摘要:

Although the beneficial status of the spiders as insectivores has been widely recognized for quite some time, biologists by and large seem to be rather unfamiliar with the specific feeding habits of this very diverse order. We present an overview of the feeding patterns of 10 groups of common agroecosystem spiders to inform entomologists and ecologists concerned with issues of natural biological control. The various spider groups discussed in this article exhibit a very diverse range of life styles and foraging modes, which is reflected in the diversity of their feeding patterns. Implications of the insectivorous activities of these predators for natural pest control are discussed.

DOI:10.1093/ee/23.6.1357

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Two simple stochastic models were developed to generate daily minimum and maximum air temperahlre time series from input monthly mean and extreme minimum and maximum normals. Factors taken into account in the temperature generation are latitudinal and vertical lapse rates, as well as the latitudinally and seasonally-variable correlation between daily minima and maxima. The first model assumes that daily values are independently and normally distributed random variables, whereas the second takes into account serial autocorrelations in the temperatures of successive days. Parameter values for both models were obtained using weather data from stations distributed over the eastern seaboard of the United States. The temperature traces generated by each model were compared with actual data. Four different insect phenology models were also used to compare the two weather simulation methods with actual weather data in terms of the phenology forecasts generated. It was found that the degree of autocorrelation between minima or maxima on successive days, as well as the correlation between daily minima and maxima, vary systematically with time of year and latitude. Altitudinal and latitudinal lapse rates also vary with time of year. Both models produce weather traces that are statistically indistinguishable from actual weather data. Phenology forecasts using deterministic air temperature regimes were considerably late compared with forecasts obtained from either stochastic regimes or actual data. The variability of phenology forecasts produced using synthetic weather traces as input was smaller than that obtained using real weather data as input, particularly with the serially independent temperature regimes generated by model 1.

DOI:10.1093/ee/23.6.1368

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Spatial patterns ofleaf-curling plum aphid,Brachycaudus helichrysi, aggregates and alate colonization of sunflower fields were studied over several years. Monte Carlo test procedures, based on indices of aggregation and spatial autocorrelation statistics, were used for spatial data analysis. In most cases, neighboring plants were colonized and infested independently. Over large areas, spatial structures could exist but temporal changes in spatial patterns from week to week were often observed for alatae as well as for apterae. Heterogeneity in plant development seemed to be of importance for alate landing, apterous multiplication, and their spatial patterns. The implications for pest management and sampling are discussed.

DOI:10.1093/ee/23.6.1381

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Population development of the hop aphid,Phorodon humuli(Schrank), was studied on insecticide-free field-grown hopsHumulus lupulusL. in 1992. The influence of predators was assessed using large sleeve cages installed 2 July after aphid immigration ended. Aphid immigration numbers increased geometrically throughout July in cages that excluded predators but increased more slowly and then fell in cages with access by predators. Aphid numbers remained much lower on uncaged plants. Hop cone yields were 97, 381, and 598 g per plant from exclusion-caged, open-caged and uncaged plants, respectively. The main predators were Coccinellidae,Coccinella transversoguttataFaldermann andHippodamiaconvergens Guérin-Méneville; Chrysopidae,Chrysoperla carnea(Stephens),C. rufilabris(Burmeister) andChrysopaspp.; Hemerobiidae, Hemerobius sp.; Anthocoridae,Orius tristicolor(White); Geocoridae,Geocorissp.; Nabidae,Nabissp. Predatory Diptera were scarce as were hymenopterous parasitoids. Hops are dioecious, perennial, climbing plants that are grown on a 6-m trellis. They grow best where day length increases rapidly in the spring (45–51°N or S) and do not grow well where days are<14 h long. The hop cones (female flowers) contain pollen-like, lupulin glands. The commercial value of hops lies in the lupulin glands, which contain resins and oils. The resins are used for bittering beer, and the essential oils contribute to beer flavor.

