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Auad A.M.,Embrapa Dairy Cattle Research Station | Fonseca M.G.,Embrapa Dairy Cattle Research Station | Monteiro P.H.,Federal University of Juiz de fora | Resende T.T.,Embrapa Dairy Cattle Research Station | Santos D.R.,Federal University of Juiz de fora
Annals of the Entomological Society of America | Year: 2013

The predator Diomus seminulus (Mulsant) has been found frequently on forage grasses feeding of Sipha flava (Forbes), suggesting that it is a natural predator of this aphid and has potential as a biological control agent for this pest in Brazil. The objectives of this study were to evaluate the effect of temperature on biological aspects of D. seminulus and to determine whether odor is used by this predator to locate prey on forage grass infested with S. flava. We performed daily evaluations of the viability and duration of each instar of the larval and pupal stages at 16, 20, 24, and 28°C. The reproductive capacity and longevity of adults were estimated at 24°C. The use of odor by D. seminulus to search for aphids was evaluated using a Y-tube olfactometer. The average duration of the embryonic period, each instar, larval, and pupal stages decreased significantly with increasing temperatures from 16 to 24°C. Eggs were blackened and parched, leading to low viability at 16 and 28°C. However, viability of the instars and larvae were not significantly affected by temperature. Adults of D. seminulus survived for >135 d; however, peak oviposition occurred 20-50 d after emergence, suggesting that this is the ideal duration of adult maintenance in laboratory culture. The predator D. seminulus used the odors from aphid prey or volatile compounds released from attacked plants to locate their prey. These results provide support for the use of D. seminulus as a successful biological control for aphids. © 2013 Entomological Society of America.


Parchen H.A.,Federal University of Juiz de fora | Auad A.M.,Embrapa Dairy Cattle Research Station
Florida Entomologist | Year: 2016

In Brazil, the forage species Brachiaria spp., Pennisetum purpureum (Schumacher), and Cynodon dactylon (L.) (Poaceae) are important components in the feed that is used to rear animals for meat and milk production. Aphids are among the insects that feed on these forage species and, at high population levels, greatly reduce the amount and quality of forage. Hence, the aim of this study was to determine the nutritional suitability of the forage species Brachiaria decumbens Stapf, C. dactylon, and P. purpureum for the aphids Sipha flava (Forbes), Rhopalosiphum maidis (Fitch), Hysteroneura setariae (Thomas), and Rhopalosiphum padi (L.) (Hemiptera: Aphididae). Nymphs, which were up to 24 h old, of the 4 aphid species were observed for a biological cycle (1 full generation) on the 3 species of forage. For each association between a species of plant and a species of aphid, 70 aphids were used to create the individual units. The number of instars and the duration and survival of each instar and nymphal stage were evaluated. Additionally, the longevity and the reproductive capacity were recorded for the adults of each aphid species, and a fertility table was prepared. These parameters of each aphid species were compared for each of the 3 species of forage supplied as food and for the identical forage. All aphid species completed their development cycles and produced offspring on all 3 species of forage. However, the duration, survival, and reproduction of the aphid species changed dependent on the nutritional suitability of the forage. For all of the aphid species, the forage P. purpureum provided the best conditions for population growth. When the aphid species were fed the identical forage, R. padi developed better and produced more offspring on all forage species. The 4 aphid species have the potential to be pests of P. purpureum, B. decumbens, and C. dactylon.


