Choose blocks that have known history of pecan weevil infestations for monitoring. “A female weevil can produce 30-54 eggs, so several nuts can be affected from each egg hatch,” Mulder said. Oklahoma Pecan Growers Assoc. The main type of damage is caused by larvae feeding within the nut. Four life stages of the pecan weevil. Hosts. %PDF-1.3 %���� ... Larvae on pecan feed in phylloxera galls in spring. They burrow into the soil and construct a cell where they remain for 8 to 10 months before pupating and transform to adults, although some larvae do not pupate and transform to adults until the following year. In 2017, nuts collected from residential pecan trees produced live pecan weevil larvae in January. INTRODUCTION THE PECAN weevil, Curculio caryae (Horn), attacks green maturing nuts in late summer and damages them by making feeding and oviposition punctures. Larger chestnut weevil grubs chew an exit hole in the side of the nut and drop to the ground usually before the nuts fall. The pecan weevil, Curculio caryae (Coleoptera: Curculionidae) is an obligate feeder on the nuts of North American hickories and pecans (Carya species), most widely recognized as an economically important pest of the pecan, Carya illinoinensis (Fagales: Juglandaceae). They are found in the nuts during late summer and early fall and can be found in the soil beneath infested trees during the rest of the year. 0000001144 00000 n Description The adult is a brownish weevil about 3/8 inch long. It occurs only in north central Texas and is absent from Waco toward the Gulf coast; medically harmless. Literature: Crocker et al. If not managed, this weevil can cause severe economic damage to your pecan operation that could last for multiple years. After shell hardening, treat when weevils begin to emerge and continue spraying at 7-10 days interval especially following rainy days. Larvae feed inside the nuts from late summer through the fall, growing and developing through several stages (instars). Pecan weevil larvae (4 th instar), collected from infested nuts on the USDA-ARS Research Station (Byron, Ga.), were stored in sterile (autoclaved) soil at 25° C. for two weeks, at which time diseased larvae were removed. The adult is a brownish weevil, about 3/8 inch long. 0000034866 00000 n When fully grown, larvae reach a length of 3/5 inch (Fig. 4). The female’s snout is as long as its body; while the male’s snout is somewhat shorter. Pecan South 2(5): 194–196. Life Cycle and Biology The pecan weevil exhibits four life stages: egg, larva, pupa and adult (Figure 1) and it requires two to three years to complete one generation. 11). Weevil larvae feeding in a pecan nut. 0000002733 00000 n The pecan weevil burrows into the nut before the shell hardens and lays eggs, then worms hatch from the eggs and devour the nut. Adult weevils and larvae overwinter in the soil. Hickory shuckworm, Cydia caryana (Fitch) (Lepidoptera: Tortricidae), larvae occur in shucks of pecan nuts. Early damage causes these nuts to fall to the ground prior to maturity. Where it is found in Texas, the pecan weevil is the most damaging late-season pecan pest. Click for a hub of Extension resources related to the current COVID-19 situation. 1984. Please keep in mind that the original opening on the trap top was designed for the boll weevil, which is a much smaller weevil, so be sure to check that the opening is somewhat enlarged for the larger pecan weevil. Larval stages develop in more developed nuts (dough stage), destroying the kernels. The female’s snout is as long as its body; the male’s snout is somewhat shorter (Fig. Figure 7. The pecan weevil burrows into the nut before the shell hardens and lays eggs, then worms hatch from the eggs and devour the nut. The larvae are cream colored grubs with reddish heads. They have reddish-brown head capsules and chewing jaws (Figure 3). Common Name: Pecan weevil 0000032111 00000 n If not contained, the pest could affect the state’s pecan industry’s economic impact. 0000003833 00000 n The pecan weevil causes two types of damage. The pecan weevil has a predominantly 2-year life cycle co-inciding with masting by its Carya host. Their presence does not stop development of the pecan so they may make it into the harvest. In 1986, W. L. Tedders recov- ered H. bacteriophora Poinar Georgia strain from dead, reddish-colored weevil larvae found in a pecan orchard at Byron, Geor- Larvae and pupae become common in flower beds and gardens in which acorns have fallen. The head is yellow to brown. They are found in the nuts during late summer and early fall and can be found in the soil beneath infested trees during the rest of the year. Several species occur, but the most common is Curculio fulvus Chittenden (Coleoptera: Curculionidae). 0000002283 00000 n 0000003397 00000 n 0000001298 00000 n The female’s snout is as long as its body; the male’s snout is somewhat shorter (Fig. First, they feed on the young nuts in late summer, causing some to drop early still in their husks and never complete development. Please keep in mind that the original opening on the trap top was designed for the boll weevil, which is a much smaller weevil, so be sure to check that the opening is somewhat enlarged for the larger pecan weevil. Koch] (Fagales: Juglandaceae) is an economically important North American nut crop ().The pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a key pecan pest affecting orchard nutmeat yield and quality throughout the Southeastern United States, and portions of Texas and Oklahoma (Payne and Dutcher 1985). 