[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

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R. CAMPOS-HERRERA ET AL.
Heterorhabditis and Steinernema, respectively. The bacteria are carried in the nematode
intestine and released into the host upon infection (Poinar, 1990). Insect death usually
occurs within 72 h of infection, and the nematodes feed, develop to adults, and
reproduce within the host, often completing 2–3 generations, before producing a new
generation of specialized IJs, which emerge from the cadaver and seek new insect hosts
(Poinar, 1990). Because of their established safety to non-target organisms, EPNs are
exempt from pesticide registration with the Environmental Protection Agency in the
United States and are similarly exempt in many other countries.
EPNs have been used effectively in classical biological control programs. For
example, Steinernema scapterisci was discovered in Uruguay, near the presumed
center of origin of the mole cricket (Scapteriscus spp.). The nematode was
introduced into Florida where it is now established and, in combination with
introduced parasitoids, provides effective biological control of several invasive mole
cricket species (Nguyen & Smart, 1990; Adjei, Smart, Frank, & Leppla, 2006). Most
commonly, however, EPNs are used for augmentation biological control where they
function as biopesticides and treatment efficacy is expected to be of short duration,
typically a matter of 1–2 weeks (McCoy et al., 2000; Duncan et al., 2003, 2007). In
such programs, EPNs function in the same manner as non-persistent chemical
pesticides and are applied repeatedly, as needed.
Surveys have shown that some naturally occurring EPNs are more abundant in
undisturbed compared to intensively farmed habitats (Campos-Herrera et al., 2008), and
that use of various animal manure mulches can increase the prevalence of some EPNs
(Bednarek & Gaugler, 1997; Duncan et al., 2007). Such observations suggest the
possibility of developing conservation biological control tactics by which agricultural or
other managed habitats are modified in ways that enhance natural control of arthropods
by EPNs. However, reliable and effective conservation biological control tactics are as
yet unknown and remain a matter of speculation (Lewis, Campbell, & Gaugler, 1998;
Stuart, Barbercheck, Grewal, Taylor, & Hoy, 2006).
In the Florida citrus industry, Steinernema carpocapsae was the first nematode to
be developed commercially for root weevil control (Schroeder, 1987; Figueroa &
Roman, 1990; Smith, 1994) but a further discovered species, S. riobrave (formerly S.
riobravis) (Cabanillas, Poinar, & Raulston, 1994), was found to cause greater D.
abbreviatus mortality (Schroeder, 1994; Duncan et al., 1996; Bullock et al., 1999) with
some field studies reporting ~90% suppression (Duncan & McCoy, 1996; Duncan et
al., 1996; Bullock et al., 1999). However, estimates of the efficacy and profitability of
using EPNs for weevil control in citrus vary widely and probably reflect variation in
factors such as product quality, application rates, suitability of edaphic conditions for
EPNs, and experimental methods (Adair, 1994; Duncan et al., 1996; Duncan, Graham,
& Zellers, 2002; Duncan et al., 2003; 2007; Bullock et al., 1999; Stansly et al., 1997;
McCoy et al., 2000; McCoy, Stuart, Duncan, & Nguyen, 2002). Currently, S. riobrave
is marketed in Florida under the brand name Bio Vector 355 (Becker Underwood Inc.,
Ames, IA) and, in 1999, approximately 19,000 ha of citrus were treated with this
product to control citrus root weevils (Dimock, personal communication).
Despite the evident and long-recognized potential of EPNs for insect pest
management and the commercial development of effective EPN products for
augmentation, their market penetration and incorporation into broadly applied IPM