Supplementation of Maize- and Cowpea Seed-Based Artificial Diets with Diverse Pollen Sources Affects the Demographic Features of Leucania loreyi (Duponchel, 1827) (Lepidoptera: Noctuidae)

TL;DR

Adding maize pollen to artificial diets improves the growth and reproduction of Leucania loreyi, a major agricultural pest, making it easier to rear for pest management.

Contribution

This study identifies maize pollen as the optimal supplement for rearing Leucania loreyi on artificial diets, enhancing demographic traits and population growth.

Findings

Maize seed-based diets supplemented with maize pollen (D3) resulted in the shortest developmental times and highest reproductive output.

Saffron pollen supplementation (D5 and D12) led to the longest developmental times and lowest fecundity.

Cluster analysis confirmed D3 as the most nutritionally favorable diet for large-scale rearing of L. loreyi.

Abstract

The maize caterpillar, Leucania loreyi (Duponchel, 1827) (Lepidoptera: Noctuidae) has emerged as a major global agricultural pest. Optimization of its rearing would facilitate its application in management strategies. In this study, we supplemented maize- or cowpea seed-based artificial diets with pollen from six different sources—rapeseed, date palm, maize, common hollyhock, saffron, and honey bee—to examine how these dietary combinations affect insect development and population growth. Supplementation of cowpea seed-based diets—and, more notably, maize seed-based diets—with maize pollen yielded the most favorable demographic outcomes for L. loreyi, including shortened developmental durations and enhanced reproductive and life table parameters, confirming maize pollen as the most suitable dietary supplement for rearing this insect. Inclusion of saffron pollen in maize- and cowpea-seed-based diets proved to be a less suitable supplement for promoting L. loreyi population growth, whereas the other pollen types produced moderate effects. Overall, the results indicate that an artificial diet based on maize seed and supplemented with maize pollen is the most suitable for rearing L. loreyi larvae and can be effectively used for large-scale insect production.

Leucania loreyi (Duponchel, 1827) is a major lepidopteran pest that infests a wide range of crops worldwide. Effective mass production of insects for pest management programs depends on the availability of suitable artificial diets. Here, we evaluated 14 artificial diets (D1–D14) formulated from maize or cowpea seeds (19.5 g) plus standard diet components and supplemented with 1 g of pollen from different sources (rapeseed, date palm, maize, common hollyhock, saffron, and honey bee), along with control diets. We assessed their effects on demographic traits of L. loreyi. The maize seed–maize pollen diet (D3) and the cowpea seed–maize pollen diet (D10) produced the shortest developmental times (37.53 and 38.10 days, respectively), whereas the maize seed–saffron pollen (D5) and cowpea seed–saffron pollen (D12) diets resulted in the longest development (45.83 and 45.56 days, respectively). Diet also D3 yielded the shortest adult and total pre-oviposition periods (APOP and TROP), the greatest female longevity, and the highest fecundity and net reproductive rate (R0) (801.69 and 88.69 offspring, respectively). In contrast, diet D12 produced the lowest fecundity and R0 (339.73 and 68.15 offspring, respectively). Consistent with these patterns, D3 generated the highest intrinsic rate of increase (r) and finite rate of increase (λ), while diets D5 and D12 were associated with lower population growth rates. Cluster analysis further identified D3 as the most nutritionally favorable formulation under our experimental conditions, supporting its potential utility for large-scale L. loreyi rearing.

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