Solange Maria de França

Lethal and sublethal responses of Sitophilus zeamais populations to essential oils

The present study aimed to assess the lethal and sublethal responses of five populations of S. zeamais to the essential oils of Ocimum basilicum and Piper hispidinervum, through toxicity, locomotor behavior (flight and walking activities) and physiological (respiration rate and body mass) evaluations. The populations of S. zeamais were obtained from Machado—MG, Paracatu—MG, Piracicaba—SP, Recife—PE and Tunápolis—SC. To estimate the LC50 of each oil for each population, fumigation tests were performed. The population from Recife exhibited the lowest instantaneous rate of increase (ri) as well the lowest consumption of grain mass. However, Piracicaba was considered the susceptibility pattern, presenting the lowest LC50 for both essential oils, no statistical difference was observed among populations or treatments in the flight activity bioassays. The essential oils effect on walking activity and respiration rates varied among populations. The population from Recife presented the highest walked distance and walk speed, with the lowest resting time and number of stops, as well as the lowest respiration rate and body mass. The present study highlights the importance of the study on population responses, as the five populations of S. zeamais exhibited different patterns of toxic and behavioral effects when subjected to the essential oils of P. hispidinervum and O. basilicum.

Seleção de atrativos alimentares e toxicidade de inseticidas para o manejo da broca-pequena-do-tomateiro

O objetivo deste trabalho foi avaliar a preferencia alimentar, o limiar de ingestao e efeito toxico inseticidas associados atrativos, em adultos Neoleucinodes elegantalis. Foram testados os atrativos: melado e mel a 10%, extrato hexânico de frutos verdes de tomate a 0,4%, sacarose a 5%, suco de laranja e suco de uva a 30%, vinagre de vinho tinto a 10% e proteina hidrolisada a 5%. Com base no teste de preferencia alimentar, foram selecionados os atrativos sacarose, melado, mel e suco de laranja, para determinar o limiar de concentracao capaz de estimular a alimentacao de adultos de N. elegantalis. Foi testado o efeito toxico de inseticidas associados ao mel a 10%. A sacarose e o mel apresentaram o melhor resultado em relacao ao numero de pousos e ao tempo de pouso e de alimentacao de adultos de N. elegantalis. Os inseticidas nao afetaram negativamente a atracao pelo alimento dos adultos de N. elegantalis. Carbaril, cartape, deltametrina, fenpropatrina, indoxacarbe, lambda-cialotrina e lufenurom provocaram 100% de mortalidade em adultos (machos + femeas), apos 24 horas de exposicao, e mostraram-se promissores para o uso em iscas toxicas.

The Sublethal Effects of Insecticides in Insects

Studies related to the effect of insecticides on insect pests and nontarget organisms, such as natural enemies, are traditionally accessed by the estimative of lethal effects, through mortality data. Due to the limitations of the traditional methods, recent studies in the past three decades are assessing the sublethal effects of insecticides upon several important biological traits of insect pests and natural enemies. Besides mortality, the sublethal dose/concentrations of an insecticide can affect insect biology, physiology, behavior and demographic parameters. In this chapter, many sublethal effects of insecticides were addressed for several chemical groups, such as botanical insecticides, carbamate, diamide, insect growth regulators, neonicotinoid, organochlorides, organophosphates, pyrethroid and others. An accurate assessment of these effects is crucial to acquire knowledge on the overall insecticide efficacy in the management of pest insect populations, as well as on their selectivity toward nontarget organisms.

Biology and life table of Tetranychus neocaledonicus on lima bean

ABSTRACT The objective of this work was to evaluate the potential of the use of lima bean (Phaseolus lunatus) as hosts of the mite Tetranychus neocaledonicus. For such, the biology and fertility life table of T. neocaledonicus on P. lunatus plants were evaluated. The experiment was carried out in a controlled environment at 25 ± 1°C and 75 ± 10% relative humidity (RH), with a 12-h photoperiod. The eggs used in the experiments were from inventories. Evaluations were performed twice daily in the immature stage. While in the adult stage, a single evaluation was carried out, in which reproductive aspects of T. neocaledonicus were analysed, being determined the daily oviposition and the longevity of females and males. The average life cycle of females and males was 11.94 and 11.48 days, respectively. For females, the development of the mobile period of larva, protonymph, and deutonymph presented an average of 2.23, 1.17, and 1.24 days, respectively, and for males, an average of 2.20, 1.06, and 1.21 days, respectively. Regarding the post-embryonic non-mobile periods of protochrysalis, deutochrysalis, and teleiochrysalis, the averages obtained were 0.66, 0.76, and 0.78 days, respectively, for females and males 0.62, 0.68, and 0.73 days, respectively. The sex ratio was 0.77 and the average longevity of females and males was 44.30 and 48.30 days, respectively. In the life table parameters, the following variables were measured: intrinsic rate of increase (rm), 0.14 f/f/d; mean generation duration (T), 21.2 days; net reproductive rate (R0), 24.7 individuals; finite rate of increase (λ), 1.16 f/f; and population doubling time, 4.64 days. Therefore, lima bean allows the development and reproduction of the mite T. neocaledonicus. The rapid development, allied to the high viability of immature forms and the high oviposition of females, suggests that this mite can achieve pest status in this crop.

