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Biological Control 20, 76–83 (2001) doi:10.1006/bcon.2000.0879, available online at http://www.idealibrary.com on The Phytophagous Arthropods Associated with Senna obtusifolia (Caesalpiniaceae) in Mexico and Honduras and Their Prospects for Utilization for Biological Control W. A. Palmer* and K. R. Pullen† *Alan Fletcher Research Station, Queensland Department of Natural Resources, P.O. Box 36, Sherwood, Queensland, 4075, Australia; and †Division of Entomology, CSIRO, G.P.O. Box 1700, Canberra, ACT 2601, Australia Received April 3, 2000; accepted September 1, 2000; published online December 20, 2000 obtusifolia in Brazil has been described (Fontes et al., A survey of the phytophagous arthropod fauna asso- 1995; Sujii et al., 1996). ciated with sicklepod, Senna obtusifolia, was under- The genus Senna (Bauhin) Miller has over 300 taken between 1991 and 1993 to find biological control species. It is well represented in South and Central agents for this increasingly serious weed in Australia America, southern Africa, and Australia but has and its closely related congener, Senna tora. The sur- fewer representatives in North America, northern vey concentrated in Mexico on the Gulf coast, the Pa- Africa, and Asia (Irwin and Barneby, 1982; Randell cific coast, and the Yucatan peninsula. Additional and Barlow, 1998). S. obtusifolia is thought to be searching was undertaken in the state of Morelos, Mexico and Honduras. Some 108 phytophagous insect neotropical in origin (Irwin and Barneby, 1982) but species were found. Literature searches and prelimi- is now almost circumtropical as well as inhabiting nary observation indicated that 10 species were suffi- various warm temperate regions. It is found in abun- ciently stenophagous to warrant further consider- dance in Mexico, Central America, Colombia, the ation as potential biocontrol agents. Two species, Mi- Brazilian Planalto, and northwest Argentina. Within trapsylla albalineata (Homoptera: Psyllidae) and the genus Senna, S. obtusifolia and S. tora have been Conotrachelus sp. ‘Morelos’ (Coleoptera: Curculion- placed within the section Chamaefistula (Colladon) idae), have been brought to Australia for further Irwin & Barneby, a section represented in the Amer- study. © 2001 Academic Press icas by 143 described species assigned to 21 series Key Words: sicklepod; Senna tora; Cassia obtusifolia; (Irwin and Barneby, 1982). Section Chamaefistula is Mitrapsylla albalineata; Conotrachelus sp.; biological not well represented in Australia, where there are 9 control. exotic and 3 endemic species (Randell, 1988). S. tora is morphologically very similar to S. obtusifolia, from which it is thought to have evolved in Asia (Randell, INTRODUCTION 1995). The Queensland Department of Natural Resources Senna (ϭ Cassia) obtusifolia (L.) Irwin and Barneby, commenced a research project in 1990 to effect biolog- known as sicklepod, is a serious weed of field and ical control of S. obtusifolia. The first phase of this pasture in many tropical and subtropical regions such project was to conduct a survey of the insects associ- as Australia, the United States of America, and the ated with the weed in Mexico and Central America and Pacific Islands. In Australia, sicklepod is found along select prospective biocontrol agents from this fauna. the tropical east coast of Queensland, often in associ- This area was selected because it represented the ation with foetid senna, Senna tora (L.) Roxb. (Mackey northern portion of the natural range of S. obtusifolia, et al., 1997). In pastures it is an aggressive invader and which had not been surveyed, and because the work can completely dominate grass species, leading to un- could be undertaken through the North American productive monocultures. Field Station in Temple, Texas. Further, a comparison Preliminary assessments of the phytophagous fauna of the climates of the Mexican cities of Acapulco, Ve- associated with S. obtusifolia and the prospects for racruz, and Me´rida, using CLIMEX (Skarratt et al., biological control have been provided, chiefly from the 1995) indicated that there were favorable climate literature, by Cock and Evans (1984) and Waterhouse matches with the areas in Australia infested with the and Norris (1987). More recently, the insect fauna of S. weed. 1049-9644/01 $35.00 76 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved. PHYTOPHAGOUS INSECTS ASSOCIATED WITH Senna obtusifolia 77 search Service USDA, Beltsville, Maryland for iden- tification. When not identified by this laboratory, they were forwarded to other taxonomists as appro- priate. Specimens of some species were retained by the taxonomists responsible for identification. These were mostly deposited in the US National Museum of Natural History. Most specimens were returned