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Context Average sward height has traditionally been used as a grazing management variable. However, such approach ignores the spatio-temporal heterogeneity of swards. Because the intake rate responds non-linearly to average height at plant level, we expected that sheep exposed to contrasting grazing methods with similar average heights would behave differently. Aims We hypothesised that low-intensity, high-frequency grazing results in a higher daily intake rate than does high-intensity, low-frequency grazing, despite both methods having similar average sward heights over space and time. Also, we asked whether sheep exhibit the same foraging mechanisms for a given instantaneous sward state regardless of long-term grazing conditions imposed. Methods We exposed sheep to two contrasting grazing methods with similar average height; low-intensity, high-frequency (LIHF), and high-intensity, low-frequency (HILF). We then evaluated their foraging behaviour using continuous bite-monitoring paired with detailed sward measurements during grazing down. Key results Sward height decreased markedly during the grazing period in both treatments, but the sward height depletion was faster under HILF (7.5 cm and 20.3 cm for LIHF and HILF), which means that sward structure was severely disrupted. The animals exhibited markedly different herbage intake patterns between the grazing methods, with sheep under LIHF presenting greater total daily herbage intake (850 vs 630 g DM per individual). Also, sheep demonstrated a more stable and higher instantaneous intake rate in the LIHF. Despite the difference in total daily herbage intake, the grazing treatments did not affect the behavioural mechanisms beyond their indirect effects on the rate of change in the instantaneous sward conditions. Grazing treatments created different patterns of sward change and intake rate over time, but the local and instantaneous sward conditions determined intake rate regardless of the grazing method. Conclusions Intake responses of sheep differed between grazing methods with similar average height due to sward heterogeneity over time and space. Grazing mechanisms were not directly affected by the treatments but were influenced by the sward heterogeneity imposed by the grazing management. Implications Grazing management requires not only consideration of the average sward height, but also an understanding of how the resource is distributed in time and space.

Determining herbage intake is pivotal for studies on grazing ecology. Direct observation of animals allows describing the interactions of animals with the pastoral environment along the complex grazing process. The objectives of the study were to evaluate the reliability of the continuous bite monitoring (CBM) method in determining herbage intake in grazing sheep compared to the standard double‐weighing technique method during 45‐min feeding bouts; evaluate the degree of agreement between the two techniques; and to test the effect of different potential sources of variation on the reliability of the CBM. The CBM method has been used to describe the intake behavior of grazing herbivores. In this study, we evaluated a new approach to this method, that is, whether it is a good proxy for determining the intake of grazing animals. Three experiments with grazing sheep were carried out in which we tested for different sources of variations, such as the number of observers, level of detail of bite coding grid, forage species, forage allowance, sward surface height heterogeneity, experiment site, and animal weight, to determine the short‐term intake rate (45 min). Observer (Pexp1 = 0.018, Pexp2 = 0.078, and Pexp3 = 0.006), sward surface height (Pexp2, We showed an agreement between the Continuous bite Monitoring method and Double‐Weighing Technique method; Continuous Bite Monitoring method is a good proxy for determining the intake of grazing animals; Direct observation is not invasive nor disrupts natural animal behavior.

Early relationships between young mammalian herbivores and social models (e.g., mothers or peers) have been proposed as playing a major role in the process of diet learning. Diet selection is an important factor influencing animal development and ecology, especially in natural and seminatural grasslands, with a large diversity of plant species. To explore the learning process of foraging behavior and diet selection choices by foals, six free-ranging Criollo foals and their respective mares were monitored through continuous bite monitoring from birth to 130 d old, in the Pampas Grasslands of southern Brazil. Cumulative suckling time decreased exponentially from birth to 130 d old, while dry matter intake, foraging time, and bite mass of foals increased continuously. It was possible to identify three marked periods in the foal’s foraging behavior development: 1) an exploratory phase (from 0 to 40 d old) marked by limited forage intake from a large diversity of plants; 2) a specialization phase (from 40 to 110 d old) with a marked increase in forage intake and a specialization around the same plants as the ones selected by the mares; and 3) a stabilization phase (after 110 d old) in which forage intake still increases but diet composition of foals stabilized similarly to the one of the respective mares. The higher diversity at young ages could be explained by exploratory hypothesis, where foals test different forages to discover their environment, given that their nutritional needs are fulfilled by milk consumption, not by forage intake. As requirements shift toward solid items, bite mass and foraging time increase and diet choices become similar to that of the mares. Our results detail how young foals develop their foraging behavior and suggest, without testing it and under the circumstances of this study, that they learn their diet through social transmission from their mothers.

