Arizona Crops
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Pentatomids Associated with Arizona Crops Item Type text; Book Authors Butler, G. D.; Werner, F. G. Publisher College of Agriculture, University of Arizona (Tucson, AZ) Rights Copyright © Arizona Board of Regents. The University of Arizona. Download date 01/10/2021 17:54:31 Link to Item http://hdl.handle.net/10150/602185 TECHNICAL BULLETIN 140 APRIL 1960 PENTATOM I DS Associated With Arizona Crops Published by the AGRICULTURAL EXPERIMENT STATION THE UNIVERSITY OF ARIZONA, TUCSON Seventy-Fifth Anniversary 1885 -1960 PENTATOMI DS Associated With Arizona Crops by G. D. Butler, Jr.' and F. G. Werner' Illustrations by Marian S. Adachi2 Stink bugs are among the largest Hemiptera found on crop plants. Their characteristic triangular or shield -like shape makes most species easily recognizable in the field. The other families with similar shape are rarely seen in samples from crops. In case of doubt as to their identity, the true stink bugs, family Pentatomidae, can be recognized by the follow- ing combination of characters: antennae 5- segmented; scutellum triangular, not U- shaped; and legs without stout spines. Most of our species are brightly colored and most of them make their presence known by the emissions from the scent glands. Some experienced entomologists can detect their presence in a field by the odor alone. All can distinguish them in the sweep net. Most of our common species are defintely harmful to crops, especially seed crops, because they feed on developing seeds; at least one also feeds on vegetative growth. Podisus acutissimus is beneficial because it is predaceous, feeding on other insects. This species is not to be considered one of our most important predators, however, since it rarely occurs in such numbers as do the reduviids, nabids, etc. A considerable amount is known about the biology and nature of dam- age of our most important species. The available information is summar- ized under the species but the papers cited should also be consulted if more detail is desired. Several recent taxonomic studies have affected our species and further biological investigations will be needed where there is a chance that more than one species is reported under one name in the older literature. 1. Associate Entomologists, Department of Entomology, College of Agriculture, University of Arizona, Tucson. 2. Former Research Assistant, Department of Entomology, University of Arizona. -1 - LIFE HISTORY Stink bug eggs are deposited in masses averaging from 17 eggs in some species to 32 in others, arranged in three to five parallel rows. The eggs hatch in about five days in the summer and in from nine to 12 days in the spring and fall. About 30 to 40 days are required for the eggs to hatch and for the nymphs to mature, through five instars. Mating and egg - laying start within two weeks after the adult stage is reached. Adults live from 40 to 60 days in the spring and summer but from seven to nine months when they overwinter. The life cycle may be completed in some- what less than five weeks in the summer and from seven to nine weeks in spring and fall. Russell (1952) has studied the overwintering of the three common species in southern Arizona, Chlorochroa sayi, Thyanta pallido- virens spi- nosa (as T. custator) and Euschistus impictiventris. The following account is from this author. The winter is passed in the adult stage, some indi- viduals seeking shelter in late September and remaining there until mid - April. Most remain inactive from late December to early February. Euschis- tus and Thyanta may become active during warm days during this period but Chlorochroa is less active during the winter months. The adults usually overwinter in protected places near the soil surface, under low- growing plants and plant debris. A favored location is under the spreading branches of Australian saltbush, a common plant in cultivated parts of southern Ari- zona. He could find as many as 300 adults per square foot of soil surface under this plant. Emergence and resumption of normal activity on spring hosts begins in early March and may extend over several weeks before all the adults are active. Various weeds, such as Sisymbrium Trio, mallow and nettleleaf goosefoot, are preferred spring host plants. These weeds may be abundant in waste lands, along margins of fields, etc. Most of the females that have hibernated lay their eggs on these plants, which bloom and produce seeds from mid -January to late April or early May. Oviposition normally starts about March 15. Adults of the first generation begin to appear in April and early May. At this time the spring host plants are drying up and most of the second generation adults