摘要:

The population dynamics of the Banks grass mite,Oligonychus pratensis(Banks), were described, using a distribution delay model (MitMod). MitMod was linked to a comprehensive plant-microenvironment model (Cupid). Leaf temperatures throughout the canopy are calculated by Cupid and are used by MitMod in the calculation of spider mite developmental rates and fecundity. In turn, spider mite densities alter parameters in Cupid and therefore exert an influence on plant-microenvironmental variables, Simulated crop water stress, manifested by stomatal closure, caused rapid Banks grass mite population growth, primarily through enhanced canopy and soil surface temperatures. Conversely, irrigation was found to suppress Banks grass mite densities primarily through reducing canopy and soil surface temperatures. Results of simulations suggest that, in semi-arid, hot regions, spacial and temporal variation in canopy microenvironments can play an important role in determining where and when spider mite outbreaks will occur.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.329

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Developmental rates of pre-adult stages of Banks grass mite,Oligonychus pratensis(Banks), were determined under constant temperatures (23, 25, 30, 33, 36, and 39°C). Age-specific developmental rate curves were estimated, and these indicated highly temperature-dependent rates for all stages. These curves showed that the fastest development occurred between 25 and 37°C, with maximum developmental rates predicted near 37°C. The developmental time required for egg hatch was nearly 50% of the total immature developmental time. The influence of humidity on pre-adult development was studied by using specially designed humidity chambers. Chambers were calibrated to deliver high, medium, and low vapor pressure deficits at 25, 33, 36, and 39°C. Under these conditions, humidity had little effect on development, except at 39°C, low vapor pressure deficit. In this environment, egg hatch was severely reduced. This study suggests that developmental rates in high-temperature environments may contribute to Banks grass mite outbreaks. Humidity did not seem to influence the developmental rate, but may be an important variable in egg survival at high temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.338

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Departure of Banks grass mite,Oligonychus pratensis(Banks), body temperatures from leaf temperatures were calculated, using an energy budget equation. To obtain the radiation term of the equation, mite transmissivity was determined experimentally. Absorptivity estimates were ca. 0.5 in the photosynthetically active wavelengths and ca. 0.2 in the near-infrared wavelengths. However, when adjusted to account for the influence of corn leaf transmissivity, these values became, respectively, 15 and 8% of incident radiation. Mortality rates at various RHs were determined and then used to derive mite resistance to water loss. LT50values at 30°C ranged from 16.8 h at 0% RH to 67.7 h at 100% RH. Calculated resistance to water loss was 1.8 × 105sec m−1and is thus negligible in energy balance calculations. The effects of radiation are small but not negligible. Resulting calculations indicate that mites feeding on leaves will be<0.7°C above leaf temperature.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.344

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

This review discusses the calculation of paramaters expressing synergism or antagonism of insecticide lethality, using examples of insecticide-resistant insects. Calculations of “percent synergism” (%S), “log-percent synergism” (L%S), and “relative percent synergism” (R%S) express hypotheses generated from biological assay data better than does the more usually cited synergist ratio. The calculations are discussed relative to detecting potentiation between resistance mechanisms,kdrgene effects, and enhanced metabolism. The LD50values with (sLD) or without (LD) synergism in susceptible (S) or resistant (R) strains are used as their logarithms (also LD + 1) in the following relationships describing synergism: L%S = 100[(LD + 1) − (sLD + 1)]/(LD + 1); R%S(R) = 100[LD(R) − sLD(R)]/[LD(R) − sLD(S)]; and R%S(S) = 100[LD(S) − sLD(S)]/[LD(R) / sLD(S)]. The %S is 100 [LD — sLD]/LD, but the LD50values are not used as their logarithms.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.348

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Tomato plants were sprayed to runoff with permethrin (0.112 kg [AI]/ha) or endosulfan (0.560 kg [AI]/ha). At selected days postspray (1 to 21),Heliothis zea(Boddie) eggs were attached to excised leaves of treated and control plants, and exposed to adults ofTrichogramma pretiosum(Riley) within 3.8-liter laboratory containers. Permethrin residues caused significantly lower rates of parasitization by, and higher mortality of,T. pretiosumadults than those of the control for 21 days postspray. Conversely, endosulfan residues significantly reduced egg parasitism and increased adult mortality ofT. pretiosumonly on day 1 postspray, when compared with the control. OfH. zeahost eggs parasitized byT. pretiosumon leaves treated with permethrin or endosulfan, no significant differences were noted in either the female-male ratio of progeny or the mean number of parasitoids produced per host egg.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.355