DOI:10.1093/ee/23.6.1391

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

This study addressed the potential susceptibility of native Hawaiian insects to the semiochemical methyl eugenol used for male annihilation of the oriental fruit fly,Bactrocera dorsalis(Hendel). The effects of trap type (methyl eugenol, methyl eugenol + toxin, toxin only, and control) and trap height (0, 1, 2, or 4 m above ground) were studied in native forest on the island of Kauai. A malaise trap was used to determine the relative abundance of insects in the immediate vicinity of the methyl eugenol traps. Seven species of native Hawaiian Drosophilidae, two species of Muscidae, and one species of Phoridae were found to be attracted to methyl eugenol. For four other taxa, including species of Miridae, Anobiidae, and Proctotrupidae, attraction to methyl eugenol is suggested but equivocal. For all species exceptDrosophila villosipedis(Drosophilidae) andBrachyserphus hawaiiensis(Proctotrupidae) both males and females were attracted to methyl eugenol. ForDrosophila perissopoda,Drosophila basimacula,Scaptomyza varipicta, andScaptomyza rostrata, ground level traps caught significantly more individuals than traps above ground, and for all drosophilids, 4-m high traps caught the fewest individuals. Among non-Drosophilidae, trap height was not a significant factor in captures for only the Anobiidae andSaronaspecies (Miridae).Megaselia sp.(Phoridae) was similar toScaptomyza tantalia(Drosophilidae) in that almost all individuals were captured in ground level traps.Orthotylus sp.(Miridae) was the only species in which 4-m high traps caught the greatest number of individuals. ForLispocephalaspecies (Muscidae) andB. hawaiiensis, 1–2-m high traps tended to catch more individuals than the ground-level or 4-m high traps. Malaise trap data suggest that methyl eugenol traps either attracted these species roughly in proportion to their local abundance (D. villosipedis,D. basimacula) or they captured only a portion of the local pool of individuals (S. varipicta,D. perissopoda,D. kokeensis,Lispocephala spp.). Because of the low level of attraction displayed by the native insects and the potential to mitigate the impact by placement of baits in the forest canopy, it is suggested that an environmentally acceptable application of methyl eugenol can be devised for use in the Hawaiian Islands.

DOI:10.1093/ee/23.6.1397

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Abundance and seasonality of Diabroticina species were investigated using black light traps in Rio Bravo and San Fernando, in northern Tamaulipas, Mexico, from 1980 to 1993.Diabrotica balteataLeConte was the most abundant species with average captures of 11,666 beetles per year. Other species captured includedD. undecimpunctata howardi Barber,D. longicomis(Say),D. tibialisJacoby,Paranapiacaba connexa(LeConte), andAcalymma trivittatum(Mannerheim). Multivoltinism was evident forD. balteata,D. undecimpunctata howardi, andA. trivittatum. Beetles were captured more abundantly from midspring to early fall but occurred practically year around. More than 90% of the total captures ofD. balteataoccurred from May through July. Flight activity ofD. balteatadecreased as wind speed increased. A multiple regression model consisting of climatic factors as independent variables (xn) explained 86% of the variability of total yearly catches ofD. balteata(y). The model indicated abundance was adversely affected by preceding cold winter and early rainfall (1 January to 18 May) and was favored by rainfall from 19 May to 30 August. Periodic high captures ofD. balteataduring May to July might be caused by dispersal behavior, probably associated to changes in habitat quality, i.e., corn flowering and maturation. The results found herein are discussed in relation to those reported for the same or related species elsewhere.

