JONATHAN LUNDGREN (D1520-1)

Working After Hours A Nighttime View of Insect Predation

Cyclotrachelus alternans are an important predator of corn rootworm larvae, but are only active at night. TOM HLAVATY (K1289-17)

rowers have much to consider postdoctoral associate Zsofia when protecting crops from insect Szendrei, Weber studied the G activity and feeding patterns pests. Determining which insects are threats to a crop entails effective sam- of these predators over pling to get a good count of the species several 48-hour periods and life stages of pests and the beneficial during the 2006-2007 grow- insects that prey on them. Natural enemies ing season. of crop pests can help growers when ef- The researchers numbered Corn rootworms are a severe pest of corn. Shown here is forts are made to conserve and increase and photographed a total of the adult stage of the western corn rootworm. their numbers. 240 CPB egg masses before It’s becoming apparent that daytime attaching them to leaves of sampling of pests and beneficial insects potato plants in a research field. During nocturnally active predators of pests in doesn’t present the full picture for effec- each 48-hour period, they examined egg the Lower Rio Grande Valley in south tive natural pest control. Now, thanks to masses every 3 hours, looking for damage Texas. Pfannenstiel and technicians at the ARS researchers, nocturnal insect activity, to the eggs or the presence of beneficial Beneficial Insects Research Unit (BIRU) particularly beneficial predation, is getting insects on them or nearby. in Weslaco have done day and night field the attention it deserves as an important Of the many predation events observed, tests on insects feeding on lepidopteran part of the biological-control puzzle. 56 percent occurred after dark, with the eggs in cotton, corn, and soybean. fewest observed during the afternoon hours. The predators that feed on moth eggs What’s Eating the Colorado Potato The most frequently documented predator during the day are very different from Beetle? in the study, larval Chauliognathus sp.— those that feed at night, and nighttime Entomologist Don Weber, at the ARS commonly known as the “soldier beetle” predation can be much more important. Invasive Insect Biocontrol and Behavior or “leatherwing”—had not been previously Two types of nocturnal predator have stood Laboratory in Beltsville, Maryland, reported as a CPB egg predator. “This out from the rest: the cursorial (running) focuses on predation of Colorado potato finding identifies another noninsecticidal spiders, mainly Hibana futilis, and the beetle (CPB), a significant pest mainly control to protect crops from Colorado Asian cockroach, Blattella asahinai. of potato crops. When only daytime potato beetles,” says Weber. (For the Asian cockroach work, see insect populations are counted, some Adult Lebia grandis—a type of carabid “Asian Cockroaches Could Aid Texas major nocturnal predators of CPB eggs ground beetle—prey only on CPB eggs Growers,” Agricultural Research, January are underestimated or missed. With and larvae and are mostly active at night. 2008, p. 11.) Their egg consumption exceeded that of

BOB PFANNENSTIEL (D1519-1) the mainly daytime-active pink spotted BARRY FITZGERALD (K2252-8) ladybeetle (Coleomegilla maculata). Asian cockroach, Blattella True bugs like stink bugs (Perillus and asahinai, is a nocturnal predator of Podisus) and big-eyed bugs (Geocoris) lepidopteran eggs. were active almost exclusively during daylight hours.

Nocturnal Predators From Texas In the past 8 years, entomologist Bob Pfannenstiel and other ARS scientists Spider, Cheiracanthium inclusum, feeding at night on a bollworm egg on a cotton leaf. have been studying the feeding habits of

10 Agricultural Research/October 2009

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Adults of the native carabid beetle, Lebia grandis, are voracious Adult Colorado potato beetle. Adults and larvae eagerly predators of Colorado potato beetle eggs and larvae. consume potato foliage.

Cursorial spiders consume significant Wondering how so many and such and Weber organized a symposium for the numbers of moth eggs in row crop foliage. diverse species could coexist in the con- Entomological Society of America’s an- About 99 percent of their predation occurs fines of the upper surface of soil near corn nual meeting in November 2008, entitled after dark. These spiders are particularly roots, Lundgren’s research revealed that “Seizing the Night: Nocturnal Studies of important in cotton, where they benefit the answer might be separation by time. Insect Predation Yield New Insights.”— from consuming the plant’s sugars. Labo- For example, wolf spiders search for root- By Sharon Durham, Alfredo Flores, and ratory and greenhouse studies by BIRU worms during the night, while some other Don Comis, ARS. scientists, including entomologists Shoil spiders hunt during the day. This research is part of Crop Protection Greenberg and Randy Coleman, have Lundgren also found that one common and Quarantine, an ARS national program shown that the spiders also prey on other carabid beetle, Poecilus chalcites, prefers (#304) described on the World Wide Web cotton pests, including the cotton fleahop- day work, while another, Cyclotrachelus at www.nps.ars.usda.gov. per, Pseudomatoscelis seriatus, and the alternans, works a night shift, 10 p.m. to Donald C. Weber is with the USDA-ARS cotton plant bug, Creontiades signatus. 3 a.m. Invasive Insect Biocontrol and Behavior “We’ve found that the cursorial spider “So even though the two carabid species Laboratory, 10300 Baltimore Ave., Belts- prefers the cotton fleahopper, which is are abundant in the same confined area, ville, MD 20705; phone (301) 504-8369, smaller than the cotton plant bug. This they rarely run into each other in their hunt fax (301) 504-5104, e-mail don.weber@ suggests that the spider has the potential for rootworms,” Lundgren says. ars.usda.gov. to be an important predator of cotton flea- Lundgren and colleagues have two Robert S. Pfannenstiel is in the USDA- hopper,” says Pfannenstiel. main ways of spying on predators. First, ARS Beneficial Insects Research Unit, Pfannenstiel has also frequently ob- they go out just after the sun goes down 2413 E. Hwy. 83, Weslaco, TX 78596; served the cotton fleahopper as a mostly and place about 250 rootworms into the phone (956) 969-4858, fax (956) 969-4888, nocturnal predator of lepidopteran eggs in soil near corn roots. They come back 90 e-mail [email protected]. cotton, meaning it can act as both a pest minutes later with a red light to see which Jonathan G. Lundgren is with the and a predator. of their sentinels have been attacked and USDA-ARS North Central Agricultur- which predators are hanging around. Most al Research Laboratory, 2923 Medary Illuminating Nocturnal Predation insects are oblivious to red light and carry Ave., Brookings, SD 57006; phone (605) At the ARS North Central Agricultural on with their normal activities despite the 693-5211, fax (605) 693-5240, e-mail Research Laboratory in Brookings, South observers. [email protected]. ✸ Dakota, entomologist Jonathan Lundgren Another tactic is to collect predators goes into corn fields late at night and looks every 3 hours from a timed, rotating pitfall

for predators that have an appetite for corn trap. Predators that fall in are ground up, PEGGY GREB (D1516-1) rootworms, the most costly pest of corn and their stomach contents are analyzed in the world. for corn rootworm DNA. This gives Since the rootworms do most of their scientists both the time the predators are damage during their larval stage, when hunting and the amount of rootworms they they live underground, Lundgren confines are eating. his observations to the top few inches of Nocturnal predators of pests in many soil. regions and in many crops have yet to “There is abundant and diverse life be determined. Research on day-active underground, with predators including and night-active predators is important to Adult spotted pink lady beetles, Coleomegilla ground beetles, rove beetles, spiders, developing strategies that maximize their maculata, are common native predators of crickets, and daddy-longlegs.” benefits to crops. To this end, Pfannenstiel Colorado potato beetle eggs.

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