Behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae in Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Leaf-cutting ant workers care for larvae with an elaborate behavioural repertoire to satisfy the needs of the offspring. In order to investigate worker discrimination ability in the leaf-cutting ant Acromyrmex subterraneus brunneus, we compared the behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae, including the following behavioural acts: licking the larval body, transporting larvae, feeding larvae with hyphae, scraping larval mouth parts, ingesting faecal fluid excreted by the larva, and inserting hyphae of the symbiontic fungus on the larval body. We verified that workers behaved differently depending on larval origin, i.e. licking the larval body, transporting larvae and inserting hyphae of the symbiontic fungus on the larval body. Observed differences denote the ability of workers in discriminating among larvae, probably because of their different individual needs.

Description of the larva of Mnesarete pudica (Hagen in Selys, 1853) (Odonata: Calopterygidae) and notes on known genera of South American Calopterygidae larvae

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Characterization of excretory/secretory antigen from Toxocara vitulorum larvae

Toxocara vitulorum is a nematode parasite of the small intestine of cattle and water buffalo, particularly buffalo calves between one and three months of age, causing high morbidity and mortality. The purpose of this research was to characterize the excretory/secretory (ES) antigens of T vitulorum larvae by SDS-polyacrylamide gel electrophoresis (PAGE) and Western blot (WB), using immune sera and colostrum of buffalo naturally infected by T vitulorum. The parasitological status of the buffalo calves was also evaluated using sequential fecal examinations. The results showed that the ES antigen revealed eight (190, 150, 110, 90, 64, 56, 48, and 19 kDa) protein bands by SDS-PAGE. The majority of these bands were recognized in the sera and colostrum of infected buffalo with T vitulorum when analyzed by WB. However, particularly fractions of high molecular weight (190, 150, 110, and 90 kDa) were represented in more prominent bands and persisted in the groups of buffalo calves at the peak of egg output, as well as during the period of rejection of T vitulorum by the feces of the calves. During the period of post-rejection of the worms (between the day 118 and 210 of age) the serum antibodies did not react with any protein bands. on the other hand, sera from buffalo calves at one day of age (after suckling the colostrum and at the beginning of infection) reacted with the same bands detected in the serum and colostrum of the buffalo cows.

Effect of plant trichomes on the vertical migration of Haemonchus contortus infective larvae on five tropical forages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Recovery of Trichostrongylus colubriformis infective larvae from three grass species contaminated in the autumn

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Growth characteristics of skeletal muscle tissue in Oreochromis niloticus larvae fed on a lysine supplemented diet

The effect of lysine amino acid supplementation on the growth characteristics and morphological pattern of skeletal muscle tissue in Nile tilapia Oreochromis niloticus larvae was evaluated. There were four treatments (T) with increasing levels of lysine supplement (T1 = 0.0%: T2 =1.1%; T3 = 1.7%; T4 = 4.0%) and one treatment with a commercial diet (T5). In all treatments, morphological and histochemical muscle tissue analyses were similar. Two distinct layers were identified: a superficial red layer, more developed in the lateral line region, formed by fibres with intense to moderate NADH-TR reaction and strong acid-stable mATPase activity, and a deep white one, most of the Muscle mass, formed by fibres with weak NADH-TR reaction and strong alkali-stable mATPase activity. There was an intermediate layer between these two layers with fibres exhibiting either weak acid-stable or acid-labile mATPase activity. Body mass increase was significantly higher in T5 than in the lysine treatments (T1-T4). There was no difference in number and diameters of muscle fibres between lysine treatments. In T5, muscle fibre diameter and number were higher. The frequency of red fibres with diameters <= 8 mu m was higher in the lysine treatments, and with diameters between 16 and 24 mu m, was higher in T5. Most white fibre diameters in T5 were significantly larger than 24 mu m and in T1-T4 were between 8 and 16 mu m. Cell proliferation was higher in the lysine treatments and muscle growth in T5 was mainly by fibre hypertrophy. (c) 2005 the Fisheries Society of the British

Morphometric study of the midgut epithelium in larvae of Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae)

