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Biological control of agave weevil, Scyphophorus acupunctatus Gyllenhal, includes use of entomopathogenic nematodes of the genus Heterorhabditis, which have potential for managing pests with cryptic habits. Virulence of two native isolates of Heterorhabditis indica Poinar, Karunakar & David (A14 and X1) and commercial isolate Heterorhabditis bacteriophora were evaluated on a population of adult agave weevils. Isolates of larvae and pupae of sugarcane weevil, Scyphophorus incurrens, were collected in the State of Morelos, Mexico. Virulence of each isolate was determined by laboratory bioassays to calculate lethal concentration (LC50) and lethal time 50 (LT50) required to eliminate 50% of a population of adult agave weevils. The adult agave weevils were collected at Jalisco, Mexico. For the three isolates evaluated, LC50 ranged from 1,183 to 1,913 infective juveniles, with no significant differences between the isolates evaluated; however, A14 required a lesser LC50. The isolate was statistically different from X1 in terms of LT50 to eliminate 50% of the test population. Based on results of the study, native isolates had potential as biological control agents against S. acupunctatus. [ABSTRACT FROM AUTHOR]

Duponchelia fovealis Zeller, is currently considered one of the most important emergent pests of a range of crops. This pest is common in Europe, but its presence in the Americas, particularly Brazil and Mexico, has been only recently reported in strawberry crops. Since its recent arrival in Mexico interest in the potential of different entomopathogens for the control of D. fovealis has increased. Here we evaluated commercial products of the bacterium Bacillus thuringiensis; three different species of entomopathogenic nematodes; and different isolates of four species of entomopathogenic fungi. All pathogens were evaluated against 3rd instar larvae, except nematodes which were evaluated against both larvae and pupae. Analysis revealed significant differences in virulence amongst B. thuringiensis products, where the most virulent was nine times more virulent than the least virulent product. Amongst nematodes, Heterorhabditis bacteriophora was the most virulent and larvae were more susceptible to nematodes than pupae; larval mortalities at the highest dose evaluated (200 infective juveniles [IJs]) were between 80 and 95%, while for pupae they were between 25 and 40%. Mortality of larvae due to entomopathogenic fungi was lower than for the other entomopathogens; the highest mortality observed was 25% caused by an M. anisopliae isolate, although this was not statistically different to other fungal isolates. Overall, our results showed that biological control products based on B. thuringiensis or the nematode H. bacteriophora have the greatest potential; we consider that H. bacteriophora could be more convenient as it infects larvae and pupae. [ABSTRACT FROM AUTHOR]

Chagas disease is a zoonosis caused by the protozoan Trypanosoma cruzi and transmitted through the feces of triatomines, mainly in Latin America. Since the 1950s, chemical insecticides have been the primary method for controlling these triatomines, yet resistance has emerged, prompting the exploration of alternative approaches. The objective of this research was to test the capacity of the entomopathogenic nematodes Heterorhabditis indica and its symbiotic bacteria Photorhabdus luminescens , to produce mortality of Triatoma dimidiata a key vector of T. cruzi in Mexico under laboratory conditions. Two bioassays were conducted. In the first bioassay, the experimental unit was a 250 ml plastic jar with 100 g of sterile soil and three adult T. dimidiata. Three nematode quantities were tested: 2250, 4500, and 9000 nematodes per 100 g of sterile soil (n/100 g) per jar, with 3 replicates for each concentration and 1 control per concentration (1 jar with 100 g of sterile soil and 3 T. dimidiata without nematodes). The experimental unit of the second bioassay was a 500 ml plastic jar with 100 g of sterile soil and 4 adult T. dimidiata. This bioassay included 5, 50, 500, and 5000 n/100 g of sterile soil per jar, with 3 replicates of each quantity and 1 control per quantity. Data were analyzed using Kaplan-Meyer survival analysis. Electron microscopy was used to assess the presence of nematodes and tissue damage in T. dimidiata. The results of the first bioassay demonstrated that the nematode induced an accumulated average mortality ranging from 55.5 % (2250 n/100 g) to 100 % (4500 and 9000 n/100 g) within 144 h. In the second bioassay, the 5000 n/100 g concentration yielded 87.5 % mortality at 86 h, but a concentration as small as 500 n/100 g caused 75 % mortality from 84 h onwards. Survival analysis indicated higher T. dimidiata mortality with increased nematode quantities, with significant differences between the 4500, 5000, and 9000 n/100 g and controls. Electron microscopy revealed the presence of nematodes and its presumably symbiotic bacteria in the digestive system of T. dimidiata. Based on these analyses, we assert that the H. indica and P. luminescens complex causes mortality in adult T. dimidiata under laboratory conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

