Exigências Térmicas de Bemisia tabaci (Genn.) Biótipo B (Hemiptera: Aleyrodidae)

Abstract

-The development (egg-adult) of Bemisia tabaci (Genn.) B-biotype (=Bemisia argentifolii, Bellows & Perring), was studied in field conditions and in incubators at constant temperatures (15, 20, 25, 30 and 35±1ºC), using soybean, Glycine max (L.) Merrill, Msoy 8001, as host plant. The temperatures threshold (Tb) and the thermal constant (K) for egg, nymph and life cycle (egg-adult) were 11.1ºC / 98.8 degree-days; 6.8ºC / 383.8 degree-days and 8.3ºC / 472.6 degree-days, respectively. At the temperatures of 15 o C and 35ºC, insect viability was smaller. In the field, 70% of the adults emerged after 413,2 degree-day were accumulated. The degree-day pattern used was adequate for the previewing Bemisia tabaci B-biotype adult occurrence in field, and it can also be used to determine the number of generations in different areas of the country.KEY WORDS: Bemisia argentifolii, whitefly, degree-day, temperature, Glycine max, soybean.RESUMO -O desenvolvimento (ovo-adulto) da mosca-branca, Bemisia tabaci (Genn.) biótipo B (=Bemisia argentifolii, Bellows & Perring), foi estudado em condições de campo e em câmaras climatizadas, reguladas nas temperaturas constantes de 15, 20, 25, 30 e 35±1ºC, usando soja, Glycine max (L.) Merrill, cultivar Msoy 8001, como planta hospedeira. O limite térmico inferior de desenvolvimento (Tb) e a constante térmica (K) das fases de ovo, ninfa e ciclo biológico (ovo-adulto) foram 11,1ºC / 98,8 graus-dia, 6,8ºC / 383,8 graus-dia e 8,3ºC / 472,6 graus-dia, respectivamente. Nas temperaturas extremas (15 o C e 35ºC), a viabilidade dos insetos mostrou-se menor. No campo, a emergência de 70% dos adultos ocorreu depois de terem sido acumulados 413,2 graus-dia. O modelo de graus-dia utilizado mostrou-se adequado para a previsão de ocorrência de adultos de Bemisia tabaci biótipo B no campo, podendo também ser utilizado para determinação do número de gerações nas diferentes regiões do País.

Performance of Bemisia tabaci (Genn.) Biotype B (Hemiptera: Aleyrodidae) on Weeds

“…12.8 to 28.4°C), which was lower than the ideal temperature for the insect. Albergaria & Cividanes (2002) observed an 11.9-day incubation period of B. tabaci biotype B at 20°C, close to the result found in this research. The viability of the eggs remained above 94% for all treatments except pigweed, which had a mean value of 87.5% (Table 2).…”

“…When examining the mean viability of eggs, it was noted that soybean and red tasselflower induced 100% viability, differing from pigweed with 92%. As for the other treatments, the viabilities reached 99% (beggarticks), 98% (spurge and small-flower galinsoga), 97.5% (black nightshade), and 96.5% (morning glory), which are within the values normally found for this stage of the insect and similar to studies by Albergaria & Cividanes (2002), who found egg viability ranging from 58.6 to 97.7% in soybean.…”

Threats to cassava production: known and potential geographic distribution of four key biotic constraints

“…The pest causes damage from direct feeding and indirect damage through honeydew secretion, promotion of fungal growth and vectoring several plant viruses (Ko et al 2005;Nunes et al 2005;Anderson and Morales 2005;Liu et al 2007). More than 600 host plants suffer from B. tabaci attacks, causing yield losses as high as 100% in certain crops (Albergaria and Cividanes 2002;Nunes et al 2005;Anderson and Morales 2005). B. tabaci causes substantial damage from the diseases that they transmit (Ko et al 2005), most importantly, Cassava Mosaic Disease (CMD) and Cassava Brown Streak Disease (CBSD).…”

Efeitos da temperatura e do alimento no desenvolvimento de Dysdercus maurus Distant (Hemiptera, Pyrrhocoridae)

“…Segundo Silveira Neto et al (1976), a exigência térmica de uma espécie determina a velocidade de seu desenvolvimento, o número de gerações por ano e a prolificidade. No estudo das necessidades térmicas dos insetos quanto ao desenvolvimento, podem ser obtidas a constante térmica (K), em graus-dias, e a temperatura base (Tb), menor temperatura necessária para o desenvolvimento (Albergaria & Cividanes 2002;Mendes et al 2005).…”