Assis F.A.,Federal University of Lavras | Moraes J.C.,Federal University of Lavras | Auad A.M.,Embrapa Dairy Cattle Research Station | Coelho M.,Federal University of Lavras
International Journal of Pest Management | Year: 2013

We investigated sunflower leaf palatability to Chlosyne lacinia saundersii Doubleday & Hewitson (Lepidoptera: Nymphalidae) in plants treated with silicon (Si) and subjected to mechanical injury. We also examined the effects of those treatments on plant development. The experimental study was carried out as a completely randomized design, consisting of the six treatments (10 replicates each): (1) control, (2) plants mechanically injured, (3) Si applied around the plant stem (Si drench), (4) Si drench + injured, (5) Si drench + foliar spray, and (6) Si drench + foliar spray + injured. Si drench + injured significantly reduced the percentage of caterpillar-injured leaves (CIL), leaf area consumed (LAC), and caterpillar weight (CW), leading to increased caterpillar mortality. The only intrinsic plant characteristic affected by the treatments was Si content (SiC), which was higher in plants treated with either Si drench + foliar spray or Si drench + foliar spray + injured. Negative correlations were observed between SiC and the variables CIL, LAC and CW, whereas positive correlations were observed between CIL and LAC, CIL and CW, and LAC and CW. The treatment strategy of Si combined with artificial mechanical injury affects leaf palatability and development of C. lacinia saundersii, conferring resistance to sunflower plants as a function of Si accumulation, although it did not increase crop vegetative variables. © 2013 Copyright Taylor and Francis Group, LLC.


Fonseca M.G.,Embrapa Dairy Cattle Research Station | Silva S.E.B.,Federal University of Lavras | Auad A.M.,Embrapa Dairy Cattle Research Station | Paiva I.G.,Federal University of Lavras | Borges C.A.V.,Embrapa Dairy Cattle Research Station
Journal of Insect Behavior | Year: 2013

The mating behavior of Mahanarva spectabilis (Distant) was studied under laboratory conditions. Virgin adults were individually maintained in transparent cages for observation of the mating sequence. Mating behavior of 23 couples was monitored during the photophase portion of the day. Copulation was observed in 17 of the 23 pairs. The mating sequence includes male approaching the female, mounting of the female, and copulation. Of the 17 mating pairs, 70.6 % mated on the second day after emergence. Most of the copulations began between 8 and 9 h after the onset of photophase. The average duration of copulation was 268 ± 24.9 min, and most pairs mated once or twice during their lifetimes. The mating behavior of M. spectabilis is important to understand because it determines the age and ideal time for further behavioral testing, which is essential for determining the cues involved in the communication system of the species. © 2013 Springer Science+Business Media New York.


Ferreira R.B.,Federal University of Lavras | Moraes J.C.,Federal University of Lavras | Auad A.M.,Embrapa Dairy Cattle Research Station | Fonseca M.G.,Embrapa Dairy Cattle Research Station
Journal of Pest Science | Year: 2013

This study evaluated the impact of different CO2 levels on the biological characteristics of Mahanarva spectabilis (Distant) and on the performance of forage grasses. The signal grasses Brachiaria decumbens Stapf (susceptible) and Brachiaria brizantha (A. Rich.) (resistant), the elephant grass Pennisetum purpureum (Schum.), including the Roxo de Botucatu cultivar (susceptible) and the Pioneiro cultivar (resistant) and the insects were kept in climate-controlled chambers with constant low (250 ppm) CO2 levels, constant high (500 ppm) CO2 levels, or fluctuating CO2 levels (mean, 368 ppm). Among these three CO2 treatments, no significant differences were found in the nymphal survival of M. spectabilis when the nymphs were fed on two signal grass species. On the other hand, under a constant low CO2 level (250 ppm), nymphal survival rates were significantly lower when the insects were kept in Roxo de Botucatu and Pioneiro cultivars. The mean adult longevity values for M. spectabilis were not significantly different among the three levels of CO2 evaluated. We observed that increased CO2 levels improved the performance of M. spectabilis and elephant grass cultivars in accumulating dry mass, which was not evident in signal grass. We further conclude that the levels of susceptibility and resistance of the forages tested will be maintained in future scenarios under which atmospheric CO2 levels are expected to increase. © 2012 Springer-Verlag.


