Morphometrics and reproductive parameters of Rhynchophorus morphotypes(Coleoptera: Curculionidae) in Ghana

Palm weevils are widely distributed throughout Ghana causing severe economic injuries to palm plantations. However, the description and categorisation of palm weevil species based on the morphology in Ghana are lacking. This study sought to identify and determine the morphometrics and reproductive parameters of different Rhynchophorus morphotypes in Ghana. One thousand and two hundred (1200) larvae each weighing 5 grams were collected by handpicking from infested palm trunks from palm plantation site in the Middle Belt (Kobedi, Diabaa, Asuhyiae, Nsuta, Tanoso, Bomaa, and Akrodie) and Southern Ghana (Fumesua, Kubease, and Donyina). These larvae were allowed to cocoon and pupate, and the adults that emerged were described and categorised into different morphotypes using morphological description keys of Rhynchophorus species. Three Rhynchophorus morphotypes were identified and described; rusty red weevil with black spots on the pronotum (RRW), black weevil with two red stripes on the pronotum (BWS), and black weevil without a longitudinal stripe pronotum (BW). The fecundity and female longevity of morphotypes of BWS (FF = 102.6 ± 38.85, FL = 43.6 ± 12.07) and BW (FF = 100.1 ± 39.45, FL = 43.6 ± 12.10) were superior to mature RRW female morphotype (FF = 39.1 ± 28.33, FL = 38.6 ± 9.21). The RRW morphotype may require more generations to adapt to the conditions in Ghana to improve on its life history parameters. The lowest fecundity of the RRW morphotype could be an advantage to limiting its spread across palm plantation sites in Ghana.