Stiretrus decastigmus (Herrich-Schaeffer) (Hemiptera: Pentatomidae) is an important predator of the insect pest Microtheca ochroloma Stal (Coleoptera: Chrysomelidae). The present study investigated the pre-imaginal development of S. decastigmus at different temperatures. The temperatures were: 20, 25, and 30 °C, with a relative humidity of 70 ± 10% and a photofase of 12 h, and the nymphs were fed larvae of M. ochroloma. We evaluated the duration and viability of the egg and nymphal stages, the duration of each instar, and the predation potential. The incubation time decreased with increasing temperature, and the viability was highest at 25 °C. The duration of the nymphal stage was inversely proportional to the temperature, ranging from 18 days at 30 °C to 40.6 days at 20 °C. The highest S. decastigmus predation rates were found at 20 °C (90.4 larvae) and 30 °C (72.5 larvae). S. decastigmus showed the highest viability and lowest consumption of larvae of M. ochroloma at 25 °C. Resumo Stiretrus decastigmus (Herrich-Schaeffer) (Hemiptera: Pentatomidae) é um importante predador do inseto-praga Microtheca ochroloma Stal (Coleoptera: Chrysomelidae). O objetivo deste trabalho foi estudar o desenvolvimento pré-imaginal de S. decastigmus em diferentes temperaturas. Foram utilizadas as temperaturas de 20, 25, e 30 °C, umidade relativa do ar de 70 ± 10% e fotofase de 12 h, sendo as ninfas alimentadas com larvas de M. ochroloma. Foram avaliados a duração e viabilidade dos estágios de ovo e ninfa, a duração de cada instar e o potencial de predação. O período de incubação diminuiu com o aumento da temperatura e apresentou maior viabilidade a 25 °C. A duração do estágio ninfal foi inversamente proporcional a temperatura com 18 dias a 30 °C e 40,6 dias a 20 °C. A maior taxa de predação de S. decastigmus foi encontrada a 20 °C (90,4 larvas) e 30 °C (72,5 larvas). S. decastigmus teve maior viabilidade e menor consumo de larvas de M. ochroloma a 25 °C.

The objectives of this study were to estimate the plastochron in pigeonpea (Cajanus cajan (L.) Millsp.) during the period between emergence and flowering using three methods of calculating the average daily air temperature and to determine the sample size (number of plants) needed to estimate the plastochron. A uniformity test (blank experiment) was conducted in an area of 1440 m2 containing a pigeonpea crop. The area was divided into 360 plots of 2 m × 2 m, and 1 plant per plot was marked at random. In each of these 360 plants, the number of nodes on the main stem was counted at 37, 43, 50, 57, 64, 71, 78, 85, 93, 99, 106, 114 and 120 days after emergence (DAE). The average daily air temperature (Taverage) was calculated using three methods: method 1: Taverage = (Tminimum + Tmaximum)/2; method 2: Taverage = (T0 h + T1 h + T2 h + ⋯ + T23 h)/24; and method 3: Taverage = (Tminimum + Tmaximum + T9 h + 2T21 h)/5. For the three methods, the daily and cumulative thermal times were calculated from the date of emergence to early flowering and fitted to a linear regression of the average number of nodes on the main stem as a function of the accumulated thermal time. The plastochron was then calculated under each method as the inverse of the slope of the linear regression, and the required sample size (number of plants) to estimate the plastochron was determined by resampling with replacement. Plastochron values determined from the average daily air temperature calculated based on the three methods are different, and the use of the arithmetic mean of the hourly temperatures (method 2) should be favoured. Under method 2, the plastochron for pigeonpea was determined to be 21.34 °C day node−1. To estimate the plastochron with 95% confidence interval amplitudes equal to 1, 2 and 3 °C day node−1, it was necessary to count the number of nodes in 194, 50 and 24 pigeonpea plants, respectively.

O objetivo deste trabalho foi determinar o tamanho de amostra (número de insetos) para a estimação da média de duração dos períodos larval, pupal e larval + pupal de Microtheca ochroloma e de Microtheca semilaevis (Coleoptera: Chrysomelidae). Foram coletados adultos dessas espécies em uma área experimental de 0,25ha de nabo forrageiro (Raphanus sativus L.) e foi estabelecida uma criação em laboratório (temperatura de 25±2°C, umidade relativa de 60±10% e fotoperíodo de 12 horas). Após, foram mensurados os períodos larval, pupal e larval + pupal, em dias, de 119 e 81 insetos, respectivamente, de M. ochroloma e de M. semilaevis. Foram calculadas medidas de tendência central e de variabilidade. Foi determinado o tamanho de amostra por meio de bootstrap, com reposição de 10.000 amostras. Para a estimação da média dos períodos larval, pupal e larval + pupal, com intervalo de confiança de bootstrap de 95% de um dia, 42 e 35 insetos são suficientes, respectivamente, para M. ochroloma e M. semilaevis.