Fonseca M.G.,Embrapa Dairy Cattle Research Station | Santos D.R.,Embrapa Dairy Cattle Research Station | Auad A.M.,Embrapa Dairy Cattle Research Station
Journal of Insect Behavior | Year: 2014

The increasing level CO2may altered host plant physiology and hence affect the foraging behavior of herbivore insects and predator. Hence, the aim of this study was provides evidence that host plants grown at different levels of CO2can alter the choice behavior of aphid, Sipha flava and their natural enemies, Cycloneda sanguinea and Diomus seminulus. The plant used was Pennisetum purpureum, cultivar Cameron Piracicaba growing in greenhouse (mean value of CO2= 440 ppm), climatic chamber with constant value of CO2= 500 ppm and climatic chamber with fluctuating CO2(mean value = 368 ppm). A glass Y-shape olfactometer was used to verify the insects responses towards elephant grass plants cultivated under different conditions. The aphids were statistically more attracted by plants grown with constant CO2level (500 ppm) than by plants grown with fluctuating CO2level or plants grown in greenhouse. There was no difference in S. flava preference to non-infested versus infested plants by conspecifics. The predator C. sanguinea did not show difference between plants grown with constant CO2level and infested or not with S. flava. However, the predator D. seminulus showed higher preference to plants grown with constant CO2level and infested with S. flava. This study showed that the response of S. flava and its predators were affected by plants grown under different levels of CO2. © 2014, Springer Science+Business Media New York.


Auad A.M.,Embrapa Dairy Cattle Research Station | Santos J.C.,Embrapa Dairy Cattle Research Station | Fonseca M.G.,Embrapa Dairy Cattle Research Station
Florida Entomologist | Year: 2014

The effects of various temperatures on the development and survival of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) and Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) fed on Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae) were studied, and some biological aspects among these predators were compared. On average, 70 nymphs of R. padi were added to each experimental unit with predator larvae and maintained at 12, 16, 20, 24, 28, or 32 °C. The duration (days) and survival (%) were measured for each immature stage of the two predator species. The developmental durations of all H. axyridis larval instars, the total larval stage, the pupal stage and total preimaginal stage were very long at 16 °C but shortest at 24 °C for the first, second and third larval instars and at 28 C for the fourth larval instar, the total larval stage and the total pre-imaginal stage. Both at 24 °C and 28 °C, 92% of H. axyridis completed the larva to adult cycle, whereas survival was significantly reduced in the 16 to 20 °C range. At the highest temperature (32 °C), 70% of H. axyridis did not reach adulthood. In the case of C. externa, the durations of development of all larval instars and the total larval stage became progressively shorter as the temperature increased from 12 to 20 °C. At still higher temperatures the developmental duration this insect remained almost constant. The predator completed the larval stage at all temperatures from 12 to 32 °C. However, at 12 and 16 °C, mortality of the larvae was greater than 88%, and 100% of the pupae perished. Although the lower threshold temperatures estimated for both predator species were very similar, the development period from larva to adult of H. axyridis was only 59% as long as that of C. externa. By comparing certain biological parameters including durations of development and survival rates of the two predator species, it is suggested that H. axyridis has intrinsic advantages over C. externa; however, additional factors must be considered when choosing the species of predator for biological control of R. padi on grass pastures in Brazil. © Florida Entomologist 2014.


Auad A.M.,Embrapa Dairy Cattle Research Station | Silva S.E.B.,Embrapa Dairy Cattle Research Station | Santos J.C.,Embrapa Dairy Cattle Research Station | Vieira T.M.,Embrapa Dairy Cattle Research Station
Florida Entomologist | Year: 2015