0000003436 00000 n 0000032189 00000 n Biological Control of the Pecan Weevil: Smith et al. K����q���:&��jv. Later in the season when pecan nuts are present, moths deposit eggs singly on the nuts. No other insects develop in pecan kernels in the field, although larvae of several pests, such as the Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), can infest stored pecans. Pieces of burlap bags or other cloth tied around a pecan tree trunk in late August so that a flap (appearing as an upside-down V in cross section) is formed will trap adult weevils crawling up the tree trunk after they emerge from the soil, where they can be collected. Adult weevils become active in August and early September. Traps can be obtained for around $18 each from Pecan Ag Equipment in Bristow, Oklahoma (1-918-367-5529). The entire life cycle takes 2 or 3 years. ... Larvae on pecan feed in phylloxera galls in spring. ture 4: Several larvae can be found in each infested nut. Scientific Name: Curculio caryae (Horn) Ovipositional damage. Their presence does not stop development of the pecan so they may make it into the harvest. Larvae or grubs are legless, creamy white and have reddish-brown heads which grow to 3/5 inch long. Adult weevils feeding and egg laying on developing (water stage) pecan nuts, causing them to drop from the tree. Hosts. In most years, larvae damage results in the most yield loss. After shell hardening, treat when weevils begin to emerge and continue spraying at 7-10 days interval especially following rainy days. Learn how to identify damage to pecans caused by the pecan weevil. The egg is attached to the shuck with a creamy white substance visible on the shuck surface. The larvae hatch from the eggs and feed inside the nut, destroying the kernel (Fig. For more information on pecan weevil control and other research-based orchard management practices, consult OSU Extension fact sheets, available online and through all county Extension offices . 11). 0000002511 00000 n Nuts infested with larvae result in complete destruction of the kernel (Calcote 1975). Pecan Weevil in Oklahoma Figure 1. Pecan weevils damage nuts in two ways. But it does cause the nuts to be inedible. Later in the season when pecan nuts are present, moths deposit eggs singly on the nuts. But it does cause the nuts to be inedible. Larger chestnut weevil grubs chew an exit hole in the side of the nut and drop to the ground usually before the nuts fall. Pecan weevil: suppression of larvae with the fungi Metarrhizium anisopliae and Beauveria bassiana and the nematode Neoaplectana dutkyi. Circle traps are useful for weevil monitoring, providing good indications of weevil presence and abundance within an orchard. Pecan Weevil, Curculio caryae Hosts: The only economic host is the pecan where feeding and breeding take place in the developing nuts. Between late September and December larvae exit nuts through a small circular hole, drop to the ground and burrow into the soil to a depth of 4-12 inches. Texas A&M Veterinary Medical Diagnostics Laboratory, Texas A&M College of Agrculture and Life Sciences, For additional information, contact your local. Workers at an Otero County pecan cleaning plant noticed pecans with round holes about the diameter of a BB pellet, which are the pecan weevil's emergence holes. Lesser weevil grubs eat through the shells after the nuts drop. First, they feed on the young nuts in late summer, causing some to drop early still in their husks and never complete development. They are found in the nuts during late summer and early fall and can be found in the soil beneath infested trees during the rest of the year. The arid Southwest (West Texas, New Mexico, Arizona and California) has not yet had an established population of weevil develop. Weevil larvae feeding in a pecan nut. Both the adult and larval stages of pecan weevil cause a serious damage to pecan nuts. For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices. One of the most devastating insects on pecans is the pecan weevil. The pecan weevil, Curculio caryae is a serious economic pest of pecans (Caryae illinoensis).In late summer, the weevil attacks maturing nuts and damages them when making feeding and/or oviposition punctures. Proc. (Photo by Bill Ree) During my time as the pecan IPM specialist for Texas A&M AgriLife Extension, I have written several articles for Pecan South on pecan weevil management, but for this month instead of a management focus, I would like to address the potential spread of pecan weevil to new areas. Pecan weevils are scientifically called as Curculio caryae. Before shell hardening, treat if high numbers of weevils are seen or if nut drop caused by weevil feeding is high. 0000001517 00000 n One of the most devastating insects on pecans is the pecan weevil. Pecan weevil larvae devour a harvestable pecan. Biological Control of the Pecan Weevil: Smith et al. The first type is when the adult weevils puncture the nuts in early August, causing the nuts to fall after two or three days. From the Southwest Yard & Garden series. Pecan weevil larvae devour a harvestable pecan. Feeding during the water stage prior to shell hardening causes damaged nuts to drop. 1). Grovenburg, W. G., D. J. Boethel, and R. D. Eikenbary. Each female weevil can oviposit 30 to 54 eggs; therefore, one weevil could affect as many as 15 to 27 or as few as 7 to 13 pecans, assuming there are two to four larvae per nut, respectively. Adults can be sampled with emergence traps in the soil or with a beating sheet. from Ontario, Canada (Foott and Timmins 1984). INTRODUCTION THE PECAN weevil, Curculio caryae (Horn), attacks green maturing nuts in late summer and damages them by making feeding and oviposition punctures. Be sampled with emergence traps in the pecan weevil ( Curculio caryae Hosts: the only economic host the! On pecan feed in developing pecan nuts Service agent or search for other state Extension offices is. Pest management ( IPM ) program is to prevent female weevils from laying eggs in nuts be inedible North Texas... Present, moths deposit eggs singly on the developing nuts days after the eggs are deposited in. 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