Articles

Biological studies on Tomicus destruens (Wollaston) (Coleoptera Curculionidae Scolytinae): phenology, voltinism and sister broods.


Abstract


Biology and behaviour of Tomicus destruens were investigated in Sardinian pine forest in order to define the seasonal pattern of trunk attacks by breeding adults, the number of annual generations, and the number of sister broods produced per female. The counting of maternal galleries made each month in trap trees shows that T. destruens colonizes the pine trunk in all the months between October and May with the highest infestation intensity in autumn followed by decreasing values. Female laid ca. 80 to 95 eggs per gallery in October-November and ca. 70 in the following months. Although the bark beetle’s reproductive activity extended for a period of 7-8 months, the flight of new adults was concentrated in a much shorter time period between May and June, when ca. 95% of the emergences occurred. The experiments have ruled out the possibility of a second annual generation. Even the earliest emerging adults, originating from eggs laid in October, were unable to mature their gonads and oviposit before the summer stasis. Tomicus destruens females can make up to four sister broods and lay a total of ca. 170 eggs throughout their life, without regeneration feeding in the shoots. The new knowledge provides information useful to calibrate well-timed interventions to control this dangerous pest by means of the trap tree technique.


Keywords

Pine; bark beetle; control; reproductive period; fecundity

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