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Rice varieties with different levels of resistance were evaluated in the green-house and insectary to determine their effect on populations of brown planthoppers,Nilaparvata lugens.In the absence of predators,N. lugensmortality was highest on the resistant (R), intermediate on the moderately resistant (MR), and lowest on the susceptible (S) varieties. When predators were added to the cages,N. lugensmortality increased on all varieties but was highest on the R varieties. When the effect of varietal resistance onN. lugensmortality was eliminated by using Abbott's formula, predation by the spider,Lycosa pseudoannulata,was highest on the R varieties at a ratio of 20N. lugensper spider. In a field study,N. lugenspopulations at 40 days after transplanting were lowest on the R varieties, whereas predator populations were similar on all varieties irrespective of their level ofN. lugensresistance. The prey-predator ratio on the R varieties was, thus, most favorable for effective biocontrol. The field test indicated that moderate levels ofN. lugensresistance were beneficial when combined with activity of natural enemies becauseN. lugenspopulations remained below the economic threshold in the R and MR varieties, whereas the economic threshold was surpassed on the S varieties.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.359

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Bacillus thuringiensisserotype H-14 was successfully used to control larval populations of the dark rice field mosquito,Psorophora columbiae(Dyar and Knab), developing in rice fields that had been reflooded for second crop production in Jefferson Davis Parish, La., in 1982. The test was designed to assess the feasibility of the system for use by a mosquito abatement district and to determine what operational difficulties could be expected when a large work load was imposed on an abatement district work crew. Fifty-two fields totaling 735 ha were treated, and 20 fields totaling 425 ha were evaluated as untreated natural populations. The average reduction of larvae, 3rd instar or older, ranged from 45 to 76%. Operational difficulties during peak work loads resulted in nontreatment or partial treatment of portions of some fields; after exclusion of the data from these pans, so that only properly treated pans were considered, the average reduction in larval counts was 63 to 85%. The results of this test provide an estimate of the potential capability of point-source introduction ofB. thuringiensisH-14 as new methodology for control of the peakPsorophorapopulations associated with second-crop flooding of rice fields in the southern United States.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.366

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Rates of parasitism of the eggs of the codling moth,Cydia pomonella(L.), and intra- and intertree dispersal ofTrichogrammaspp. were studied in an apple orchard after inundative releases of the parasitoid. During the first 2 days after release, dispersal ofTrichogramma minutumfrom tree to tree was affected by prevailing winds. The rate of parasitism was higher in the trees downwind from the release point than in other trees. Vertical and horizontal dispersal within a tree byTrichogramma pretiosumRiley was even in all directions and was not affected by wind direction. The vertical and horizontal distribution ofT. minutumwithin the release trees also was even in all directions; however, the vertical distribution ofT. minutumwithin the trees adjacent to the release site was skewed toward the lower part of the tree canopy. Rain and low temperatures reduced the overall rate of parasitism ofC. pomonellabyT. minutum.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.371

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Individually tagged honey bee foragers were treated topically with a sublethal dose of permethrin at a feeding station, and their behavior was observed inside an observation beehive. Permethrin-treated adult bees exhibited a significantly higher percentage of time in self-cleaning, trembling dance, abdomen tucking, rotating, and cleaning of abdomen while rubbing hind legs together. In contrast, untreated bees exhibited a higher percentage of time in walking, body insertion, and food giving, and made more foraging trips.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.375

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Mated femalePseudoplusia includens(Walker) moths were held in constant temperatures ranging from 17 to 35°C to determine the effect of temperature on oviposition and longevity. Over the temperature range tested, adult female longevity decreased linearly as temperature increased. Fecundity (total number of eggs laid over the entire life span)and average oviposition rate (mean number of eggs laid per day of a lifetime) had curvilinear relationships with temperature. A curvilinear response surface significantly described effects of temperature and female age on daily oviposition rate. Maximum oviposition occurred between 26 and 32°C.

ISSN:1754-5692    

DOI:10.1093/ee/13.2.379

出版商:Oxford University Press    

年代:1984

数据来源: OUP