Comparisons between the squash bug egg parasitoids Ooencyrtus anasae and O. sp. (Hymenoptera: Encyrtidae): development, survival,and sex ratio in relation to temperature

Citation: Tracy, J. L., and J. R. Nechols. 1987. “Comparisons Between the Squash Bug Egg Parasitoids Ooencyrtus Anasae and O. Sp. (Hymenoptera: Encyrtidae): Development, Survival, and Sex Ratio in Relation to Temperature.” Environmental Entomology 16 (6): 1324–29. https://doi.org/10.1093/ee/16.6.1324.Laboratory investigations of the gregarious squash bug egg parasitoids Ooencyrtus anasae and O. n. sp. near anasae (O. sp.) were conducted at 20.8, 23.0, and 26.6°C. In both species, total developmental periods (egg to eclosed adult) were inversely related to temperature. Temperature had no significant influence on survivorship, progeny production, or sex ratio. At each temperature, O. anasae developed and emerged about a day earlier and produced a significantly higher percentage of female progeny (77%) than did O. sp. (60%). Both parasitoids deposited an average of three (2-7) progeny per host. However, O. anasae consistently deposited more female eggs per host than did O. sp. Proportion of females produced per host by O. anasae tended to increase directly with number of hosts parasitized, but no such relationship was observed in O. sp. Total preimaginal survivorship in both parasitoids was about 89%. In O. sp., male progeny that developed without females emerged about a day later at all temperatures and had a lower pharate adult survivorship than did males that developed in hosts with female siblings

Effects of squash leaf trichome exudates and honey on adult feeding, survival, and fecundity of the squash bug (Heteroptera: Coreidae) egg parasitoid Gryon pennsylvanicum (Hymenoptera: Scelionidae)

Citation: Olson, D., & Nechols, J. Effects of Squash Leaf Trichome Exudates and Honey on Adult Feeding, Survival, and Fecundity of the Squash Bug (Heteroptera: Coreidae) Egg Parasitoid Gryon pennsylvanicum (Hymenoptera: Scelionidae). Environmental Entomology, 24(2), 454-458. https://doi.org/10.1093/ee/24.2.454A laboratory experiment was conducted to determine whether leaf exudates could be used as a source of adult nutrition for the squash bug, Auasa tristis (De Geer), egg parasitoid, Gryon pennsylvanicum (Ashmead), and to compare adult and progeny fitness traits when female Wasps were provided with squash leaves, a standard honey diet, a combination of leaves and honey, or water only Results showed that fecundity, progeny developmental rates, and progeny survival did not differ significantly when females were exposed to different dietary sources. Adult longevity was shorter on squash leaves without honey than on leaves with honey or the honey-only diet. However, reproductive fitness was not reduced because oviposition had been completed before death of the adult females. When only water was provided, parasitoid females lived only a few days. Observations showed that squash leaves have two kinds of trichomes (hair-like and peg-like), both of which produce droplets that are fed on by both sexes of G. pennsylvanicum. Nutrient analyses revealed that exudates from the hair-like trichomes are composed predominantly of monosaccharides (mainly glucose and galactose), and that the peg-like trichomes produce glucose and some protein. Thus, these trichomes appear to serve as extrafloral nectaries and may provide an important energy source for augmentatively released G. pennsylvanicum

MF2223

Gerald L. Greene, Phillip E. Sloderbeck and James R. Nechols, Biological fly control for Kansas feedlots, Kansas State University, April 1998

Economic feasibility of methoprene applied as a surface treatment and as an aerosol alone and in combination with two other insecticides

Economic evaluations of integrated pest management strategies are becoming increasingly important as restrictions on conventional insecticides continue to become more stringent and chemical control costs rise. Aerosol treatments with insect growth regulators alone and in combination with conventional contact insecticides may be a feasible alternative to expensive and highly toxic fumigants such as methyl bromide for control of the Indianmeal moth (Plodia interpunctella (Hübner)). Average calculated mortality of Indianmeal moth eggs exposed to surface applied methoprene, aerosol methoprene alone and in combination with esfenvalerate and synergized Pyrethrins is 55.0, 69.0, and 94.6%, respectively. Temperature effects on development time makes frequency and timing of insecticide applications very important as evidenced by simulations of population levels in response to a variety of treatment dates by diet, and become critical in situations where survival of Indianmeal moth is high. Using a measurement of risk that is equal to deviations below a target mortality goal (99%), we are able to optimize cost and frequency of application using simulated mortality data for each of the treatment strategies. Optimal timing of each insecticide treatment depends heavily on the rate of development by diet. This type of analysis helps pest control operators and managers by showing consequences of treatment scenarios in time and cost

