Lai, M.T., & Chang, N.T. 2007 Evaluations of the effectiveness and economic benefits of different pesticide-application techniques in controlling a mealybug, Planococcus minor, on the winter crop of sugar apple, Annona squamosa. . Plant Protection Bulletin (Taipei) 49(2): 111-126

Notes: The efficacy and economic benefits of using manual (MA) and mobile fogger (MFA) pesticide-application techniques in the control of a mealybug, Planococcus minor, on the winter crop of sugar apple, Annona squamosa, were evaluated in 2005. The mean fruit injury area after using both methods were 2.1 and 6.42%, respectively. In comparison with the injury area of the non-treated fruit, the control efficacy of MA was as high as 93.6% and significantly higher than that of MFA (78.4%). Based on the number of mealybugs counted (y) and the percentage of fruits area infested (x), the regression equation of y = 237.69x - 3.59 (r¡ª0.9761, p<0.05) was calculated. The number of mealybugs on fruit with injury area >30% which has no commercial value on market, is about 70/fruit. Based on the various control costs and market values, the actual incomes for treatments of without pesticide application, MA, and MFA were 244,636, 467,317 and 441,779 NTD/ha, respectively. Due to the 2.87-fold costs of MA, the net incomes (actual income - control cost) by using MFA (426,279 NTD/ha) was about 3500 NTD/ha more than that by MA (422,817 NTD/ha). Results of the analysis of their economic benefits showed that the MFA was a better method. In order to improve the control efficacy of MFA, an improved mobile fogger application method (IMFA) of combining MFA and MA, was added in the tests of 2006. The control percent of IMFA (84.1%) was significantly higher than that of MFA (78.7%). Based on our studies on the occurrence of mealybugs, its movement and infestations in the field, and the control costs and benefits of sugar apple production, the best control timing for the mealybugs would be in the spring from March to April and in the fall from September to October, when the nymphs and adults of the mealybugs were crawling upward from the root bases to the fruits. Also, the use of IMFA would be mostly effective in the control of the mealybugs in an orchard.