DOI:10.1093/ee/23.6.1409

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

A life table study with five replicates was conducted through age 9 d at 25°C with eight male and eight femaleLiriomyza sativaeBlanchard caged with a lima bean plant (Phaseolus lunatusL. ‘Henderson’) and provided honey. Oviposition peaked in 2- to 6-d-old adults. Overall, 80% of females but only 50% of males lived to age 9 d. Fecundity through adult age 9 d in four cohorts ranged from 1,355 to 1,737 offspring, but one cohort produced only 569 offspring. In a separate experiment at 25°C, fecundity through age 9 d by cohorts of eight small (mean = 435 μg) versus eight large (mean = 731 μg) females with males was 1,461 and 2,038 offspring, respectively. Effect of leafminer size on life history parameters at 25°C was examined more specifically by providing a male-female pair (each of known pupal weight) with a lima bean plant and honey each day until death. Males were removed after 8 d to standardize female exposure to males. Mean longevity of the 33 females weighing an average of 667 μg was 27.1 ± 1.8 d (mean ± SEM) with females producing 362 ± 30.8 offspring. Net reproductive rates (Ro) of females weighing700 μg were 170, 166, and 197 female offspring per female, respectively. Placement ofL. sativaepupae in 20, 40, 60, 70, 80, 90, and 95% RH regimes at 25°C within 30 min after dropping from leaves resulted in 49, 81, 90, 97, 100, 99, and 94% survival to adult eclosion, respectively.

DOI:10.1093/ee/23.6.1416

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The sweetpotato whitefly,Bemisia tabaci(Gennadius), was trapped throughout the southern desert agricultural region of California during two consecutive growing seasons. Trap data revealed changes in whitefly population densities that provide insight into the epidemiology of lettuce infectious yellows virus (LIYV) in fall melon and lettuce. Whitefly abundance increased rapidly from July to September in cotton. During that period, there were significant correlations between number of cotton fields in a region and number of whiteflies trapped in that region. Beginning in August and September, whitefly densities increased in melon, and the proportion of viruliferous whiteflies increased in cotton and melon. After the defoliation of cotton was initiated in September, whiteflies migrated to melons, which not only served as their host but also as a reservoir for LIYV. In October and November high numbers of viruliferous whiteflies were found in melon and lettuce. As melons were harvested and the fields dried, viruliferous whiteflies migrated to newly emerged lettuce.

DOI:10.1093/ee/23.6.1422

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Survival and growth was measured for five geographically distinct strains ofScirpophaga incertulas(Walker) (the yellow stem borer) reared on three wild species of rice (Oryza nivara, O. barthii, andO. officinalis), three traditional cultivars ofO. sativarice (‘C018’, ‘W1253’, and ‘Rexoro’), and three modern, high yielding rice (O. sativa) cultivars (‘IR56’, ‘IR40’, and ‘IR62’). All yellow stem borer strains showed differential survival and weight gain across the nine rice hosts. There were significant differences in mean survival of the five stem borer strains on all of the rice hosts except two wild rices,O. nivaraandO. officinalis, where all five strains had similar survival. Statistically significant host-by-strain interaction in both survival and weight indicates that differences among populations of theS. incertulaswere host-dependent and were most likely the result of genetic differentiation. There was some indication of similarity between geographically related stem borer strains, but this was not consistent. The importance of these findings to the development of strategies for deploying rice varieties with resistance toS. incertulasis discussed.

DOI:10.1093/ee/23.6.1428

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Six strains ofChilo suppressalis(Walker) were collected from rice,Oryza sativa L., farms in the Philippines. One strain originated from each of four distinct locations, and two strains originated from a fifth location. Survival and growth of these strains were measured simultaneously on the following hosts: three wild species of rice,Oryza nivara(Sharma et Shastry),O. barthii(Chev.), andO. officinalis(Wall ex Watt); three modern high-yieldingO. sativarice cultivars (‘IR40’, ‘IR56’, and ‘IR62’); and three traditional cultivars ofO. sativa(‘CO18’, ‘W1253’, and ‘Rexoro’). Survival and weight gain of all stem borer strains were influenced by the specific rice host, withO. officinalisplants resulting in the lowest larval survival and weight. Survival was also low on ‘Rexoro’, but the surviving larvae did not have low weights. There were significant differences among strains in survival over all rice hosts, but strains did not differ in mean weight of 18-d-old larvae. There was no host-by-strain interaction effect for survival or weight, so there is no evidence that the six insect strains were differentially adapted to specific rice hosts.

DOI:10.1093/ee/23.6.1436

出版商:Oxford University Press    

年代:1994

数据来源: OUP