Inactivation of Arsenophonus by antibiotic treatment leads to decrease in fitness of Ommatissus lybicus
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The dubas bug (DB), Ommatissus lybicus de Bergevin (Hemiptera: Tropiduchidae), is a destructive pest afflicting the date palm in the Middle East and North Africa. This pest has needle-like sucking mouthparts and feeds exclusively on plant sap. Although plant sap is rich in carbohydrates, it is devoid of most essential amino acids and many vitamins. The absence of essential amino acids in diet is suggested to be ameliorated by endosymbionts in O. lybicus. Arsenophonus is one of the facultative endosymbionts prevalent in O. lybicus. In this study, tetracycline (50μg/ml) was used to eliminate Arsenophonus from O. lybicus (Fin population) to study its effects on demoghraphic parameters of this pest. All experiments were carried out at 27±2˚C, 65±5% RH, and a photoperiod of 14:10 (L: D) h on shahani date palm cultivar. Bacteria specific 16S Polymerase chain reaction (PCR) was used to ascertain Arsenophonus absence (accession no. KX790335) with differential effects on other endosymbionts present in O. lybicus. Our results revealed that Arsenophonus negative (A-) group had decreased nymphal survival as compared to control (A+) (19.04% and 85.36%, respectively). Elimination of this bacterium within the hatched eggs has led to emergence of decreased number of progeny in A- group. The total development time of immature stages was 140.25 and 116.66 days, respectively for A- and A+ group. Arsenophonus inactivation significantly decreased the longevity of both A- males and females. The average longevity of A- and A+ males was 16.00 and 33.06 days, respectively. Female longevity was 15.00 days for A- group and 33.78 days for A+ group. The average number of eggs laid by an A+ female was 54.52, while for A- females no fecundity was recorded. This study revealed the significant increase in developmental time of immature stages and reduction in different life-history parameters like fecundity, nymphal survival and adult longevity of A- group as compared to A+. These observations confirmed the positive influence of Arsenophonus on O. lybicus fitness and give a new insight about the probable role of this bacterium in O. lybicus, that need to be explored further.
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