Higher Beetle Diversity in Native Vegetation Than in Stands of the Invasive Arundo, Arundo donax L., along the Rio Grande Basin in Texas, USA.

Within the cattle fever tick quarantine zone along the Rio Grande, a steady displacement of native vegetation by Arundo donax L. has been occurring for over a century. Arundo rapidly grows to a height of 3-6 m creating a dense wall of vegetation impeding surveillance and interception of stray cattle breaching the cattle fever tick quarantine from Mexico. Additionally, arundo monocultures may decrease the number and diversity of predatory beetles feeding on cattle fever ticks. To compare predatory beetle abundance and diversity within and between arundo and native vegetation, beetles were trapped at 10 locations twice a month for 16 mo (=38,400 trap nights) in the cattle fever tick quarantine zone along the Mexico-American border between Brownsville and Del Rio, TX. In total, 766 beetles were trapped, which included 34 genera and 43 species. Native vegetation provided more beetles, greater species richness, and increased biological diversity. Thus, greater beetle diversity was found in the more complex native vegetation compared with arundo stands. However, because predatory beetle sample numbers were modest, it is unlikely these mostly polyphagous, opportunistic arthropod predators would apply much pressure on tick populations, leading us to conclude that beetle predation would have little effect on tick populations in native vegetation or within stands of arundo.

Staphylococcus aureus bacteremia in immunosuppressed patients: a multicenter, retrospective cohort study.

Staphylococcus aureus bacteremia (SAB) causes significant morbidity and mortality. We assessed the disease severity and clinical outcomes of SAB in patients with pre-existing immunosuppression, compared with immunocompetent patients. A retrospective cohort investigation studied consecutive patients with SAB hospitalized across six hospitals in Toronto, Canada from 2007 to 2010. Patients were divided into immunosuppressed (IS) and immunocompetent (IC) cohorts; the IS cohort was subdivided into presence of one and two or more immunosuppressive conditions. Clinical parameters were compared between cohorts and between IS subgroups. A competing risk model compared in-hospital mortality and time to discharge. A total of 907 patients were included, 716 (79%) were IC and 191 (21%) were IS. Within the IS cohort, 111 (58%) had one immunosuppressive condition and 80 (42%) had two or more conditions. The overall in-hospital mortality was 29%, with no differences between groups (IS 32%, IC 28%, p = 0.4211). There were no differences in in-hospital mortality (sub-distribution hazard ratio [sHR] 1.17, 95% confidence interval [CI] 0.88-1.56, p = 0.2827) or time to discharge (sHR 0.94, 95% CI 0.78-1.15, p = 0.5570). Independent mortality predictors for both cohorts included hypotension at 72 h (IS: p < 0.0001, IC: p < 0.0001) and early embolic stroke (IS: p < 0.0001, IC: p = 0.0272). Congestive heart failure was a mortality predictor in the IS cohort (p = 0.0089). Fever within 24 h (p = 0.0092) and early skin and soft tissue infections (p < 0.0001) were survival predictors in the IS cohort. SAB causes significant mortality regardless of pre-existing immune status, but immunosuppressed patients do not have an elevated risk of mortality relative to immunocompetent patients.

Clinical prediction rules in Staphylococcus aureus bacteremia demonstrate the usefulness of reporting likelihood ratios in infectious diseases.

Infectious diseases specialists often use diagnostic tests to assess the probability of a disease based on knowledge of the diagnostic properties. It has become standard for published studies on diagnostic tests to report sensitivity, specificity and predictive values. Likelihood ratios are often omitted. We compared published clinical prediction rules in Staphylococcus aureus bacteremia to illustrate the importance of likelihood ratios. We performed a narrative review comparing published clinical prediction rules used for excluding endocarditis in S. aureus bacteremia. Of nine published clinical prediction rules, only three studies reported likelihood ratios. Many studies concluded that the clinical prediction rule could safely exclude endocarditis based on high sensitivity and high negative predictive value. Of the studies with similar high sensitivity and high negative predictive value, calculated negative likelihood ratios were able to differentiate and identify the best clinical prediction rule for excluding endocarditis. Compared to sensitivity, specificity and predictive values, likelihood ratios can be more directly used to interpret diagnostic test results to assist in ruling in or ruling out a disease. Therefore, a new standard should be set to include likelihood ratios in reporting of diagnostic tests in infectious diseases research.

