Records of Two Pest Species,Leptoglossus zonatus(Heteroptera: Coreidae) andPachycoris klugii(Heteroptera: Scutelleridae), Feeding on the Physic Nut,Jatropha curcas, in Mexico

Abstract

The physic nut, Jatropha curcas L. (Mal phighiales: Euphorbiaceae), is one of 75 plant species suitable for the production of biodiesel. Moreover, it is considered as having great agro industrial potential worldwide, on account of its potential for obtaining high quality oil, and its ease of cultivation (Martin & Mayeux 1984; Azan et al. 2005). Plantings of J. curcas have been es tablished around the world, and more recently in various states of Mexico (Michoacan, Chiapas, Puebla, Yucatan, Veracruz, Guerrero, Oaxaca and Morelos) with the principal aim of obtaining bio diesel (Martinez et al. 2010). However, unlike in other countries where this plant is extensively cultivated, in Mexico no studies have been carried out to identify potential insect pests that could af fect J. curcas production. The aim of this research was to study insects associated with J. curcas, and to determine potential pests of this plant in Mexico, where it probably originated. The study took place between Aug and Nov 2008, in an experimental crop (30 x 20 m2) of J. curcas at the fruiting stage, located in the Centro de Desarrollo de Productos Bioticos del Instituto Politecnico Nacional CEPROBI-IPN (18° 49'20 N and 99° 05'38 W at 1105 m asi), with a mean annual temperature of 22.7 °C, warm sub humid climate with summer rains and annual rainfall of 945.7 mm. The experimental crop was enclosed by other crops of J. curcas, peanut (Arachis hypogaea L.: Fabales: Fabaceae), bean (Phaseolus vulgaris L.: Fabales: Fabaceae), maracuya (Passiflora edu lis Simms; Malpighiales: Passifloraceae) and un dergrowth and is skirted by the River Yautepec. Direct surveys were conducted using an ento mological net made of fine mesh of 30.5 cm diam, once a wk, at 3 different times of day, 7:30 to 9:30 h, 13:00 to 15:00 h and 18:00 to 19:30 h, during the study period. The fruits where the insects were collected during the sampling period were examined for pest damage. The insects collected during sampling were deposited in plastic 50 mL flasks containing 25 mL of 70% alcohol. These flasks were labeled with place, date and time of collection and were deposited for taxonomic iden tification in the Laboratorio de Entomologia del Instituto de Investigaciones Agricolas Forestales (IIAF) of the Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoacan, Mexico. Of the 14 insect species belonging to 18 families and 8 orders (Table 1) identified in this study, two species of true bugs stand out; Leptoglossus zona tus (Dallas) (Heteroptera: Coreidae) and Pachycoris klugii Burmeister (Heteroptera: Scutelleridae). The species were determined by the keys of McPherson et al. (1990), Borror et al. (1989) and Peredo (2002). L. zonatus was observed feeding directly on tender fruits. This resulted in the development of necrotic spots and consequently fruit abscission by the plant. Generally, this species of true bug was observed in groups and even more frequently copulating pairs were seen on the fruits or leaves. They were collect ed continuously and in large numbers, i.e., between 3-5 insects per plant and exceptionally 40 adults per fruiting inflorescence. Given the number of this species on the fruits, it is considered to be a pest. It should be noted that in crops such as sorghum, the action threshold against L. zonatus is just one bug per panicle (Pineda 1999). P. klugii was observed ovipositing on the underside of the leaves. This true bug was less prevalent than L. zonatus, and was found sporadically. In contrast to the results found in the present study, P. klugii is considered the main pest affecting J. curcas in Nicaragua due to its abundance and resulting damage (Grimm 1996; Grimm & Maes 1997; Grimm & Somarriba 1998). These 2 species have previously been recorded in Mexico, i.e., L. zonatus feeding mainly on corn and sorghum (Zucchi et al. 1993), and P. klugii feeding naturally on its native host plant known as chaya de monte or mala mujer, Cnidoscoulus multilo bus (Pax) I. M. Johnston (Malpighiales: Euphorbia ceae) (Peredo 2002). However, they have not been recorded on J. curcas. Both these species of true bug have been reported as J. curcas pests in countries where it is cultivated. L. zonatus and P. klugii are considered J. curcas pests in Honduras, El Salva dor (Alfonso 2008) and Nicaragua (Grimm 1999). L. zonatus is distributed throughout the Americas (Al len 1969), and is a polyphagous species with a wide range of hosts (Grimm 1999; Schaefer & Panizzi 2000). Souza & Amaral Filho (1999) mention that