The spittlebug or froghopper is an important pest of sugarcane that encompasses a complex of species in the genera Aeneolamia and Prosapia (Hemiptera: Cercopidae). Control of these insects is carried out with chemical insecticides; however, effective control is not always achieved. Also, entomopathogenic fungi, such as Metarhizium anisopliae, have been applied, and the use of entomopathogenic nematodes (EPN) has been proposed. In this study, we assessed the field virulence of two native strains, Steinernema sp. CP13ES (group IV, bicornutum-certophorum-riobrave) and Heterorhabditis indica CP13JA, collected from sugarcane fields of Constancia and La Gloria sugarcane mills in Veracruz, Mexico. Field trials were conducted in two areas of these sugarcane mills. Both strains were mixed with the adjuvant Break-Thru® and were sprayed in sugarcane plots infested with spittlebug nymphs. In the first trial, we tested the efficacy of the two EPN strains in conjunction with a dispersant agent to select the most appropriate strain. In the second trial, we evaluated Steinernema sp. strain considering 1-m2 field plots. Results from trial 1 showed that both strains were significantly similar (P > 0.05) in their virulence: H. indica, recorded 73% mortality and Steinernema sp. 62%. Results from trial 2 demonstrated that the Steinernema strain was able to maintain a significantly lower (P = 0.25) spittlebug population for 4 days when compared to the control, whereas the nymph populations doubled during the same time period. These studies show the potential of the native EPN for field control of spittlebug nymphs in Mexico. [ABSTRACT FROM AUTHOR]

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A new species of nematode in the genus Heterorhabditis was found in the northern part of the state of Tamaulipas, Mexico. Morphological and molecular data indicate that this nematode is a new species. The new species is described as Heterorhabditis mexicana n. sp. and is a sister taxon to H. indica. Heterorhabditis mexicana n. sp. is morphologically similar to H. bacteriophora, H. brevicaudis and H. indica and can be distinguished from these species mainly by male and female characters. Of the examined specimens of H. mexicana n. sp., 70% of males have eight pairs of bursal papillae, compared to nine in all other species. The ratio of the gubernaculum to spicule length (GS ratio) is higher than that of H. bacteriophora, H. brevicaudis and H. indica and the length of the spicule relative to anal body width (SW) is lower than all other species. For females, the vulval form of the new species is quite different from that of those species with a similar morphology (i. e ., H. bacteriophora and H. indica) and more closely resembles that of H. zealandica. The new species can also be distinguished from H. megidis, H. zealandica and H. marelatus by the body length, pharynx length of the infective juvenile and D% (distance from anterior end/pharynx length × 100), GS and SW ratios of males. In the ITS region of the rDNA tandem repeating unit, H. mexicana n. sp. has evolved 13 autapomorphic nucleotide character states, differing from its sister taxon H. indica at 113 aligned positions. The morphological and molecular data are sufficient to identify cladogenesis and delimit H. mexicana n. sp. as evolving independently from the other members of the genus. [ABSTRACT FROM AUTHOR]

We evaluated the pathogenicity of the entomopathogenic nematodes native to Mexico, Heterorhabditis indica, Heterorhabditis sp. and Steinernema sp., towards M. domestica under controlled conditions. For adults, concentrations of 1,600 (A) and 1,200 (B) nematodes/ml were considered. For larvae, only the first concentration applied to filter paper, wheat bran, and peat moss as substrates was evaluated. An analysis of variance showed that the differences in adult mortality were only significant (p = 0.0001) among nematode species but not among concentrations within species. However, differences were significant (p = 0.0001) when data were analyzed when 50% of the individuals died (LT 50 ). For H. indica, the LT 50 were 46.5 h and 65.8 h for the concentrations A and B, respectively. Females were more susceptible than males. H. indica recorded the highest mortality, with 79.2% and 35.5% for females and males, respectively. Significant differences (p ≤ 0.05) were recorded in larval mortality. H. indica induced the highest mortality (53.3%) when applied on peat moss. The results are a fundamental basis for future management studies of M. domestica by entomopathogenic nematodes., (© 2018 The Society for Vector Ecology.)