Compatibility with Pesticides

Entomopathogenic nematodes are compatible with many agrochemicals including herbicides, fungicides, acaricides, insecticides and fertilizers, as well as soil amendments (Rovesti and Deseo 1990; Gupta 2003). Infective Juveniles are tolerant to short-term exposures and therefore, can be tank mixed for applying together. Thus, entomopathogenic nematodes can also be included in the integrated pest mvanage-ment programme. But in several cases, nematode activity and its survival is reduced due to addition of some pesticides (Grewal et al. 1998) and sometimes chemicals used as inert ingredients or adjuvants used in formulation can prove toxic to nematodes (Krishnayya and Grewal 2002). Therefore, compatibility of each formulation with the specific nematode species should be evaluated before final application. There are various pesticides, which act synergistically with entomopathogenic nematodes and improve their efficacy in inundative applications. Easwaramoorthy and Sankaranarayanan (2003) have found that S. glaseri is compatible with carbofuran, phorate, quinalphos and aldrin. Compatibility of S. carpocapsae with dimethoate, endosulfan, malathion, mancozeb and zineb at recommended dosages have also been reported (Das and Divakar 1987). Gitanjalidevi (2007) conducted an experiment to test the effect on the viability and infectivity of freshly emerged infective juveniles of Steinernema sp. and H. indica on different formulations of formaldehyde, charcoal and alginate capsule. The result indicated that there was no significant difference in viability in the two nematode species in water + 0.1% formaldehyde + charcoal and water + 0.1% formaldehyde + alginate capsule treatment. The survival of the infective juveniles was highest in the formulation containing 0.1% formaldehyde + alginate capsule, followed by 0.1% formaldehyde + charcoal, for H. indica and Steinernema sp. Wang et al. (2007b) evaluated the combined efficacy of chemical pesticides, chlo-rpyriphos, imidacloprid and entomopathogenic nematode, S. carpocapsae against

Rhabdoscelus lineaticollis, a pest of palm and sugarcane. It was found that the mortality of R. lineaticollis was highest (88.89%) in the combined treatment of chlorpy-riphos, imidacloprid and S. carpocapsae as compared to individual application of chlorpyriphos (72%), imidacloprid (25%) and S. carpocapsae (27.7-52.6%). Composted manure and urea do not influence S. carpocapsae but fresh manure may affect virulence (Shapiro-Ilan et al. 1997). Mahmoud (2007) conducted a laboratory bioassay to determine the potential of combination between S. feltiae and botanical insecticides, neem seed kernel extract, NeemAzal T (5%) and Neemix (4.5%) against the third-instar larvae of peach fruit fly, Bactrocera zonata. Of 25 treatment combinations between neem seed kernel extract and S. feltiae, 18 gave synergistic response, four were additive, none antagonistic and three without any response. Shapiro-Ilan et al. (2004) has reported antagonistic relationship between the fungi Paecilomyces fumosoroseus and H. indica or S.carpocapsae. Rumbos et al. (2007) investigated the effect of PL251, a strain of nematophagous fungi, Pp. lilacinus on the survival and virulence of S. feltiae, H. bacteriophora and H. megidis under controlled conditions. The survival and pathogenicity of all the three nematode species were not affected by PL251 application. In an experiment, S. carpocapsae when combined with nucleopo-lyhedrovirus against the beet armyworm S. exigua, caused additive mortality of sp. exigua larvae without causing any affect on reproduction of S. carpocapsae (Gothama et al. 1995, 1996). Pasteuria penetrans, a bacterial pathogen of plant parasitic nematodes did not infect Steinernema sp. under laboratory condition (Mohotti et al. 1998; Somasekhar and Mehta 2000). Heterorhabditis spp. and S. glaseri were also found not causing any infection on earthworm Eudrilus eugeniae (Prabhuraj et al. 2000).

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