Economic injury level and sequential sampling plan for Bemisia tabaci in outdoor tomato

Abstract

This work aimed to determine the economic injury levels and to establish sequential sampling plans for nymphs and adults of the whitefly Bemisia tabaci Genn. (Sternorrhyncha: Aleyrodidae) in tomato fields. Densities of nymphs and adults, as well as crop yield were evaluated in 13 commercial tomato fields to determine the economic injury levels. The whitefly nymphs were sampled by direct counting in a leaf from the lower part of the canopy and the adults were sampled by beating an apical leaf against a white plastic tray. The sequential sampling plan was based on data collected in eight commercial tomato fields. The validation of the sequential sampling plan was carried out based on the curves of operational characteristics and average sample numbers. The decisions reached with the conventional and the sequential sampling plans in 21 commercial fields were compared for the intended validation of the sequential plan. The economic injury levels were four nymphs per leaf and one adult per tray. The decisions taken based on the sequential sampling plan were similar to those obtained through the conventional sampling plan. Most of the decisions taken with the sequential sampling plan were obtained through the minimum number of seven samples per field for nymphs and 11 samples per field for adults, with reductions of 84.44% and 54.17% in the number of samples required to reach a decision with the sequential sampling plan compared with the conventional sampling plan.

Calcium silicate and organic mineral fertilizer increase the resistance of tomato plants to Frankliniella schultzei

“…The control of F. schultzei is accomplished, traditionally, with chemical insecticides (Cox et al 2006), but the use of these products above recommended rates reduces the beneficial fauna, which in turn increases problems with pests (Atakan 2006;Gusmão et al 2006;Leite et al 2006).…”

Population Dynamics, Demography, Dispersal and Spread of Bemisia tabaci

“…Recent effort has focused on a number of other crops including tomato (Miranda et al 1998;Arno et al 2006;Gusmao et al 2005Gusmao et al , 2006, cantaloupe (Gould and Naranjo 1999;Lin et al 2006), cucumber, watermelon and muskmelon (de Moura et al 2003;Shen et al 2005a), grapes (Haji et al 2001), peppers (Fernandez et al 2002;Lacasa-Plasencia et al 2004), sesame (Laurentin and Pereira 2002), common bean (Pereira et al 2004a, b), eggplant (Shen et al 2005a) and gerbera (Yao and Zheng 2007). Cotton also continues to be a focus of sampling research (e.g., Ahmad and Aslam 2002;Atakan and Canhilal 2004;Gencsoylu 2007;Karut and Kazak 2007).…”

Insect economic levels in relation to crop production

“…Random plants are examined when mobile insects are being surveyed (Binns and Nyrop 1992). In this case, the next plant to be examined will not be adjacent to you but will be some distance away (Gusma´o et al 2006) (Figure 2). …”