Marilu Lopez-Edwards's research while affiliated with Universidad de Colima and other places

Scyphophorus acupunctatus is the main pest of Agave tequilana . Its adults are vectors of Erwinia carotovora , which causes plant destruction. The susceptibility of S. acupunctatus larvae to various strains of entomopathogenic nematodes has been demonstrated previously (Molina et al., 2004). In the current paper, the use of seven different concentrations: 0, 10, 20, 50, 100, 200, and 500, of infected juveniles per larva in petri dishes containing a filter paper against Steinernema carpocapsae strains All, Ca, and Fl, and also against native insolated N1, N2, N4, belonging to the genera Steinernema sp. The studies were conducted under laboratory conditions to determine the susceptibility of S. acupunctatus larvae to entomopathogenic nematodes. One hundred percent mortality of S. acupunctatus larvae was achieved by S. carpocapsae strains All, Ca, and Fl with exposure to 100 infected juveniles. In the case of native isolates, N2 registered 95% mortality, and for N4 and N1, mortality registered was 75%. An analysis of variance was conducted in order to determine whether strain or isolate had the highest virulence against S. acupunctatus larvae. Means for S. acupunctatus larvae by entomopathogenic nematodes presented significant differences (F = 57.01; df = 55, 223; P < 0.0001), resulting in two levels. At the first level, S. carpocapsae All, Fl, and Ca are statistically the same as isolate N4. At the second level, the isolates N4 and N1 are statistically the same. The results indicate the high susceptibility of S. acupunctatus larvae. The infectivity of native isolates as well as S. carpocapsae strains All, Fl, and Ca are associated with the symbiotic bacterium Xenorharbdus sp., suggesting they have potential for use against S. acupunctatus larvae.

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC50 against adult horn flies (8.08 x10²conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults. Resumen La susceptibilidad de los estados biológicos de larva, pupa y adulto de Haematobia irritans (L.) (Diptera: Muscidae) a aislados de los hongos Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., y Paecilomyces fumosoroseus (Wize) Brown y Smith, fue evaluada bajo condiciones de laboratorio. Grupos de 20 huevos de 4 h de edad fueron colocados sobre 50 g de excremento de vaca fresco en una proporción de 10:1 de excremento de vaca: harina de pescado deshidratada y ellos se asperjaron con una suspensión a una concentración de 1 X 10⁶ conidias/ml. Otros grupos de 20 pupas de menos de 48 h de edad fueron asperjados con una suspensión conteniendo 1 X 10⁸ conidias/ml, y cuatro grupos de 20 adultos fueron asperjadas con una suspensión de cada aislado. Los huevos, pupas y adultos de la mosca de los cuernos fueron susceptibles a los hongos entomopatógenos. Los aislados Ma2, Ma3, Ma 15, Ma25, Pfr1, y Pfr8 causaron una reducción en la emergencia de los adultos desde 3.8 a 6.3% en comparación con el testigo (72%). Las pupas fueron micosados por los aislados Ma2, Ma25 y Pfr10 en un rango entre 50 y 71.3%; los porcentajes de mortalidad de adultos mayor que 90% con los aislados Ma6, Ma 10, Ma 14, Pfr 9, Pfr 10, Pfr 11 y Pfr12. La CL50 más baja (8.08 x10²conidias/ml) en contra de adultos de moscas de los cuernos, la produjo el aislado Ma6. Los resultados apoyan la hipótesis de que los aislados de M. anisopliae y P. fumosoroseus son patógenos de diferentes estados biológico de las moscas del cuerno y que estos hongos reducen la emergencia de adultos cuando son aplicados a grupos de huevos y pupas y producen mortalidad cuando son aplicados a adultos de esta plaga.

Larvae of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) and soil samples were collected in six Mexican states. Larvae were collected from whorl-stage corn, grain sorghum, forage sorghum, and Sudan grass fields in 64 locations during the summer of 2000, to determine the occurrence of entomopathogens and parasitic nematodes. A total of 5591 FAW larvae from 64 locations were examined for indigenous FAW biological control agents. Overall total larval mortality was 3.935%. The larval mortality percent due to entomopathogens and parasitic nematodes was 3.524%, other causes reached 0.411% of total mortality. Three species of entomopathogenic fungi representing two classes, Hyphomycetes (Nomuraea rileyi, and Hirsutella sp.) and Zygomycetes (Entomophthora sp.) were recovered from FAW larvae, and two species of Hyphomycetes (Metarhizium anisopliae and Beauveria bassiana) were isolated from soil samples. An unidentified microsporidian was recovered from four locations in the State of Jalisco, three from Michoacan, three from Nayarit, and one from Veracruz and Colima, respectively. Mermithid nematodes were recovered from 24 FAW larvae at three locations in Nayarit and three larvae were recovered from two locations in Veracruz. Six larvae showing symptoms of viral disease were collected from Sinaloa (2), Jalisco (2), Michoacan (1), and Nayarit (1). Entomopathogenic nematodes from the genus Heterorhabditis sp. and Steinernema sp. were isolated from soil samples from Colima in one and two locations, respectively. Steinernema sp., and Heterorhabditis sp. were isolated from soil in one location in Michoacan. Steinernema sp. was recovered from two locations of Jalisco. In this survey, N. rileyi, mermithid nematodes, and microsporidia were the most frequent pathogens and parasites.

