Comparative Evaluation of Development and Reproductive Capacity of Two Biotypes of Lilioceris cheni (Coleoptera: Chrysomelidae), Biological Control Agents of Air Potato (Dioscorea Bulbifera) in Florida

© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. A Chinese biotype of Lilioceris cheni Gressitt and Kimoto (Coleoptera: Chrysomelidae) is being mass reared and released in Florida for biological control of the invasive air potato vine, Dioscorea bulbifera L. (Dioscoreales). Another biotype from Nepal is under investigation for determining whether its release would benefit the ongoing biological control program.We compared temperature-dependent development, fecundity, life table parameters, and consumption of the two biotypes in the laboratory. Both biotypes completed development at 20-30 C, although survival of Chinese beetles was higher at 20 C and 27.5 C, and survival of Nepalese beetles was higher at 30 C. In addition, Nepalese beetles developed at a faster rate at 20 C, and consumed air potato foliage at a higher rate at 25 C. The most important difference between the biotypes, with regard to biological control purposes, was the shorter generation time of Nepalese beetles, which resulted in a higher intrinsic rate of population increase, despite much higher fecundity of Chinese beetles. The higher intrinsic rate of increase of the Nepalese beetles may allow a more rapid population increase in the field, and thus, greater damage to air potato plants. However, differences in other life history traits, such as overwintering ability, diapause, and cold tolerance, will also influence field performance

Modeling groundwater recharge through rainfall in the Far-North region of Cameroon

The Far-North region of Cameroon is threatened by extreme water shortage. Over the years groundwater has increasingly been used as the main source of domestic water supply. In spite of the increased, groundwater exploitation has been done without adequate planning. One of the key parameters of a sustainable groundwater management is the regional groundwater recharge rate, which defines the upper limit for which groundwater abstraction should not exceed. This paper summarizes the results of transferring the water balance model GROWA to the Far-North region of Cameroon. The main aim was to assess the spatial distributed groundwater recharge rate through rainfall. Due to the lack of adequate regional data bases, international data sources, e.g. the World soil map in scale of 1: 3,000,000 were used to derive the input parameters needed to run GROWA model. The simulated GROWA results show a satisfying agreement with existing groundwater recharge rate assessments for most areas of the study region. Against this background, it was concluded that GROWA model results represent reliable reference values for groundwater recharge through rainfall even though the input parameters were derived from small-scale generalized international maps. This approach provides a relevant initial step for a more detailed groundwater recharge estimate. A more accurate estimation for groundwater recharge should be carried out once the input data for the study area are available in higher spatial resolution including runoff records for a plausibility check of the modeled water quantities for groundwater recharge