudos são realizados para o seu manejo, integrando táticas de controle químico, biológico ou através de plantas resistentes. No intuito de oferecer alternativas a um manejo eficiente dessa praga com a mínima utilização de agrotóxicos, a tecnologia das plantas geneticamente modificadas resistentes a insetos tem sido objeto de muitos estudos. Neste trabalho, o objetivo foi avaliar a infestação natural de lagartas de S. frugiperda e respectivas injúrias em condições de campo, em híbridos transgênicos de milho comparados aos seus isogenes convencionais, em duas épocas de semeadura e em duas regiões. Os híbridos foram semeados na "safrinha" de 2010 em Jaboticabal, SP, e no verão em 2010/2011, em Jaboticabal, e Pindorama, SP, em delineamento de blocos ao acaso, com sete tratamentos (híbridos) e quatro repetições. Diferentes níveis de infestação de lagartas ocorreram durante todo o desenvolvimento fenológico das plantas nos híbridos convencionais e nos híbridos geneticamente modificados, com significativas diferenças entre os dois grupos na maioria das avaliações. O híbrido 2B710HX foi o menos infestado com lagartas e o com menor área foliar danificada, o que se conclui que a toxina Cry1F foi a mais efetiva na proteção da planta em relação às demais proteínas.