Developmental differences of local populations of alfalfa weevil (Hypera postica) (Coleoptera: Curculionidae)

Abstract

Many invasive insect pests show phenotypic variation between local populations across their geographical range. Understanding and integrating such differences will help to improve pest management. Population differences are the result of local adaptation to environmental conditions and may be detected using ecological analyses. Immature stages may represent especially interesting study objects as they represent important stages in the life cycle of insects and in many cases may be the most destructive stage. The alfalfa weevil, Hypera postica (Gyllenhal, 1813), is a variable worldwide pest that heavily damages alfalfa fields and is widely distributed in Iran. The lack of information about Iranian populations of H. postica has motivated us to examine immature life stages of three western populations (Karaj, Hamedan, Tuyserkan) and one eastern population (Jovein) under laboratory conditions. We measured the percentage of survival and the developmental times of each immature stage. The results suggested that the mean duration of the pupa stage significantly differs among the eastern population and all western populations (P < 0.005). Egg survivorship was lower in the eastern population (72.5%). The importance of differences in development times between populations is discussed in regards of pest management strategies.

Effects of Temperature and Relative Humidity on the Embryonic Development of Hypera postica Gyllenhal (Col.: Curculionidae)

“…Although, at low temperatures, very few eggs of H. postica hatched at humidity levels below 95% in a previous study [ 30 ], our results showed that nearly 50% of the eggs survived at a low RH regime. The differences between our results and others from North America or Middle East could be due to differences between regional populations [ 19 , 21 ], as has been reported when the influence of temperature in the postembryonic development of H. postica was studied [ 14 , 18 ].…”

“…However, our results differ from those of these authors because a high proportion of eggs hatched even at a medium and low HR. (3) The survival of eggs was higher at a medium RH at middle-high temperatures (24, 28, and 32 °C), indicating that a globally medium RH is the best regime for egg hatching for Spanish populations of H. postica, which was also observed in studies done with populations from the Asian Middle East [ 14 , 19 ].…”

“…Most of the studies regarding the temperature-dependent development of H. postica have been focused in larvae and pupae and have been carried out with populations from North America and Middle East Asia [ 14 , 18 ]. The results of these studies suggested wide variations in geographical regions [ 19 , 20 , 21 ]. On the other hand, literature dealing with the effect of abiotic factors on embryonic development is scarce.…”

Global genetic diversity, lineage distribution, and Wolbachia infection of the alfalfa weevil Hypera postica (Coleoptera: Curculionidae)

“…Several factors may have contributed to the mitochondrial lineage divergence and diversification in H. postica ; these may include population history, adaptation to different hosts, or disrupted interpopulation gene flow (Iwase, Nakahira, et al, ; Iwase, Tani, et al, ; Sanaei & Seiedy, ; Sanaei, Seiedy, & Momtazi, ; Sanaei et al, ). One additional potentially important agent is the intracellular alpha‐proteobacteria Wolbachia (Hertig, ; Werren, ).…”

Deep divergence and evidence for translocations between Iranian and European populations of the alfalfa weevil (Coleoptera: Curculionidae) based on mitochondrial DNA

“…However, geometric morphometric analyses showed that the Jovein population has significant differences in pronotum shape compared to other Iranian populations (Sanaei et al 2015b). In addition, the separation of the eastern population (Jovein) from other western populations was observed in some important ecological aspects (Sanaei and Seiedy, in press): immature life stage analysis indicated that the pupal stage of the Jovein population is one day longer than in the western populations (Sanaei and Seiedy, in press). Our mitochondrial data is compatible with these previous morphometric and life table data, but cannot support them strongly (Table 3).…”