Bean Kernel (AcanthosсElides Obtectus)

Pest Type: Bean Pest

Row: Coleoptera – Coleoptera

Family: Grains – Bruchidae

In Russia, it is distributed in the zone of growing beans with individual local foci. The main fodder plants of bean kernels are all types of beans: multiflorous, holly, plain, golden, etc .; in granaries can damage peas. Artificial settlement harms the offspring of fodder beans and soybeans.

The beetle is 2.8-3.5 mm in size, covered with grayish hairs on top, forming numerous dim spots, pronotum without denticles on the sides, somewhat bell-shaped, with one sharp tooth and 2-3 similar teeth behind them on the inner edge of the lower thighs of the hind legs. The egg is 0.5-0.7 mm in size, oval, sometimes slightly bent, white, matte. Larva about 4 mm, cylindrical, strongly curved, with long setae; younger larvae with three pairs of legs that disappear with the following centuries. The pupa is 3-4 mm, yellow-white.

They hibernate inside the grain in storages, in the field, in carrion, soil, under the remains of plants. Warehouses quickly breed in the summer and slowly in other periods, especially in winter. In warm rooms they breed throughout the year, developing in 5-6 generations, overlap each other. In the field, the bean kernel develops in one, in the south of Russia sometimes there is an optional second generation. In spring, beetles fly from wintering places to a distance of 3 km, feed on generative organs, pollen, petals, flowers of various leguminous plants. On beans, they appear at the beginning of the formation of beans, in mass, at the beginning of the ripening of beans. Beetles lay their eggs on bean leaves, in wrinkles, cracks or pits, gnawed by a female in the bean’s back seam, much less often from other sides. The egg-laying period reaches 12-18 days. The fertility of females is 50-60 eggs. Depending on the air temperature, the development of the embryo in the field lasts 6-11 days. Larvae immediately after exiting the egg bite into the bean, then into the grain. In the summer period, the full development of larvae is completed in 21 days, pupae in 8-10 days.

Bean kernel is a thermophilic species with clearly expressed needs for increased air humidity (75-90%). The lower temperature threshold of development is +14 ° С, the upper one is + 36.3 ° С, the optimum temperature is 18.7-30.3 ° С. The pest is very sensitive to low positive temperatures and especially to negative air temperatures. Beetles that are outside the bean grain, under the influence of temperatures of 0-2 ° C, die after 15 days, at 4 ° C – after 10, and at -12. -18 ° C-after 1-2 days. Negative temperature is a limiting factor in limiting the propagation of bean kernels in areas where such a regime in granaries is common in winter. In warehouses in the south of Ukraine, they are able to winter only in the beetle stage in relatively warm winters, when the negative temperature in the warehouses is a short-term phenomenon. In such cases, after hibernation, beetles can populate crops, as well as remain indoors, laying eggs on grain. A single grain can contain a significant number of larvae (up to 18 and even up to 30), destroying it almost completely. The whole cycle of the development of the grain occurs in the grain, the beetle’s exit through rounded holes. As the number of holes increases, grain similarity decreases dramatically. Beetles cause harm more often too early crops of beans; late crops show asynchrony in terms of departure of beetles and ripening of beans, so such crops are slightly damaged. beetles exit through rounded holes. As the number of holes increases, grain similarity decreases dramatically. Beetles cause harm more often too early crops of beans; late crops show asynchrony in terms of departure of beetles and ripening of beans, so such crops are slightly damaged. beetles exit through rounded holes. As the number of holes increases, grain similarity decreases dramatically. Beetles cause harm more often too early crops of beans; late crops show asynchrony in terms of departure of beetles and ripening of beans, so such crops are slightly damaged.

Protective measures. Sowing seeds free from bean kernels. Timely and lossless harvesting of bean beans to their cracking. Grain cooling according to instructions. Spraying crops with insecticides at the beginning of the formation of beans.

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