Resistance of Lima Bean (Phaseolus lunatus L.) to the Red Spider Mite Tetranychus neocaledonicus (Acari: Tetranychidae)

The red spider mite, Tetranychus neocaledonicus (Acari: Tetranychidae) can be an important pest on lima bean (Phaseolus lunatus L.). Thus, the objective of this work was to assess the antibiosis and antixenosis effects of lima bean genotypes on T. neocaledonicus, through the evaluation of performance parameters as well as the host preference for food and oviposition. Nine lima bean genotypes from the Active Bank of Germplasm of the Federal University of Piauí – BGP / UFPI were screened. To assess antibiosis parameters, eggs of T. neocaledonicus were individually placed on leaf disks of each genotype. The period and survival of the different stages of development (larvae, protonymph, deutonymph and adult), pre-oviposition, oviposition and post-oviposition period, longevity and fecundity of females were evaluated, and fertility life table parameters were calculated. In choice tests, adult females of T. neocaledonicus were used. The numbers of mites and eggs were counted for each genotype. The protonymph, egg-adult, longevity and oviposition period, fertility life table parameters, as well as the food and oviposition preference were affected by lima bean genotypes. We found that some genotypes reduced adult female longevity, increased the larval and egg-adult period, decreased oviposition period, negatively affected the fertility life table parameters, reducing the net reproductive rate (Ro), the intrinsic rate of increase (rm) and the finite rate of increase (λ), while increasing the population doubling time (DT), exhibiting a reliable antibiosis effect upon T. neocaledonicus. Nevertheless, these same genotypes were the most preferred for food and oviposition. By contrast, some other genotypes reduced the adult female longevity and oviposition period, elongated the larval period and affected fertility life table parameters, demonstrating an antibiosis effect upon T. neocaledonicus. Moreover, these other genotypes were among the less preferred for food and oviposition, exhibiting an additional antixenosis effect. Thus, our results demonstrate that the genotypes of lima bean may present distinct levels of resistance to T. neocaledonicus, and this resistance may be an important tool for Integrated Pest Management. This is one of the first studies aiming to describe mite resistance sources in lima bean.

FRUIT FLIES (DIPTERA: TEPHRITIDAE) AND THEIR PARASITOIDS ASSOCIATED WITH DIFFERENT HOG PLUM GENOTYPES IN TERESINA, PIAUÍ

The aim of this work was to identify and quantify the infestation of fruit fly species and their parasitoids, associated with 20 hog plum genotypes (Spondias mombin L.) in a commercial orchard in Teresina, Piauí, Brazil. The survey was conducted by fruit sampling and monitoring through traps stocked with bait food, in the period from January to December 2012. Overall, 6560 fruits were collected (79.58 kg), resulting in 23059 pupae, of which 10080 fruit flies of the genus Anastrepha and 4984 braconid parasitoids emerged. Anastrepha obliqua species was the predominant with 99.92%. F16P13 and F11P10 genotypes had the highest infestation indexes and F15P11 and F04P01 genotypes, the lowest. The main parasitoids collected were Opius bellus (77.65%), Doryctobracon areolatus (19.88%) and Utetes anastrephae (2.47%). The average parasitism rate among genotypes was of 30.46%. In traps, a total of 1434 fruit flies were collected, whose species were: A. obliqua (97.6%), A. serpentina (1.4%), A. fraterculus (0.4%), A. striata (0.4%), A. dissimilis (0.1%), A. pseudoparallela (0.1%). Anastrepha obliqua species was predominant in the area, based on faunistic analysis. The infestation index in the orchard was relevant for five months (January-May), coinciding with the period of availability of hog plum fruits, reaching the highest peak in March (2.86 FAT). There was a significant negative correlation between number of fruit flies in the orchard and the average air temperature, and a significant positive correlation with rainfall and relative humidity. However, the main factor that influenced the observed infestation index in the hog plum orchard was fruit availability.