2008 Annual Report
1a.Objectives (from AD-416)
Biological control strategies will be evaluated for management of emerging cotton pests and the exotic weed, Arundo donax. The lethal and sub-lethal effects of pesticides on key natural enemies of glassy-winged sharpshooter will be investigated to support IPM programs for this pest. Specific objectives are:.
1)Identify, collect, culture, and evaluate candidate natural enemies for efficacy against lepidopteran pests, including the beet armyworm and the cotton bollworm, as well as the green cotton mirid;.
2)Evaluate the effects of pesticides on selected natural enemies of glassywinged sharpshooter and selected predaceous spiders in the cotton agroecosystem;.
3)Evaluate the potential of entomopathogens to manage the varroa mitre and glassywinged sharpshooter; and.
4)Determine the distribution and origin of Arundo donax, giant reed, in the Rio Grande River Basin, and assess the potential impact of candidate biological control agents to manage this invasive weed of riparian habitats.
1b.Approach (from AD-416)
The BIRU will discover and evaluate beneficial insects and pathogens for biological control of the most serious pests and weeds of agriculture in the southwestern U.S., with applications of this research at the national and international level. Changes in cotton production in this region due to the potential eradication of the boll weevil and adoption of transgenic Bt cotton varieties has reduced use of broad spectrum insecticides to control key pests. This pest management strategy has resulted in the emergence of formerly secondary insects such plant bugs as serious pests. New management strategies must be developed to reduce the pesticide use in cotton. The biology and ecology of these emergent pests will be investigated, with the goal of learning where they originate before entering crops, identifying their natural enemies, devising methods to manipulate or otherwise conserve them, and to import new natural enemies for classical biological control. Further, the role of nocturnal spiders will be investigated to quantify the important role they play as predators of Lepidoptera eggs (beet armyworm & bollworm) and to support their conservation in the agroecoystem. The effects of pesticides on key natural enemies, including those of the green cotton mirid and glassy-winged sharpshooter, will be measured, and least toxic insecticides will be identified. This will allow producers to reduce their pest problems while protecting natural enemies. The insect pathology program will concentrate on technology transfer of a pathogen treated hive strip for control of varroa mite with honey bees. Water resources are critical to agriculturists, land managers, and urban users in the arid southwestern U.S. A biological control program to manage giant reed, an exotic water-using weed in the Rio Grande Basin, will be initiated.
Quarantine laboratory studies of the biology of the stem-galling wasp Tetramesa romana and the scale insect Rhizaspidiotus donacis were completed. These studies determined the size and duration of the immature life stages; the size, longevity and fecundity of the adult stage for each insect; and the generation time for each insect. Additional studies compared life history parameters between French and Spanish populations of these candidate biological control agents, and determined environmental influences on egg-laying behavior by the stem-galling wasp. A major new research focus was initiated on the impact of field populations of T. romana wasps that were introduced via unknown means in Laredo, Texas along the Rio Grande. These studies determined the number of wasps in giant reed stems and assessed the amount of damage done to mature and young giant reed shoots and the impacts on shoot growth.(NP 304 Crop Protection and Quarantine)
Behavioral assay for cursorial spiders in cotton:
Scientists in the Beneficial Insects Research Unit, Weslaco, TX, have developed a behavioral assay to evaluate the effects of nectar ingestion and exposure to nectar odors on the searching behavior of cursorial spiders. This methodology was used to compare responses of spiders to feeding on both prey eggs and nectar and to demonstrate, for the first time, that the responses to nectar ingestion induced localized searching behavior in spiders similar to that induced by feeding on prey eggs. (NP 304, Component II)
Investigation of the biology of the arundo wasp:
Specific information about the biology of candidate insects being considered as biological control agents of giant reed, Arundo donax is a required part of field release petitions submitted to the USDA-APHIS Technical Advisory Group (TAG) on Biological Control of Weeds. In quarantine laboratory studies,conducted by scientists at the Beneficial Insects Research Unit, Weslaco, TX, the size and duration of the immature life stages (egg, larval, and pupal) of the wasp, Tetramesa romana, a candidate biological control agent of giant reed, were determined, as was the total amount of time needed by the wasp to complete one generation (33 days). The lifespan (3-4 days) and reproduction (average of 20 offspring per female) by adults were also determined. Spanish wasps were more fecund and lived longer than French wasps. This accomplishment illustrated the potential for the wasp, T. romana, to rapidly establish populations and have impacts on giant reed, and contributed to the petition submitted to the USDA-APHIS-TAG in March 2008, which in August 2008 was recommended for approval. (NP 304, Component II).
