Victor Luiz de Souza Lima

Estimativa do índice de área foliar e determinação do coeficiente de extinção luminosa da abóbora Cucurbita moschata var. japonesa

Os metodos indiretos para a determinacao do indice de area foliar (IAF), que sao caracterizados em medidas da radiacao total que penetram no interior da cobertura vegetal, sao atualmente os mais utilizados, por serem mais praticos. O estudo teve como objetivo medir e estimar o indice de area foliar, ajustar uma equacao atraves do produto de (comprimento x largura x area foliar) e determinar o coeficiente de extincao luminosa em abobora Cucurbita moschata var. japonesa. Para desenvolver um modelo, foram medidas vinte folhas determinando-se o comprimento e a largura e para a estimativa do indice de area foliar, foram utilizados cinco repeticoes de 1m2, sendo feitas tres medidas no interior das folhas e uma medida na parte superior das plantas. Posteriormente, suas folhas foram coletadas para medicoes de area foliar em laboratorio. Para a obtencao do coeficiente de extincao luminosa (k) foram medidos quinze pontos da cultura, em condicoes de sol e de sombra. O IAF medido foi 1,145 e o estimado 2,624, mostrando um modelo matematico com crescimento linear originando uma reta e o coeficiente de extincao foi de 0,59. Este trabalho foi importante para determinar os valores de IAF medido, estimado e o coeficiente de extincao para a cultura de abobora.

Functional response of Trichogramma pretiosum on Trichoplusia ni eggs at different temperatures and egg densities

The objective of this work was to determine the functional response of the parasitoid Trichogramma pretiosum on Trichoplusia ni eggs at different temperatures (20, 25, and 30oC) and egg densities (5, 10, 15, 20, 25, and 30 eggs). The logistic regression showed a type-II functional response for all temperatures. The search efficiency of T. pretiosum was reported as 0.049±0.0019, 0.069±0.0042 and 0.068±0.0033 per hour, and the estimated handling times were 1.82±0.0424, 1.69±0.0398, and 1.54±0.0498 hour at 20, 25 and 30oC, respectively. Females of Trichogramma pretiosum show greater efficiency at 30oC and a type-II functional response. The parasitism rate decreases, when host density increases.

Thermal requirements, development and number of generations of Duponchelia fovealis (Zeller) (Lepidoptera: Crambidae)

In this study, the effect of temperature on the growth of the European pepper moth, Duponchelia fovealis (Zeller), was assessed at five constant temperatures (18, 21, 24, 27 and 30 °C). The European pepper moth was observed to complete its developmental stages (from egg to adult) at all the temperatures evaluated. From the results, it was evident that temperature affected the rate and development time of all the growth stages, to a significant degree. The length in time of the embryonic, larval, pupal and total (egg-adult) stages was observed to drop as the temperature rose from 18 to 24 °C, but remained constant between 27 and 30 °C. The developmental time in the pre-pupal stage dropped between 18 and 30 °C. The European pepper moth takes 454 degree-days to complete development at 11.7 °C temperature threshold. The D. fovealis survival was thus inversely proportional to temperature over range of 18 to 30 °C. On assessing the number of annual generations for the five largest strawberry-producing municipalities in Espírito Santo State, an average of 5.5 generations per year was estimated. This is a first report of temperature on D. fovealis development.