Aphis craccivora Koch (Hemiptera: Aphididae) é um afídeo-praga que ocorre em diferentes cultivos e causa danos relacionados ao hábito da sucção de seiva. No Brasil, são raros os registros de plantas daninhas hospedeiras dessa espécie, particularmente no Estado do Rio Grande do Sul (RS). Plantas daninhas infestadas com afídeos foram encontradas em área experimental localizada no campus da Universidade Federal de Santa Maria (UFSM), RS, em duas datas, 22/02/2010 e 25/03/2010. No segundo registro (25/03/2010), cada planta daninha foi medida e avaliada quanto ao número de afídeos. A espécie foi identificada como Aphis craccivora e as plantas daninhas hospedeiras, como Amaranthus hybridus Linnaeus, 1753 (Amaranthaceae), caruru-roxo, e Solanum americanum Mill, 1768 (Solanaceae), maria-pretinha. Este trabalho faz o primeiro registro de A. hybridus e S. americanum hospedando A. craccivora em Santa Maria, no Rio Grande do Sul.

Avaliaram-se as características de carcaça de ovelhas de descarte das raças Ideal e Texel terminadas em dois sistemas de alimentação. Utilizaram-se 20 ovelhas (10 da raça Ideal e 10 da raça Texel) aleatoriamente distribuídas de acordo com o grupo genético em dois manejos alimentares (confinamento e pastagem cultivada). Os abates foram realizados quando os animais atingiram 3,5 pontos de condição corporal. Os pesos de carcaça quente (PCQ) e de carcaça fria (PCF) e os rendimentos de carcaça quente (RCQ) e de carcaça fria (RCF) das ovelhas Texel foram maiores que os das ovelhas Ideal: 27,85 e 19,04 kg; 27,08 e 18,43 kg; 47,25 e 45,20% e 45,95 e 43,72%, respectivamente. O peso dos cortes perna, paleta, pescoço e costela e os pesos de músculos, ossos e gordura da perna dos animais da raça Texel foram superiores aos obtidos na raça Ideal. Quando avaliadas em porcentagem do peso corporal, no entanto, essas características não diferiram entre as duas raças. O manejo alimentar não influenciou as características de carcaça de ovelhas de descarte. Ovelhas Texel apresentam cortes maiores que os de ovelhas Ideal.

Brazil is among the world's biggest maize producers and fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), is the main insect pest on this crop in the country. Despite the importance of its natural enemies, there still is a lack of information about parasitoids species that attack this insect-pest, such as larval parasitoids. This research reports Euplectrus furnius Walker (Hymenoptera: Eulophidae) parasitizing S. fugiperda larvae on maize crop in Brazil.

First record of larvae of Allograpta exotica Wiedemann (Diptera, Syrphidae) preying on Aphis gossypii Glover (Hemiptera, Aphididae) in watermelon in Brazil. Brazil is one of the largest world producers of watermelon (Citrullus lanatus Thumb. Mansf.) and Aphis gossypii Glover, 1877 (Hemiptera, Aphididae) is among the most important pest on this crop. Larvae of Allograpta exotica Wiedemann, 1830 (Diptera, Syrphidae) were found preying on A. gossypii in watermelon crop, in Santa Maria, Rio Grande do Sul State, what represents the first report of this tritrophic association in Brazil.Primeiro relato de larvas de Allograpta exotica Wiedemann (Diptera, Syrphidae) predando Aphis gossypii glover (Hemiptera, Aphididae) em melancia no Brasil. O Brasil é um dos maiores países produtores de melancia e Aphis gossypii Glover, 1877 (Hemiptera, Aphididae) está entre as pragas mais importantes da cultura. Larvas de Allograpta exotica Wiedemann, 1830 (Diptera, Syrphidae) foram registradas predando A. gossypii em cultivo de melancia em Santa Maria, Rio Grande do Sul, o que representa o primeiro relato desta associação tritrófica no Brasil.

