Parthenogenesis affects interspecific competition between Megalurothrips usitatus and Frankliniella intonsa (Thysanoptera: Thripidae) in changing environment: evidence from life table study

Abstract

The thrips Megalurothrips usitatus Bagnall and Frankliniella intonsa Trybom (Thysanoptera: Thripidae) are important pests in cowpea-growing areas of south China. Parthenogenesis is an important reproductive form of thysanopterans, and plays an important role in maintaining population growth. To understand the developmental and reproductive characteristics of these 2 thrips species during parthenogenesis, we compared the age–stage life tables of M. usitatus and F. intonsa on cowpea pods under natural regimes during the summer and winter. The results showed that the total preadult period and total preoviposition period of M. usitatus were significantly longer than those of F. intonsa in both seasons. Moreover, longevity of adult M. usitatus (29.53 days) was shorter compared with adult F. intonsa (34.00 days) in summer, whereas higher fecundity (220.8 eggs/female) and more oviposition days (37.83 days) were observed in M. usitatus compared with F. intonsa in winter (fecundity = 179.83 eggs/female, oviposition days = 33.03 days). The net and gross reproductive rates of M. usitatus were significantly greater than those of F. intonsa during winter. In addition, the intrinsic and finite rates of increase of M. usitatus were significantly lower than those of F. intonsa, and the mean generation time of M. usitatus was significantly longer than that of F. intonsa both in summer and winter. These results indicated that parthenogenesis has species specificity among thrips, which in turn affects population development, especially under changing environments.