Bionomics and Formation of "Bonsai" Colonies With Long-Term Rearing of Coptotermes formosanus (Isoptera: Rhinotermitidae).

This laboratory study reports the ability of Formosan subterranean termite, Coptotermes formosanus Shiraki, colonies to survive for at least 9 yr while restricted to a sweater box. Colonies survived by limiting queen size and worker numbers, allowing these bonsai colonies to thrive. Queen physogastry appeared to plateau with 9-yr-old queens not larger than 6-yr-old queens, but nearly triple the size of 2-yr-old queens. Nine-year-old colony worker numbers were not greater than 6-yr-old colonies, but worker numbers were greater than in 2-yr-old colonies. Such colony survival under conditions of restricted resources provides a mechanism for re-infestation of areas following extensive area-wide control efforts. "Bonsai" colonies are relevant to the ability of marginalized colonies to avoid detection and then expand and invade into areas once the large, mature colonies are eliminated, and their potential to produce alates to start new C. formosanus colonies in areas which have been subjected to colony elimination programs impacts termite management strategies.

Effects of a fipronil spot treatment on field colonies of Coptotermes formosanus (Isoptera: Rhinotermitidae).

This field study investigated the colony effect of a fipronil spot treatment applied to active infestations of Formosan subterranean termite, Coptotermes formosanus Shiraki. Spot treatments were applied to a single active independent monitor from each of four colonies in which multiple independent monitors were established. All treated monitors were abandoned, and the contents of the treated monitors were replaced with untreated wood at the approximately 30-d posttreatment inspection. All colonies survived treatment and only one colony exhibited long-term effects, which included significant reductions in termite collections and increased worker size. The affected colony was treated within 1 m of its primary nest. Two colonies exhibited a correlation between monitor termite production and distance from treatment. Distance appears to be a factor limiting fipronil's colony effects. The Formosan subterranean termite may not be a good candidate for the exterior perimeter and localized interior treatment label option because of the large range and size of the colony.

Improved chemical control for the Mexican rice borer (Lepidoptera Crambidae) in sugarcane: larval exposure, a novel scouting method, and efficacy of a single aerial insecticide application.

A three-treatment aerial application insecticide experiment was conducted in five commercial sugarcane, Saccharum spp., fields in south Texas to evaluate the use of pheromone traps for improving chemical control of the Mexican rice borer, Eoreuma loftini (Dyar), in 2009 and 2010. A threshold of 20 moths/trap/wk was used to initiate monitoring for larval infestations. The percentage of stalks with larvae on plant surfaces was directly related to the number of moths trapped. Reductions in borer injury and adult emergence were detected when a threshold of >5% of stalks with larvae present on plant surfaces was used to trigger insecticide applications. Novaluron provided superior control compared with beta-cyfluthrin; novaluron treated plots were associated with a 14% increase in sugar production. A greenhouse experiment investigating establishment and behavior of E. loftini larvae on two phenological stages of stalkborer resistant, HoCP 85-845, and susceptible, HoCP 00-950, sugarcane cultivars determined that more than half of larvae on HoCP 00-950 and > 25% on HoCP 85-845 tunneled inside leaf mid-ribs within 1 d of eclosion, protected therein from biological and chemical control tactics. Exposure time of larvae averaged < 1 wk for all treatments and was shortest on immature HoCP 00-950 and longest on mature HoCP 85-845. This study shows a short window of vulnerability of E. loftini larvae to insecticide applications, and demonstrates the potential utility of pheromone traps for improving insecticide intervention timing such that a single properly timed application may be all that is required.

Seasonal infestations of two stem borers (Lepidoptera: Crambidae) in noncrop grasses of Gulf Coast rice agroecosystems.

