Demographic Analysis of Effect of Host Plants, Sex Ratio and Male Attractant on the Population Traits of Bactrocera dorsalis (Hendel) Based on Two-sex Life Table Theory

• Main Authors: Yu-Bing Huang, 黃毓斌
• Other Authors: 齊心
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/50682923739877623738

博士 === 國立中興大學 === 昆蟲學系所 === 103 === The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most destructive pests in the Asia and Pacific area and is an important quarantine pest for the United States and many countries. This fly attacks more than 150 cultivated and wild fruits in Taiwan. To build an ecological database, the life table of B. dorsalis reared on seven host plants and an artificial diet at 25 ± 1°C, 70 ± 10% R.H., and a photoperiod of 12:12 (L:D) h was studied. The life history raw data were analyzed using an age-stage, two-sex life table. The mean fecundity (F) ranged from 252.3 to 1300.3 eggs per female, and the highest fecundity was observed on pomelo; the net reproductive rate (R0) ranged from 100.9 to 588.3, and the highest reproductive rate was observed on jujube. The intrinsic rate of increase (r) was 0.1790, 0.1667, 0.1333, 0.1261, 0.1161, 0.1128, 0.1120, and 0.0797 d-1 on pitaya, artificial diet, guava, sweet orange, wax apple, pomelo, jujube, and wild-type mango in descending order, respectively. These studies were explained not only the high fitness of B. dorsalis as a pest in many areas but also the difficulty in managing this pest in past decades. For a two-sex population, the sex ratio plays an important role in population ecology and pest management. Male annihilation and sterile insect release are used as major strategies in fruit fly control. Therefore, the effect of the sex ratio must be understood for the quantitative planning of these methods. In this study, the life tables of the oriental fruit fly, at different adult sex ratios were collected. At the sex ratio 1♀:1♂, the adult pre-oviposition period (APOP, time duration from adult emergence to the first reproduction) and total pre-oviposition period (TPOP, time duration from birth to the first reproduction) was 11.0 d and 28.9 d, respectively. The females mated an average of 2.2 times during their lifespan. The net reproductive rate (R0), intrinsic increase rate (r), finite rate (λ), and mean generation time (T) were 555.0 offspring, 0.1689 d-1, 1.1840 d-1, 37.4 d, respectively. Both the APOP (7.7 d) and TPOP (25.2 d) were significantly shorter than those at the sex ratio 1♀:1♂, although the females laid an average of 1610.2 eggs. The population parameters R0, r, λ, and T were 31.6 offspring, 0.0727 d-1, 1.0754 d-1, and 47.5 d, respectively. At the female-biased sex ratio of 50♀:1♂ and no-choice mating, the APOP and TPOP were 44.4 d and 63.4 d, respectively. Males mated an average of 53.3 ± 12.2 times during their life time, but females mated only once. Females laid an average of 578.0 eggs. The values of R0, r, λ, and T were 566.6 offspring, 0.1199 d-1, 1.1274 d-1, and 52.9 d, respectively. The APOP and TPOP were 33.2 d and 52.3 d, respectively, at the female-biased sex ratio of 50♀:1♂ and free-choice mating. The females laid an average of 701.7 eggs. The values of R0, r, λ, and T were 687.9 offspring, 0.1326 d-1, 1.1417 d-1, and 49.3 d, respectively. Methyl eugenol (ME) is a powerful attractant for males of many tropical tephritid fruit flies. Since the 1980s, mixtures of ME and a variety of pesticides have been used in the control and monitoring of B. dorsalis in Taiwan. However, the effect of ME on the population parameters and population growth of B. dorsalis in Taiwan remains unclear. The life table raw data were analyzed by using the age-stage, two-sex life table to compare population parameters. The mean fecundity (F) ranged from 1082.9 to 1778.0 eggs, and the highest fecundity observed in ME-male cohort. The net reproductive rate (R0) ranged from 542.0 to 888.0 eggs, and the highest reproductive rate was observed in the same ME-male cohort. The intrinsic rate of increase was 0.1744, 0.1695, and 0.1616 d-1 on the male-fed-ME cohort, female-fed-ME cohort, and ME-deprived cohort, respectively. Results showed that females of the male-fed-ME cohort had the highest fecundity; however, no significant differences in the net reproductive rate and intrinsic rates. Because the oriental fruit flies are an ectothermic organisms, their development, survival, and reproduction are significantly affected by abiotic conditions. The studied indicated that life table is the most comprehensive and important basis of population ecology and pest management. Moreover, life tables are affected by host plants, sex ratio and other biotic factors, i.e., natural attractants. For an effective pest management program, we need to collect life tables of major pests on their main factors and under different environmental conditions. Population projection is also an important tool for detecting population growth trends, for describing stage structure, and for scheduling the pest management strategies.