Monitoring the appearance and possibility for prevention of the apple sawfly in Croatia
The apple sawfly Hoplocampa testudinea Klug has recently become a widespread pest in Croatian apple orchards. It causes severe damage in the blooming period due to the fact that infested fruit fall off.This article shows results collected over three years of field research on trap catches of sawflies, the period of laying eggs, the appearance of larvae and detection of damage. In the climate of northwestern Croatia, adult sawfly appear in April during the blooming period of the early apple variety of Idared.By monitoring temperatures from January 1, adults were detected when the thermal constant reached 210 day-degrees. Our observations showed that the larvae emerged when the sum of thermal constants reached ca. 110 day-degrees.The investigation of effective control strategies with insecticides showed high efficacy of thiametoxam (Actara), imidacloprid (Confidor), thiacloprid (Calypso) and betacyfluthrin + oxydemeton-methyl (Enduro) and lower efficacy of phosalone (Zolone), chlorpyrifos-methyl (Reldan), and lambda cyhalothrin (Karate).
The apple sawfly, Hoplocampa testudinea: a temperature driven model for spring emergence of adults
The effect of temperature on post‐diapause development of the apple sawfly Hoplocampa testudinea Klug was studied under controlled conditions. Survival was found to decrease at temperatures higher than 15 °C, the lethal temperature being close to 25 °C. The lower thermal threshold was 4.5 °C; the values for males and females did not differ significantly. However, different values were established for unprotected individuals, in vermiculite and in potting compost respectively. Based on the overall mean and variance of the developmental time and the overall thermal threshold a simple soil temperature driven phenology model was constructed using a time‐ varying distributed delay. The validation with independent field and semi‐field data revealed the model to be a reliable tool to predict apple sawfly phenology and hence to determine the optimal time for the installation of white sticky traps or for control measures such as insecticide treatments.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.