Infestations of two stem borers, Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were compared in noncrop grasses adjacent to rice (Oryza sativa L.) fields. Three farms in the Texas rice Gulf Coast production area were surveyed every 6-8 wk between 2007 and 2009 using quadrat sampling along transects. Although D. saccharalis densities were relatively low, E. loftini average densities ranged from 0.3 to 5.7 immatures per m(2) throughout the 2-yr period. Early annual grasses including ryegrass, Lolium spp., and brome, Bromus spp., were infested during the spring, whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and Vasey's grass, Paspalum urvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host (41-78% relative abundance), but Vasey's grass (13-40% relative abundance) harbored as much as 62% of the recovered E. loftini immatures (during the winter). Young rice in newly planted fields did not host stem borers before June. April sampling in fallow rice fields showed that any available live grass material, volunteer rice or weed, can serve as a host during the spring. Our study suggests that noncrop grasses are year-round sources of E. loftini in Texas rice agroecosystems and may increase pest populations.

Categorizing sugarcane cultivar resistance to the sugarcane aphid and yellow sugarcane aphid (Hemiptera: Aphididae).

Sugarcane (Saccharum spp.) in Louisiana is colonized by two aphid species, the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes) (Hemiptera: Aphididae). The main problem associated with M. sacchari is transmission of sugarcane yellow leaf virus, a casual agent of yellow leaf disease whose absence has been added to certification standards for micropropagated sugarcane in Louisiana. Greenhouse studies were conducted to categorize dominant commercial sugarcane cultivars for their ability to tolerate aphid injury and to express antixenotic or antibiotic effects on both aphid species. Antixenosis tests showed no preference among cultivars by either aphid species. Loss of chlorophyll content in tolerance tests also did not show differences among cultivars for both aphid species. However, antibiosis tests revealed that life history parameters such as the duration of the reproductive period and fecundity of both aphid species were negatively affected on 'HoCP 91-555' compared with 'L 97-128'. Estimation of demographic statistics indicated that both aphid species exhibited a significantly lower intrinsic rate of increase (1.8-2.8-fold) and longer doubling time (1.7-3.1-fold) on HoCP 91-555 relative to L 97-128. From these tests, cultivars in the current study can be ranked from most to the least susceptible as L 97-128 > 'LCP 85-384' > 'HoCP 96-540' > 'Ho 95-988' > HoCP 91-555 for M. sacchari and L 97-128 > LCP 85-384 > HoCP 91-555 for S. flava. Therefore, antibiosis is an important category of resistance in sugarcane to both aphid species, and HoCP 91-555 might provide useful germplasm for developing aphid resistant cultivars.

Cotton harvest at 40% versus 75% boll-splitting on yield and economic return under standard and proactive boll weevil (Coleoptera: Curculionidae) spray regimes.

The standard practice of two or three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (when 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), control does not provide reliable protection of cotton, Gossypium hirsutum L., lint production. This study, conducted during 2004 and 2005, showed that three to six fewer spray applications in a "proactive" approach, in which spraying began at the start of large (5.5-8-mm-diameter) square formation and continued at approximately 7-d intervals while large squares were abundant, resulted in fewer infested squares and 1.4- to 1.7-fold more lint than the standard treatment. Fewer sprays and increased yield made proactive spraying significantly more profitable than the standard approach, which resulted in relatively low or negative economic returns. Harvest at 75% boll-split in the proactive spray regime of 2005 resulted in four-fold greater economic return than cotton harvested at 40% boll-split because of improved protection of large squares and the elimination of late-season sprays inherent to standard spray regime despite the cost of an extra irrigation in the 75% boll-split treatments. The earlier, 40% harvest trigger does not avoid high late-season boll weevil pressure, which exerts less impact on bolls, the predominant form of fruiting body at that time, than on squares. Proactive spraying and harvest timing are based on an important relationship between nutrition, boll weevil reproduction, and economic inputs; therefore, the tactic of combining proaction with harvest at 75% boll-split is applicable where boll weevils are problematic regardless of climate or region, or whether an eradication program is ongoing.

Role of oviposition preference in an invasive crambid impacting two graminaceous host crops.

