Preface

Resistance of insects to insecticides was first recorded in scale insects in 1914, when their con‐ trol with inorganic insecticides proved inefficient. From that year until the end of the World War II, further eleven occurrences of resistance of insects to inorganic insecticides had been reported. The development of DDT and other organic insecticides made us think that prob‐ lems with resistance of insects to chemical agents for protection of plants were a thing of the past. Unfortunately, this was not so. Already in 1947, the occurrence of DDT resistance of housefly was reported. Growers faced the problem of insects resistant also to numerous newer groups of insecticides such as organophosphates, carbamates, pyrethroids etc.

Genetics and intensive application of insecticides are the major reasons for the rapid devel‐ opment of insecticide resistance in insects. Selectivity to insecticides enables some insects that have resistance genes to survive after insecticides have been applied to pass the resist‐ ance to their offspring. The percentage of resistant insects in populations thus increases and in the end surpasses the percentage of those that can be controlled by insecticides. At that point insecticides are no longer efficient.

The speed at which insects develop resistance to insecticides is determined by various fac‐ tors; important among these are the speed at which insects reproduce and migrate, durabili‐ ty of insecticides in the environment and their specificities, time and number of applications of insecticides on plants etc. The phenomenon of insects' resistance to insecticides thus ap‐ pears earlier in greenhouses, where harmful insects multiply faster and the input or over‐ flight of susceptible specimens is low, while growers repeatedly treat plants with the same insecticidal preparation or preparations from the same chemical group.

Because of the phenomenon of insects' resistance to insecticides, food production becomes less economical, as the above-mentioned unwanted phenomenon in intensive agricultural production causes increased yield loss and the need for additional treatments with insecti‐ cides. Less economical production can be counteracted by more efficient use of insecticides, which requires careful planning of agrotechnical measures throughout the growth period.

The best way to avoid the phenomenon of insects' resistance to insecticides is preventive. An increasing number of experts on pest control advocate programs dealing with resistance of insects to insecticides as one of the most important integral parts of integrated plant pro‐ tection. Among the key elements of these programs are monitoring of harmful organisms, taking into account economic thresholds, using different methods of controlling harmful or‐ ganisms during the growth period, selecting appropriate time for applying insecticides, us‐ ing insecticides from different chemical groups during the growth period, care for natural enemies and providing areas where harmful organisms susceptible to insecticides can repro‐ duce and survive so they will mate with those resistant to insecticides, thus decreasing the portion of resilient genes.

In this book, experts from different continents represent some topical problems because of insecticides' resistance and the reasons for this undesirable phenomenon and provide solu‐ tions for overcoming this problem. Their main aim of the book is the transfer of new infor‐ mation on insecticide resistance; this still very important agricultural and human health topic to researchers, scientists, students and end users (farmers, doctors).

This book is dedicated to my family, wife Milena, daughters Špela, Neža and Urška, and sons, Gašper, Miha and Peter, who assisted me in many ways. I extend them my love and appreciation.

#### **Stanislav Trdan**

Head of the Chair of Phytomedicine, Agricultural Engineering, Crop Production, Pasture and Grassland Management, Dept. of Agronomy, Biotechnical Faculty, University of Ljubljana, Slovenia **Insecticide Resistance and Insect Pests**

duce and survive so they will mate with those resistant to insecticides, thus decreasing the

In this book, experts from different continents represent some topical problems because of insecticides' resistance and the reasons for this undesirable phenomenon and provide solu‐ tions for overcoming this problem. Their main aim of the book is the transfer of new infor‐ mation on insecticide resistance; this still very important agricultural and human health

This book is dedicated to my family, wife Milena, daughters Špela, Neža and Urška, and sons, Gašper, Miha and Peter, who assisted me in many ways. I extend them my love and

Head of the Chair of Phytomedicine, Agricultural Engineering,

Crop Production, Pasture and Grassland Management,

Dept. of Agronomy, Biotechnical Faculty,

University of Ljubljana, Slovenia

**Stanislav Trdan**

topic to researchers, scientists, students and end users (farmers, doctors).

portion of resilient genes.

appreciation.

X Preface

**Chapter 1**