Effect of Temperature on Plant Resistance to Arthropod Pests

Temperature has a strong influence on the development, survival, and fecundity of herbivorous arthropods, and it plays a key role in regulating the growth and development of their host plants. In addition, temperature affects the production of plant secondary chemicals as well as structural characteristics used for defense against herbivores. Thus, temperature has potentially important implications for host plant resistance. Because temperature directly impacts arthropod pests, both positively and negatively, distinguishing direct effects from indirect effects mediated through host plants poses a challenge for researchers and practitioners. A more comprehensive understanding of how temperature affects plant resistance specifically, and arthropod pests in general, would lead to better predictions of pest populations, and more effective use of plant resistance as a management tactic. Therefore, the goals of this paper are to 1) review and update knowledge about temperature effects on plant resistance, 2) evaluate alternative experimental approaches for separating direct from plant-mediated indirect effects of temperature on pests, including benefits and limitations of each approach, and 3) offer recommendations for future research

Effects of Intra- and Interpatch Host Density on Egg Parasitism by Three Species of Trichogramma

Host-foraging responses to different intra- and interpatch densities were used to assess three Trichogramma spp. (Hymenoptera: Trichogrammatidae) Trichogramma deion Pinto and Oatman, T. ostriniae Pang and Chen, and T. pretiosum Riley — as potential biological control agents for the Indian meal moth, Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Single naïve females were allowed 6 h to forage in Plexiglas arenas with four different spatial arrangements of host eggs, nine single-egg patches), nine four-egg patches, 36 single-egg patches, and 36 four-egg patches. No significant differences were found among species in the number of patches parasitized. As expected, all three species parasitized the most eggs in the 36 four-egg patch treatment and the least in the nine single-egg patch treatment. T. deion parasitized significantly more eggs than T. pretiosum on the nine four-egg patches. T. ostriniae parasitized significantly more patches when intrapatch density was greater, regardless of interpatch density. In contrast, T. deion only parasitized more patches at the greater intrapatch density when the interpatch density was low. Patch density had no effect on T. pretiosum. The spatial pattern of parasitism was more aggregated for T. deion and T. ostriniae in the 36 four-egg patches treatment compared to the 36 single-egg patches treatment. Therefore, intrapatch density was more important than interpatch density for T. ostriniae, and potentially for T. deion, but not for T. pretiosum. T. deion may be the best candidate for augmentative biological control because it parasitized either slightly or significantly more eggs than the other two species in all four treatments. Furthermore, the pattern of parasitism by T. deion in the 36 four-egg patches treatment was the most aggregated among the three species, suggesting a more thorough searching pattern. In contrast, T. pretiosum had the least aggregated pattern of parasitism and therefore may have used a more random foraging pattern

Integrating adverse effect analysis into environmental risk assessment for exotic generalist arthropod biological control agents: a three-tiered framework

Environmental risk assessments (ERAs) are required before utilizing exotic arthropods for biological control (BC). Present ERAs focus on exposure analysis (host/prey range) and have resulted in approval of many specialist exotic biological control agents (BCA). In comparison to specialists, generalist arthropod BCAs (GABCAs) have been considered inherently risky and less used in classical biological control. To safely consider exotic GABCAs, an ERA must include methods for the analysis of potential effects. A panel of 47 experts from 14 countries discussed, in six online forums over 12 months, scientific criteria for an ERA for exotic GABCAs. Using four case studies, a three-tiered ERA comprising Scoping, Screening and Definitive Assessments was developed. The ERA is primarily based on expert consultation, with decision processes in each tier that lead to the approval of the petition or the subsequent tier. In the Scoping Assessment, likelihood of establishment (for augmentative BC), and potential effect(s) are qualitatively assessed. If risks are identified, the Screening Assessment is conducted, in which 19 categories of effects (adverse and beneficial) are quantified. If a risk exceeds the proposed risk threshold in any of these categories, the analysis moves to the Definitive Assessment to identify potential non-target species in the respective category(ies). When at least one potential non-target species is at significant risk, long-term and indirect ecosystem risks must be quantified with actual data or the petition for release can be dismissed or withdrawn. The proposed ERA should contribute to the development of safe pathways for the use of low risk GABCAs