migrate; they turn up on small grains, sugar beet seed fields, etc. The seasonal sequence in the Salt River Valley was as follows: weeds, Feb. 15 to April 15; sugar beets, April 15 to June 15; small grains, April 15 to May 31; alfalfa, June 15 to Sept. 15; cotton, July 1 to Oct. 15; and grain sorghum, Sept. 1 to Oct. 15. In the Safford area the spring emergence is somewhat later and range plants, such as alfileria, serve as hosts for the first generation. Enormous numbers of Say stink bug adults sometimes descend on ripening grain fields in May. RECORDS The samples reported here have been segregated from "sweepings" of crops in all major agricultural areas of the state, as detailed in the fore- word to Ariz. Agr. Exp. Sta. Tech. Bul. 132 and the introduction to Tech. Bul. 133. The crops selected for sampling were not always mature and for this reason the number of samples with stink bugs is relatively small. A crop in a purely vegetative stage may have none at all. Table I sum- marizes the collection records. Two species not taken in the sweeping -2 - Table I. The number of collections of the various species of stink bugs in 522 samples from Arizona crops made in 1954 -56. Total Chlorochroa Chlorochroa Chlorochroa Thyanta Euschistus Podisus County Samples sayi uhleri ligata p -v. spin. impictiv. acutiss. Yuma 76 8 4 9 22 Maricopa 187 16 9 46 19 1 Pinal 50 2 2 13 1 2 Pima 74 7 6 22 9 Sta. Cruz 21 1 5 3 1 Cochise 43 8 4 14 2 9 Graham 27 3 10 Greenlee 6 2 1 4 1 Yavapai 12 4 2 5 Gila 4 1 Mohave 7 3 Coconino 5 3 2 Navajo 4 1 2 3 Apache 6 2 2 Totals: 522 58 15 15 138 47 23 samples have been included, one because it is commonly seen on weeds and sometimes attacks crops and the other because it sometimes feeds on developing peach fruit and occasionally on alfalfa and other crops. The authors wish to acknowledge the assistance of Drs. H. H. Ruckes and R. I. Sailer for identification of critical specimens and to thank Dr. Sailer for pointing out the key characters used in segregating Chlorochroa uhleri from C. sayi. CLASSIFICATION An attempt has been made, in the key that follows, to define our species closely enough that any additional species that may be taken will be eliminated from consideration. Arizona has a rich pentatomid fauna and there is a possibility that other species than those included may be seen, particularly in weedy fields and those near the desert. Because the specimens must be examined closely when this key is used, a second key is added, this one designed for use in the field. In most cases this key should be adequate for identification. The species are considered individually in the body of the text and are arranged alphabetically, without regard to relative importance. Key to Adults 1. Bucculae distinct throughout their length, of almost uniform width, and with the first segment of the beak embedded between them. Cheeks without a lateral tooth near their tips 2 Bucculae distinct anteriorly, becoming evanescent behind, not enclosing the first segment of the beak except at its base. Second abdominal sternite with a slender median spine that projects forward to the hind coxae. Humeral angles of pronotum sharply spined. Ground color pale olive -green to pale yellow, marked with dark brown to dull red. The most heavily marked specimens have the markings dark brown, as follows: posterior portion of pronotum, behind a line connecting the humeral spines; apical half of scutellum except for a white tip and a feeble pale midline; and a narrow longitudinal band on the hemelytral membrane. Base of scutellum infuscated except for three elongate white spots. There is a small but very well defined black spot at the middle of the apical third of the corium and there are two black spots at the hind margin of the head. Lightly marked specimens retain the spot on the corium (brown instead of black) and at least a pale brown stripe on the hemelytral membrane. All the other markings may be reduced in extent and dull red in color. The white spots at the base of the scutellum may also be replaced by dull red. The hind margin of the pronotum is often pale. Length 7.5 - 10.0 mm., mean 9.0 . (Fig. 5) Podisus acutissimtes 2. Second abdominal sternite not produced forward in a stout spine . 3 Second abdominal sternite produced forward in a stout spine, which reaches the middle of the hind coxae. Cheeks not surpassing tylus. Osteolar canal long, tapering, much surpassing the middle of its sup- porting plate. Humeral angles of pronotum obtusely produced, not spined. Color uniformly pale green except for the transparent hemely- tral membrane, very narrow yellowish to pink lateral margins on head and pronotum and narrow black posterior borders on the exposed por- tion of the abdominal tergites.