COMMUNITY AND ECOSYSTEM ECOLOGY Ichneumonoidea (Hymenoptera) Community Diversity in an Agricultural Environment in the State of Yucatan, Mexico DAVID A. CHAY-HERNA ´ NDEZ, 1 HUGO DELFI ´ N-GONZA ´ LEZ, 1,2 AND VI ´ CTOR PARRA-TABLA 3 Environ. Entomol. 35(5): 1286Ð1297 (2006) ABSTRACT Ichneumonoidea is an important group in terrestrial ecosystems, although its commu- nity structure in tropical agricultural environments is unknown. Consequently, a characterization of ichneumonoid communities was done in an agricultural environment consisting of a cultivated area with and without surrounding vegetation in the state of Yucatan, Mexico. The characterization helped to understand how Ichneumonoidea diversity changes in the vegetation structure adjacent a crop. Three sampling sites were established: nine experimental plots in open area with continual agricultural use without surrounding vegetation (NSV), nine experimental plots with surrounding vegetation in a remaining patch (WSV), and nine plots inside of secondary vegetation of a remaining 7-yr-old patch (SV). Ichneumonoidea specimens were collected with Malaise and yellow pan traps. A total of 1,715 specimens were collected, divided into 40 subfamilies, resulting in 138 genera and 480 species. Of these, Braconidae accounted for 1,115 specimens from 21 subfamilies, 84 genera, and 342 species, whereas Ichneumonidae was represented by 600 individuals from 19 subfamilies with 54 genera and 142 species. Braconidae had higher species richness, abundance, and diversity than Ichneumonidae. Both families exhibited higher diversity in the treatment with surrounding vegetation. Koinobiont species were most common in both families. We suggest that vegetation structure and spatial distribution seem to have greater effect on community structure. Our results suggest that Ichneumonoidea could be a better indicator of the degree of disturbance than of environmental preservation. KEY WORDS agricultural landscape, parasitoids, Braconidae, Ichneumonidae Parasitoids account for 80% of Hymenoptera (LaSalle and Gauld 1991) and are an important guild in natu- rally maintaining insect population densities below economic threshold levels. They have a signiÞcant effect in the control of potentially damaging pest spe- cies, contributing to the natural balance of terrestrial ecosystems (LaSalle and Gauld 1993, Hawkins et al. 1997). As a result, they are ecologically important and could be the most successful parasitoids in biological control programs (Price 1975, Greathead 1986, God- fray 1994). Many parasitoids used in biological control pro- grams have been obtained from tropical areas (Gauld and Bolton 1988, Altieri 1991, LaSalle and Gauld 1991, Garcõ ´a 1998). These areas are currently experiencing serious biodiversity loss as a result of anthropogenic activities, such as agriculture and cattle (Chapin et al. 2000). The effect of this transformation on parasitoid diversity is largely unknown or has only been gener- ally addressed (Cirelli and Penteado-Dias 2003a, b, Scatolini and Pentado-Dias 2003). One of the para- sitoid groups, Ichneumonoidea (Braconidae and Ichneumonidae), can be used to evaluate variable patterns of habitat disturbance and modiÞcation (Hol- loway and Stork 1991, Kremen et al. 1993, Samways 1993, Delfõ ´n and Burgos 2000), because they are sen- sitive to environmental changes (Lewis and WhitÞeld 1999). Diversity of these two families in agricultural sys- tems is inßuenced by vegetation diversity in and around the system and the speciÞc cropÕs management (Hawkins 1994, Kuniata and Sweet 1994, Cerda 1995, Khan et al. 1997, Chay-Herna ´ ndez 1999, Nicholls and Altieri 1999). It is still unclear, however, if diversiÞ- cation of that systems favors high parasitoid diversity. Some authors have reported that temperate simpliÞed agricultural systems and open areas have higher para- sitoid diversity than diversiÞed systems and preserved areas (Lewis and WhitÞeld 1999, Menalled et al. 1999, Klein et al. 2002). Establishment of local level agri- cultural production systems involves handling the sur- rounding vegetation in different areas with different management and preservation methods. Conse- quently, the response of parasitoid communities to the establishment of these systems need to be understood to support development of local parasitoid manage- ment strategies. It is also important to evaluate the response of spe- cialist (koinobionts: temporarily paralyzed host) and generalist species (idiobionts: permanently paralyzed host) (Askew and Shaw 1986, Shaw and Huddleston 1 Departamento de Zoologõ ´a, Universidad Auto ´ noma de Yucata ´ n, Carretera Me ´ rida-Xmatkuil Km. 15.5, Me ´ rida, Yucata ´ n, Me ´ xico. 2 Corresponding author, e-mail: gdelÞn@tunku.uady.mx. 3 Departamento de Ecologõ ´a, Universidad Auto ´ noma de Yucata ´ n, Carretera Me ´ rida-Xmatkuil Km. 15.5, Me ´ rida, Yucata ´ n, Me ´ xico. 0046-225X/06/1286Ð1297$04.00/0  2006 Entomological Society of America