Marcus Alvarenga Soares

SELETIVIDADE DE ATRAZINE E NICOSULFURON A Podisus nigrispinus (HETEROPTERA: PENTATOMIDAE)¹ Selectivity of Atrazin and Nicosulfurom to Podisus nigrispinus (Heteroptera: Pentatomidae)

RESUMO - O milho tem sido cultivado em duas safras anuais no Brasil e consumido porhumanos e animais. O uso de herbicidas no controle de plantas daninhas nessa culturapode comprometer o ambiente em funcao dos efeitos sobre organismos nao alvos. O objetivodeste trabalho foi avaliar a seletividade de atrazine e nicosulfuron sobre o predador Podisusnigrispinus. Os tratamentos constaram da aplicacao de atrazine, nicosulfuron e da misturadestes, em doses equivalentes a comercial, mais um tratamento controle a base de agua.A solucao com os herbicidas foi aspergida sobre ovos de dois dias de idade de P. nigrispinuse em cada um dos cinco estadios ninfais e fase adulta do inseto. A viabilidade dos ovos deP. nigrispinus diminuiu sob acao dos herbicidas, sem eles diferirem quanto ao tempo deeclosao. A sobrevivencia de ninfas foi baixa sob acao dos herbicidas, sendo mais afetadanegativamente sob acao da mistura destes. Para a aplicacao em cada estadio, observou-sebaixa sobrevivencia de ninfas do primeiro ao terceiro estadio sob acao do herbicida atrazine,isolado ou em mistura, e ate o segundo estadio para o nicosulfuron. Tambem ficou evidenteem todos os demais estadios do inseto a menor seletividade a mistura dos herbicidas, emcomparacao ao efeito isolado. Conclui-se que ovos de P. nigrispinus sao sensiveis aosherbicidas testados e que a aplicacao na cultura do milho desses produtos podera diminuiro controle biologico de pragas promovido por esse inseto.Palavras-chave: Asopinae, controle biologico, pos-emergentes, toxicidade.ABSTRACT - Corn is traditionally grown in two annual harvests in Brazil and consumed by humansand animals. The use of herbicides to control weeds in this crop may compromise the environment,affecting non-target organisms. The aim of this study was to evaluate the selectivity of atrazine andnicosulfuron on the predator Podisus nigrispinus Dallas, 1851 (Heteroptera: Pentatomidae). Thetreatments consisted of application of a combination of atrazine and nicosulfuron in doses equivalentto the commercial dose, plus a water-based control. The solution with herbicides was sprayed ontwo- day- old eggs of P. nigrispinus and at each of the five nymphal stages and adult phase of theinsects. The viability of eggs of P. nigrispinus decreased under the action of the herbicides,without differences regarding time of hatching. The survival of nymphs was low under the effect ofthe herbicides, being more adversely affected by the action of the herbicide mixtures. For the applicationat each stage, we observed a low survival rate of nymphs from the first to the third instar under theaction of the herbicide atrazine, alone, or in combination, and even at the second stage for nicosulfuron.Lower selectivity to herbicide mixture also became evident at all the insect stages, compared to theisolated effect. It was concluded that eggs of P. nigrispinus are sensitive to herbicides and thatapplication of such products on corn may decrease the biological pest control provided by thisinsect.Keywords: Asopinae, biological control, post emergent, toxicity.

Do floral resources in Eucalyptus plantations affect fitness parameters of the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)?

Adult parasitoids depend on sugar-rich foods such as nectar and honeydew to meet their energy requirements. The availability of nectar, honeydew or fruit sap affects the longevity, fecundity and dispersal of parasitoids and consequently their potential as biocontrol agents. The aim of this study was to evaluate the development and reproduction of an important parasitoid of Brazilian ecosystems, Palmistichus elaeisis (Delvare and LaSalle 1993) (Hymenoptera: Eulophidae), fed with nectar from Eucalyptus flowers and flowering herbs. Males and females of this parasitoid were individualized in glass tubes, and their survival and longevity were evaluated in the following treatments: flowers of Bidens pilosa L. 1753, Emilia fosbergii Nicolson 1975, Galinsoga parviflora Cav. 1796, Sonchus oleraceus L. 1753, Taraxacum officinale F.H. Wigg. 1780 (Asteraceae) and Eucalyptus sp. (Myrtaceae), a honey droplet or no food. In the second trial, six P. elaeisis females were placed into plastic pots containing one Tenebrio molitor L. 1758 (Coleoptera: Tenebrionidae) host pupa under the same treatments. Parasitism and emergence, the duration of the egg–adult period, the number of adults per pupa, the sex ratio, the width of the head capsule and the body length of P. elaeisis were evaluated. Food sources of honey or flowering herbs increased the survival, longevity, period of parasitism, percentage of parasitized pupae and number of progeny of P. elaeisis. Longevity and reproduction were seriously compromised in the absence of sugar feeding.