Oviposition preference studies of the Mexican rice borer, Eoreuma loftini (Dyar), on sugarcane, Saccharum spp., and rice, Oryza sativa L., showed that drought stressed sugarcane was 1.8-fold more attractive based on egg masses/plant than well watered sugarcane. The E. loftini susceptible sugarcane cultivar LCP 85-384 was 1.6-fold more attractive than HoCP 85-845 based on numbers of eggs per egg mass. Egg masses were 9.2-fold more abundant and 2.3-fold larger on sugarcane than on rice. Rice, however, was preferred to sugarcane on a plant biomass basis. Oviposition on sugarcane occurred exclusively on dry leaf material, which increased under drought stress. Egg masses per plant increased on drought stressed sugarcane and were correlated with several foliar free amino acids essential for insect growth and development. The more resistant (based on injury) but more attractive (based on oviposition) rice cultivar XL8 had higher levels of several free amino acids than the susceptible cultivar Cocodrie. The association of host plant characteristics to oviposition preference is discussed. Projected oviposition patterns relative to sugarcane and rice production areas were estimated for Texas and Louisiana based on the availability of each host in different regions of each state. These results suggest that, where sugarcane and rice co-occur, the majority of eggs would be found on sugarcane early in the season, because of this crop's substantially greater biomass compared with rice. Abundance later in the season would also favor sugarcane; however, the abundance on rice would be greater than expected solely based on host availability, largely because of the greater preference per gram of rice plant dry weight.

Grandlure dosage and attraction of boll weevils (Coleoptera: Curculionidae).

The effects of grandlure dosage on of boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), attraction were assessed. Traps collected more boll weevils under field and laboratory conditions as the amount of grandlure in laminated plastic strips was increased from 0 to 10, 30, and 60 mg. Spreading the point source of the lure by cutting the strip into quarters and positioning each quarter on separate corners of the large capacity trap to create an expanded source for the pheromone plume, however, resulted in fewer trap captures than traps with quartered lures all positioned on a single corner. The large capacity trap with the quartered lure on one corner also caught more weevils than the traps with an intact lure fastened to one corner. Although aging lure strips for three weeks reduced emissions of the four pheromone components and their attractiveness to boll weevils, cutting the aged lure into quarters resulted in greater emissions and attraction than lures that were aged intact or as quarters. Some pheromone components volatilized faster than others, resulting in time-related changes in blend ratios, but the underlying factor in boll weevil attraction to grandlure strips was dosage, the amount of volatilized pheromone available for interacting with an adult boll weevil.

Effects of planting dates on boll weevils (Coleoptera: Curculionidae) and cotton fruit in the subtropics.

The effects of planting dates 2-3-wk apart on boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), field-level populations, and feeding and oviposition damage to cotton, Gossypium hirsutum L., squares and bolls, were studied during 2002 and 2003 in the Lower Rio Grande Valley of Texas. Squares were 44-56% more abundant in some later planted treatments than in the earlier planted treatments, but mean cumulative numbers of oviposition- and feeding-damaged squares were 2.7 - 4.8-fold greater in some later planted treatments than in earlier treatments. Increased square production in later planted cotton was offset by boll weevil infestations that occurred when squares are most vulnerable and contribute most toward the pest's reproduction. Early planting avoided boll weevil population buildups in the field when large squares were abundant. Lint yields in 2002 did not differ significantly between the planting date treatments, but in 2003, mean yield in the middle treatment was 23% greater than in the early and late-planted treatments. Insecticide sprays in the earliest planted treatment of each year, based on the 10% damaged squares threshold, were >33% and >43% fewer than in the corresponding middle and latest planting treatments, respectively. Delayed planting, relative to the onset of favorable cotton-growing weather, at the field level, even when not applied uniformly on an areawide scale, is more cost-effective than planting too early or too late.

Leptodictya tabida (Hemiptera: Tingidae): a potential threat to sugarcane production in Lower Rio Grande Valley of Texas.

