Interference of tritrophic (grape × medfly × parasitoid) interactions by mineral and biomaterial films.

Fruit fly infestation is one of the main obstacles to the exportation of fresh agricultural produce. Films of mineral particles and biomaterials have the potential to protect fruits against tephritid fruit fly infestation. The present study evaluated the effects of particle films on the tritrophic interactions of grape (Vitis vinifera L.), the fruit fly Ceratitis capitata (Wiedemann) and the parasitoid Diachasmimorpha longicaudata (Ashmead) under semi-field conditions. Grapes were biometrically characterised (i.e. colour, firmness, mass, length and diameter), treated with mineral particles, biomaterials or distilled water (control), and then used in oviposition and parasitism bioassays. In the oviposition bioassay, the treated grapes were exposed to 50 C. capitata pairs in field cages, and after 48 h, the punctures and eggs on each fruit were counted. In the parasitism bioassay, treated grapes were artificially infested with third-instar C. capitata larvae (two per fruit), exposed (2 h) to 50 D. longicaudata pairs in field cages to determine parasitism index, larval and pupal viabilities and number of flies and parasitoids emerged. Treatment with the mineral film affected fruit colour and reduced C. capitata oviposition but failed to significantly affect the parasitism capacity of D. longicaudata. The ability of the parasitoid to locate and parasitise C. capitata larvae in kaolin-coated fruits suggests that kaolin films could be used in conjunction with biological agents to control fruit flies.

Insecticides in Use and Risk of Control Failure of Boll Weevil (Coleoptera: Curculionidae) in the Brazilian Cerrado.

Growers rely on synthetic insecticides to control the boll weevil throughout the reproductive cotton stage. An average of 19.6 insecticide applications (range: 10 to 30) for control of boll weevil were found in a survey with growers in the Brazilian Cerrado, covering an area of 494,100 hectares of cotton. Twenty-one insecticides were applied, with 64.8% of the applications made with malathion, fipronil, carbosulfan, and thiamethoxam + lambda-cyhalothrin. These four insecticides were used by 100, 76, 70, and 62% of the growers, with respectively 7.2, 2.1, 1.8, and 1.6 applications. Growers classified their boll weevil control achieved into four categories (fair, good, very good, or excellent), without correlation between these categories with the number of insecticide applications. Control of cotton regrowth and volunteer cotton plants were the major obstacles for effective boll weevil management, followed by the low efficacy of insecticides. Five registered insecticides to spray cotton against other pests than boll weevil were enlisted by growers with potential for recommendation. A boll weevil standard population for susceptibility was assayed with 27 insecticides and the results presented within a failure risk quotient (FRQ). The FRQ of eight, six, and 13 of the 27 tested insecticides was high, intermediate, and low, respectively. The high FRQ included 7 of 10 pyrethroid formulations, pymetrozine, and methomyl. On the opposite end, fipronil had the lowest FRQ value.

Influence of Mineral Particle Films and Biomaterials on Guava Fruits and Implications for the Oviposition of Anastrepha obliqua (Macquart) (Diptera: Tephritidae).

Anastrepha obliqua (Macquart, 1835) is an important pest of tropical fruits, especially Anacardiaceae and Myrtaceae, in the Americas. The objective of this study was to evaluate the influence of mineral films and biomaterials on the coloring of guava fruits (Psidium guajava L.) and implications for the oviposition of A. obliqua. Before the bioassays, color, firmness characteristics, total soluble solids, pH, and titratable acidity were determined to characterize the maturation stage of the fruits. Pieces of guava fruit covered in aluminum foil were immersed in suspensions of mineral particles (Surround® WP kaolin; kaolins 605, 607, 608, and 611; and talc) and biomaterials (chitosan, cassava and potato starch, and guar gum) and distilled water (control). After drying, the fruits were exposed to two A. obliqua pairs for 48 h in choice and non-choice tests, and the numbers of eggs per fruit were counted. Mineral films (Surround® WP kaolin, and kaolins 605, 607, 608, and 611) and biomaterials (cassava and potato starch) interfered with the color of guava (luminosity, chroma, and hue angle), inhibiting the oviposition of A. obliqua. Talc, chitosan, and guar gum did not influence the oviposition of A. obliqua in guava.

Oviposition preference and biological performance of Ceratitis capitata in Anacardiaceae, Cactaceae and Vitaceae fruit / Preferência de oviposição e performance biológica de Ceratitis capitata em frutos de Anacardiaceae, Cactaceae e Vitaceae

The objective of this study was to compare the use of fruits of great economic and social importance for the northeast of Brazil by Ceratitis capitata Wied. (Diptera: Tephritidae) for oviposition, larval development, size and longevity of adults. Fruits of mango (Mangifera indica L.), quiabento (Pereskia bahiensis Gürke), forage palm [Opuntia fícus indica (L.) Mill] and grape (Vitis vinifera L.) were used, as well as flies from a hybrid laboratory population. Initially, four treatments (fruits) and six replications were used; the fruits were offered to 10 C. capitata couples, with later (96 hours) egg count. The second was conducted with six treatments and 10 replicates, offering two types of fruits simultaneously, combined two to two, to 10 C. capitata couples. The last bioassay comprised four treatments and six replicates, where 20 g of fruit were offered to 20 first-instar C. capitata larvae. After six days, the larvae were placed in plastic pots containing vermiculite until pupation, quantifying larval and pupal periods, viability and pupal mass, besides longevity and adult size. The data were submitted to ANOVA using the R Core Team software. Ceratitis capitata oviposits and completes its biological cycle in the four hosts studied, exhibiting no preference for oviposition and low biological performance in quiabento fruits. It yielded smaller adults and lower grape survival. Cactaceae palm and quiabento allow the survival of C. capitata in the laboratory, and this knowledge has been reported for the first time, proving that they can act as alternative hosts in the field.(AU)

O objetivo do estudo foi comparar a utilização de frutos de importância econômica e social para o nordeste do Brasil por Ceratitis capitata Wied. (Diptera: Tephritidae) para oviposição, desenvolvimento larval, tamanho e longevidade de adultos. Foram utilizados frutos de manga (Mangifera indica L.), quiabento (Pereskia bahiensis Gürke), palma-forrageira [Opuntia fícus indica (L.) Mill] e uva (Vitis vinifera L.) e moscas procedentes de uma população híbrida de laboratório. Inicialmente, utilizaram-se quatro tratamentos (frutos) e seis repetições, com o oferecimento dos frutos a 10 casais de C. capitata, com posterior (96 horas) contagem de ovos. O segundo teste foi conduzido com seis tratamentos e 10 repetições, oferecendo-se dois tipos de frutos simultaneamente, combinados dois a dois, a 10 casais de C. capitata. O último bioensaio compreendeu quatro tratamentos e seis repetições, sendo oferecidos 20 g de fruto a 20 larvas de primeiro instar de C. capitata. Após seis dias, as larvas foram colocadas em potes plásticos contendo vermiculita até a empupação, quantificando-se: períodos larval e pupal, viabilidade e massa pupal e longevidade e tamanho do adulto. Os dados foram submetidos à análise de variância (ANOVA) pelo Programa R Core Team. Ceratitis capitata oviposita e completa seu ciclo biológico nos quatro hospedeiros estudados, exibindo não preferência para oviposição e baixa performance biológica em frutos de quiabento. Este proporcionou adultos menores e a uva permitiu a menor sobrevivência. As cactáceas palma e quiabento permitem a sobrevivência de C. capitata em laboratório, sendo esse conhecimento relatado pela primeira vez, comprovando que essas espécies podem atuar como hospedeiros alternativos no campo.(AU)