Fall armyworm larvae, Spodoptera frugiperda (J. E. Smith) were collected from whorl stage corn or sorghum in the states of Michoacán, Colima, and Jalisco in August, and Tamaulipas, Mexico in September 1998. Eleven species of hymenopteran parasitoids were recovered representing 3 families: Ichneumonidae (Ophion flavidus Brulle, Campoletis flavicincta Ashmead, and Pristomerus spinator F.); Braconidae (Aleiodes laphygmae Viereck, Cotesia marginiventris Cresson, Meteorus laphygmae Viereck, Meteorus sp., Chelonus insularis Cresson, Chelonus sp. probably cautus Cresson, and Chelonus sp.); and Eulophidae (Euplectrus platyhypenae Howard). The overall rate of parasitism was 11.3%, based on 2219 larvae collected. The highest rate of parasitism from a single collection was 26.5%, representing 6 species of parasitoids in Michoacán. The next highest rate of parasitism, 23%, was by a single species, C. flavicincta, in Michoacán. The most widely distributed species was P. spinator, occurring in 12 collections from 3 states. Chelonus sp. was collected from all four states in only 6 collections. The greater diversity of parasitoids and higher rates of parasitism in Michoacán may be related to the more diverse habitat with more forests, orchards, and pastures near the cornfields in that state.

Fall armyworm, Spodoptera frugiperda (J. E. Smith) (FAW) larvae and soil samples were collected from corn and sorghum fields in the Mexican states of Michoacán, Colima, and Jalisco during August 1998. Additional FAW larvae were collected from a sorghum field in Tamaulipas, Mexico in September. A total of 2219 FAW larvae from 20 locations and 76 soil samples from 19 locations were examined for indigenous FAW biological control agents. Four species of entomopathogenic fungi representing two classes, Zygomycetes (Entomophthorales) and Hyphomycetes ( Beauveria bassiana, Nomuraea rileyi, and Hirsutella sp.) were recovered from 43 (1.94%) of FAW larvae. An unidentified microsporidian was collected from 32 (1.44%) of FAW larvae, 29 from Colima, 2 from Jalisco, and 1 from Michoacán. Forty nine larvae (2.21%) parasitized by mermithid nematodes were collected in the state of Colima. Two (0.09%) larvae infected with ascovirus were collected in Tamaulipas. Three species of Hyphomycetes ( Paecilomyces fumosoroesus, B. bassiana, and Metarhizium anisopliae) were isolated from soil samples using Galleria mellonella larval traps. Entomopathogenic nematodes ( Steinernema sp. and Heterorhabditis sp.) were recovered from soil samples from 5 of 19 localities using Galleria mellonella larval traps. Bacillus thuringiensis was isolated from soil samples from 12 locations. The most widely distributed microbial control agent on FAW larvae in the Western Coast of Mexico was the fungus N. rileyi, and from soil were the bacterium B. thuringiensis and steinernematid nematodes. The microsporidian was found predominantly in Colima and the mermithid nematodes only in Colima. Thus, Colima had the highest total percent mortality (9.67%) due to fungi, microsporidia and mermithids.

The susceptibility of larvae, prepupae, and pupae of the grass looper Mocis latipes (Guenée) to the entomopathogenic nematode Heterorhabditis bacteriophora (Poinar) NC strain was evaluated under laboratory conditions. Concentrations of 0, 5, 10, 20, 40, 60, and 120 nematodes per larva, applied in 1 ml of sterile-distilled water, were bioassayed, applying them to groups of 20 individuals of each instar, prepupa or pupa. Mortality was recorded daily for 5 d. All instars and the prepupal stage were the most susceptible to H. bacteriophora. Mortality ranged from 22.5 to 100%. Prepupae had 97.5-100% mortality starting at 10 nematodes per prepupa. Pupal mortality ranged from 27.5 to 41.3% as nematode concentration was increased. H. bacteriophora presented LC50 values that ranged between 5.26 and 37.66 nematodes per larva and LT50 values that ranged between 1.5 and 4.3 d. Results of this study suggest that H. bacteriophora has potential as a biocontrol agent against M. latipes.