Areawide surveys and replicated cultivar trials were conducted in 2001 and 2002 in sugarcane (Saccharum spp.) fields in the Lower Rio Grande Valley of Texas to assess the distribution and incidence of the sugarcane tingid Leptodictya tabida (Herrich-Schaeffer). L. tabida was found in all fields surveyed during both years, infesting 60 and 68% of the plants, respectively. The average percentage of leaves infested was 11% in 2001 and 15% in 2002. In 2001, 'CP70-1133' was the most infested, 'CP72-1210' was the least infested, and intermediate infestation levels were evident in 'CP70-321' and 'TCP87-3388'. In 2002, however, TCP87-3388 and CP70-321 were more heavily infested, and CP71-1240 and CP71-1405 were the least infested. Mean densities of L. tabida recovered per plant varied between 1.2 bugs on CP72-1210 and 5.1 on CP70-1133 in 2001, and in 2002, from zero bugs on CP71-1240 and CP71-1405 to 5.3 on CP72-1210. In the cultivar trials, cultivar differences also were evident in both plant and leaf infestation levels, and the proportion of immatures to total L. tabida populations; 'HoCP91-555' had the lowest L. tabida infestations and 'NCo-310' had the greatest levels in both years. Although >5000 L. tabida from the field were collected and kept in the laboratory, no parasitoids were found. The distribution of the infestations during the surveys and in the field trial evaluations suggested that L. tabida populations have been spreading in sugarcane across the Lower Rio Grande Valley. Potential varietal resistance mechanisms are discussed.

Effect of aging on pheromone emission from a commercial beet armyworm (Lepidoptera: Noctuidae) lure and trap efficiency.

The effect of aging on a commercial pheromone-based lure for attractiveness to male adult beet armyworms, Spodoptera exigua (Hübner), was assessed in terms of trapping efficiency and volatile emissions of two key components: (Z,E)-9,12-tetradecadienyl acetate and (Z)-9-tetradecen-1-ol. In field assays conducted in the Lower Rio Grande Valley, Texas, for 9 wk (June-August 2000) and for 8 wk (March-May) in Tamaulipas, Mexico, 0-1-wk-old lures collected greater than four-fold more male beet armyworm adults than lures that had been aged for 3-4 wk. Using solid phase microextraction and gas chromatographic analysis of the volatiles, mean (Z,E)-9,12-tetradecadienyl acetate emission declined by 32% after 5 wk of aging in a ventilated environmental chamber at 29.4 degrees C, 3.5% RH, to simulate subtropical summers. Mean (Z)-9-tetradecen-1-ol emission was reduced by 62% after 4 wk of aging. Under the tropical and subtropical conditions of this study, the capacity of the lure to attract moths into the trap declined after aging for 3 wk. The blend ratio (Z,E) -9,12-tetradecadienyl acetate: (Z)-9-tetradecen-1-ol declined 29% when the lure was aged for 5 wk. This study will assist in the development of a standard trapping system for assessing adult beet armyworm populations in the tropical and subtropical conditions to which the species is endemic.

Effects of burial and soil condition on postharvest mortality of boll Weevils (Coleoptera: Curculionidae) in fallen cotton fruit.

Effects of soil condition and burial on boll weevil, Anthonomus grandis grandis Boheman, mortality in fallen cotton, Gossypium hirsutum L., fruit were assessed in this study. During hot weather immediately after summer harvest operations in the Lower Rio Grande Valley of Texas, burial of infested fruit in conventionally tilled field plots permitted significantly greater survival of weevils than in no-tillage plots. Burial of infested squares protected developing weevils from heat and desiccation that cause high mortality on the soil surface during and after harvest in midsummer and late summer. A laboratory assay showed that burial of infested squares resulted in significantly greater weevil mortality in wet than in dry sandy or clay soils. Significantly fewer weevils rose to the soil surface after burial of infested bolls during winter compared with bolls set on the soil surface, a likely result of wetting by winter rainfall. A combination of leaving infested fruit exposed to heat before the onset of cooler winter temperatures and burial by tillage when temperatures begin to cool might be an important tactic for reducing populations of boll weevils that overwinter in cotton fields.

Deterrent effects of four neem-based formulations on gravid female boll weevil (Coleoptera: Curculionidae) feeding and oviposition on cotton squares.