Nomuraea rileyi (Hypocreales: Clavicipitaceae) in Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae in Brazil

Summary Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is one of the most important polyphagous pests globally. It was reported in Brazil at the end of the 2012/2013 crop season. The aim of this study was to report the occurrence of an entomopathogenic fungus on H. armigera larvae in Brazil. We collected 589 larvae from cotton plantations in Bahia State, Brazil, and transported them to the laboratory of biological control of Embrapa Milho e Sorgo in Sete Lagoas, Minas Gerais State, Brazil. Of the 320 dead larvae, 106 were infected by Nomuraea rileyi (Farl.) Samson (Hypocreales: Clavicipitaceae), causing 33.1% of the total mortality. This is the first report on the natural occurrence of the fungus N. rileyi infecting H. armigera larvae in Brazil.

First Record of the Sweet Potato Pest Bedellia somnulentella (Lepidoptera: Bedelliidae) in Brazil

Summary Bedellia somnulentella (Zeller) (Lepidoptera: Bedelliidae) is a specialist Convolvulaceae pest. Its larvae damage host plants by mining young and mature leaves. This is the first report of B. somnulentella in the Brazilian territory. This pest was observed on young and mature Ipomoea batatas (L.) (Solanales: Convolvulaceae) leaves in Diamantina, Minas Gerais State, Brazil. This insect alters the leaf appearance due to its mines, changing the leaf color to yellowish-brown, which reduces the photosynthetic area. The presence of B. somnulentella in Brazil makes it necessary to include this insect in pest monitoring programs in sweet potato plantations.

Preference of red mite Tetranychus ludeni Zacher (Acari: Tetranychidae) to sweet potato genotypes

Tetranychus ludeni damages the sweet potato. Pest development can vary between plant genotypes. The objective was to identify the preference of Tetranychus ludeni for Ipomoea batatas genotypes, from the germplasm bank at the Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM). Natural infestations of this mite were observed on 54 sweet potato genotypes in potted, in a greenhouse. Three mite-infested leafs of each genotype were collected and analyzed. The red mite showed different population density rate in genotypes. The BD 29 genotype was found to be highly susceptible, the BD 08, BD 57, BD 17 and Espanhola genotypes were moderately susceptible, and the others forty-nine genotypes showed low susceptibility to the mite.

Spatial Distribution of Phytophagous Insects, Natural Enemies, and Pollinators on Leucaena leucocephala (Fabaceae) Trees in the Cerrado

Abstract Leucaena leucocephala (Lam.) de Wit (Fabaceae) is widely used to regenerate degraded landscapes in tropical and subtropical regions and serves as a protein source for animals in agrosilvopastoral systems. Thus, our objective was to assess the spatial distribution of insects on the tree crown (vertical: upper, middle, and basal canopy; horizontal: north, south, east, and west) and leaf surfaces (adaxial and abaxial) of L. leucocephala. Phytophagous insects, natural enemies, and pollinators were quantified fortnightly in 20 trees for 2 yr. North-facing tree branches had the greatest numbers of phytophagous insects, natural enemies, and pollinators. Branches facing west had the most species-rich and biodiverse phytophagous and pollinator assemblages, whereas for natural enemies, species richness and biodiversity were greatest on branches facing north or south. The greatest numbers of individuals and highest levels of species richness of phytophagous insects, natural enemies, and pollinators were observed in the upper and middle parts of the L. leucocephala canopy. The most individuals and highest levels of species richness and biodiversity for phytophagous insects, natural enemies, and pollinators were observed on the abaxial face of L. leucocephala leaves. The species with the highest abundance and k-dominance (common or constant species) on L. leucocephala trees were the phytophagous insects Trigona spinipes F. (Hymenoptera: Apidae: Meliponinae) and Tropidacris collaris Stoll (Orthoptera: Romaleidae) and the natural enemies Camponotus sp.2 (Hymenoptera: Formicidae) and Brachymyrmex sp. (Hymenoptera: Formicidae). These results can inform strategies related to pest control and maintenance of natural enemies and pollinators in L. leucocephala plantations. Biopesticide application, for example, may be more effective at eliminating target organisms if directly applied on their preferred sites, and a targeted application can minimize negative effects for non-target organisms.