Resumo: Um experimento foi conduzido com o objetivo de avaliar as características da carcaça e dos componentes não carcaça de cordeiros nascidos de parto simples ou duplo. Dezesseis cordeiros mestiços Texel × Ile de France, machos não castrados, foram desmamados aos 56 dias de idade e abatidos com aproximadamente 28kg de peso corporal. Imediatamente após o abate, cada componente corporal foi pesado separadamente, sendo as carcaças avaliadas após 24 horas de refrigeração a 2°C. Os cordeiros oriundos de parto simples apresentaram superioridade no peso e nos rendimentos da carcaça, além de maior área de olho de lombo. Por outro lado, proporcionalmente ao peso de corpo vazio, o rúmen é maior em cordeiros nascidos de parto duplo, o que resulta incremento da proporção de conteúdo gastrintestinal ao abate. Os resultados deste estudo indicam que, quando abatidos a um mesmo peso, cordeiros oriundos de parto simples possuem carcaças de melhor qualidade, em comparação a cordeiros nascidos de parto gemelar. [Carcass and non-carcass traits of single and twin lambs]. Abstract: An experiment was conducted to evaluate the carcass and non-carcass traits of single and twin lambs. Sixteen Texel × Ile de France crossbred, non-castrated male lambs were weaned at 56 days of age and slaughtered at 28kg of body weight. Immediately after the slaughter each body component was individually weighed, while carcasses were evaluated after a 24h period of refrigeration at 2°C. Single lambs presented higher values of carcass weight and carcass dressing percentage. Moreover, the Longissimus muscle area was also greater for single lambs. On the other hand, as a proportion of empty body weight, rumen was greater for twin lambs, increasing their gastrointestinal content at slaughter. The results of this study indicated that at a same slaughter weight single lambs have better quality carcasses in comparison with those from twin lambs.

Carcass traits of twenty Texel x Ile de France crossbred lambs slaughtered after weaning (52 days of age), or at 25, 30 and 35kg live weight were evaluated. Lambs were placed in individual stalls (1.5m²) and fed ad libitum with a diet composed of sorghum silage (Sorghum bicolor (L.) Moench) and a concentrate mix (ground corn, soybean meal, calcium carbonate and salt). Commercial dressing percentage was related quadratically with slaughter weight, being highest in lambs slaughtered after weaning. Real dressing percentage increased linearly. Shoulder proportion decreased with slaughter weight, whereas leg, rib and neck proportions remained constant. Carcass fat was positively correlated to the slaughter weight. Slaughter of feedlot Texel x Ile de France crossbred lambs can be recommended at 28kg live weight. Foram avaliadas as características da carcaça de cordeiros Texel x Ile de France abatidos após o desmame (52 dias de idade) ou aos 25, 30 e 35kg de peso vivo. Utilizaram-se 20 cordeiros, confinados em baias individuais (1,5m²) e alimentados ad libitum com dieta composta por silagem de sorgo (Sorghum bicolor (L.) Moench) e mistura concentrada (grão de milho triturado, farelo de soja, calcário calcítico e sal comum). O rendimento de carcaça comercial relacionou-se quadraticamente ao peso de abate, sendo máximo para os animais abatidos após o desmame. O rendimento de carcaça real elevou-se linearmente. Foi observado decréscimo linear da proporção de paleta à medida que se elevou o peso de abate, ao passo que as proporções de perna, costela e pescoço permaneceram constantes. A proporção total de gordura da carcaça foi positivamente correlacionada ao peso de abate. Recomenda-se que o abate de cordeiros Texel x Ile de France confinados seja realizado aos 28kg de peso vivo.

Microtheca semilaevis Stal is a phythophagous insect associated to Brassicaceae, and frequently occurs with other species of beetles, such as Microtheca ochroloma Stal. Despite its importance to organic farmers, there is no information in the Brazilian literature about its natural enemies. Stiretrus decastigmus (Herrich-Schaeffer) was first found and here reported preying an adult of M. semilaevis in Chinese cabbage in Santa Maria, RS, Brazil (29°43'28″S, 53°43'19″W).

Microtheca spp. (Coleoptera: Chrysomelidae) are insect pests primarily related to Brassicaceae crops. In the State of Rio Grande do Sul (RS), southern Brazil, they are found on forage turnip, Raphanus sativus L. var. oleiferus Metzg., which is commonly grown during fall/winter seasons. This work reports the predation of Microtheca spp. larvae by Toxomerus duplicatus Wiedemann, 1830 (Diptera: Syrphidae) larvae, on forage turnip crop, in Santa Maria, RS. This register provides new information about Microtheca spp. natural enemies in Brazil, which might be a new option for integrate pest management of these species.