Elisangela Gomes Fidelis de Morais

Bioassay method for toxicity studies of insecticide formulations to Tuta absoluta (meyrick, 1917)

O principal metodo utilizado no controle da traca-do-tomateiro Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) e a aplicacao de inseticidas. As tecnicas atuais de avaliacao da toxicidade de inseticidas sobre essa praga nao simulam a situacao de campo e nao possibilitam a verificacao se as doses usadas no campo sao eficientes no seu controle. Assim, neste trabalho, objetivou-se desenvolver uma metodologia que represente as condicoes de campo para inseticidas de acao rapida (neurotoxicos e inibidores respiratorios) e de acao lenta (Bacillus thuringiensis e reguladores de crescimento. A metodologia mais eficiente para estudos de toxicidade de formulacoes comerciais a T. absoluta foi a imersao de folhas em calda inseticida. Para os bioensaios de inseticidas de acao rapida, sugere-se que estes sejam realizados em placas de Petri, contendo foliolos de tomate da 4a folha a partir do apice da planta, infestados com 10 larvas de 3o instar e eles podem durar 48 horas. Quanto aos bioensaios de toxicidade de inseticidas de acao lenta, sugere-se que sejam realizados em garrafas PET transparentes, de dois litros, contendo a 4a folha de tomate a partir do apice da planta infestada com 10 larvas de 2o instar e seu peciolo inserido em vidro de 120 mL contendo agua. Nesse caso, o bioensaio pode durar sete dias sem prejuizo na eficiencia.

Sampling plan for Thrips (Thysanoptera: Thripidae) on cucumber

This work determines the best technique, sampling unit and the number of samples to compose a sampling plan for Frankliniella schultzei (Trybom) and Thrips palmi (Karny) (Thysanoptera: Thripidae) on cucumber. The efficacy of three sampling techniques: leaf beating on a plastic tray, direct counting of insects on the lower leaf surface, and whole leaf collection in bags were compared in nine commercial cucumber crops using three sampling units (a leaf from a branch located in the apical, median or basal third of the canopy). The number of samples was determined based on the relative variance and the economic precision for the best technique and sampling unit. The direct counting of insects on the apical third of the plant canopy was the best sampling technique for F. schultzei based on one leaf surveyed per plant using 38 plants per field. The best sampling technique for T. palmi was the leaf beating on a tray using one leaf of the apical third per plant and 35 plants per field. When joining both species, the best sampling system was the direct counting on the apical third, and it requires sampling one leaf per plant using at least 35 plants per field. These results facilitate the decision-making for the management of thrips on cucumber and aggregate the benefits of the correct decision for the adoption of strategies for population reduction.

Potential geographical distribution of the red palm mite in South America.

Among pests that have recently been introduced into the Americas, the red palm mite, Raoiella indica Hirst (Prostigmata: Tenuipalpidae), is the most invasive. This mite has spread rapidly to several Caribbean countries, United States of America, Mexico, Venezuela, Colombia and Brazil. The potential dispersion of R. indica to other regions of South America could seriously impact the cultivation of coconuts, bananas, exotic and native palms and tropical flowers such as the Heliconiaceae. To facilitate the development of efficacious R. indica management techniques such as the adoption of phytosanitary measures to prevent or delay the dispersion of this pest, the objective of this paper was to estimate the potential geographical distribution of R. indica in South America using a maximum entropy model. The R. indica occurrence data used in this model were obtained from extant literature, online databases and field sampling data. The model predicted potential suitable areas for R. indica in northern Colombia, central and northern Venezuela, Guyana, Suriname, east French Guiana and many parts of Brazil, including Roraima, the eastern Amazonas, northern Pará, Amapá and the coastal zones, from Pará to north of Rio de Janeiro. These results indicate the potential for significant R. indica related economic and social impacts in all of these countries, particularly in Brazil, because the suitable habitat regions overlap with agricultural areas for R. indica host plants such as coconuts and bananas.

Biological performance of Diclidophlebia smithi (Hemiptera: Psyllidae), a potential biocontrol agent for the invasive weed Miconia calvescens.

Abstract Diclidophlebia smithi Burckhardt, Morais and Picanço (Hemiptera: Psyllidae) is a promising biological control agent of Miconia calvescens DC. (Melastomataceae), a neotropical invasive weed in forest ecosystems in French Polynesia and Hawaii and a threat in Australia, where it was also introduced. A study on the reproductive performance of D. smithi under laboratory conditions through life expectancy and fertility tables is presented. Results indicated that this psyllid has a high reproductive capacity (R 0>1 and r m >0) and a short life cycle (46–47 days) and can have up to nine generations per year. The critical period of its life cycle is during the nymphal stage which is clearly inadequate for field introductions. The best age for introducing D. smithi against M. calvescens is the 4th day of the adult stage. D. smithi is easily mass-reared and has a short life cycle and a high reproductive capacity, which are desirable characteristics for a biological control agent.

