Mealworm larvae have the potential to be a future food and feed. One of the difficulties in rearing mealworms efficiently, is their need for both dry and wet feed. Extensive research has been done on dry feed and distributing this feed is easy with the existing technology. However, the wet feed (frequently chopped up vegetables) comes with several challenges. The nature of the wet feed (neither solid nor liquid) complicates automation, making manual feeding still the norm in many farms. This may result in an unequal distribution of the wet feed. The goal of this study was to assess the influence of distance to the wet feed (substituted by agar) on density, growth rate and growth rate variability of mealworm larvae. The entire larval growth stage was assessed from less than 1 mg up to more than 100 mg, as differences in mobility were expected for different sized larvae. The results indicate that the distribution of the agar plays a major role in the distribution and growth of the larvae, with less larvae and a decrease in growth rate observed when the agar was more than 5 to 10 cm away from the larvae. Few mealworms were found more than 15 cm from the agar, and their growth was inhibited resulting in a biomass up to 150 times lower than near the agar. The effects were mainly observed in larvae weighing less than 30 mg, heavier mealworms were mobile enough to crawl to and from the agar. Based on the results, and in order to ensure that all larvae sizes grow equally well and are well distributed in the crate, we strongly advise against distances of 10 cm or more and we recommend the placement of wet feed within 5 cm from the larvae.

Tenebrio molitor larvae live, at least partially, inside their feed. Hence, they do not live on a 2D plane but in a 3D environment. However, previous studies mainly focused on the optimal number of larvae for a given surface area, not the available volume. The goal of this study was to assess the growth and survival of mealworms in a standardized semi-industrial setting with a varying density (cm3) and substrate height. A full factorial experimental design was used with five larval densities (0.5–8 larvae/cm3) and four feed heights (1–8 cm) in 60 × 40 cm crates. Furthermore, the in-crate temperature was monitored and linked to the density. The results of this study clearly indicate that mealworm larvae prefer a low density (cm3). At low larvae densities, the substrate height was less important, with a slight preference for a thicker layer. In contrast, at high(er) larval densities, a lower layer thickness resulted in better growth. The in-crate week temperature varied up to 14 °C (25–39 °C) between treatments and could be predicted well based on the number and size of the larvae. These results may help the industry to improve their production efficiency in terms of larvae density, substrate height and room temperature.

For optimal growth, Tenebrio molitor needs both dry feed and wet feed. Storing dry feed is not a problem, but storing wet feed over a prolonged period is more challenging due to spoilage. It could be stored in a refrigerated room, but this process is energy consuming and therefore increases the price of production. Another option is to ferment the feed, as is done regularly in other branches of agriculture. No energy is needed, and the feed remains stable due to low pH levels. In this study, we assessed the growth of mealworm larvae fed with wheat bran and agar-agar gel. Different treatments received agar-agar gel of a specific pH, varying between 3 and 9 in increments of one pH unit, resulting in seven assessed pH values. The average weight of the larvae was determined every week until maximum weight was achieved. Mealworms at harvest grown at the lowest pH (3.02) were on average 8.1% lighter than their counterparts grown at higher pH levels. However, within ranges that could realistically occur in a mealworm production setting (pH > 3.5), no significant differences were found. In conclusion, fermentation can be used to store mealworm wet feed, without pH having a detrimental effect on mealworm growth.

Insect farming can be an important tool in the realization of a more sustainable future. With a growing insect industry, animal transportation between and within farms is expected to increase. For Tenebrio molitor, using eggs may be convenient as it eliminates the risk of cannibalism, food shortages and has a low risk of asphyxiation. However, there are at least three important variables during regular transport: time, temperature and relative humidity. For each one, as well as their interactions, there is a need to assess the effect on the hatch rate and establish lower and upper boundaries at which a good hatch rate of the eggs is possible. In this study, a total of 20 temperature/RH combinations were assessed (between 5–40 °C and 40–80% RH), with an exposure time ranging between 1 and 6 days for each combination. The results indicated that between 15 and 30 °C no negative effects were observed at any of the assessed RH or exposure times. Higher temperatures did result in a lower hatch rate; no eggs hatched at 40 °C, even after one day. Lower temperatures of 5 and 10 °C can be endured without pronounced adverse effects but only for a limited time (resp. 1 or 2 days). Including relative humidity in the model did improve the overall fit, but the effect is limited (compared to temperature or exposure time) with a slightly better hatch rate in dryer conditions at the extreme temperatures.

Problems with aphids in small grain cereals, either direct by feeding, or indirect by transmission of Barley Yellow Dwarf Virus, are expected to increase due to climate change and a recent ban on neonicotinoid seed treatments by the European Union. Moreover, insecticide resistance against pyrethroid insecticides is reported at multiple locations throughout the world. Therefore, a better understanding of cereal aphid population dynamics and increased attention towards an integrated pest management is needed. In this study, cereal aphids were monitored on 193 maize and small grain cereal fields throughout Flanders, Belgium. The population dynamics and species distribution were observed throughout the year and the effects of spatio-temporal variables were explored. A significant negative effect was found of grassland in a 1,000 m radius and a positive effect of grain maize in a 3,000 m radius around a small grain cereals field on the maximum infestation rate with aphids in autumn within this field. In a 3,000 m and 5,000 m radius, a significant positive effect of grain maize and a significant negative effect of other small grain cereals was found on the maximum infestation rate during the whole growing season within this field. The mean daily average temperature from 118 to 19 d before sowing had a significant positive effect on the maximum infestation rate in autumn. Mean precipitation, wind speed, and humidity from 52 to 26, 46 to 23, and 107 to 13 d before sowing respectively, had a significant negative effect on the maximum infestation rate in autumn.