No abstract

To determine the efficacy of Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) for control of Anastrepha ludens (Loew) (Diptera: Tephritidae), field experiments were performed in a mango orchard with soil temperatures of 24–29 °C. The density of third‐instar A. ludens (50–500 larvae per plot) released into 0.25 m2 wood‐framed experimental plots containing soil (16% wt/wt moisture) previously treated with 125 infective juveniles per square centimetre soil surface did not significantly influence the prevalence of infection by H. bacteriophora. In subsequent experiments, the percentages of infection of fly pupae were positively correlated with the concentration of infective stages applied to soil plots. The highest average percentage of infection (74% at 250 infective juveniles per square centimetre) was observed when fly larvae were released simultaneously onto soil, compared to larvae that emerged from laboratory‐infested mangoes over a period of 8 days (52% infection at 500 infective juveniles per square centimetre). Double applications of infective juveniles at an interval of 4 days did not greatly improve the prevalence of infection (∼10% higher) compared to single applications. Between 9 and 15% of larvae that remained within infested mangoes became infected by nematodes, irrespective of the concentration of nematodes applied to each experimental plot. We conclude that effective control of A. ludens requires very high densities of H. bacteriophora. The successful use of this nematode for biocontrol of A. ludens will depend on identifying ways of overcoming the fly's ability to avoid infection.

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Strategus aloeus L (Coleoptera: Scarabaeidae), known as “Little bull” or oil palm “chiza” is a limiting pest in palm plantation in Cesar Colombia. Its management is based on pesticide use or old palm removal in renewal lots. Therefore, other alternatives are being sought out. Entomopathogenic nematodes isolated from the Colombian Andean region were evaluated. Under laboratory conditions S. aloeus third instar larvae exposure to 160 infective juveniles (IJs) per/cm2Steinernema sp3 JCL027, S. feltiae SCT125, S. websteri JCL006, S. colombiense SNI0198, Heterorhabditis bacteriophora HNI0100, H. bacteriophora HASA702, H. indica SL0708 (n = 20) was evaluated under a completely randomized design. The experiment was repeated three times on different dates. Significant differences were observed (F = 11.127, df = 7. 24, p = 0.0054), registering mortality between 3 and 14 days. Steinernema sp3 JCL027 was the strain producing the highest mortality rate (19.3 ± 8 %), followed by H. bacteriophora HNI0100 (5.2 ± 9 %). Thus, we evaluated Steinernema sp3 JCL0270 using a randomized design at 0, 160, 290, 420, 550, 680, 810 IJs/cm2 (n = 12). The experiment was repeated three times on different dates. Significant differences were found among treatments (44 ± 5 %, F = 14.676; df = 6. 21, p = 0.001), with 680 IJs/cm2 producing the highest mortality followed by 810 IJs/cm2 (22 ± 5 %). In conclusion, this alternative must be further explored in search of pesticide use and cost reduction, in addition to young palm loss in a plantation.