Control Potentials of Three Entomopathogenic Bacterial Isolates for the Carob Moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae) in Pomegranates

Ectomyelois ceratoniae (Lepidoptera: Pyralidae) is the primary pest of pomegranates in Saudi Arabia and is mostly controlled using broad-spectrum pesticides. Providing environmentally sound choices to limit reliance on chemical management is a major challenge in the control of E. ceratoniae and, as a consequence, in the protection of pomegranate crops from its invasion. Entomopathogenic bacteria (EPB) symbiotically associated with entomopathogenic nematodes (EPNs) are well-known biocontrol agents of soil-dwelling or aerial pests. The bacterium symbiont (EPB) is the real insect-killing biocontrol agent, while the nematode (EPN) serves as a vector. We wondered whether the EPB vector, which is extremely vulnerable to adverse environmental conditions, like drought, high temperatures, and repellent soil microorganisms, could be omitted. We intended to evaluate the biocontrol potential of directly applied EPB cells and cell-free culture media (CFCM) on the larval instar E. ceratoniae. Xenorhabdus budapestensis DSM 16342 (EMA), X. szentirmaii DSM 16338 (EMC), and Photorhabdus luminescens ssp. laumondi (TT01) strains were used. After three days of exposure, the cells of EMA, EMC, and TT01 strains resulted in 100%, 88%, and 79.3% larval mortality rates, respectively. The applied EMA CFCM resulted in 53.7% larval mortality, indicating the presences of (at least) one extremely strong component produced by EMA. We concluded that the direct application of either the EPB cells or the CFCM must be a prospective alternative biocontrol of E. ceratoniae, especially to protect the important fruit (pomegranate, Punica granatum) cultivars. Especially, newly identified local EPB isolates could be applied as bio-pesticides for integrated management practices or organic pomegranate production.

Effect of Two Essential Oils From the Asteraceaes Family Against Ectomyelois Ceratoniae Zell. (Lepidoptera, Pyralidae): Case Of Artemisia Herba-Alba Asso. And Artemisia Compestris L.

The current work was done Artemisia herba-alba and Artemisia compestris essential oils harvested from the Eastern Algerian Sahara, their insecticidal characteristics against the eggs and adults of the date moth Ectomyelois ceratoniae. Indeed, two treatment modes were used; by contact application on eggs and by inhalation against adults. It appears from the results that the hatch rates were less than the hatching rate recorded in the control (96% ±00.00). The hatching rate reported on eggs treated by the highest dose (160 μl/ml) of Artemisia herba-alba and Artemisia compestris essential oils are 16.66 ± 08.81 and 37.77 ± 13.47 respectively. Statistical treatment results by the Chi-square test (χ2), attest that the treatment by A. herba-alba and Artemisia compestris essential oils at the same dose (160 μl/ml) affect significantly (χ2 = 35.62, p = 0.00 and χ2 = 21.17, p = 0.00 respectively) the hatching rate compared to the control. The sensitivity of adults to essential oils is expressed by 100% mortality rates obtained after 10 min of treatment by the highest doses (80 μl/ml and 160 μl/ml) of A. herba-alba essential oils, the same mortality rates (100%) were notified with the same doses (80 μl/ml and 160 μl/ml) after 20 min and 15 min of treatment by Artemisia compestris essential oils respectively. The dose-dependent mortality data revealed that there was a significant difference between the five doses of A. herba-alba essential oil tested except at the last treatment time (20 min) for which it was appeared p = 0.571, while for A. compestris essential oil, a significant difference was recorded with p varying between 0.00 and 0.003. The lowest LD50 value (0.09 μl/ml and 16.71 μl/ml) were noted during the longest treatment time (20 min), while the highest LD50 value (75.85 μl/ml and 263.7 μl/ml) were found during the shortest time (5 min) of A. herba-alba and A. compestris respectively. J. Bio-Sci. 29(2): 09-17, 2021 (December)