Lepidopterans as potential agents for the biological control of the invasive plant, Miconia calvescens.

Abstract This work investigated eight species of Lepidoptera associated with Miconia calvescens DC. (Myrtales: Melastomataceae) in Brazil, including six defoliators, Salbia lotanalis Druce (Lepidoptera: Pyralidae), Druentia inscita Schaus (Mimallonidae), Antiblemma leucocyma Hampson (Noctuidae), three Limacodidae species, a fruit borer Carposina cardinata Meyrick (Carposinidae), and a damager of flowers Pleuroprucha rudimentaria Guenée (Geometridae). Based on host specificity and the damage caused to plants, S. lotanalis and D. inscita are the most promising species for biological control of M. calvescens. Furthermore, if C. cardinata and P. rudimentaria have host specificity in future tests, these caterpillars could also be considered as appropriate biocontrol agents.

Population fluctuations in the pink hibiscus mealybug and its natural enemies in Annona squamosa (Annonaceae) in Roraima, Brazil

Maconellicoccus hirsutus (Hemiptera, Pseudococcidae), a species of economic interest, especially for fruit plants, is expanding on the South American continent. Information about the population dynamics of this pest associated with control by natural enemies and cultural practices is fundamental for its management. Our objective was to study the population fluctuations in M. hirsutus and its natural enemies in a sugar-apple (Annona squamosa) orchard in Roraima, northern Brazil. Trees were evaluated monthly over a 12-month period. Infestation rates by M. hirsutus and its parasitism were also estimated for potential host plants around the study area. Highest infestation occurred in August and February-March. Alternative hosts were infested during the off-season, mainly fruit. Lacewings and the parasitoid Anagyrus kamali (Hymenoptera, Encyrtidae) were abundant natural enemies. Average parasitism by A. kamali in fruits was 50%, with highest rates in periods of greatest infestation by M. hirsutus. Fruitification pruning reduced M. hirsutus populations.

Amblyseius largoensis in controlling red palm mite under semi-field conditions

The objective of this work was to evaluate the efficiency of two Amblyseius largoensis (Acari: Phytoseiidae) populations in controlling Raoiella indica (Acari: Tenuipalpidae). The treatments were: release of A. largoensis from the island of La Reunion; release of A. largoensis from the state of Roraima, Brazil; and a control, without predator release. Initially, 20 predators were released per plant; three other releases were done at a rate of ten adults per plant, at 46, 135, and 156 days after the first release. The population densities were estimated every 20 days, during six months. Both A. largoensis populations evaluated are not sufficiently efficient to control the R. indica population.

The invasive red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), in Brazil: range extension and arrival into the most threatened area, the Northeast Region

ABSTRACT Raoiella indica Hirst (Acari: tenuipalpidae), commonly known as the red palm mite (RPM), is an invasive polyphagous pest, which has emerged as a threat to agriculture in the Americas. In the Americas, the mite has not only spread quickly, but also greatly extended its host range in the new areas where it has been observed. We present here new records of the RPM in Brazilian states, with focus on its arrival into the most threatened area, the Northeast Region. Coconut and banana are important crops in this region of Brazil and represent the main threatened crops by this pest. These new records of RPM reinforce the idea that this species is already widely distributed throughout Brazil eight years after its introduction into the extreme North state of Roraima. Comments on the possible economic, social and environmental impacts are presented.

Effect of relative humidity on the biology of the predatory mite Amblyseius largoensis (Acari: Phytoseiidae)

ABSTRACT Amblyseius largoensis Muma (Acari: Phytoseiidae) is a common predator in the humid tropics, where it has been found in association with Raoiella indica Hirst (Acari: Tenuipalpidae), an important coconut pest. The objective of this study was to assess the performance of A. largoensis from Recife, Pernambuco, northeast Brazil (Atlantic Forest biome), under different levels of relative humidity (RH). Also, to analyse the world-wide distribution of A. largoensis. This phytoseiid was evaluated at the following development RH levels (20%, 36%, 56%, 65%, 72%, 80%, 89%, and 95%) and on reproduction RH levels (66%, 83%, 91%, and 98%) at 27°C. Amblyseius largoensis failed to complete development at or below 72% RH. Maximum population increase of the predator (about 26-fold in one generation) occurred at 91% RH. Only 7% of the records of the distribution of A. largoensis were from hot arid areas. The results suggested, that while the Recife population of A. largoensis is well adapted to survive high RH conditions, its efficiency as a biological control agent might be limited in drier inland areas. Thus, populations of A. largoensis that occur in drier areas of the world should be evaluated as to their potential as biological control agents of R. indica.