Research Note

NATURAL ENEMIES OF OF THE GENUS EMPOASCA (HOMOPTERA: CJCADELLIDAE) IN PIGEON PEAS ' The Empoasca spp. has A survey of leafhoppers was undertaken been reported as a major pest from all the on the farms of Isabela and Fortuna Exper­ pigeon pea growing areas in Puerto Rico.23 iment Stations. We collected plant material, Its presence has always been a difficult natural parasites and predators from June problem for the growers of pigeon peas, and to November 1980. Six plots of pigeon peas its damage has often resulted in the com­ of variety 2 B-Bushy were planted in both plete failure of this crop.4 Leafhoppers also locations to increase populations of leafhop­ attack other crops and ornamental pers and natural enemies. No pesticides plants.5-6-7-8 Injuries are apparently more se­ were used on these plots. Specimens were vere during hot dx*y weather. Control by collected and observations were made on chemical means has been the only method each plot and in each area twice monthly. used. No work has been conducted and no We collected samples by sweeping with an information appears to have been published net near the center of each plot. The regarding control by natural enemies of bag containing the samples was carried to Empoasca spp. However, biological control the laboratory and then the leafhoppers measures have been emphasized in other were transferred to rearing cages with food. countries with other crops. The search for Plant samples containing Empoasca spp. natural parasites and predators in commer­ eggs were reared for possible egg parasites. cial pigeon peas, both introduced and newly Leaves and stems infested with leafhopper developed varieties, might result in a per­ populations were removed from the plant manent safe and less expensive control of and taken to the laboratory and placed on the leafhopper. moist filter paper in petri dishes inside rear- ing cages and in half gallon ice cream con­ The purpose of this investigation was to tainers. Observations were made daily to gather preliminary infonnation on the oc­ detect emerging parasites. Parasites and currence of natural enemies in pigeon pea predators were also observed in pigeon pea fields. fields.

'Manuscript submitted to Editorial Board 16 June 1988. 2Ouz, C, 1975. Chemical control of the leafhopper (Harris) on snap beans. J. Ag?ic. Univ. P. R. 59 (1): 82-4. 3 , 1979. Thiodan y Lannate registrados para controlar los insectos del gandur. Esta. Exp. Agrie. P. R. Adelantos Cientificos 89. 'Estaeidn Experimental Agricola, U. P. R., 1977. Conjunto tecnologico para la produc­ tion de gandules: su situacion y sus perspectivas. Esta. Exp. Agrie. Univ. P. R. Publ. 116: 21. 5Wolcott, J. N., 1948. The of Puerto Rico, J. Agrie. Univ. P. R. 32 (1-4): 975. 6 , 1955. Entomologia Economiea Puertomquena. Esta. Exp. Agrie. Univ. P. R. Bui. 125: 124-5. 7Caldwell, J. S. and L. P. Martorell, 1950. Review of the Auehenorynchous Homoptera of Puerto Rico. J. Agrie. Univ. P. R. 34 (1): 116-32. 8Martorell, L. F., 1976. Annotated food plant catalog of the insects of Puerto Rico. Agrie. Exp. Stn. Univ. P. R.

161 162 COTTE & CRUZ/PIGEON PEAS, EMPOASCA

TABLE 1.—Predators obseived feeding on Empoasca spp. in Isabela and FoHuna Substa­ tions (June 1980-November 1980) Order Family Scientific Name Neuroptera Chrysopidae Ckrysopa collaris Schneider Anthocoridae Onus insidiosus Say Hemiptera Reduviidae Zelus longipes (L.) Diptera Dolichopodidae Chrysolus spp. Diptera Micropezidae Taeniaptera sp Coleoptera Coccinellidae Chilocorus cacti L. Coleoptera Coccinellidae Cycloneda sanguinea L. Coleoptera Coccinellidae Hyppodamia convergent (Guer) Hymenoptera Formicidae Solenopsis geminat-a (Fabricius) Hymenoptera Vespidae Polistes crinit-s Felton Odonata Coenagrionidae Enallagma civile (Hagen) Araneida Miscellaneous spiders