Photoperiodic responses of the squash bug (Heteroptera: Coreidae): Diapause induction and maintenance

Citation: Nechols, James R. 1988. “Photoperiodic Responses of the Squash Bug (Heteroptera: Coreidae): Diapause Induction and Maintenance.” Environmental Entomology 17 (3): 427–31. https://doi.org/10.1093/ee/17.3.427.The squash bug, Anasa tristis DeGeer, undergoes a reproductive diapause from late summer to spring in northeastern Kansas. In the laboratory, diapause was induced in 100% of adult females reared under photoperiods shorter than 14:10 (L:D) and in a variably lower percentage of the population under all longer photoperiods. The critical photoperiod for diapause induction falls between 14:10 and 14.5:9.5; this range compares closely with prevailing natural daylengths when 50% of the adult population enters diapause in the field. Between October and March, short daylengths maintained, and long daylengths terminated, diapause in field-sampled adults. Under natural daylength at 26°C, the duration of diapause became progressively shorter with advancing sample date. In nature, the photoperiodic maintenance of diapause is completed in most of the population by late May. A prolonged diapause probably serves to prevent premature postdiapause development during the thermally variable spring conditions encountered in Kansas. Some implications of these findings for biological control and pest management programs are discussed

Voltinism, seasonal reproduction, and diapause in the squash bug (Heteroptera: Coreidae) in Kansas

The squash bug (SB),Anasa tristis DeGeer, completes 1.5 generations per yr in northeastern Kansas. Overwintered adults mate and oviposit on cucurbitaceous host plants from early June to mid-August. Most eggs are deposited from June to early July when female survivorship is highest, but some oviposition occurs through mid-August. First-generation adults begin to emerge between the 1st and 3rd wk of July. Oviposition commences 7-10 d after emergence. Females that emerge before late July avoid diapause and produce a second generation. Thereafter the incidence of diapause increases progressively, reaching 100% in first- and second-generation females that emerge in early September. Diapausing females do not mate or reproduce until the following spring. SB males also appear to undergo diapause but, unlike females, they overwinter with mature reproductive organs. The primary expression of male diapause is suppressed reproductive behavior. Reproductive periods of overwintered and first summer-generation adults overlap. The extent of this overlap depends in part on spring temperature conditions that influence field entry by overwintered adults; the oviposition schedule; and development of first-generation progeny. During cool springs, a large proportion of first-generation SB emerge late in the season and enter diapause. In these years, smaller, less-damaging, populations occur

Responses of the squash bug (Hemiptera: Coreidae) and its egg parasitoid, Gryon pennsylvanicum (Hymenoptera: Scelionidae) to three Cucurbita cultivars

Citation: Vogt, A, and James R Nechols. 1993. “Responses of the Squash Bug (Hemiptera: Coreidae) and Its Egg Parasitoid, Cryon Pennsylvanicum (Hymenoptera: Scelionidae) to Three Cucurbita Cultivars.” ENVIRONMENTAL ENTOMOLOGY 22 (1): 8.Laboratory experiments were conducted to quantify effects of resistant and susceptible host plants on the preimaginal and adult biologies of the squash bug, Anasa tristis (De Geer), and its egg parasitoid, Gryon pennsylvanicum (Ashmead). `Early Prolific Straightneck' squash, `Green Striped Cushaw' pumpkin, and `Waltham Butternut' squash served as test plants. Preimaginal development of the squash bug (egg to adult) was similar on all three cultivars (range: 31-35 d). However, survivorship to the adult was significantly lower on `Green Striped Cushaw' and `Waltham Butternut' than on `Early Prolific Straightneck'. Statistical differences in survivorship were not observed in second-generation squash bugs, suggesting that some selection may have occurred. Squash bug reproduction and longevity were similar on all three cultivars. However, the reduced juvenile survivorship on `Green Striped Cushaw' and `Waltham Butternut' resulted in significantly lower r[subscript max] values on these cultivars than on the more susceptible `Early Prolific Straightneck'. The dietary history of adult squash bugs did not significantly affect development, preimaginal survival, or reproduction of G. pennsylvanicum. However, adult longevity of the parasitoid was significantly reduced when its larvae developed in eggs of squash bugs that were reared on the most resistant cultivar (`Waltham Butternut')