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The pecan weevil, Curculio caryae (Horn), is a key pest of pecans, Carya illinoinensis (Wangenh.) K. Koch. The entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin are pathogenic to and are being developed as microbial control agents for pecan weevil. One approach to suppressing pest populations and the resultant damage might be to apply entomopathogenic fungi when adult pecan weevils are emerging from the soil. Here we report the efficacy of B. bassiana (GHA strain) and M. anisopliae (F52 strain) applied to trees in orchards at three locations: Byron, GA, Fort Valley, GA, and Comanche, TX. At Fort Valley, treatments included B. bassiana as an oil-based spray with a UV-protective screen applied to the trunk, M. anisopliae applied as an impregnated fiber band stapled onto the trunk, and a nontreated check. At Byron, GA, we compared the B. bassiana trunk treatment to a nontreated check. Treatments at the Texas location were the B. bassiana trunk application, M. anisopliae applied as a trunk band and as a soil drench, and a nontreated check. At each location, weevils were trapped and transported to the laboratory for 15 to 17 days post-treatment to record mortality and mycosis. At both Georgia locations, B. bassiana caused ≥80% mortality and mycosis, which was significantly greater than mortality observed in the check (≤33%); mortality and mycosis in the M. anisopliae treatment at Fort Valley did not differ from that observed in the check. In Texas, due to insufficient replication in plots, statistical comparison among treatments was not possible. However, mean percentages of mortality of pecan weevils after 7 and 14 days were 38 and 55% in the check, 75 and 88% in the B. bassiana-treated plots, and 57 and 75% in the M. anisopliaetreated plots. These results indicate potential for B. bassiana trunk sprays to suppress adult pecan weevil. Future research is needed to determine if the approach contributes to economic levels of crop protection.
Russian wheat aphid populations have been monitored for the development of biotypes since the pest first appeared in the United States. Recent studies have confirmed the presence of five unique Russian wheat aphid biotypes in Colorado (Haley et al. 2004, Weiland et al. 2008), two of which were found on noncultivated grass hosts. The objective of this study was to confirm that while the Russian wheat aphid has undergone many changes as a species, the important grass hosts have not changed and are consistent each season. Species of noncultivated grass hosts were inventoried at field sites in four Colorado counties, Baca County, Montezuma County, Washington County, and Weld County, and the presence of Russian wheat aphids on the identified hosts was documented. Field sites were sampled in spring and fall 2005–2006 and the number and species of grass hosts were recorded and compared to look at host consistency across different geographic locations. Twenty-three grass species were identified across all counties. In Baca County, six of 14 grass species hosted Russian wheat aphids. In Montezuma County, Russian wheat aphids were found on five of 13 grass species. In Washington County, Russian wheat aphids were found on six of 18 grass species, and in Weld County, the aphid was found on five of eight grass species. Russian wheat aphids were collected most consistently from crested wheatgrass, Agropyron cristatum (L.) Gaertn., downy brome, Bromus tectorum L., Canada wildrye, Elymus canadensis L., and intermediate wheatgrass, Thinopyrum intermedium (Host) Barkw. & D.W.
The Russian wheat aphid, Diuraphis noxia (Mordvilko), is a severe pest of wheat, Triticum aestivum L; barley, Hordeum vulgare L; other small grains; and grasses. Although the Russian wheat aphid is a significant pest of small grains, its feeding effects on grain yield and vegetative biomass in large-scale wheat fields have not been well documented. Data were collected for 3 years in dryland and irrigated wheat fields in Texas and Oklahoma. The insect reduced grain yield 50.2 to 82.9% and biomass by 55.4 to 76.5%. These results suggested that winter wheat suffers significant economic loss from Russian wheat aphid.
The large and attractive flower flies Milesia scutellata Hull and Milesia virginiensis (Drury) are harmless mimics of queens of yellowjackets (family Vespidae). Both flower flies are reported in sympatry in Bastrop State Park, Bastrop County, TX, near the western limits of their ranges. This constitutes the first published record of M. scutellata from Texas. The biologies of these two sister species are compared, hilltopping behavior is reported for M. scutellata, and the first illustrations of its juvenile stages are provided.
