MT& BIOLOGY AND ECOLOGY OF TWO PREDATORS, Geocoris pallens Stàl and G. bullatus (Say) Teclmical Bulletin No. 1446 0^ Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE ABSTRACT Biology and ecology of Geocoris pallens and G. bullatus, two omnivorous preda- tors, were studied. Laboratory-rearing and interbreeding tests were conducted to differentiate the life stages of both species. Eggs of Geocoris hatched at 21° to 41° C, and egg developmental rate varied with temperature and also with time of adult collection. Combination of sunflower seeds, insects, and green plant food was the best diet for the quickest developmental rate, highest egg production, and the greatest survival rate. Sunflower seed when placed in the field concentrated Geocoris and increased oviposition. Alfalfa as interplants in a mixed-culture ex- periment served as a breeding and reservoir site for Geocoris. Geocoris was also the most abundant predator in the predator complex in the mixed-culture experi- ment. Daily high temperatures above 24° appear to be correlated with the increase in Geocoris flight. In the seasonal-life-history studies on alfalfa G. bullatus over- wintered in the adult and egg stage and had at least three generations per year, but G. pallens overwintered as adults and had at least two generations per year. Both species decline in September on cultivated crops, but G. bullatus is found in great abundance in orchardgrass in the fall. ACKNOWLEDGMENT We wish to thank B. J. Landis, R. L. Wallis, and H. R. Moflitt of this station, K. S. Hagen of the University of California, Berkeley, Calif., and C. A. Johansen, Washington State University, Pullman, Wash., for their critical review of the manuscript. Credit should be given to P. D. Ashlock of the University of Kansas for suggesting that sunflower seeds be investigated as a possible source of supple- mental food for Geocoris in the field. We are also indebted to W. T. Mondor for preparation of the photographs and tables. Mention of a proprietary product in this publication does not constitute a guar- antee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval by the Department to the exclusion of other products that may also be suitable. CONTENTS Introduction ^^f Discriminatory characteristics 3 Interbreeding 3 Description of life stages 3 Adult ' ' 4 Egg ,//.../..,,.,[. 4 First Instar 4 Second Instar 4 Third Instar 4 Fourth Instar g Fifth Instar * Q Life history and biology g Egg development and temperature g Laboratory evaluation of different foods H Pea aphids and sunflower seeds XI Pea aphids, sunflower seeds, and beans H Sugarbeet leaves, beet leafhoppers, and green peach aphids 18 Field-collected adults on different diets 19 Conclusions and discussion 19 Field evaluation of sunflower seeds 22 Arrests 22 Oviposition 24 Conclusions and discussion 24 Alfalfa interplant study 27 Experimental design 27 Prey complex 27 Lygus 27 Pea aphids 27 Green peach aphid 3Q Predator complex 3Q Geocoris OQ Geocoris and other predators 34 Conclusions and discussion 3g Predator of Myzus persicae in a greenhouse study 36 Field biology and ecology 39 Ovipositional sites 39 Flight activity 39 Seasonal life history 4;^ Spring emergence 4;!^ Overwintering 4-1^ Number of generations on alfalfa 43 Summary 43 Literature cited 45 Washington, P.C. Issued March 1972 For sale by the Superintendent of Documents. U.S. Government Printing Office Washington, D.C. - Price 50 cents stock Number 0100-1485 ÎÎ BIOLOGY AND ECOLOGY OF TWO PREDATORS, Geocoris pallens Stâl and G, bullatus (Say) ^ By GEORGE TAMAKI, research entomologist, and R. E. WEEKS, agricultural research technician, Entomology Research Division, Agricultural Research Service INTRODUCTION In the Yakima Valley of Washington, the two eous on species of weevils that were introduced most common species of Geocoris are G. pallens into California for the control of puncturevine, Stal and G. bullatus (Say) (Lygaeidae: Geoco- Tribulus terrestris L. rinae). G. atricolor Montandon is much less nu- Fapers by York (Í6) and Sweet (J^l) contrib- merous. These insects are found in nearly all uted to better understanding of Geocoris, York cultivated fields, orchards, residential yards, found that G. pallens and G. punctipes required weedy areas, and even in meadows of the Pinus moisture as well as insect food and fed on plants ponderosa zone about 3,000-foot elevation on the as the primary source of moisture. Sweet report- eastern slopes of the Cascade Mountains. Be- ed on the seed-feeding habits of Lygaeidae and cause of their great abundance and wide distri- established the subfamily Geocorinae as definite- bution, we undertook the study of comparative ly predaceous. He also found that Geocoris ulig- biology and ecology of G. pallens