A network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests.
PestNet is a network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests. It started in 1999. Anyone with an interest in plant protection is welcome to join. PestNet is free and is moderated, ensuring that messages are confined to plant protection.
November 2002. Papua New Guinea asked where it was possible to say whether the weevils in the photo are Oribius cruciatus Faust. These specimens vary from the described Oribius cruciatus (see photo to right) in the whitish scale patterns on the elytra. They seem to be the same species showing varying scale patterns. Oribius cruciatus is a serious pest causing shothole damage to wide range of crops including coffee, cocoa, rubber, cashew nuts, etc. in Papua New Guinea. To date, collections have only been made in the Popondetta area of PNG. The variation could be due to their restriction to certain geographic area.
A reply from CSIRO said that it was mpossible to tell just from these photographs and a few specimens. The specimen identified as O cruciatus is evidently a male, while the two on the other photo appear to be females. The difference in colour pattern could be due to sexual dimorphism, but colour is often highly variable in weevils (particularly in entimines), and both males and females of O cruciatus may have a full or only a partial “cross”. Geographical variation can also be involved if your specimens come from different localities and/or populations. On the other hand, closely related species may indeed differ in colour pattern such as this one.
It was thought likely that the specimens were from the same species, but without actual specimens (series of both sexes!) and checking the genitalia and other critical structures it was not possible to tell.