Ataenius spretulus (Haldeman) (Coleoptera: Scarabaeidae) is the most common grub in golf course fairways in Michigan. Ataenius spretulus grubs are 3- to 10-fold more abundant in golf course fairways (mowed at a height of 1.5 cm) than in the roughs (mowed at a height of 5.0 cm or higher). Predation and infection by Paenibacillus sp. were previously reported to be greater in the rough, and may partially explain outbreaks of A. spretulus grubs in golf course fairways. In addition to natural enemies, cultural practices of irrigation and mowing could also be important factors, especially if A. spretulus prefers to oviposit in the fairway over the rough. In this paper we examine the impact of soil moisture and mowing height on oviposition and habitat selection. In a greenhouse experiment where A. spretulus adults were given a choice of turf maintained at fairway or rough height, no ovipositional preference for one or the other was observed. In three different growth chamber experiments where adults were allowed to choose among fairway or rough turf plugs held in soil at different moisture levels, adults preferred turf plugs in soil at a volumetric moisture content of 13% to 26% over turf plugs in soil at 8% to 9% moisture for their habitat selection. We conclude from these greenhouse and growth chamber experiments that A. spretulus adults do not choose turf habitat based on mowing height, but may be influenced by soil moisture levels.
Alexandra Delgado, Angel L. Gonzalez*, and Maria Del C. Libran
Peach cultivars are being evaluated for their adaptation to the conditions of the central region of Puerto Rico. The root weevil, Diaprepes abbreviatus (L.), a common insect pest in the area, is being previously reported on peach trees. With the purpose of evaluating the potential feeding damage that this insect might represent for future peach production, choice and no-choice tests were made with leaf discs (feeding) and leaf strips (oviposition) to determine adult feeding and oviposition behavior in comparison with `Navel' orange. Larval feeding behavior on the roots was studied on a peach rootstock and `Cleopatra' mandarin planted in 18.9-L containers. In the no-choice test, adults fed significantly more on `Navel' orange foliage than on peach foliage. In the choice test, adults preferred to feed on `Navel' orange leaf discs. Oviposition occurred on both peach cultivars tested, but more egg masses were laid on Navel orange leaf strips in the no-choice test. However, given the choice, adults preferred to oviposit on peach leaf strips while fed on `Navel' orange leaf strips. In some replications this behavior was reversed. At 90 days after infestation, larval feeding damage on the roots was severe on `Cleopatra' mandarin where most of the cortex tissue on the primary root was removed and growth of roots and foliage was reduced. Larvae bore also on peach trees, but there was no sign of growth reduction on foliage or the roots compared to the control. These preliminary results indicate that D. abbreviatus will not be a primary pest on peach.
Ki-Cheol Son, Ray F. Severson, and Stanley J. Kays
Methodology was developed for the rapid quantitative and qualitative screening of sweetpotato [Ipomoea batatas (L.) Lam.] germplasm for the concentration of the major sweetpotato weevil oviposition stimulant, boehmeryl acetate, and its alcohol, boehmerol. The major surface components were rapidly quantified, using a minimum of plant material. Boehmeryl acetate, present in methylene chloride root extracts, did not degrade when held under normal laboratory conditions for 45 days. Boehmeryl acetate and boehmerol were found only in the outer 1 to 1.2 mm of periderm and the distribution of the compounds appeared to be relatively uniform over the surface of the root.
Barbara E. Liedl, Darlene M. Lawson, Kris K. White, Joseph A. Shapiro, William G. Carson, John T. Trumble, and Martha A. Mutschler
Acylsugars, the primary components of the exudate secreted by type IV trichomes of Lycopersicon pennellii (Corr.) D'Arcy LA716, mediate the resistance of this accession to silverleaf whitefly, Bemisia argentifolii Bellows & Perring, n. sp. Reduction in the settling of the adult silverleaf whiteflies correlates with the concomitant increase in applied acylsugars. Oviposition of B. argentifolii is also affected by acylsugars, resulting in a reduction in the number of eggs and nymphs found; however, acylsugars do not affect hatching of nymphs. The threshold amount of acylsugars required for deterring settling and oviposition is under the amount of acylsugars (50 to 70 μg·cm–1) required for control of other insects.
John A. Juvik
Heliothis zea (Boddle) is one of agriculture's worst insect pests. Reduction in crop productivity and costs for insecticidal control of this cosmopolitan pest cost U.S. agriculture many millions of dollars annually. The sesquiterpenes (+)-E-å-santalen-12-oic and (+)-E- endo- β–bergamoten-12-oic acids isolated from hexane leaf extracts of the wild tomato species, Lycopersicon hirsutum, have been shown to attract and stimulate oviposition by female H. zea. Extracts from other host plants (tobacco, corn, and cotton) also possess attractant/oviposition stimulant activity to female H. zea. Studies are underway to assess the potential use of these and other phytochemicals for the control or monitoring of population levels of H. zea in tomato, corn and cotton fields.
The isolation and structural identification of insect pest oviposition stimulants in horticultural crop species can provide valuable information to plant breeders involved in developing cultivars with improved insect host plant resistance. This information could be used to develop cultivars lacking the chemical cues used by insects for host plant location and recognition. Risks of public exposure to toxic insecticides through consumption of agricultural produce and polluted ground water emphasize the critical need for the development of crop genotypes with improved best plant resistance as a supplementary method of insect pest management in agricultural ecosystems.
