EVALUATION OF INUNDATIVE RELEASES OF TRICHOGRAMMA EXIGUUM (HYMENOPTERA: TRICHOGRAMMATIDAE) FOR SUPPRESSION OF NANTUCKET PINE TIP MOTH (LEPIDOPTERA: TORTRICIDAE) IN PINE (PINACEAE) PLANTATIONS

Abstract

The Canudian Enromologisr 132: 373 -386 (2000) Inundative releases of Trichogramma exiguum Pinto and Platner were evaluated for suppression of the Nantucket pine tip moth, Rhyacionia frustrana (Cornstock), in first-year loblolly pine, Pinus taedu L., plantations. Three releases. spaced 7 d apart. were made in three 0.4-ha plots during second-generation R. frusrruna egg deposition. Each release included three cohorts of 7: exiguum developmentally separated by 25 degree-days. Mean -t SD field release rate for each cohort was 328 238 it 88 379 females/ha. Mean 7: exiguum emergence under laboratory conditions for released cohorts was 96 f 2%, with 74 f 3% females, of which 1 + 1% of females displayed brachyptery; female longevity was 18 + 3 d. Field emergence averaged 96 -c 4%. Parasitism of R. frusrrana eggs was significantly increased, ranging from 40 f 19 to 73 it 22% in 1: exiguum-treated plots and 17 f 17 to 67 + 21% in control plots. Data from all treated plots combined showed R. frustrunu egg survival (hatching) was significantly reduced by 46%, and larval populations were significantly reduced by 60%. There was no significant difference in the percentage of terminals damaged between ?: exiguum-treated (31 f 16%) and control plots (45 + 10%); however, length of terminal damage was significantly lower in treated plots. The percentage of damage to top whorl shoots was significantly lower in ?: exiguumtreated plots compared with control plots, but there was no significant difference in length of tunneling damage. Damage to remaining shoots was not significantly different between i? exiguum-treated and control plots. Microhabitat significantly influenced both mean maximum and minimum temperature and the number of consecutive hours per day that were at or above 35°C (critical temperature for 7: r.riguum survival). Soil surface with no cover had the greatest number of hours at or above 35°C. followed by soil surface with herbaceous cover, and canopies of small trees (0.4 m tall). Canopy habitats in larger trees (0.9-I .8 m tall) had the most moderate temperature conditions. Parasitoid emergence was significantly reduced in response to increasing number of consecutive hours at or above 35°C. Predation of parasitoids prior to emergence was significantly affected by microhabitat and by the length of time capsules were in the field before 7: exiguum emergence (i.e.. cohort number).

Influence of Cotton Microhabitat on Temperature and Survival ofTrichogramma(Hymenoptera: Trichogrammatidae) within Cardboard Capsules

“…These events have been reported to occur in other cropping systems (Orr et al 1997, but were negligible in the current study. However, based on the high level of ant predation reported by Orr et al (2000) in pine plantations, we suspect that cotton Þelds infested with Þre ants or other small predaceous ants may substantially reduce the number of Trichogramma wasps available for emergence.…”

The Nantucket Pine Tip Moth (Lepidoptera: Tortricidae): A Literature Review with Management Implications

“…Each of three releases were separated by 7 days at rates of 328,238 rt 88,379 femaleslha in capsules hand-placed at 100 release points within each 0.4-ha plot. Egg parasitism rates were significantly increased by 29%, and hatch significantly reduced by 46% (Orr et al 2000). Both the percentage of infested shoots and the length of damage along the shoots were significantly reduced in the release plots.…”

“…Experimental inundative releases of approximately 330,000 female T. exiguum females per ha in eastern North Carolina loblolly pine plantations resulted in significant increases in tip moth egg parasitism (Orr et al 2000). Mean parasitism rates were increased from 42% in the control plots to 54% in the release plots.…”

Trichogramma Wasps Trichogramma spp. (Insecta: Hymenoptera: Trichogrammatidae)

“…Fragile body structures and loss of curated reference wasp specimens (type specimens collected and stored in museums or university collections) has resulted in many misidentifications of species in the family Trichogrammatidae (Pinto et al 1983, Pinto and Stouthamer 1994, Knutson 1998, Sumer, et al 2009). (Knutson 1998, Orr et al 1999, Orr et al 2000, LeBeck and Leppla 2021.…”