Investigation of the biology of the Arundo scale:
Specific information about the biology candidate insects being considered as biological control agents of giant reed, Arundo donax, is a required part of field release petitions submitted to the USDA-APHIS, Technical Advisory Group (TAG), on Biological Control of Weeds. The size and duration of the immature (larval) life stages of the scale insect, Rhizaspidiotus donacis, a candidate biological control agent of giant reed (Arundo donax L.) were determined. This insect uses its stylet-like mouth parts to drink juices in plant tissues. Scientists in the Beneficial Insects Research Unit, demonstrated that the scale completed one mobile ‘crawler’ stage, and one additional immature stage, followed by emergence of short-lived winged adult males 40-50 days after crawler infestation of plants, and continued feeding and development of adult females. Individual females completed the life cycle by producing 100-200, crawlers 5-6 months after being placed as crawlers on giant reed plants. This accomplishment illustrated the potential for the scale insect, R. donacis, to establish large, long-lived populations on giant reed, and contributed to the petition submitted to the USDA, APHIS, TAG in March 2008. (NP 304, Component I)
Investigation of Nocturnal Predators in Cotton:
The actions of egg predators of the beet armyworm and other lepidopteran pests, particularly those predators that are nocturnal, and the effects of malathion on them, need to be defined. This field research is needed to enhance the Boll Weevil Eradication Program by minimizing secondary pest outbreaks. Nocturnal studies of predation, by scientists in the Beneficial Insects Research Unit, Weslaco, TX, yielded new insights into the exotic Asian cockroach. This cockroach was discovered in the lower Rio Grande Valley in 2006 (it was first discovered in the U.S. in 1986 in Florida) and was observed frequently feeding on eggs of lepidopteran pests of soybean and cotton. During 2006 and 2008, this cockroach was the most important predator of lepidopteran eggs in soybean. (NP 304)
Investigation of Spiders as Agroecosystem Predators:
Little is known about the biology of cursorial spiders as predators in the cotton agroecosystem. Research is needed to determine the interactions of spiders and extrafloral nectaries in cotton. A novel behavioral assay was developed to evaluate the effects of nectar ingestion and exposure to nectar odors on the searching behavior of cursorial spiders. This methodology was used to demonstrate, for the first time, that nectar ingestion induces localized searching behavior and that cursorial spiders are innately attracted to nectar odors. Scientists at the Beneficial Insects Research Unit, Weslaco, TX, also demonstrated, for the first time, that these spiders could be conditioned to respond to novel odors associated with non-prey food. Information from this study has enhanced our basic knowledge of the searching behavior of cursorial spiders. This information is being applied to developing management techniques that enhance and conserve these spiders' population. Increased population levels of spiders will minimize pest outbreaks in cotton and other subtropical crops. (NP 304, Component II)
Release of biological control agents for Arundo donax:
Petitions for release of two biological control agents for Arundo donax were submitted to the USDA-APHIS Technical Advisory Group (TAG). Arundo donax, is an invasive riparian weed, which is a serious ecological threat to the Rio Grande River Basin and other watersheds in the Southwestern U.S. Scientists at the Beneficial Insects Research Unit, Weslaco, TX, have imported four biological control agents from Europe into USDA quarantine facilities in Texas for biological control of A. donax, carrizo cane. These biological control agents are a shoot-feeding wasp, Tetramesa romana, a cane-burrowing fly, (Cryptonevra spp.), a rhizome-infesting scale, (Rhizaspidiotus donacis), and leaf sheath mining fly, (Lasioptera donacis). This program for biological control of an invasive weed has stimulated significant interest and support for the project from the International Boundary and Water Commission, Department of Homeland Security, Bureau of Reclamation, Fish and Wildlife Service, Texas Rio Grande Watermaster, Texas Parks and Wildlife, Texas Department of Transportation, Texas Lower Rio Grande Valley Irrigation Districts, PRONATURA Mexico, and CONANP Mexico. (NP 304, Component II)
|Number of New Germplasm Releases||4|
|Number of Non-Peer Reviewed Presentations and Proceedings||14|
|Number of Other Technology Transfer||2|
Pfannenstiel, R.S., Booth, W., Vargo, E.L., Schal, C. 2008. The Asian cockroach Blattella asahinai Mizukubo (Dictyoptera: Blattellidae): A new predator of lepidopteran eggs in south Texas soybean. Annals of the Entomological Society of America. 101:763-768.
Goolsby, J., Adamczyk Jr, J.J., Bextine, B., Lin, D., Munyaneza, J.E. 2007. Development of an IPM program for management of the potato psyllid to reduce incidence of zebra chip disorder in potatoes. Subtropical Plant Science. 59:85-94.