This study quantified how different shading levels alter the foliar nutrient, C:N ratio, chlorophyll content and key leaf characters in azalea `Delaware Valley White' Rhododendron mucronatum (Blume) (Ericales: Ericaceae), which influenced, in turn, feeding, oviposition, survival and development of the azalea lace bug, Stephanitis pyrioides (Scott) (Heteroptera: Tingidae). The mean contents of N, Ca, Fe, and Zn increased linearly with increases in the shading level, whereas P, K, B, Mn, and the C:N ratio of leaves were significantly decreased. Although injured leaves contained significantly less chlorophyll than uninjured leaves, the mean relative chlorophyll content of leaves increased linearly with the level of shading. Mean leaf area and moisture content of leaves increased linearly with increased degree of shading, while the mean trichome density decreased. The mean number of oviposited eggs and the percent of nymphs reaching adulthood increased linearly with the degree of shading. Azalea shoots suffered increased feeding injury as the season progressed, yet unshaded plants suffered more feeding injury than shaded plants. While the mean number of eggs laid, and the mean number of reared adults, were significantly and positively correlated with the mean leaf N, the mean feeding injury was negatively correlated with leaf N. Although these dependent variables were not correlated with K nor Ca, the mean number of eggs laid, and the mean number of reared adults were negatively correlated with the mean leaf P and with the mean C:N ratio. Mean feeding injury was positively correlated with leaf P and with the C:N ratio, but negatively correlated with N. This study shows that shaded plants are of better quality as hosts and that these plants can tolerate infestations by the lace bug.
Jo-Ann Bentz and Alden M. Townsend
The suitability of container-grown clones of red maple, Acer rubrum L., as a host to the potato leafhopper, Empoasca fabae Harris (Homoptera: Cicadellidae), under different fertilization regimes was determined, and compared to different freeman maple cultivars (A. ×freemanii E. Murray). Three clonal selections of red maple (USNA numbers 56026, 59904, and 55410), and three freeman maple cultivars (55892 `Indian Summer', 67256 `Jeffersred' [trademark Autumn Blaze], and 55890 `Armstrong') were potted in 7.6-L containers, fertilized with either 0, 3.3, or 6.6 g/pot of calcium nitrate and used in experiments. When given a choice, female leafhoppers laid more eggs on leaves of red maple clone 56026 than on leaves of clone 59904, with oviposition linearly increasing on both clones with increases in the fertilization level applied to the trees. Yet, when female leafhoppers were confined to leaves using organza sleeve cages, oviposition increased linearly as fertilizer level increased, without a significant clonal effect. Oviposition did not differ among freeman maple cultivars, nor was it influenced by the fertilizer level applied to the freeman maple trees. Nymphs had the lowest odds of surviving to adulthood when reared on the freeman maple `Jeffersred', but highest when reared on red maple 59904. Red maple 59904 had the fastest growth rate while red maple 55410 had the slowest. Leaf initiation and expansion in red maple 56026 was significantly slower than in the other selections. Leaf development of these three red maple clones was significantly accelerated by the application of fertilizer, regardless of level. The maple selections differed in their mean amounts of foliar macronutrients and micronutrients, which related to the fertilizer level applied to trees. Unfertilized trees had the highest C to N ratio, which decreased as fertilizer level applied to trees was increased. This study showed that fertilization improved the performance of the potato leafhopper on previously nonpreferred maple selections, and that the foliar nutrient content and C to N ratio could be used as indicators of tree susceptibility to insect attack under different growing conditions.
Matthew R. Chappell*, Carol Robacker, Sherrod Baden, and Allen Byous
Azalea Lace Bug (ALB) is a significant pest on azalea species. ALB feeding injury causes a stippled appearance on the leaves of susceptible genotypes from late spring until leaf drop. To determine whether leaf surface lipids are a factor in determining resistance or susceptibility to ALB, epicuticular leaf wax was extracted from the leaves of eight azalea genotypes, half with resistance and half susceptible to ALB. Leaf wax from each genotype was extracted and re-suspended in an 2 ethanol: 1 water solution for application to all entries in a full diallel manner, including a control of solution only. Each treatment included three replications. The leaf wax solution was applied to each replication (single leaf) by painting the solution on one side of the midrib, on both abaxial and adaxial surfaces. By applying solution to one side of the leaf, the untreated leaf surface served as a control. Each leaf and two female ALB were placed in separate 50-mL sealed tubes at 24 °C and 12-hour daylength for 48 hours, at which time the number of live adults, frass spots, and eggs were counted. Frass and egg data were recorded separately for treated and untreated sides of each leaf. The application of leaf wax solution had an impact on the level of frass and egg deposition by ALB in all genotypes. The effect was most pronounced when solution of resistant genotypes was placed on susceptible genotypes, resulting in lower numbers of frass spots and eggs. The solution alone had little effect on frass or egg numbers. This research acknowledges that a major constituent of an azalea's resistance or susceptibility to ALB is via epicuticular wax components.
Antonios E. Tsagkarakis, Michael E. Rogers, and Timothy M. Spann
tied to the presence of new shoot growth (flush), which is required for oviposition (egg laying) and nymph development; ACP populations decline during periods of limited or no flush production ( Michaud, 2004 ; Pluke et al., 2008 ). Mature citrus trees
Emily G. Tenczar and Vera A. Krischik
, phenolic glycosides, and furanocoumarins ( Rhoades, 1979 ). However, specialist insects become physiologically (cytochrome P-450 systems for detoxifying phytochemicals) and behaviorally (feeding, oviposition) adapted to these toxins ( Berenbaum and Zangerl