Evaluating an attract and kill strategy to manage Tortricid moth pests using plant volatile-based lures and the biopesticide Bacillus thuringiensis va

Progress report for GNE21-256

Project Type: Graduate Student
Funds awarded in 2021: $13,411.00
Projected End Date: 12/31/2022
Grant Recipient: University of Massachusetts
Region: Northeast
State: Massachusetts
Graduate Student:
Faculty Advisor:
Dr. Jaime Pinero
University of Massachusetts
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Project Information

Project Objectives:

Objective 1 (field research): To evaluate the efficacy of an attract-and-kill strategy involving plant volatile-based lures and biopesticides to control major tortricid moths (codling moth, oriental fruit moth and obliquebanded leafroller) under field conditions.

Hypothesis: I hypothesize that by installing lures around the perimeter of the orchard will concentrate pest population within that area, so the rest of the orchard will have low pest pressure.

Objective 2 (laboratory research): To quantify the residual effect of commercially available B.t. product Dipel against the larval stage of three tortricid moths (codling moth, oriental fruit moth, and obliquebanded leafroller).

Hypothesis: I hypothesize that commercially available B.t. product will be effective in killing different instar larvae of three species of tortricid.

Objective 3 (Extension/outreach): To disseminate the findings of my research among commercial apple growers.

Introduction:

The purpose of this study is to investigate the applicability of an attract-and-kill system to manage codling moth, oriental fruit moth, and obliquebanded leafrolllers, which are important pests of apple and related fruit species, in apple orchards. I will also conduct complementary study at laboratory to find out the field efficacy of commercially available B.t. against these pests.

Apple is one of the most valuable commodities in New England with approximately 13,600 acres producing 84,000 metric tons annually (NASS, USDA 2020). In eastern North America, apple orchards are often attacked by several insect pest species in the Lepidopteran family Tortricidae. Tortricid moths are notorious pests of pome (e.g., apple) and stone (e.g., peach) fruit because the immature stages (caterpillar) feed on leaves, shoots, buds, and fruits. Some common fruit pests of economic importance from this family are codling moth (Cydia pomonella) (CM), oriental fruit moth (Grapholita molesta) (OFM), and obliquebanded leafroller (Choristoneura rosaceana) (OBLR) (Lacey et al., 2007).

Two common management options used by growers to control tortricid pests are pesticide-based control and mating disruption. These control measures are suitable mainly for large scale conventional growers (Akotsen-Mensah et al., 2020; Orpet et al., 2020). However, applications of synthetic insecticide is detrimental to the environment and to non-target species and there is a growing evidence of pest resistance to various types of insecticides (Ioriatti and Lucchi, 2016; Wan et al., 2019). While the use of synthetic insecticide is not a suitable option for organic growers, mating disruption and biocontrol represent viable options for organic growers (Ioriatti and Lucchi, 2016).

The mating disruption technique utilizes sex pheromone to confuse male moths so that they will not find females. Mating disruption is generally appropriate for orchards with areas over 5-6 acres (Ioriatti and Lucchi, 2016). For smaller areas mating disruption may not work because mated females may penetrate into the orchard, lay eggs, and the caterpillars cause injury (Burks et al., 2020). For small scale growers this IPM method is logistically inapplicable and expensive. Therefore, we need to find an eco-friendly and cost-effective approach for these notorious pests.

Research

Materials and methods:

Insects: For the laboratory experiments (objective 2), eggs of codling moth, oriental fruit moth and obliquebanded leafroller will be bought from Benzon Research Inc., (Carlisle, PA). The subsequent larva of each species will be reared in artificial diet made for general noctuids. A colony of each species will be established which later will be used to evaluate the efficacy of B.t.

Biopesticide: Bacillus thuringiensis var kurstaki will be used in both field and laboratory experiment as a kill component. The commercially available B.t. product that will be used is DiPel.

Lures and traps: The plant volatile lure Megalure 4K (a blend of four plant volatiles) for codling moth and oriental fruit moth, and LR Combo for obliquebanded leafroller will be purchased from Trécé Inc (Adair, OK). All lures will be placed inside orange-colored delta-shaped traps (Pherocon VI, Trécé Inc.) with liners coated with adhesive.

Study 1: Attract-and-Kill of Multiple Species of Tortricid Moths Using plant volatile-based lures: This study will be conducted in six apple orchards (Cold Spring Orchard in Belchertown, Clarkdale in Deerfield, Agriculture Learning Center in Amherst, Small Ones Farm in Amherst, Ragged Hill Orchard in West Brookfield, and Red Apple Farm in Phillipston) in Massachusetts. Those orchard blocks will not receive any chemical sprays against any Tortricids. For each orchard, 4 perimeter-row trees will be selected. Each tree will be assigned one of the following four treatments: (1) presence of lures (+) and B.t. application (+), (2) presence of lures (+) but no B.t. application (-), (3) no lures (-) and B.t. application (+), and (4) no lures (-) and no B.t. application (-) (Figure 1). Each experimental tree will be at least 50 meters apart from each other.

