0851996884.pdf

them more susceptible to disease (Goodwin,
1984; Maddox, 1987). The following sum-
mary of pathogens in natural enemies and
pollinators will include those reported from
both field-collected and mass-reared individ-
uals. An overview of pathogen presence in
mite and insect genera that include species
used in biological control or pollination is
presented in Table 10.1.

Causes of Diseases in Natural Enemies

and Pollinators

Insect diseases may be broadly categorized
as either infectious or non-infectious, based
on the respective presence or absence of a
transmissible, living organism. Diseases
classified as non-infectious may be caused
by mechanical injury, adverse physical envi-
ronmental factors, chemical toxins or poi-

sons, injuries made by predators and para-

sitoids, genetic abnormalities or nutritional

deficiencies (Thomas, 1974; Gaugler, 1987).

In contrast, infectious diseases among

insects are caused by a variety of pathogens,

including viruses, bacteria, fungi, protozoa

and nematodes (Thomas, 1974; Tanada and

Kaya, 1993).

Diseases caused by viruses

Viruses have been isolated from more than

1000 species of insects, representing at least

12 insect orders, and have also been reported

from mites, ticks and marine crustaceans

(Martignoni and Iwai, 1981; Tanada and

Kaya, 1993).Viruses are obligate, intracellular

pathogens that consist of one or more nucleic

acid template molecules, normally encased

in a protective coat or coats of protein or

134 S. Bjørnson and C. Schütte

Table 10.1.Pathogen presence in mite and insect genera that include species used for biological control
or pollination.

Unidentified

Viruses Bacteria Protozoa Fungi Nematodes disease

Steinernema XXX
Heterorhabditis XXX
Metaseiulus XX
Neoseiulus XX XX X
Phytoseiulus XX X X
Aphidoletes X
Chrysoperla XXX
Adalia XXX
Coccinella XXX
Coleomegilla XX
Harmonia XXX
Hippodamia XXX
Aphidius X
Aphytis X
Cotesia XXX
Dacnusa X
Encarsia XX
Eretmocerus XX
Lysiphlebus X
Muscidifurax XX
Nasonia X
Opius X
Pediobius X
Trichogramma XX
Bombus XX XXX

X, pathogen from respective group present.