Cereal leaf beetle, Oulema melanopus (L.), invaded northern Alabama and Georgia more than a decade ago and since has become an economic pest of winter wheat and other cereal crops in the southeastern United States. A series of trials was conducted beginning in 1995 to determine optimal rate and timing of applications of selected foliar insecticides for managing cereal leaf beetle in soft red winter wheat. These trials, cage studies with larvae, and a manual defoliation experiment were used to provide information on cereal leafbeetle yield loss relationships and to develop economic decision rules for cereal leaf beetle in soft red winter wheat. Malathion, methomyl, carbaryl, and spinosad effectively controlled larval infestations when treatments were applied after most eggs had hatched. Encapsulated endotoxin of Bacillus thuringiensis, methyl parathion, and disulfoton applied at the lowest labeled rates were not effective treatments. Organophosphate insecticides generally were not effective when applied before most eggs had hatched. The most effective treatments were the low rates of lambda cyhalothrin when applied early while adults were still laying eggs and before or near 50% egg hatch. These early applications applied at or before spike emergence virtually eliminated cereal leaf beetle injury. The manual defoliation study demonstrated that defoliation before spike emergence has greater impact on grain yield and yield components than defoliation after spike emergence. Furthermore, flag leaf defoliation causes more damage than injury to lower leaves. Grain test weight and kernel weight were not affected by larval injury in most trials. Regression of larval numbers and yield losses calculated a yield loss of 12.65% or 459 kg/ha per larva per stem, which at current application costs suggested an economic threshold of 0.4 larvae per stem during the spike emergence to anthesis stages.
Cereal leaf beetle, Oulema melanopus (L.), invaded northern Alabama and Georgia more than a decade ago and since has become an economic pest of winter wheat and other cereal crops in the southeastern United States. A series of trials was conducted beginning in 1995 to determine optimal rate and timing of applications of selected foliar insecticides for managing cereal leaf beetle in soft red winter wheat. These trials, cage studies with larvae, and a manual defoliation experiment were used to provide information on cereal leafbeetle yield loss relationships and to develop economic decision rules for cereal leaf beetle in soft red winter wheat. Malathion, methomyl, carbaryl, and spinosad effectively controlled larval infestations when treatments were applied after most eggs had hatched. Encapsulated endotoxin of Bacillus thuringiensis, methyl parathion, and disulfoton applied at the lowest labeled rates were not effective treatments. Organophosphate insecticides generally were not effective when applied before most eggs had hatched. The most effective treatments were the low rates of lambda cyhalothrin when applied early while adults were still laying eggs and before or near 50% egg hatch. These early applications applied at or before spike emergence virtually eliminated cereal leaf beetle injury. The manual defoliation study demonstrated that defoliation before spike emergence has greater impact on grain yield and yield components than defoliation after spike emergence. Furthermore, flag leaf defoliation causes more damage than injury to lower leaves. Grain test weight and kernel weight were not affected by larval injury in most trials. Regression of larval numbers and yield losses calculated a yield loss of 12.65% or 459 kg/ha per larva per stem, which at current application costs suggested an economic threshold of 0.4 larvae per stem during the spike emergence to anthesis stages.
The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147 Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester.
This study reports the occurrence of the adults of Phyllophaga spp. and other major scarab species in three different geographic regions of Alabama. Thirty-three species of Phyllophaga were found during the trapping study. Five species accounted for 97% of the specimens of Phyllophaga trapped in Marion Junction: P. crinita (Burmeister), P. forbesi (Glasgow), P. hirtiventris (Horn), P. mississippiensis Davis, and P. perlonga Davis. Two species accounted for 55% of the specimens trapped in Camp Hill: P. micans (Knoch) and P. hirticula (Knoch). At Winfield, P. crenulata (Froelich), P. ephilida (Say), P. latifrons LeConte, P. micans, and P. quercus (Knoch) were the most abundant species, making up 49% of the specimens. Of these 11 most abundant species, 5 species were collected in spring (March, April and/or May): P. crenulata, P. hirticula, P. micans, P. mississippiensis, and P. perlonga. Phyllophaga hirtiventris adults were collected in late May–June. Adults of P. crinita were collected in June and early July, and were abundant in each year, suggesting that the species has an annual life cycle in Alabama. Phyllophaga ephilida, P. forbesi, P. forbesi, P. latifrons and P. quercus adults were collected in mid-summer (June, July and/or August). Six species of Phyllophaga found during this study have not been previously reported from Alabama: P. bipartita Horn, P. congrua (LeConte), P. hirtiventris, P. mississippiensis, P. praetermissa (Horn), and P. soror Davis. Cyclocephala lurida Bland, Dyscinetus morator (F.), Euetheola humilis rugiceps (LeConte), and Ligyrus gibbosus gibbosus (DeGeer), other potential pests of grasses, were abundant in the black-light traps. The dung beetle, Onthophagus gazella F., an African species that was purposely introduced into the United States, was abundant at all three sites.
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