The previously undescribed female of Jacob's crane fly, Tipula (Yamatotipula) jacobus Alexander, is described and the known range of the species is summarized and extended more than 400 km northwestward with a first record from Michigan. The habitat was birch-red maple forest, and a mating flight was observed in mid-June.
Mario Onofre Cortez-Rocha, José Luis Ríos-Soto, Reyna Isabel Sánchez-Mariñez, Francisco Javier Wong-Corral, Armando Burgos-Hernández, Jesús Borboa-Flores, Josue Leos-Martínez
Fourteen varieties of maize were analyzed for physical and chemical characteristics to study their relationship with susceptibility to maize weevil, Sitophilus zeamais (Motschulsky). Free-choice and no-choice tests were carried out at 27°C and 70% relative humidity. The susceptibility of maize varieties to attack by maize weevil was not related to grain hardness nor chemical composition. Insects selected softer and harder varieties for oviposition. The number of damaged grains was positively correlated with insect emergence. Germination was less in varieties susceptible to the insect. No α-amylase inhibitors were detected in the maize varieties.
Diagnostic dose (DD) of permethrin was determined in Aedes aegypti (L.), from three states (Coahuila, Sonora, and Tamaulipas) in northern Mexico. After exposing 10 groups of 100 females to the DD obtained and producing 50% mortality, individuals were divided into two categories: survivors and dead. Mosquitoes in each of these categories were dissected to separate the head, thorax, and abdomen. Biochemical tests were done on the head and thorax to determine activity by resistance-related enzymes including: α and β-esterases, mixed-function oxidases (MFOs), glutathione-S-transferase (GST) and insensitive acetyl cholinesterase (iAChE). Results were compared with those for a susceptible strain of Ae. aegypti from New Orleans. A population from Coahuila showed iAChE as the only enzyme activity that surpassed the threshold established with the susceptible strain, however, this mechanism is not associated with resistance to pyrethroids, but rather with resistance to organophosphate and carbamate insecticides. For the populations from Tamaulipas, none of the mechanisms studied were important in conferring resistance to permethrin. MFOs were present at elevated levels of activity, appearing as the main detoxifying mechanism, in the population from Sonoita, Sonora state.
Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) is an important predator of Planococcus citri Risso (Hemiptera: Pseudoccocidae), an important citrus pest. Its use to control this insect pest has been considered a valuable tool because other biological control methods have been ineffective due to the waxy coat that covers insect body in addition to its feeding habits. The objectives of this work were the evaluation of predatory ability and predatory efficiency of C. montrouzieri toward P. citri. A colony of P. citri was established using pumpkins as a natural diet and crawlers to initiate each generation. A colony of C. montrouzieri was established using adults reared inside plastic cages containing pumpkins infested with ovisacs of P. citri, for feeding and oviposition. Newly hatched larvae were reared on fresh pumpkins infested with any stage of P. citri to continue the life cycle. Both colonies were maintained under controlled environmental conditions. To determine predatory ability and predatory efficiency, confrontation bioassays were conducted in Petri dishes, using first-instar larvae (L1), third-instar larvae (L3), and adults of C. montrouzieri against first-instar nymphs (N1), second-instar nymphs (N2), third-instar nymphs (N3), and females of P. citri. In all treatments, five individuals of C. montrouzieri of each stage were confronted with 0.1 g of P. citri of each stage. Number of individuals of P. citri ingested by C. montrouzieri was obtained by the difference between the initial and the final individual numbers. Results indicated that predatory ability and efficiency of C. montrouzieri were different and varied according to its developmental stage and that of its prey. The C. montrouzieri adult was the most predatory and efficient stage compared to the other developmental stages. L3 had a similar predatory efficiency than adults and L1 preyed on significantly fewer P. citri individuals, exhibiting also the lowest predatory efficiency against females than any other C. montrouzieri stage. Predatory activity of C. montrouzieri increased with insect development and each stage showed noteworthy predatory efficiency.
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