Developmental and reproductive response of Brachmia macroscopa (Lepidoptera: Gelechiidae) to three host plants

The sweet potato leaf folder, Brachmia macroscopa Meyrick (Lepidoptera: Gelechiidae), which is a significant pest of plants in the family Convolvulaceae, is rapidly expanding its range in South China and other subtropical regions. Studies were designed to examine the effects of three different host plants (sweet potato, Ipomoea batatas (L.) Lam.; water spinach, I. aquatica Forsskål; and morning glory, Pharbitis purpurea (L.)) on the development and life table parameters of B. macroscopa under laboratory conditions. We found that the intrinsic rates of increase of B. macroscopa were 0.17 ± 0.004, 0.21 ± 0.005 and 0.16 ± 0.004 on I. batatas, I. aquatica and P. purpurea, respectively. The highest net reproduction rate was 158.06 ± 18.22 per female reared on I. aquatica. The larvae had five instars when reared on I. batatas and I. aquatica, but required six instars on P. purpurea. The mean generation lengths of B. macroscopa ranged from 24.32 ± 0.18 days when reared on I. aquatica to 29.40 ± 0.24 days on P. purpurea. The survival of all stage and fecundity curves was intuitively manipulated using the age-stage-structured and two-sex population life table method, to enable comprehensive descriptions of the stage and population trends of B. macroscopa on the three Convolvulaceae plants. Our results indicated that I. batatas and I. aquatica were more suitable host plants than P. purpurea.