A number of predators (table 1) were ob­ trol upon leafhopper population levels dur­ served feeding upon adults and nymphs of ing the period of this study. According to Empoasca spp. in the pigeon pea fields. Woleott6-6 and Cruz2-3 rainfall and humidity Some of the predators reached high popula­ affect Empoasca spp. in Puerto Rico. It be­ tion levels in the fields and must be influenc­ comes abundant during dry weather and ing leafhopper population levels. The nature scarce during rainy season. The variations and extent of this influence was not deter­ in weather conditions may also contribute mined, because studies were confined to to the variations and fluctuations in fungus casual observations in the field. Most of and leafhopper populations. 9 I0 n these predators are general feeders - - Table 2 is a partial list of beneficial in­ which prey upon other insects in the pigeon sects (predators, parasites and pollinators) pea fields such as aphids and pod borers found in pigeon pea fields. Although not ob­ (Heliothis, Etiella, Fundella). served feeding on leafhopper, they have Emphasis was placed upon the some influence or importance upon this in­ hymenopterous parasites of the eggs of Em­ sect. poasca spp. However, no insect parasites Further studies should be conducted to were found in any of the leafhopper stages. determine the relationship between the en- During the rainy season the parasitic tomophagus insects and leafhopper popula­ fungus Metarrhizium anisoplae (Moniliales: tions. They appear to be responsible for Moniliaceae) attacked the adults of this maintaining the equilibrium of insect pest species. The host, after death, turns to populations. a pale yellowish, whereas the fungus The failure to obtain parasites could not growth varies from white to green. The at­ be due to decreased leafhopper populations. tack was sporadic, not enough to exert con­ According to Subba Rao12 as the number of '-'Mancia, J. E. and M. L. Cortes, 1972. Estudio preliminar sobre los enemigos naturales (parasitos y predatores) de las principales plagas del frijol. XVIII Reunion Anual PCCMA. Managua, Nicaragua, Mayo 6-10, 194-203. j0Subba Rao, B. R., P. Balder, R. Atma, R. P. Singh and M. L. Srivastada, 1965. Studies on the parasites and predators of Empoasca devastans Distant (Jassidae: Homopt- era). Indian J. Entomol. 27: 104-6. !lVan Den Bosh, R. and K. S. Hagen, 1966. Predaceous and parasitic in California cotton fields. Cat. Agric. Exp. Stn. Bui. 820: 1-32. l2Subba Rao, B. R., P. Balder, R. Atma, R. P. Singh and M. L. Shrivastada, 1968. Distribution of Empoasca devastans and its egg parasites in the Indian Union, Ent. Exp. El. Appl. 11: 250-4. J. Agric. Univ. P.R. VOL, 73, NO. 2, APRIL, 1989 163

TABLE 2.—Partial list of predators, parasites and pollinators found on pigeon pea fields at Isahela and Fortuna Substations (June 1980-November 1980) Scientific name Order Family Predator Parasite Other Calosoma sp. Coleoptera Carabidae Photinus sp, Coleoptera Lampyridae Tkonalmus sp, Coleoptera Lycidae Scymnus sp. Coleoptera Cocci nellidae Baccha sp. Diptera Syrphidae Apis mellifera L. Hymenoptera Apidae Pollination Xilocopa brasilianorum (L.) Hymenoptera Xilocopidae Pollination Aphidius sp. Hymenoptera Braconidae Enicaspilus sp. Hymenoptera Ichneumonidae Brackymeira sp. Hymenoptera Chalcididae leafhoppers per leaf decreases the percent­ lations, judicious use of insecticides and pre­ age of parasitism increases. In order to pro­ servation of native predators and parasites. mote parasitism, if chemical control is Considering that chemical control for Em- necessary in pigeon pea fields, a selective poasca spp. in pigeon peas is generally insecticide must be used, so that a fair necessary, particularly during dry periods, chance is given to the parasites or predators we must recommend the use of selective in­ to build up their populations. In search for secticides whenever possible. parasites the investigator must select pi­ Further research on selective insec­ geon pea fields where pesticides have not ticides and the biology and ecology of the been applied for many years. fauna in pigeon pea fields would The pest control program using chemi­ be needed in order to implement an integ­ cals on pigeon peas in Puerto Rico has ex­ rated control program. panded in recent years. On the other hand, Osvaldo Cotle the integrated control program emphasized Extension Specialist in Entomology by the Extension Service is based primarily Carlos Cruz upon careful field evaluation of insect popu­ Entomologist