A larva de Diatraea saccharalis Fabricius (broca-da-cana) tem grande interesse econômico, pois afeta o cultivo e aproveitamento industrial da cana-de-açúcar. Entretanto, poucos são os estudos sobre a morfologia interna desse inseto. O objetivo deste trabalho foi estudar, morfometricamente, o seu epitélio intestinal, ao longo de seu comprimento, visando caracterizar regiões estruturalmente diferentes. O intestino médio de larvas no último instar foi subdividido em três regiões: proximal, mediana e distal e os fragmentos foram processados para observação em microscopia de luz. Os cortes histológicos foram analisados em sistema computadorizado de análise de imagens para medir comprimento, largura e área do epitélio, das diferentes células epiteliais, dos seus respectivos núcleos e do lúmen intestinal. Os dados obtidos foram submetidos ao teste estatístico de Kruskal-Wallis e à análise multivariada. Nossos resultados mostraram que o intestino médio apresentou-se constituído, morfometricamente, por duas diferentes regiões, proximal e distal; a região mediana apresentou valores coincidentes tanto com a região proximal quanto com a distal, sugerindo ser região intermediária. As células epiteliais (colunares, caliciformes e regenerativas), quando avaliadas pela análise estatística multivariada, não apresentaram diferença morfométrica nas diferentes regiões do intestino médio. Entretanto, a análise de variância, realizada para variáveis isoladas, mostrou que as células regenerativas apresentaram maior variabilidade morfométrica.

Morphological study of the hindgut in larvae of Anticarsia gemmatalis Hübner(Lepidoptera: Noctuidae)

A lagarta da soja (Anticarsia gemmatalis Hübner) tem grande interesse econômico, pois afeta significativamente a cultura da soja em todo o mundo. Este trabalho descreve a morfologia do intestino posterior de larvas de A. gemmatalis, com ênfase nos seus aspectos histológicos. O intestino posterior é constituído por regiões morfologicamente distintas, identificadas como piloro, íleo, cólon e reto. Independente da região, a parede do intestino posterior é constituída por fina cutícula, epitélio simples e camada muscular. A íntima cuticular apresenta espículas no anel intersticial posterior, entre o intestino médio e o posterior, e na região posterior do piloro. A musculatura do reto é formada por camada única de largas fibras circulares, diferindo das demais regiões do intestino posterior que apresentam duas camadas de fibras musculares. As extremidades distais dos túbulos de Malpighi atravessam as paredes do reto, constituindo o sistema criptonefridial característico de Lepidoptera.

Morphological regional differences of epithelial cells along the midgut in Diatraea saccharalis Fabricius (Lepidoptera : Crambidae) larvae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The influence of initial feeding on muscle development and growth in pacu Piaractus mesopotamicus larvae

The effects of different feeding schemes on pacu Piaractus mesopotamicus early development were evaluated with respect to growth, survival, muscle development, and differential gene expression of MyoD and myogenin. The pacu larvae (4 days post hatch-dph, 0.77 mg wet weight) were given six feeding treatments intentionally designed to cause variations in the larvae growth rate: (A) only artemia nauplii; (CD) only a commercial diet; (ED) only a semi-purified experimental diet; (ACD) and (AED) two treatments that involved weaning; and (S) starvation. Early weaning from artemia nauplii to the formulated diets (ACD and AED) affected growth and survival of the pacu larvae compared with the exclusive use of artemia (A). Starvation (S) and the commercial diet (CD) caused total mortality in pacu larvae at 18 dph. The experimental diet (ED) assured low fish survival and growth. The skeletal muscle morphology was not affected by the delay in somatic growth from early weaning onto the formulated diets. Three distinct muscle compartments were observed throughout the larval development in treatments A, ACD and AED: superficial, deep and intermediate, accompanied by muscle thickening. Severe undernourishment caused drastic differences in growth and in the morphology of the muscle fibers. Pacu larvae fed only formulated diets (CD and ED) showed muscle characteristics similar to the larvae in starvation (S) during the first 15 dph. At 27 and 35 dph, a slight increase in epaxial muscle mass was noted in larvae fed only the experimental diet (ED). At 35 dph, we observed a high frequency of fibers >= 40 mu m in the larvae that were weaned onto the formulated diets (ACD and AED), indicative of hypertrophy. In contrast, the larvae fed only artemia nauplii (A) displayed a larger number of fibers with diameters <= 20 mu m, which is indicative of hyperplasia. The expression of the MyoD and myogenin genes in pacu larvae at 35 dph was not affected by initial feeding (p>0.05). In conclusion, the formulated diets used impaired pacu larvae growth and survival; therefore, they were inadequate for pacu, at least at the times they were introduced. Artemia nauplii were the most adequate food source during first feeding of the pacu, and they produced bigger fish upon completion of the experiment. Moreover, the contribution of hyperplasia to the skeletal muscle growth appeared higher in fast- than in slow-growing pacu larvae. (C) 2011 Elsevier By. All rights reserved.

