Insect Control: Biological and Synthetic Agents - Index of

As molecular analysis has the ability to link anamorphic
stages with appropriate teleomorphic genera,
the use of a dual nomenclature system is probably
superfluous, but may be hard to lose in the short
term.
The main classes that contain entomopathogenic
species are reviewed in the following sections.
Examples of insects infected with entomopathogenic
fungi are presented in Figures 1–15.
11.2.1. Phylum Oomycota
11: Entomopathogenic Fungi and their Role in Regulation of Insect Populations 389
Oomycetes are characterized by cellulose containing
coenocytic hyphae, biflagellate zoospores, and usually
contain no chitin. Sexual reproduction can
occur between gametangia (antheridia and oogonia)
on the same or different hyphae. While a number of
species are saprophytes and parasites of animals and
plants, two genera contain species pathogenic to
mosquito larvae. The best studied species is Lagenidium
giganteum (Lagenidiales), a pathogen of mosquito
larvae (Glare and Milner, 1991; Kerwin and
Petersen, 1997). Other species of Lagenidium can
cause infections in aquatic crustaceans, such as
crabs (e.g., Hatai et al., 2000).
Leptolegnia spp. (Saprolegniales) have also been
reported to be pathogenic to mosquitoes, chironomids,
and several other Diptera. These species are
thought to infect via a secondary zoospore formed
after encystment of the primary zoospore derived
from sporangia (Zattau and McInnis, 1987).
11.2.2. Phylum Chytridiomycota
Chrytridiomycetes are characterized by cell walls
containing chitin and no cellulose. Posteriorly uniflagellate
zoospores and gametes settle and grow
into a thallus, which becomes either a resting spore
or coenocytic hyphae. This group is considered
basal to the fungal branch under SSU rRNA
phylogenetic comparisons. The Blastocladiales genus
Coelomomyces contains most of the common entomopathogenic
Chytridiomycetes. There are over 70
entomopathogenic species described in the Coelomomyces
(Lucarotti et al., 1985). These species have
been described from Diptera (mainly mosquitoes)
and Heteroptera. Several species have an obligate
intermediate host, such as copepods. They are characterized
by formation of both thick walled resistant
sporangia and flagellate zoospores. Other entomopathogenic
species are known from Coelomycidium
(Blastocladiales) and Myriophagus (Chytridiales);
the former is found on blackflies and mosquitoes,
and the latter has been reported as a pathogen
on dipterous pupae by Sparrow, 1939 and Karling,
1948 (in Samson et al., 1988).
11.2.3. Phylum Zygomycota
Traditionally, the Zygomycota are separated on the
basis of often nonseptate, multinuclear hyphae, and
production of zygospores by copulation between
gametangia. However, molecular analyses have
not found the Zygomycota to be monophyletic
Figure 1 Larvae of the European wireworm, Agriotus obscurus, killed by Metarhizium anisopliae. The progression of the emergence
of the fungus from the cadavers and subsequent development of fungal structures is seen from left to right, with the larva on the
right completely covered by the green spores of the fungus. (Photo courtesy of T. Kabaluk.)