Greetings apple growers!

We have some fun results to share. This report provides you a description of how we developed our model and a first year evaluation of your native bee community in your orchard. We are happy to find that we have very conclusive data just in our first year.

Why should you care about your native bee population?

A diverse native bee community not only supports plant diversity but it also has potential to drive pollination in apple.  Our 8 years of historical data show us that native bee abundance influences production of apple by increasing seed set (Figure 1; P = 0.008), while honey bee abundance has NO EFFECT (P= 0.36) on seed set, a similar result found in several other crop systems (Garibaldi et al, 2013).  Many studies have overwhelmingly determined that increased seed set influences uniformity of fruit shape (Figure 2), thus producing a higher proportion of Grade A fruits for market.

Using our historical data on pesticide use, surrounding natural habitat and the relationship between native bee abundance and seed set (figure 1; Park et al, 2015), we developed criteria for determining whether an orchard has enough native bees present during bloom time to provide full and efficient pollination.  Our original 15 minute ‘aerial net’ surveys determined that, if we catch an average of 9 native bees/15 min, the orchard is heavily dependent on native bees and would not be pollinator limited if honey bees were not present.

Validating and incorporating Smartphone data into our prediction model

In order to make connections between our historical data and the smartphone survey App data, we ran parallel 15-min ‘net’ surveys at multiple orchards and correlated native bee counts from ‘aerial net’ collections to the ‘smartphone App’ counts (figure 3).  Using the ‘equation’ of the slope of the trendline of that relationship, we calculated the expected ‘value’ of native bees that we would expect the app to record by inputting the significant value of 9 native bees/ 15 minutes (the significant historical net collection count) for X (see equation in figure 3). The result for the smartphone App count (Y) rounded to the nearest whole number was ‘4’ native bees per 5-minutes.  Therefore you need to count at least 4 native bees/5-min survey (on average) to conclude that you rely heavily on native bees (see lower orange line in figure 5).

IPM techniques: an easy step to take that benefits native bees

The smartphone data show us that growers who consider themselves ‘conventional’ have lower native bee averages than growers who consider themselves ‘IPM’ (See figure 4 below).  This suggests that a ‘conventional’ grower who is concerned about native bees could simply incorporate more IPM practices and potentially see an increase in native bee abundance over 3-5 years, that time range being the minimum time it takes native bees to respond to habitat enhancements.  It is important to note that this response is strong even considering the broad use of the term IPM that growers identify with.

Results for 2016 participants

The graph in Figure 5, below, highlights the 19 orchards that submitted at least 3 surveys this year; each bar is the ‘average’ count of native bees per 5-minutes across all surveys.  Seven orchards (M-S) have four or more native bees per 5-minutes. Using the predictive model that takes into account the year-to-year flux of native bee populations and uses GPS data, we can make recommendations.

For example, even though Orchard M (Figure 5) is surrounded by a large amount of natural habitat, they just barely meet the 4 native bees criteria. Given that they identify their pesticide program as ‘conventional’, we determine that they ride the edge of supporting a robust enough native bee population especially in bad weather years.  As a management recommendation we would suggest that they incorporate more IPM practices.

In the case of Orchard Q, we determine they have a robust native bee community but given that they are a conventional orchard we would recommend they either create more native bee habitat (forage & nesting sites) or tighten up their IPM practices to buffer years with low native bee populations, especially if they did not want to rent honey bees.

Orchards R and S easily meet all criteria and rely heavily on native bees for pollination insurance in the face of honey bee decline.

2016 participants will be receiving individualized feedback with in the next 24 hours.

Looking towards spring 2017 we are excited to add to this growing data set and make new connections to more growers.  Get your neighbor growers to use the app, compare results with them.  We want to share this with all New York apple growers.