Dispersal and predation behavior in larvae of Chrysomya albiceps and Chrysomya megacephala (Diptera : Calliphoridae)

Chrysomya albiceps and Chrysomya megacephala are exotic blowfly species known by producing myiasis in humans and other animals and by transmitting pathogens mechanically. C. albiceps stand out by being a facultative predator of other dipteran larvae. In this paper we investigated the influence of larval predation on the dispersal of larvae of C. albiceps and C. megacephala single and double species for three photophases. An experimental acrylic channel graduated and covered with wood shavings was used to observe the larval dispersal. The results showed that C. albiceps attacks C. megacephala larvae during dispersal and keeps an aggregated pattern close to the release point, in single and double species, independently of the different photophases. Chrysomya megacephala single species exhibited the same pattern, but in double species this was changed to a random distribution.

Theoretical estimates of consumable food and probability of acquiring food in larvae of Chrysomya putoria (Diptera: Calliphoridae)

An indirect estimate of consumable food and probability of acquiring food in a blowfly species, Chrysomya putoria, is presented. This alternative procedure combines three distinct models to estimate consumable food in the context of the exploitative competition experienced by immature individuals in blowfly populations. The relevant parameters are derived from data for pupal weight and survival and estimates of density-independent larval mortality in twenty different larval densities. As part of this procedure, the probability of acquiring food per unit of time and the time taken to exhaust the food supply are also calculated. The procedure employed here may be valuable for estimations in insects whose immature stages develop inside the food substrate, where it is difficult to partial out confounding effects such as separation of faeces. This procedure also has the advantage of taking into account the population dynamics of immatures living under crowded conditions, which are particularly characteristic of blowflies and other insects as well.

Prey choice by facultative predator larvae of Chrysomya albiceps (Diptera: Calliphoridae)

In this study we investigated predation rates on third instar larvae of Chrysomya putoria and C. megacephala by third instar larvae of C. albiceps in a two-choice situation. The highest predation rate occurred on C. putoria larvae and this result is compared to previous experiments, in which C. macellaria larvae were present. Our results suggest that, when C. macellaria is absent C. albiceps larvae attack more C. putoria than C. megacephala larvae. Prey choice decisions and its implications for introduced and native blowflies are discussed.

A morphometric study of the midgut in resistant and non-resistant Anticarsia gemmatalis (Hubner) (Lepidoptera: Noctuidae) larvae to its nucleopolyhedrovirus (AgMNPV)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vertical migration of Haemonchus contortus third stage larvae on Brachiaria decumbens grass

The present study aimed at evaluating the vertical migration of Haemonchus contortus third stage larvae (1-3) on Brachiaria decumbens grass, as well as at verifying whether larval numbers on pasture varies over the day due to climatic conditions. Feces containing H. contortus L3 were deposited on the soil in the middle of herbage which was initially 30 cm high. Seven days later, samples of different herbage strata (0-10, 10-20 and >20 cm), remaining feces and a layer of approximately 1 cm soil were collected. Tests were carried out in four periods: September 2006, December 2006, March 2007, and June 2007. Samples were collected at sunrise, mid-day, sunset, and mid-night. The humidity and temperature conditions observed in different months influenced larval migration from the feces to the grass. In September, December and March, it rained after fecal deposition on pasture, which favored migration of larvae from the feces to the herbage. Conversely, in June 2007, when there was no rainfall after fecal deposition and temperatures were lower, L3 were mainly recovered from feces. As regards the vertical migration of larvae, the numbers of H. contortus L3 in the forage strata remained relatively constant over the day. This indicates there is not a determined period in which sheep on pasture are at higher risk of infection. Finally, in all collection periods a considerable amount of third stage larvae was observed on the herbage top, which is the first plant part consumed by sheep. (C) 2008 Elsevier B.V. All rights reserved.