Three commercial neem-based insecticides, Agroneem, Ecozin, and Neemix, and a neem seed extract formulation, bitters, containing 1,036, 16,506, 471, and 223 microg/ml azadirachtin, respectively, were assessed for feeding and oviposition deterrence against gravid female boll weevils, Anthonomus grandis grandis Boheman, in the laboratory. In choice assays, excised cotton squares dipped in the separate formulations were first physically contacted by the weevils' tarsi or antennae fewer times than nontreated control squares. In choice and no-choice assays, each formulation repelled the weevils for > or = 90 min. After 24 h in the choice assays, feeding punctures on the squares treated with Agroneem, Ecozin, or bitters were significantly fewer compared with controls. Egg punctures on the Ecozin- and the bitters-treated squares were significantly fewer than on control squares after 24 h. In the no-choice assay, no significant difference was detected. Aging the formulations under outdoor conditions for 24 h before weevils were exposed resulted in 46-60% and 62-82% reductions in feeding and oviposition punctures, respectively, compared with controls. Agroneem- and bitters-treated squares had > 37% fewer feeding punctures after being aged for 48 h. No significant difference was detected after 72 h of aging. Because the deterrence of the gravid female boll weevils was not correlated with amounts of azadirachtin, azadirachtin does not seem to be the only, or the most influential, component of neem that induced the observed deterrence.

Effects of kaolin-based particle film application on boll weevil (Coleoptera: Curculionidae) injury to cotton.

This study examined a non-insecticidal tactic for suppressing boll weevil, Anthonomus grandis grandis Boheman, damage to cotton, Gossypium hirsutum L. In cage assays, kaolin, a reflective white mineral, applied to excised cotton squares or to the cotton foliage, initially resulted in lower levels of boll weevil injury to squares than nontreated squares. Boll weevil oviposition and feeding on kaolin-treated squares and squares on kaolin-treated cotton plants increased when nontreated squares and cotton plants were in short supply. A laboratory assay and field trials suggested that boll weevils distinguished between cotton plots based on color differences caused by kaolin and this appeared to influence levels of damage to squares. Random sampling in small plots indicated that oviposition damage to squares in plots treated with kaolin was reduced (P < 0.05) compared with nontreated controls, except when rain washed the kaolin off the foliage. Lint yield differences were not detected between the small plots, but the kaolin-treated small plots yielded as much as 2.36 times more cotton lint than a large but unreplicated adjacent nontreated control plot, and up to 1.39 times more than another large but unreplicated adjacent plot sprayed twice with preemptive applications of azinphosmethyl when cotton squares were first developing (pinhead stage). Potentially important avenues for future research on boll weevil injury suppression using kaolin are discussed.

Spodoptera exigua oviposition and larval feeding preferences for pigweed, Amaranthus hybridus, over squaring cotton, Gossypium hirsutum, and a comparison of free amino acids in each host plant.

The beet armyworm, Spodoptera exigua (Hübner), can utilize a number of different host plants for oviposition and larval development, but some host plants are preferred over others. This study, using cage choice tests and olfactometer assays, demonstrates the beet armyworm's preference for pigweed, Amaranthus hybridus L., over cotton, Gossypium hirsutum L. Cage and olfactometer choice assays indicated that olfaction plays an important role in host selection by ovipositing females. First instars exhibited no feeding preference, but the more mobile third instars showed a significant feeding preference for excised pigweed leaves. The higher quantities and more diverse accumulations of free amino acids in pigweed might, in conjunction with other physiochemical and mechanical attractant and deterrent factors in the two-plant species system, play roles in the tendency of the beet armyworm to select pigweed over cotton and in providing a superior array of easily absorbed amino acids as compared to cotton.

Augmentation and aldicarb treatment of nematodes in selected sugarcane weed habitats.

In a single experiment, field-grown Louisiana sugarcane was augmented with phytoparasitic nematodes, treated with aldicarb, or left untreated in both weedy and weed-free habitats to study interactions among nematodes, weeds, sugarcane, and sugarcane free amino acid titers. Aldicarb reduced three of the six phytoparasitic nematode genera at various times during the two growing seasons and was associated with 17% more free proline in the sugarcane. Nematode augmentation resulted in higher field populations of Meloidogyne spp. Free cysteine, histidine, proline, and serine concentrations in sugarcane were lower where nematodes were added. Densities of Tylenchorhynchus annulatus and total phytoparasitic nematodes were lower in weedy habitats compared to weed-free conditions. Sixteen of the 17 sugarcane free amino acids were significantly lower in weed-free areas. It is suggested that further research be conducted on the relationship of plant stresses to free amino acid levels to better understand plant-mediated interactions among crop pests.