RESUMO
The temperature is among the abiotic factors that directly affect the developmental time and behavior of insects. The adaptability to climatic conditions is a key point for the success of mass-rearing and establishment of parasitoids in biological control programs. The objective of this study was to evaluate the developmental time and parasitism of Lysiphlebus testaceipes (Cresson) on Aphis gossypiiGlover as host in different temperatures. The tests were carried out in climatic chambers at 15, 20, 25 and 30 ± 1°C, 60 ± 10% RH and 10h photophase. Parasitized nymphs of A. gossypii were kept individualized in petri dishes (6 cm of diameter) on a leaf disk (2 cm diameter) of chrysanthemum (Dendranthema grandiflorum Tzvelev) Yellow Snowdon cultivar on a layer of agar. The developmental time of L. testaceipes was 26.9, 14.8, 11.3 and 12.2 days at 15, 20, 25 and 30ºC, respectively. Parasitism rates were 76, 68, 65 and 40% at 15, 20, 25 and 30°C, and emergence rates were 80, 61, 62 and 14% at these temperatures. The combination of a low developmental time (11.3 days) and parasitism and emergency higher than 60% occurred at 25ºC, indicating that this temperature could be the most adequate for reproduction and establishment of L.testaceipes as a biological control agent of A. gossypii in protected cultivation.
A temperatura está entre os fatores abióticos que influenciam o desenvolvimento e o comportamento dos insetos. A adaptabilidade às condições climáticas é um dos pontos chaves para o sucesso da multiplicação e estabelecimento de parasitóides em programas de controle biológico. Estetrabalho teve como objetivo avaliar o desenvolvimento e o parasitismo de Lysiphlebus testaceipes (Cresson) em diferentes temperaturas, tendo como hospedeiro Aphis gossypii Glover. Os testes foram conduzidos em câmaras climáticas nas temperaturas de 15, 20, 25 e 30 ± 1°C, 60 ± 10% UR e fotofase de 10h. Cada ninfa hospedeira parasitada foi individualizada em placa de Petri (6 cm de diâmetro), contendouma camada de agar-água e um disco foliar (2 cm de diâmetro) de crisântemo (Dendranthema grandiflorum Tzvelev) cultivar Yellow Snowdon. O período de desenvolvimento de L. testaceipes foide 26,9; 14,8; 11,3 e 12,2 dias nas temperaturas de 15, 20, 25 e 30ºC, respectivamente, e a porcentagem deemergência foi de 80, 61, 62 e 14% nas mesmas temperaturas. A taxa de parasitismo foi de 76, 68, 65 e 40%nas temperaturas de 15, 20, 25 e 30°C, respectivamente. A combinação do menor período de desenvolvimento e da porcentagem de parasitismo e de emergência maiores que 60%, encontrados a 25ºC, indicam que essa temperatura é a mais indicada para multiplicação e estabelecimento de L.testaceipes como agente de controle biológico de A. gossypii em ambientes protegidos.
