Morphology of the Preimaginal Stages ofLasioptera donacisCoutin (Diptera: Cecidomyiidae), a Candidate Biocontrol Agent for Giant Arundo Cane

Donald B Thomas,John A Goolsby

doi:10.1155/2015/262678

Abstract

The larval stages ofLasioptera donacisCoutin consist of three instars which develop within the mesophyll of the leaf sheaths ofArundo donax(L.) (Poaceae). The larvae feed aggregatively on mycelia of an ambrosia fungus. The third instars are similar to other members of the genus except for a three-pronged spatula (typically two-pronged) and five lateral papillae (typically four) and with a nonbristled first instar. A related species,L. arundinis(Schiner) which breeds on fungus inPhragmites(Poaceae), also has a three-pronged spatula and five lateral papillae but has a bristled first instar. The third instar ofL. donacishas a feeding and a nonfeeding prepupal stage. Papillae associated with the spatula are sensory organs, sensilla chaetica, sensilla trichodea, and sensilla ampullacea, perhaps related to extraoral digestion of the fungal mycelia. Pupation occurs in the host plant within a silken cocoon. Egression of the adult is through an escape hatch excavated by the third instar.

Highlights

The genus Lasioptera Meigen 1818 is defined taxonomically by structures on the postabdomen and ovipositor of the adult female [1]
The fungus rewards its symbiont for providing transport to potential host plants by providing nourishment in the form of an ambrosia, a filamentous mycelial mass which fills the tunnels inhabited by the larvae [4]
Characterized by a fourth instar that lacks the spatula, paedogenesis has not been reported in Lasioptera, nor did we observe this phenomenon in L. donacis

Summary

Introduction

The genus Lasioptera Meigen 1818 is defined taxonomically by structures on the postabdomen and ovipositor of the adult female [1] These structures are mycangia, organs which function in the transport of fungal conidia. The fungus rewards its symbiont for providing transport to potential host plants by providing nourishment in the form of an ambrosia, a filamentous mycelial mass which fills the tunnels inhabited by the larvae [4]. In these cases of symbiosis the inoculation of the fungus into the plant by the insect has been documented for the Platypodidae (Coleoptera) [5], the Siricidae (Hymenoptera) [6], and the Cecidomyiidae (Diptera) [3, 7]. The preimaginal stages have morphological features which adapt them to this resource niche and the objective of this study is to describe some of those adaptations

Objectives

Methods

Results

Conclusion