This study aimed to evaluate the impact of constant and fluctuating temperatures on the biology of Sipha flava (Forbes) (Hemiptera: Aphididae) in order to determine whether the results of laboratory studies can be extrapolated to those performed in natural conditions. We compared the biological parameters of S. flava kept in an uncontrolled greenhouse in which temperatures fluctuated (treatment 1) with those kept in a phytotron-type climate chamber that simulated the mean hourly average temperatures of the greenhouse (treatment 2). In addition, we compared the effects of treatment 2 versus the effects of having a set temperature during photophase and another set temperature during scotophase versus a constant daily average temperature. The experimental design was completely random, and 150 nymphs were used per treatment at the outset of the biossays. However, the number of repetitions was altered in relation to survival of the aphids in the different instars and treatments. By daily use of a stereoscopic microscope, we evaluated the following parameters: the duration (days) and survival (%) of each instar and stage as well as the reproductive capacity (offspring per female per day) and the longevity (days) of adults. The simulation of mean hourly temperatures of an uncontrolled greenhouse favored the survival, reproductive capacity, and longevity of adults - which are factors of great importance in the insect population growth - compared with those insects kept at 27 °C (photophase) and 18 °C (scotophase) or kept at the constant daily average temperature. The results showed that much caution must be exercised in extrapolating results obtained in the laboratory under constant temperatures to predict the population dynamics of field populations of S. flava.


Auad A.M.,Embrapa Dairy Cattle Research Station | Fonseca M.G.,Embrapa Dairy Cattle Research Station | Resende T.T.,Embrapa Dairy Cattle Research Station | Maddalena I.S.C.P.,Embrapa Dairy Cattle Research Station
Florida Entomologist | Year: 2012

This study examined effects of elevated CO2 alone and in combination with elevated temperature on plant-aphid interactions. CO 2 levels in which the host plants were grown affected the durations of some nymphal stadia, but not the survivorship within each instar or of all nymphal instars. Sipha flava (Forbes) (Hemiptera: Aphididae) adults kept under a constant high CO2 environment (500 ppm) and fed on plants grown under fluctuating CO2 levels (avg. 440 ppm) in a greenhouse had significantly greater longevity and greater reproduction than aphids fed on plants grown either under a constant high CO2 level (500 ppm) or under fluctuating CO2 levels (avg. 368 ppm). Nevertheless, no significant differences were observed in these biological parameters of S. flava that were kept individually in a greenhouse, regardless of the CO2 and temperatures under which the plants used to feed them were grown. However, populations of aphids kept and fed on plants grown in the greenhouse produced significantly more nymphs and adults than did those fed plants grown in a climate-controlled chamber under a constant high CO2 level (500 ppm). The combination of elevated CO2 and high temperature significantly decreased the duration of nymphal stadia, the longevity and reproductive success of S. flava but not nymphal survival. Adults produced fewer nymphs in an environment with elevated CO2 and high temperature than an environment with elevated CO2 and lower fluctuating temperatures. Based on these results, we concluded that S. flava populations will significantly decrease under future climatic conditions when both the concentration of atmospheric CO2 and temperature are projected to increase.


PubMed | Embrapa Dairy Cattle Research Station
Type: | Journal: Journal of insect science (Online) | Year: 2016

The aim of this study was to determine the favorable constant temperature range for Mahanarva spectabilis(Distant) (Hemiptera: Cercopidae) development as well as to generate geographic distribution maps of this insect pest for future climate scenarios. M. spectabilis eggs were reared on two host plants (Brachiaria ruziziensis(Germain and Edvard) and Pennisetum purpureum(Schumach)), with individual plants kept at temperatures of 16, 20, 24, 28, and 32 C. Nymphal stage duration, nymphal survival, adult longevity, and egg production were recorded for each temperature*host plant combination. Using the favorable temperature ranges for M. spectabilis development, it was possible to generate geographic distribution. Nymphal survival was highest at 24.4 C, with estimates of 44 and 8% on Pennisetum and Brachiaria, respectively. Nymphal stage duration was greater on Brachiaria than on Pennisetum at 20 and 24 C but equal at 28 C. Egg production was higher on Pennisetum at 24 and 28 C than at 20 C, and adult longevity on Pennisetum was higher at 28 C than at 20 C, whereas adult longevity at 24 C did not differ from that at 20 and 28 C. With these results, it was possible to predict a reduction in M. spectabilis densities in most regions of Brazil in future climate scenarios.

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