Figure 1: Experiment Design

The field study will start in the first week of April 2022, with the installation of traps and lures. For this part of the research I won’t be requesting SARE funding. For codling moth and oriental fruit moth, dual species Megalure 4K (Trécé Inc.) lures will be used, and for obliquebanded leafroller LR Combo (Trécé Inc.) lures will be used. Lures will be hanged on the inner side of the orange-colored delta shaped trap (Pherocon VI, Trécé Inc). Each baited tree will receive two Megalure 4K traps and two LR Combo traps. These traps will be hanged at the upper third of the tree canopy. All the lures and sticky liners will be replaced after 4 weeks. Field trapping will continue until the last week of September 2022 (SARE support is requested starting on 1 August 2021). Traps will be monitored once a week and at each trapping session I will collect all moths. All moths will be identified to species and dissected under microscope to know the sex of the moths.

The information collected will be used to setup a biofix for all three species (CM, OFM and OBLR). The first continuous capture of moths will be considered as biofix and based on that Biofix degree days will be calculated to determine the egg hatch for each generation and time our B.t spray. For CM first generation, B.t. will be sprayed at 250 DD (base 50ﹾF), and for second generation, B.t. will be sprayed at 1400 to 1600DD using same biofix. For first generation OFM, B.t. will be sprayed from petal fall to 380 DD (base 45ﹾF) and for second generation at 1100 DD after biofix. Lastly, for OBLR, B.t will be sprayed at 360 DD (base 43ﹾF). Since they have extended flight and egg laying period, 3 sprays at 10 days apart will be done(“NE tree fruit management guide,” 2017).

Apple trees will be sprayed with B.t. using a motorized backpack sprayer at the rate of 0.65 liter per tree (DiPel standard dose for pome fruits: 1.14 grams of DiPel per gallon) targeting both top and bottom part of leaves. Four adjacent trees will be sprayed to prevent the spillover effect of the moths. Injury data will be collected mid-season (July, 2022) and at harvest (September, 2022). For each block, I will visually inspect 100 fruits from each treatment (4) trees, 100 fruits from 4 trees surrounding each treatment trees, and 100 fruits from 4 interior trees, for a total of 900 fruits from each block. Across all 6 orchards and blocks, 5400 fruits were visually inspected. All fruits that were suspected of having tortricid injury will be brought to the laboratory and dissected for the signs of tunneling and/or the presence of larvae.

Study 2: Residual effect of commercially available B.t. product Dipel against the larval stage of three tortricid moths (codling moth, oriental fruit moth, and obliquebanded leafroller). For this laboratory experiment, one apple tree in one of the orchards will be sprayed with B.t. at the recommended dose. The sprayed leaves will be collected on the same day (= fresh), day 4, and day 7 after the sprays. Colonies of three species of tortricids (codling moth, oriental fruit moth and obliquebanded leafroller) will be established in the laboratory at the University of Massachusetts (UMass), Amherst starting in May 2021. Larvae will be reared on an artificial diet. Only the second generation or subsequent generation will be used in the study. For the feeding bioassay study, ten either, 2nd or 4th instar larvae of one species will be placed inside one petri dish that has one sprayed apple leaf either from same day, day 4 or day 7, and one unsprayed leaf (control). This way we will be testing two larval instars of each moth species against 4 types of leaves resulting in 8 treatments for each moth species. Each treatment will be replicated 6 times. The mortality of larva will be observed and recorded at 12 hours, 24 hours, 48 hours and 72 hours.

 

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

The outreach will occur during the months of July 2021 to March 2022. Extension activities include one field day at the UMass Cold Spring Orchard, one orchard walk (grower cooperator land), publication of 2 articles in the UMass Healthy Fruit Newsletter, extension documents, one fact sheet, and one presentation at a national conference.

During field trial, I will show growers trap positioning, installation, and B.t application process, and any preliminary findings (lab as well as field).

As extension materials, the lab trial will be documented from the beginning and its efficacy will be cross examined with the result from field trails. The replication of lab result will be narrowly scrutinized with the field trials, and all steps will be video documented. For wider audience, the video will also be posted in the UMass Extension Fruit Team youtube page. Along with the video, a record of data collection and statistical interpretation will be done. It will be utilized to prepare a simple instructional factsheet for the growers, student researchers and education instructors. This video and data can be an effective tool to convey our findings and lobby for this practice among small scale as well as organic growers, researchers, and extension workers.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.