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principais pragas da goiabeira no Brasil. As fêmeas ovipositam em frutos pequenos e as larvas desenvolvem-se acompanhando o amadurecimento dos frutos. Quando as larvas atingem o desenvolvimento máximo, abandonam o fruto severamente danificado e pupam no solo. Este trabalho foi realizado para determinar o ciclo biológico do gorgulho-da-goiaba em laboratório. Goiabas atacadas por gorgulhos foram coletadas em pomares e colocadas em caixas plásticas com areia umedecida. Depois da emergência, os adultos foram colocados individualmente em caixas de acrílico e lhes foi fornecido água e alimento. Os adultos imediatamente após a emergência foram colocados juntos para possibilitar os acasalamentos, depois dos quais, as fêmeas foram isoladas. Os ovos produzidos foram colocados em placas de Petri contendo lâminas de goiaba madura sobre papel de filtro umedecido. A eclosão das larvas foi monitorada diariamente e o número de ínstares foi determinado através da medição da largura da cápsula cefálica. A duração da fase ovo foi de 3,9 ± 0,58 dias. A duração da fase larval foi de 16,0 ± 3,80 dias, sendo identificados quatro ínstares. Larvas no máximo desenvolvimento (pré-pupas) enterraram-se no solo. A fase de pré-pupa foi de 142,0 ± 32,00 dias e o período pupal foi de 16,0 ± 0,90 dias. Os adultos permaneceram enterrados por 34,0 ± 18,00 dias e, após saírem do solo, viveram 148,0 ± 89,00 dias. A fecundidade variou entre 539 e 793 ovos/fêmea e a porcentagem de ovos férteis foi de 96.5%. PALAVRAS-CHAVE: Psidium guajava, ciclo biológico, ínstarABSTRACT -The guava weevil, Conotrachelus psidii Marshall, is a severe pest of guava fruits in Brazil. The mated females lay eggs in small unripe fruits. As the fruits develop, so do the larvae. Mature larvae abandon the ripe fruits and pupate underground. Larval feeding causes extensive damage to the fruit. We conducted this study to understand the weevil biology under laboratory conditions. Weevil-infested ripe guava were collected in orchards and placed inside cages with moist sand. After emergence, the adults were individually placed in acrylic boxes with food and water. Recently emerged adults were also placed inside plastic boxes for mating, after which the females were isolated. The eggs were placed on moist filter paper in petri dishes containing slices of ripe guava fruit. Egg-hatching was monitored daily and the number of larval instars established by measuring the width of their head capsules. The egg incubation period lasted 3.9 ± 0.58 days. The larval period was 16.0 ± 3.80 days and four instars were identified. After burrowing in the soil, the mature larvae (pre-pupa) remained underground for 142.0 ± 32.00 days and then pupated. The pupal period lasted 16.0 ± 0.90 days, but the adults remained underground for a further 34.0 ± 18.00 days. After emerging from the soil, adults lived 148.0 ± 89.00 days. Fecundity varied from 539 to 793 eggs/female, and the percent egg hatch was 96.5%.

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The division of labor between the different worker castes of leaf-cutting ants may reflect in their capacity to exchange liquids by trophallaxis. The crop capacity of and trophallactic exchanges between different size classes of worker leaf-cutting ants of the sub-species Acromyrmex subterraneus subterraneus were investigated. Size classes were defined from head capsule widths and crop capacity of each class was determined following ad libitum feeding on dye solution. Experiments were carried out to investigate trophallactic exchanges between donor ants and recipient ants of each class size combination on a one to one basis. An experiment was also performed to investigate dye distribution within mini-colonies following introduction of three classes of donor ants. Worker ants were categorized into four size classes from their head capsule widths (C1=0.8-1.0 mm; C2=1.2-1.5 mm; C3=1.6-2.0 mm; C4=2.1-2.4 mm). C1 ants crop capacity was 0.13 microL; C2: 0.21 microL; C3: 0.52 microL; C4: 1.03 microL. Ants of each class previously fed on the dye solution (donors) were placed individually with an unfed ant of each class (recipients) and the presence of dye solution, passed from the donor to the recipient by oral trophallaxis was observed after 1h. Results showed that all classes of donor ants performed trophallactic exchanges with all recipient classes. However, statistically fewer exchanges were seen for C2 donor ants when placed with C3 recipient ants. Ten donor ants of each of three classes (C2, C3 and C4) were introduced into mini-colonies without queen ants. It was observed that C1 and C2 ants were poor recipients, whilst C3 and C4 received the highest percentages of dye. Within 10h of introducing the donor ants, 14 to 20% of their nest-mates had received dye solution, with 58 to 77% of dye passed to recipients. These studies show the altruistic nature of "food-laden" leaf-cutters and indicate that ants involved in garden maintenance activity are less likely to receive liquids from foraging workers.