and G. bullatus linosus (Say), G. bullatus, and Hypogeocoris pi- for the better understanding of these predators ceus (Say) were by no means obligate predators and for the possibility of manipulating popula- because adults survived upon sunflower seeds tions in an integrated control program. and water for as long as 3 or 4 months. He hy- A paper by McGregor and McDonough {28y pothesized that *This apparent omnivorousness presented one of the earlier studies that used may well account for the high abundance of quantitative data to evaluate Geocoris as a pred- many geocorines, which has always puzzled stu- ator. They reported that G. punctipes (Say) dents who have considered them strictly preda- was an effective predator of the two-spotted tory. In view of the prevalence of seed feeding, spider mite, Tetranychus urticae Koch; but, as it is very likely that Geocorinae and the Clera- Usinger U2) has reported, early references, al- dini are derived from seed feeding ancestral most without exception, refer to Geocoris as de- forms." structive insects. These references were often A prey list of Geocoris species, their localities, based on superficial evidence of the occurrence and references are found in table 1. An attempt of the insects on a given plant. After the mid- was made to list only the earliest reference to a 1930's, most of the literature established Geoco- particular prey species. Undoubtedly the list is ris as a beneficial insect ; however, Goeden and incomplete. Table 1 definitely establishes Geoco- Ricker (15) found that G. pallens was predac- ris as omnivorous predators because of their wide prey range. Geocoris encompass a wide iPublished in cooperation with the College of Agricul- habitat range, including legumes, cotton, sugar- ture, Research Center, Washington State University, beet, vegetables, citrus, ornamentals, tobacco, Pullman 99163. and other cultivated and noncultivated plants, 2 Italic numbers in parentheses refer to Literature Cited, p. 45. throughout most of the world. TECHNICAL BULLETIN 1446, U.S. DEPARTMENT OF AGRICULTURE TABLE 1.—Prey list of Geocoris species Prey Predator Reference Location Hemiptera : Therioaphis maculata G. pallens Smith and Hagen (1956) ... California. (spotted alfalfa aphid). Do G, atricolor do Do. Do G, punctipes do Do. Nearctaphis bakeri G. bullatus Smith (1923) Idaho. (clover aphid). Acyrthosiphon pisum G. atricolor Knowlton and Stains (1941).... Utah. (pea aphid). Myzus persicae G. decoratus Knowlton (1936) Do. (green peach aphid). Circulifer tenellus G. pallens Essig (1926) California. (beet leaf hopper). Empoasca devastans G. tricolor Subba Rao and others (1965) ... India. (leaf hopper). Do G. jucundus ..do Do. Empoasca solans G. punctipes Moflitt (1967) California. Aleyrodes spiraeoides G. pullens.. Landis and others (1958) Washington. (whitefly). Trialeurodes abutilonea do do Do. (banded-winged whitefly). Paratrioza cockerelli G. decoratus Knowlton (1933) Utah. (potato psyllid). Trioza maura G. atricolor Knowlton (1942) Do. (psyllid). Ferrisia virgata G. tricolor Otanes and Butac (1935) Philippines. (striped mealybug). Citrus red scale G. liolestes Hesse (1947) South Africa. Creontiades pallidus G. amabilis.. Soyer (1942) Africa. (mirid). Nysius ericae G. atricolor Knowlton (1935) Utah. (false chinch bug). Calocoris angustatus G. tricolor Rangarajan and others (1964) India. (mirid). Ragmus importunitus do do Do. (mirid). Psallus seriatus G. punctipes Isely (1927) Arkansas. (cotton fleahopper). Lygus pra,tensis do ..do Do. (lygus bug). Adelphocoris rapidus do do Do. (rapid plant bug). Coleóptera : Myllocerus viridanus G, tricolor Rangarajan and others (1964). India. (weevil). Amorphoidea lata do Otanes and Butac (1935) Philippines. (weevil). Lady beetle G. liolestes Hesse (1947) South Africa. Epitrix pa^rvula G. punstipes Chamberlin and Tenhet (1923) Florida and (flea beetle). Georgia. Lepidoptera : Protoparce sp. -do Gilmore (1936). North Carolina. (horn worm). Heliothis zea G. uliginosus Bell and Whitcomb (1964) Arkansas. H, virescens do do.. Do. BIOLOGY AND ECOLOGY OF GEOCORIS FALLENS AND G. BULLATUS TABLE 1.—Prey list of Geocoris species—Continued Prey Predator Reference Location Acariña: Tetr any chus urticae G. punctipes McGregor and McDonough (1917) South Carolina. (two-spotted spider mite). Paratetranychus indicus Geocoris sp. Cherian (1933) India. (cholam mite). DISCRIMINATORY CHARACTERISTICS During the summer, when Geocoris were pair was placed in a cylindrical plastic cage (15 found in great abundance in the Yakima Valley, cm. in diameter and 6 cm. deep) with sugarbeet the genus was generally represented by two spe- leaves, green peach aphids (Myzus persicae cies, G. pallens and G. bullatus. Except for the (Sulzer)),