**6. An integrated approach to CPB control**

cides. Pattern II resistance is characterized by resistance ratios (and/or reductions in the sensitivity of AChE) that are approximately equivalent for both carbamates and OPs. There are also a few species for which an insensitive AChE has been reported and for which molecular data have been collected, but for which the resistance profiles for both OPs and carbamates

In a few cases of each pattern, gene sequencing has identified the molecular nature of the alteration leading to the lowered sensitivity to inhibitors. Although it is not possible yet to relate with full confidence the mechanism by which these structural changes alter sensitivity to inhibitors. Pattern I mutations may involve changes in the active site, such as a common Gly^Ser mutation in the oxyan–ion hole, whereas Pattern II changes may result in a constriction of the cleft leading to an active site that limits the access of inhibitors and, presumably, of ACh itself. Insensitivity to inhibitors may be accompanied by a reduced ability to hydrolyze ACh. Whether this is always deleterious to the organism is unclear since it is generally considered that, as in vertebrates, AChE is present in insects at a level considerably in excess of that needed

Biochemical studies using an affinity-purified AChE from the SS strain established that the AChE associated with CPB possessed typical characteristics of other AChEs and consists of two different molecular forms: the major form (92%) was a hydrophilic dimer, whereas the minor form (8%) was an amphiphilic dimer. Both molecular forms had virtually identical molecular weights and isoelectric points. Amino acid analysis indicates that the mole percen‐ tages of amino acids of the AChE from CPB were highly comparable to those previously

According to Zhu and Clark [77], affinity (Km) and hydrolyzing efficiency (Vmax) of AChE purified from a near-isogenic azinphosmethyl-resistant (AZ-R) strain of CPB to selected substrates, including acethylthiocholine, acetyl-(5-methyl) thiocholine, and propionythiocho‐ line, were lower than those of AChE purified from a susceptible (SS) strain. AChE from the SS strain was significantly inhibited by higher amounts of acethylthiocholine and acetyl-(fjmethyl) thiocholine, whereas AChE from the AZ-R strain was activated by higher amounts of

Finally, it is important to notice results on toxicological tests and measuring activity of AChE of CPB populations in Serbia, resistant to OPs and carbamates [88]. The order of resistance levels for OPs and carbamates was completely opposite. Experiments showed that acetylcho‐ linesterase (AChE) activity of CPB was very pronounced and easily measured. At a constant AChE concentration, increasing the substrate concentration will cause a positive, linear, and dependent increase in the reaction. The same applies in the reaction with constant substrate concentration and increased enzyme concentrations. AChE activity is significantly affected not only by location, but also by substrate concentration (acetylthiocholine iodide ATChI). Considering that ATChI (substrate) in increased concentrations inhibits normal AChE activity, it can be concluded that altered AChE affected the change in the population order. The total

AChE activity is in correlation with the determined resistance to carbamates.

have not been reported. For CPB, both patterns were registered.

for basic neurological functions under normal physiological conditions.

reported for AChE from Drosophila [77].

all four substrates examined.

30 Insecticides Resistance

The IRAC recommendation [89] is that the most effective strategy to combat insecticide resistance is to do everything possible to prevent it from occurring in the first place. It is recommended to develop and apply IRM (Integrated Resistance Management) programs as one part of a larger IPM program. Field researchers and entomologists should be focused on three basic components: pest monitoring, economic injury levels, and integration of multiple control strategies. It is essential to widely implement Economic Thresholds (ET) (use of insecticides only if pest populations are able to cause economic losses that exceed the cost of the insecticide plus application, or where there is a threat to public health). Integrated Control Strategies: Incorporate as many different control strategies as possible including the use of synthetic insecticides, biological insecticides [90, 91, 92, 93, 94], beneficial insects (predators/ parasites) [2, 95], cultural practices, transgenic plants (where allowed), crop rotation, pestresistant crop varieties, and chemical attractants or deterrents [96, 97, 98, 99, 100].

Applications of insecticide must be timed correctly, targeting the most vulnerable life stage of the insect pest. The use of spray rates and application intervals recommended by the manu‐ facturer and in compliance with local agricultural extension regulations is essential.

Integrated pest management (IPM), with the reduced application of synthetic insecticides, has an increasing need for alternative methods of plant protection. Together with systematic insecticide resistance monitoring [6, 12, 89], application of plant extracts with antifeedant and repellent effects could be one of the tools in efficient IPM program [101, 102, 103].

According to Boiteau [7], our understanding of the potato ecosystem and a number of preventive and curative control methods is sufficient to undertake a holistic approach to insect pest management. The harmonization of concepts should stimulate the integration of insect control methods beyond the level of the single pest. The greatest challenge is to bring together bad and good control methods, as well as conventional and sustainable (or organic) crop protection. This will require learning how to manage the unpredictability (uncertainty) of ecologically based IPM methods. Active adaptive management (AAM) is one approach that has been suggested to manage the different types of uncertainty [104]. Research and openness to new ideas will be essential for harmonization of the different insect control approaches and potato crop protection systems [7].