Nasutitermes corniger shows preferential feeding for the wood of different tree species, but it is not known whether attractiveness is a function of the state of decay. This study examined the foraging behavior of N. corniger towards wood in different stages of decay. Wood was exposed to weather for durations of 0, 3, 6 or 9 months. Then the wood was placed in a standard foraging arena with termites. Exploration and recruitment behavior were recorded for 1 h. Separate bioassays were conducted for three species: Pinus elliottii, Eucalyptus grandis and Manilkara huberi. In the tests with P. elliottii and E. grandis, more individuals were recruited to wood decayed for 6 months  (191 and 185, respectively) than to undecayed wood (12 and 69, respectively). Similarly, more individuals were recruited to decayed M. huberi wood than undecayed, but only after 9 months (249 and 7, respectively). Decayed wood has therefore been demonstrated to be more attractive to N. corniger than undecayed wood. The different decomposition rates necessary to increase attractiveness may be explained by differences in wood density.

Atta sexdens rubropilosa is a leaf-cutting ant that is a significant agricultural and forestry pest in the Neotropical region. This ant is parasitized by flies from the genera Neodohrniphora spp., Apocephalus spp. and Myrmosicarius spp. This study was carried out to determine which species of Neodohrniphora spp. are found near foraging trails of Atta sexdens rubropilosa and to evaluate the specificity of attack behaviour of these parasitoids. From May 2002 to April 2004, we sampled Neodohrniphora spp. hovering over foraging trails of Atta sexdens rubropilosa between 8:00 and 11:00 h and between 15:00 and 18:00 h. To investigate the attacking behaviour against the ants, flies were released individually inside an observation chamber containing a single leaf-cutting ant worker. Each parasitoid was confronted successively with a worker ant of A. sexdens rubropilosa, Atta laevigata Smith, Acromyrmex crassispinus Forel and Acromyrmex subterraneus molestans Santschi. Phorids of three species were identified: Neodohrniphora elongata Brown, Neodohrniphora declinata Borgmeier and Neodohrniphora tonhascai Brown. The three phorid species were active throughout the year and often along the same foraging trails, but N. elongata was the most frequent species. In the laboratory assay, N. elongata, N. declinata and N. tonhascai attacked workers of A. sexdens rubropilosa, A. laevigata and A. crassispinus, but not of A. subterraneus molestans.

-We investigate structural and behavioral differences between male and female adults of guava weevil, Conotrachelus psidii Marshall, 1922 to help in sex determination. Weevils collected from a commercial guava orchard were individually caged and maintained under laboratory conditions. Every day ten individuals were grouped and their behavior was observed. During mating the males and females were identified. Fifty weevils of each sex were killed and they were observed with stereoscopic microscope. The antenna insertion on the rostrum and hair on the thorax and abdomen surfaces were examined. Length and width of body, pronotum, last abdominal sternite and rostrum were also taken. Behaviorally, the male weevils produce audible sound by stridulation of abdomen while females do not. In the females, the body and pronotum width and body a rostrum length were higher than in the males, but the last abdominal sternite was smaller. Three other structural differences were visible with the naked eye: 1) the anterior region of pronotum have scarce hair or have not in the females and hair is dense in the males; 2) the last tergite of females is hidden by the penultimate tergite whereas in the males is visible; 3) the first abdominal sternite of females is more prominent, very convex and without or with little bristle. In the males it is slightly concave and with abundant hair. The male-female differences found in this work allow, without hurt or change insect behavior, an efficient sex determination of guava weevil.KEY WORDS: Sex differentiation, curculio, stridulation RESUMO -Este trabalho teve como objetivo determinar diferenças que permitam identificar o sexo de adultos de Conotrachelus psidii Marshall, 1922. Gorgulhos coletados em um pomar comercial de goiaba foram individualizados em caixas e mantidos em laboratório. Diariamente, dez gorgulhos eram agrupados e seu comportamento observado. Durante o acasalamento, os machos e as fêmeas eram identificados. Cinqüenta gorgulhos de cada sexo foram sacrificados e observados sob microscópio estereoscópico. Foram examinadas a inserção da antena no rostro e a distribuição de pilosidade na superfície do tórax e abdome. Também, foi medido o comprimento e a largura do corpo, pronoto, último esternito abdominal e rostro. Do ponto de vista comportamental, machos emitem sons por estridulação enquanto que as fêmeas não. A largura do corpo, do pronoto e o comprimento do corpo e do rostro nas fêmeas foram maiores, enquanto que a largura do último esternito abdominal foi menor. Três outras diferenças morfológicas são visíveis a olho nu: 1) A região anterior do pronoto das fêmeas possui pilosidade reduzida ou ausente enquanto que nos machos é abundante; 2) o último tergito nas fêmeas fica recoberto pelo penúltimo enquanto que nos machos é parcialmente visível; 3) o primeiro esternito abdominal nas fêmeas é mais proeminente, convexo e com pilosidade reduzida ou ausente. Nos machos esse segmento é ligeiramente côncavo e com pilosidade em toda a superfície. As diferenças entre machos e ...