Virulence of four entomopathogenic nematode against different stages of the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae)

Background Ceratitis capitata Wiedemann (Diptera: Tephritidae) (Mediterranean fruit fly), is one of the important polyphagous pest species in the world that harms almost all fruits causing significant yields losses. Control of this pest which is on the quarantine list of many countries is highly important. Due to the negative effects of chemical control on the environment and human health, biological control approaches have gained importance. Entomopathogenic nematodes (EPNs) are a potential biological control agent that can be used for effectively controlling the Medfly. Results In this study, effects of four EPNs species on larvae, pupae and adults of Medfly were investigated under laboratory conditions. Four different concentrations of EPNs species were used against each stage of the pest. It pest showed different sensitivity to different concentrations of each of the tested EPNs. High mortality rate of 94% was caused by Heterorhabditis bacteriophora (11 KG),, followed by H. bacteriophora (TOK-20) with 91%, Steinernema carpocapsae (85%) and S. feltiae (Tokat-Emir) with 71% at highest concentration (200 IJ/larvae. The highest effect on adult mortality (100%) was recorded by the species S. feltiae (Tokat-Emir) at the highest concentration (200 IJ/adult) in the trials, followed by H. bacteriophora (11 KG) with 92%, H. bacteriophora (TOK-20) with 91% and S. carpocapsae (Tokat-Bakışlı05) with 87.37% mortality rates at the same concentrations. Conclusions It was determined that the EPNs tested in this study had insecticidal properties and they might be used in biological control programs against the Medfly.

Mediterranean fruit fly genes exhibit different expression patterns between heat and cold treatments

Invasive Tephritid fruit flies are a global threat to both agriculture and horticulture industries. Biosecurity has played a critical role in reducing their damage but becomes more and more challenging after several key chemical pesticides were banned or withdrawn for health or environmental reasons. This has led to non-chemical approaches including heat and cold treatments being broadly utilized to get rid of fruit fly infestation. However, the molecular mechanisms to kill the flies underlying these stressors are not clear yet. This knowledge will certainly help refine current post-harvest treatment strategies and develop more efficient, cost-effective and environmentally friendly approaches for fruit fly management. Previously, the molecular response of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) to heat was examined thoroughly, in which 31 key genes were identified with significant changes in expression levels and their high-resolution expression timeline was constructed across 11 timepoints. However, whether these candidate genes respond to cold in the same way was unknown. Here, a temperature bioassay was conducted and the expression profiles of these genes were investigated across the same 11 timepoints using cold treatment. The results showed that most of candidate genes exhibited divergent expression profiles compared to heat treatment, suggesting that the fly molecular response to cold may be different from those to heat. This study provides new knowledge of Tephritid fruit fly response to cold at a molecular level, which could aid in improving current fruit fly management and facilitate the development of new strategies to control this serious horticultural insect pest.

Spinosad combined with entomopathogenic nematode for biocontrol of the Mediterranean fruit fly (Ceratitis capitata [Wiedemann]) on citrus

Background Cultivation of citrus (Sapindales: Rutaceae) crops is continuously expanding in Egypt given the favorable ingredients of citriculture. Notwithstanding the Egyptian rank as the world's largest orange exporter, the Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is one of the major pests that considerably reduces the quality of citrus crops. Contrary to hazardous organophosphate insecticides that are commonly used to control the Medfly, biologically-based C. capitata control tactics were tried herein. The effect of spinosad as a bacterial fermentation product and the nematode Steinernema riobrave as biological insecticides applied singly or in combination on laboratory and field strains of Medfly were investigated. Results A significant difference in LC50 values was observed between laboratory strain (4.78 PPM) and field strain (8.12 PPM) of C. capitata larvae exposed to spinosad. A 1.7 fold decrease in susceptibility of field strain was recorded after treatment with spinosad. In a field experiment, a reduction in Medfly population by 80, 37, and 92% for spinosad, S. riobrave, and spinosad + nematode treatments was recorded, respectively. Conclusions Utilization of spinosad-S. riobrave combination in citrus fields, as a novel alternative for unhealthy chemical insecticides to control C. capitata in Egypt can be suggested. Use of this combination should be incorporated into a holistic management package that can be economically feasible and environmentally sustainable for Egyptian agriculture.