**Resistance to Insecticides in Populations of the Coffee Leafminer**

Daianna P. Costa, Flávio L. Fernandes, Flávia M. Alves, Ézio M. da Silva and Liliane E. Visôtto

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61466

#### **Abstract**

Coffee leafminer *Leucoptera coffeella* is an important pest on coffee. The continued use of chemicals can result in loss of efficacy and selection of leafminer-resistant populations. We aimed to identify *L. coffeella* populations resistant to old and new neurotoxic insecti‐ cides in regions of Brazil. We collected seven populations of *L. coffeella* in Brazil. Low lev‐ els of resistance were observed for the insecticides chlorantraniliprole (1.02-3.23 times), abamectin (1.19-4.80 times), and deltamethrin (1.05-5.35 times). High resistance levels were observed for profenofos (65.3-522 times) and chlorpyrifos (4.53-18.63 times). We conclude that Brazilian *L. coffeella* populations showed greater resistance to organophos‐ phate insecticides. Furthermore, resistance may be associated with the distance between the coffee-producing regions.

**Keywords:** Anthranilamide, *Coffea* spp, Lepidoptera, lethal time, organophosphate

#### **1. Introduction**

The coffee leafminer *Leucoptera coffeella* (Guérin-Méneville, 1842) (Lepidoptera: Lyonetiidae) is originally from Africa and has become a pest species of great significance in many countries producing coffee (*Coffea arabica* and *Coffea canephora*) [1,2]. The extremely variable life cycle of this species and their damage to coffee crops make them a pest with a high destruction capacity [3-5]. Insecticides provide the most efficient method of controlling this pest, with more than 30 different active pesticides registered for use against this *L. coffeella* in Brazil [6]. Despite the existence of several active ingredients, the overuse of pesticides by farmers has led to the insects becoming resistant [7].

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The first documented case of resistance was in 1914, in San Jose Scale (*Quadraspidiotus perniciosus)* (Comstock, 1881) (Hemiptera: Diaspididae) exposed to repeated doses of sulfur powder [8]. Reports of insect resistance began to increase in the 1940s as insecticides and miticides emerged. There are over 7740 reported cases of resistance, involving 331 compounds and more than 540 species of insects and mite pests [9]. From 1914 to 2007, the vast majority of cases of resistance occurred in Lepidoptera, with 1799 confirmed cases.

Lepidopteran species such as *Alabama argillacea* (Lepidoptera: Noctuidae) [10], *Plutella xylostella* (Lepidoptera: Plutellidae) [11], and *Tuta absoluta* (Lepidoptera: Gelechiidae) [12] have shown resistance to several groups of insecticides. These authors studied insect populations from different locations, using different groups of insecticides with varying mechanisms of action. Studies with *L. coffeella*, however, have focused only on the organophosphate group with no studies on other chemical groups [13,14]. As such, studies of different populations and various insecticide groups are needed.

Among the insecticides used, most are neurotoxins, and it is this group that presents the most problems of insect resistance [9]. These neurotoxic insecticides (e.g., organophosphates and pyrethroids) cause rapid death of susceptible insects, and abamectin, neonicotinoids, and diamides are slower in causing death of insects [15].

It is therefore possible to detect resistance to a particular active ingredient by comparing the time of death of each population to different neurotoxic insecticides. Similar experiments have been done with other insects, such as the mosquito *Culex tarsalis* (Diptera: Culicidae) [16]. Slower deaths may indicate the population is beginning to become resistant. Delayed mortality could be compared to the effect of sublethal doses, which put the insects in a state of stress and reduce their metabolism before death [17]. One way to detect resistance using the lethal time of death (LT) is to collect geographically distant populations to obtain more precise information and compare populations across regions since the resistance is relative. Thus, based on the mechanism of action of each insecticide group, it is possible to compare resistance by meas‐ uring how quickly the insecticides act on a population.

There are two studies focusing on the detection of insecticide resistance among populations of *L. coffeella* and just with organophosphate insecticides. Our proposal is to study different groups and regions. This study aimed to recognize populations of *L. coffeella* in different regions of Brazil that were resistant to neurotoxic insecticides by comparing the lethal time.