and are retained in the collection at the Alan Fletcher Research Station. Duplicate material was deposited in the collections of Texas A&M University and the Universidad Nacional Auto´nomadeMe´xico. After identification, the insects were first classified as phytophagous or nonphytophagous. Species thought to feed on plant parts other than nectar, pollen, or dead tissue were considered phytophagous (Strong et al., 1984). Nonphytophagous insects were known preda- tors, parasites, fungivores, pollen or nectar feeders, FIG. 1. Survey sites ( ) in Mexico and Honduras from which and others whose habits indicated only casual associ- insects were collected. ation with the plant. Insects captured only in a non- phytophagous life stage (e.g., adult Lepidoptera and MATERIALS AND METHODS almost all adult Diptera) were treated as nonphytopha- gous and are not reported. The investigation was conducted from Temple and The host range of each identified, phytophagous Cuernavaca (Morelos, Mexico), where the first and sec- species was assessed by consulting entomologists ond authors, respectively, were based. It was under- knowledgeable about the particular species or group, taken from September 1991 to December 1993. The insect collections in various institutions, and the area of search (Fig. 1) in Mexico consisted of the Gulf literature. All available knowledge about each spe- coast states of Veracruz and Tamaulipas, the Pacific cies was used to assign it to host range categories coast states of Guererro, Oaxaca, Michoaca´n, and Jalisco, (Table 1), from “*” for a species thought to have hosts the central state of Morelos, and the Yucatan peninsula outside the Order Fabales to “******” for one having states of Yucatan and Quintana Roo. One collecting trip only S. obtusifolia as its host. However, it must be was also made to Honduras in December 1993. emphasized that these ratings in many cases are no Throughout these areas, plants were usually exam- more than our “best estimate” at the conclusion of ined along roadsides after being spotted from a car. the project. Selected areas such as Lake Tequesquitengo (Morelos), Each species was recorded in a computer database Chapultepec and Cruz Grande (Guerrero), Playa Vi- (Palmer, 1995) along with details gathered at the cente (Veracruz), and Temascal (Oaxaca) were reexam- time of collection and relevant literature. In this way ined on a number of occasions. In all, stands of S. a profile of each species was developed and these are obtusifolia were examined on some 93 separate occa- available on request from the first author. sions during the project. S. obtusifolia is mostly an annual. In the area of survey, germination commences after the onset of the RESULTS rainy season in July, flowering commences by Septem- General Analyses ber, and the plants usually begin senescing by Decem- ber with mature pods remaining on the plants. Search- The phytophagous fauna associated with S. obtusi- ing was therefore undertaken mainly in the second half folia in Mexico and Honduras is listed in Table 1. Some of the year to coincide with this phenology. 108 species representing seven orders and 40 families Insects were collected both by visually inspecting the were found. The orders represented were Orthoptera (3 plant and, when appropriate, by sweeping the foliage. species, 2.8% of species), Thysanoptera (3, 2.8%), When evidence of internal insect infestation was Hemiptera (16, 14.8%), Homoptera (33, 30.6%), Co- present, either the plant part was removed and placed leoptera (45, 41.7%), Diptera (1, 0.9%), and Lepidop- in an emergence enclosure or it was opened and the tera (7, 6.5%). insect removed. Any evidence of feeding by the insect Many of the insects were found only once or twice, was noted. Immatures were reared to maturity to ob- indicating that S. obtusifolia is utilized intermittently tain adults for identification. by a large number of species. Only 20% of the fauna All insect specimens were first submitted to the was found either “occasionally” or “commonly” (our Systematic Entomology Laboratory, Agricultural Re- criteria). Six species were endophagous. 78 PALMER AND PULLEN TABLE 1 The Phytophagous Insects Associated with Senna obtusifolia in Mexico and Honduras Frequencya Stagesc Plantd Specificitye Pestf Species of collection Distributionb found part index status Orthoptera Gryllidae Oecanthus fultoni Walker R 2 A Leaf * * Pyrgomorphidae Sphenarium sp. R 2 A Leaf — Tettigoniidae Anaulocomera sp. R 3 A Leaf — Thysanoptera Thripidae Caliothrips phaseoli (Hood) C 2 L, P, A Leaf * * Frankliniella nr. curiosa Priesner R 2 A Franklinothrips vespidiformis (Crawford) R 4 A Leaf Hemiptera Alydidae Megalotomus sp. R 1 A Leaf — Coreidae Anasa scorbutica (F.) R 1 A Leaf * * Sagotylus confluens (Say)

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