RESUMO
Fecundity and longevity of Aphis gossypii Glover, 1877 (Hemiptera, Aphididae) at different temperatures and commercial chrysanthemum cultivars (Dendranthema grandiflora Tzvelev). The aphid A. gossypii is one of the main pests in a number of crops both under field and protected conditions. The objective of the present study was to evaluate the fecundity and longevity of A. gossypii under different temperatures and commercial chrysanthemum cultivars (Yellow Snowdon, White Reagan and Dark Splendid Reagan) with different trichomes densities (11.3; 16.6 and 21.6 trichome/mm² of the leaf, respectively) The trials were carried out in climatic chambers, at four temperatures (15, 20, 25 and 30 ±1 ºC), 70 ± 10 percent RH and photophase 10h. The reproductive period significantly decreased with increase of temperature in the three cultivars. In Yellow Snowdon cultivar average duration of the reproductive period was 14.3 days at 25 ºC. The maximum fecundity was obtained at the temperature of 25 ºC with 3,1; 2,8 and 3,6 nymphs/female/day in the Yellow Snowdon, White Reagan and Dark S. Reagan cultivars, respectively. The total fecundity was reduced by extreme temperatures (15 and 30 ºC), and was obtained at 25 ºC with 35,9 nymphs/female. Females maintained in Yellow Snowdon cultivar significantly showed superiority (30,7 nymphs/female) in total fecundity in relation to White Reagan (22,1 nymphs/female) and Dark S. Reagan (22,9 nymphs/female). The Yellow Snowdon cultivar (with a lower trichome density) had a significant influence in daily and total capacity of nymphs production, showing a higher fecundity of A. gossypii females. The aphid's longevity was affected by cultivars and temperature, and this longevity decreased whit increase of temperature. The results showed that there was an interaction between the temperature and host plant on reproductive parameters of A. gossypii
Assuntos
Animais , Afídeos/fisiologia , Biologia , Hemípteros , ReproduçãoRESUMO
The aphid Aphis gossypii Glover is associated with several vegetable and ornamental greenhouse crops, especially chrysanthemum (Dendranthema grandiflora Tzvelev). The effect of different temperatures and chrysanthemum cultivars (Yellow Snowdon, White Reagan and Dark Splendid Reagan) on developmental time and survival of A gossypii were evaluated. The trials were carried out at environmental chambers, at constant temperatures: 15, 20, 25 and 30°C, 70±10 percent RH and photophase 10h. Nymphs of A. gossypii were kept individually on chrysanthemum leaf discs (2 cm diameter) of different cultivars in glass petri dishes, with 10ml of sterile solution of agar/water 1 percent. The increase of temperature from 15°C to 30°C, caused a significant reduction in the developmental time of the instars, and the first instar was the most affected. The survival of the nymphs of 1st and 2nd instars was affected by all chrysanthemum cultivars evaluated. These cultivars presented different densities of trichomes/mm² on the leaf (11.3, 16.6 and 21.6 trichomes, respectively), which provided higher survival to nymphs maintained on Yellow Snowdon cultivars (88.5 and 96.6 percent for the 1st and 2nd instars, respectively). The nymphal period decreased from 13.5 days at 15°C to 5.0 days at 30°C. Temperature and chrysanthemum cultivars affected the developmental time and the survival of the initial instars of A. gossypii, and this information is important for A. gossypii management in greenhouse crops.
O pulgão Aphis gossypii Glover está associado a culturas de grande importância econômica em cultivos protegidos, especialmente o crisântemo. Neste trabalho, avaliou-se o efeito de diferentes temperaturas e cultivares comerciais de crisântemo (Yellow Snowdon, White Reagan e Dark Spendid Reagan) sobre o desenvolvimento e a viabilidade de ninfas de A. gossypii. O experimento foi conduzido sob temperaturas constantes de 15, 20, 25 e 30°C, UR de 70±10 por cento e fotofase de 10h. Ninfas de A. gossypii foram mantidas individualizadas em discos foliares (2 cm de diâmetro) das cultivares de crisântemo, em placas de Petri, contendo 10 ml de solução estéril de agar/água a 1 por cento. O incremento da temperatura de 15°C para 30°C reduziu significativamente a duração dos ínstares, sendo o 1° ínstar o mais afetado. A sobrevivência das ninfas de 1° e 2° ínstar foi afetada pelas cultivares de crisântemo Yellow Snowdon, White Reagan e Dark Spendid Reagan as quais apresentaram diferentes densidades de tricomas/mm² na folha (11,3; 16,6 e 21,6 tricomas, respectivamente). Foi obtida maior sobrevivência para ninfas mantidas na Yellow Snowdon (88,5 e 96,6 por cento para o 1° e o 2° instares, respectivamente). O período ninfal decresceu de 13,5 a 15°C para 5,0 dias a 30°C. A temperatura e as cultivares de crisântemo afetaram o tempo de desenvolvimento e a sobrevivência dos instares iniciais de A. gossypii, sendo isso um importante parâmetro para a adoção de táticas de manejo desse pulgão em condições de ambientes protegidos.