IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 10, Issue 1 Ver. I (January. 2017), PP 54-58 www.iosrjournals.org DOI: 10.9790/2380-1001015458 www.iosrjournals.org 54 | Page Ovarian development in Cosmopolites sordidus Germar (Coleoptera: Curculionidae) Richard P. Uzakah* Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria Abstract: This study was undertaken to determine the ovarian development of banana weevils. Results indicated that female banana weevils have a meroistic and telotrophic ovariole. Four (4) stages of ovarian development were observed. Newly emerged females belonged to stage I, characterized by virtual absence of oocytes in female germarium; while fully mature adult females belonged to stage IV, characterized by the presence of mature, chorionated eggs in female calyces. The intermediate stages II and III were characterized by presence of small, undeveloped oocytes, and presence of developed but non-chorionated oocytes in the vitellarium of female ovarioles, respectively. The preoviposition period in this insect was found to range between 27 and 41 DAE and egg-loads in calyces ranged from 2 to 11. All females at ovarian stage IV (i.e. ages 25 DAE and above) were found to have mated, and were ready for ovulation and oviposition. Monitoring the reproductive phenology of crop pests may be helpful for predicting (forecasting) potential outbreaks. it could also aptly guide the timing of control options, and also aid varietal screening works. Field samplings that result in heavy female populations and with predominant numbers at final stages of ovarian development, may be a danger signal that should trigger instant interventions. Keywords: meroistic, telotrophic ovariole, ovarian development, pre-oviposition period, reproductive phenology I. Introduction The banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is a major insect pest of bananas and plantains the world-over; causing considerable reductions in yearly productions of the crop globally [1], [2], [3]. The pest attacks all species of Musa and no cultivar is known to have a total resistance to it; although certain cultivars are now known to be more susceptible to the borer than others [3], [4], [5]. At present, no single control strategy provides effective control [5], and so integrated approaches involving pseudostem trapping, crop hygiene, careful varietal selections, pheromone trapping, poison baiting and use of properly selected insecticides are often adopted in controlling this pest. For the development of novel control, knowledge of various facets of pest biology, ecology and behaviour is absolutely essential [6], [7]. Also, according to [8], thorough unde rstanding of an insect’s phenology allows for increased precision in the implementation of management techniques. The present study was therefore, aimed at investigating C. sordidus’ ovariole type, ovarian development and pre-oviposition period with a view to help shed some light on vital aspects of the weevil’s reproductive structure and phenology. It is hoped that the knowledge gained from this would help to reveal the reproductive status of field-females captured from surveys and traps, since such information is known to have a direct relationship with the damaging potential of pests [9]. Heavy female catches with significant proportions also being at late or final stages of ovarian development, will soon give rise to high field infestations and so should necessitate instant control measures, such as intensive trapping or even chemical control. II. Materials and methods 2.1 Reproductive structure (Studies on Ovariole type) Longitudinal sections of ovarioles of dissected adult females were passed through several histological processes of fixing in Boine’s solution for 48 hours, washing-off excess fixatives and dehydrating the tissues in ascending alcohol grades of 30%, 50%, 70%, 90% and absolute alcohol; and clearing in chloroform. Tissues were then infiltrated in molten paraffin wax and kept in an oven maintained at 56°C for 5 hrs (renewing the paraffin wax at intervals of 1, 2 and a further 2 hours, respectively). Tissues were thereafter embedded in molten paraffin wax and sectioned using Jung rotary microtome at six micron (6 μ) thickness. Sectioned tissues were mounted on microscope slides, stained with haematoxylin and counterstained with Eosin. Stained sections were finally examined under the compound microscope (Leitz Laborlux K) in order to determine the ovariole type of this pest.