Twenty isolates of the fungus Metarhizium anisopliae (Metsch). Sorkin (Ma) were evaluated to determine their virulence against last instar and adult emergence of Mexican fruit fly, Anastrepha ludens (Loew). Larvae were exposed by immersion in a conidial suspension at a concentration of 10(8) UFC/ml under laboratory conditions. Larvae and pupae cumulative mortality rates ranged from 37.9 to 98.75%. Thirteen isolates caused mortality rates > 83.7%, and their LT50 values ranged from 1.8 to 6.2 d. The Ma2, Ma8, and Ma16 isolates were evaluated at seven different concentrations ranging from 10(1) to 10(7) UFC/ml, showing LC50 values from 3.7 to 4.8 x 10(5) UFC/ml. In a field-cage experiment, 200 ml of a conidial suspension of Ma2, at a concentration of 2.5 x 10(6) UFC/ml, was applied on 2,500 cm2 soil surface (2 x 10(5) UFC/cm2). The fungus reduced adult emergence, 22% fewer adults emerging in a sandy loam soil, and 43% fewer in loam soil, compared with the controls. M. anisopliae may offer a preferable alternative to chemicals as a biological control agent against A. ludens.

Twenty isolates of the fungus Metarhizium anisopliae (Metsch.) Sorkin (Ma) were evaluated to determine their virulence against last instar and adult emergence of Mexican fruit fly, Anastrepha ludens (Loew). Larvae were exposed by immersion in a conidial suspension at a concentration of 108 UFC/ml under laboratory conditions. Larvae and pupae cumulative mortality rates ranged from 37.9 to 98.75%. Thirteen isolates caused mortality rates >83.7%, and their LT50 values ranged from 1.8 to 6.2 d. The Ma2, Ma8, and Ma16 isolates were evaluated at seven different concentrations ranging from 101 to 107 UFC/ml, showing LC50 values from 3.7 to 4.8 × 105 UFC/ml. In a field-cage experiment, 200 ml of a conidial suspension of Ma2, at a concentration of 2.5 × 106 UFC/ml, was applied on 2,500 cm2 soil surface (2 × 105 UFC/cm2). The fungus reduced adult emergence, 22% fewer adults emerging in a sandy loam soil, and 43% fewer in loam soil, compared with the controls. M. anisopliae may offer a preferable alternative to chemicals as a biological control agent against A. ludens.

The susceptibility of third-instar larvae of Anastrepha ludens (Loew) to the entomopathogenic nematodes Steinernema carpocapsae (Weiser) (All and Tecomán strains), S. feltiae (Filiipjev), S. glaseri (Steiner) (NC strain), S. riobrave (Cabanillas, Poinar & Raulston), and Heterorhabditis bacteriophora Poinar (NC, Patronato, and Tecomán strains), was evaluated under laboratory conditions. Sterile distilled water (1.0 mL) with 4000 infective juvenile nematodes were applied on 300 g of moistened sterile soil into 1000-mL pots, and 20 third-instar larvae were placed on the soil surface, 1 mL of distilled water without nematodes was applied as control. Each nematode treatment was replicated four times. After nematode application, pots were incubated at 25 °C. Mortality of larvae and pupae was evaluated 6 and 12 d after inoculation. Cadavers of larvae and pupae were dissected and examined for the presence of nematodes. Our results showed that Mexican fruit larvae were susceptible to entomopathogenic nematodes. S. riobrave and S. carpocapsae All strain caused 90% of larval and pupae cumulative mortality, H. bactetiophora NC strain and S. feltiae killed more than 80%, whereas H. bacteriophora Tecomán and S. glaseri caused a 52.5% mortality. These results suggest that the nematodes S. riobrave and S. carpocapsae All strain have a potential as biological control agents against A. ludens .

Virulence of several isolates of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill., Metarhizium anisopliae (Metsch.) Sor. and Paecilomyces fumosoroseus (Wize) Brown & Smith were evaluated on adult weevils of Anthonomus fulvipes Boheman at dose of 10 ⁸ spores/mL under laboratory conditions. The study was complemented by testing one isolate each of M. anisopliae and P. fumosoroseus against adult weevils on organically grown Barbados cherry trees at dose of 2 × 10 ¹⁵ spores/ha. All fungi species showed high virulence against A. fulvipes adults, with mortality ranging from 92% to 100%. LT 50 values varied 2.7 to 4.8 d. The M. anisopliae isolate 10, and the P. fumosoroseus isolate 1 were selected for field evaluation because laboratory insect cadavers presented the best sporulation. After applying the fungi to the trees, total weevil captures were 38, 56, and 100 for the P. fumosoroseus, M. anisopliae, and the check (untreated) plots, respectively. Statistical differences in fruit damage were detected among treatments: M. anisopliae and P. fumosoroseus treatments showed an average of 50% of undamaged fruits, whereas in the control plots presented 36% of undamaged fruits. Laboratory and field experiments suggest that entomopathogenic fungi have a potential as microbial control agents against the weevil A. fulvipes in organically grown Barbados cherry trees.