**2. Management of Colorado potato beetle**

**1. Introduction**

20 Insecticides Resistance

Colorado potato beetle – CPB (Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae) is an oligophagous species that attacks numerous plants of cultivated and spontaneous flora in the Solanaceae family in North America, Europe, and parts of Asia [1, 2, 3]. Within the genus *Leptinotarsa*, the Colorado potato beetle has the widest host range, feeding on at least 10 species of wild and cultivated solanum [4]. Defoliation of potatoes, which is most intense during the

From the botanical aspect, the potato, *Solanum tuberosum* L., is a perennial plant, yet in practice it is often grown as an annual plant due to its vegetative method of propagation. The potato is a crop of the Western Hemisphere. It first appeared in Europe in 1573 in Spain, and in 1586 it reached England and Ireland. In Western Balkan, the potato did not come until 1759, when it arrived in Banat region. It is the third-largest crop in our country when it comes to growing areas, right after the maize and wheat. However, the total number of areas under potatoes is

The potato is in all stages of its vegetation period susceptible to pests, the most important of which is the Colorado potato beetle (CPB). In Balkan region, this pest can also be found on tomatoes, aubergines, and peppers, or buttercups – when it comes to plants from spontaneous flora. Colorado potato beetle is a limiting factor to potato production in our region and in the rest of the world, while in some regions it is also a harmful pest of tomatoes and aubergines. In our conditions, CPB produces two generations per year (as well as incomplete 3rd genera‐ tion), thus ensuring large populations for which 3-4 control treatments per year are necessary. Although there are some alternative methods [7], conventional insecticides are still most

Adults can overwinter in the soil at the depth of 7.5–12.5 cm. After emerging from the soil in spring, they spread by walking and flying on adjacent fields, where they immediately start to feed on host plants. After 5–10 days, females lay eggs (in clusters of 20–60 eggs) on the underside of leaves. In laboratory conditions, females live for 120 days, and their maximal fecundity is over 4,000 eggs [1]. The eggs are hatched simultaneously, and the hatched larvae immediately start to feed. Larval development (four stages) lasts for 10–20 days, depending on temperatures. Feed consumption depends on plant hosts, and for one plant host it is relatively constant in all larval stages. Defoliation of potatoes, most intensive during the flowering period, makes great losses in tuber yields [8, 9, 5]. Considerably lower yields were a result of strong defoliation (20%) few weeks before harvest [10]. After feeding has stopped, the fourth instar larvae drop from the plant, burrow into the soil, and pupate. Imagoes eclode in the ground, from where they emerge, find the closest plant host, and start to feed. Depending on a number of factors (temperature, photoperiod, and the state of the plant host), imagoes mate and produce a new generation of beetles, fly to other fields or stop feeding and enter

Remarkable ability of CPB has to adjust to adverse environmental conditions, manifested in its resistance to insecticide, which results in increased costs of potato production, environ‐ mental pollution, and a disturbance in biocenotic balance. A whole series of resistance

bloom, makes huge losses in tuber yield, depending on the growth stage [5].

declining, which is a general tendency in Europe [6].

important in CPB management.

diapause [1].

Rapid adjustment to new biotic and abiotic conditions is highly present within CPB popula‐ tions. As a result, it is considered to be the most serious defoliator pest of potatoes in the world [11]. Nontreated pest populations can defoliate and completely destroy yields in the period of tuber formation [1]. Before CPB, we did not have a pest able to seriously harm potato crops. After coming to a new habitat, this pest finds conditions favorable for life and reproduction, which enables them to occur permanently and at a massive scale. The destructive activity of this pest is such that potato crops would be destroyed without efficient protection [13].

In most regions with dense CPB populations, chemical treatments are still the number one method in potato protection, considering that alternative measures are not efficient enough [11]. Most potato protection programs require decreasing CPB populations at the beginning and middle of the vegetation period, and tolerating higher populations at the end of the vegetation period. In general, the goal of such programs is to limit total defoliation to 10–25% during the most critical periods of potato development. Without chemical treatments, yield losses would amount to 74% [6].

In Balkan region, potatoes are treated with insecticides 3–4 times per year to ensure normal yields [14]. CPB management costs potato growers hundreds of million dollars a year [2]. Large numbers of pesticides from different chemical classes have been used so far to manage CPB, such as insecticides from the class of chlorinated hydrocarbons, organophosphates, carba‐ mates, pyrethroids, nereistoxins, insect growth regulators, neonicotinoids, as well as bacterial products, GMOs, products of plant origin (azadirachtin), etc. Over the last few decades, only a few insecticides in our country have been satisfactorily efficient [15, 16, 17, 18].
